Javaweb文件上传和下载、UUID、注解案例
程序员文章站
2022-07-10 18:50:12
文章目录文件的上传和下载文件上传UUID文件下载注解代替jdbc.properties文件的上传和下载文件上传在JavaWeb阶段的文件上传我们需要借助Apache下的commons-io和commons-fileupload两个jar包。上传文件的前台页面：<%@ page contentType="text/html;charset=UTF-8" language="java" %> 上传文件&l...</div>
<div class="content">
<p>
<br></p>
<div class="toc">
<h3>
文章目录
</h3>
<ul>
<li>
<a href="#_1">文件的上传和下载</a>
</li>
<ul>
<li>
<a href="#_3">文件上传</a>
</li>
<li>
<a href="#UUID_116">UUID</a>
</li>
<li>
<a href="#_137">文件下载</a>
</li>
</ul>
<li>
<a href="#jdbcproperties_278">注解代替jdbc.properties</a>
</li>
</ul>
</div>
<p>
<br></p>
<h1>
<a id="_1" target="_blank" rel="nofollow" href="/default/index/url?u=aHR0cHM6Ly93d3cuMTBxaWFud2FuLmNvbQ=="></a>文件的上传和下载
</h1>
<h2>
<a id="_3" target="_blank" rel="nofollow" href="/default/index/url?u=aHR0cHM6Ly93d3cuMTBxaWFud2FuLmNvbQ=="></a>文件上传
</h2>
<p>
在JavaWeb阶段的文件上传我们需要借助Apache下的<code>commons-io</code>和<code>commons-fileupload</code>两个jar包。
</p>
<p>
上传文件的前台页面：
</p>
<pre><code class="prism language-jsp"><%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>上传文件</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/upload" method="post" enctype="multipart/form-data">
<%--action使用EL表达式获取项目上下文路径，method使用post请求--%>
用户名：<input type="text" name="username">
<br>
<input type="file" name="file">
<br>
<input type="submit" value="提交">
</form>
</body>
</html> </code></pre>
<p>
使用Wireshark抓取请求/upload时的POST请求体数据。
</p>
<p>
<img onerror="this.src='/statics/superweb999/images/image_error.jpg'"src="/default/index/img?u=aHR0cDovL2ltYWdlczUuMTBxaWFud2FuLmNvbS8xMHFpYW53YW4vMjAyMDA4MjgvYl8wXzIwMjAwODI4MTQxNTI1NTY5NC5wbmc=" alt="Javaweb文件上传和下载、UUID、注解案例" title="Javaweb文件上传和下载、UUID、注解案例"></p>
<p>
后台在收到前台提交的POST请求后：
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>demo<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>commons<span class="token punctuation">.</span>fileupload<span class="token punctuation">.</span>FileItem<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>commons<span class="token punctuation">.</span>fileupload<span class="token punctuation">.</span>FileUploadException<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>commons<span class="token punctuation">.</span>fileupload<span class="token punctuation">.</span>disk<span class="token punctuation">.</span>DiskFileItemFactory<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>commons<span class="token punctuation">.</span>fileupload<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>ServletFileUpload<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>ServletException<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>WebServlet<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServlet<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServletRequest<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServletResponse<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>File<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>IOException<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>List<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>UUID<span class="token punctuation">;</span> <span class="token comment">/**
* @author lwj
* @date 2020/8/25 9:16
*/</span> <span class="token annotation punctuation">@WebServlet</span><span class="token punctuation">(</span>name <span class="token operator">=</span> <span class="token string">"UploadServlet"</span><span class="token punctuation">,</span> value <span class="token operator">=</span> <span class="token string">"/upload"</span><span class="token punctuation">)</span> <span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">UploadServlet</span> <span class="token keyword">extends</span> <span class="token class-name">HttpServlet</span> <span class="token punctuation">{</span> <span class="token annotation punctuation">@Override</span> <span class="token keyword">protected</span> <span class="token keyword">void</span> <span class="token function">doPost</span><span class="token punctuation">(</span>HttpServletRequest request<span class="token punctuation">,</span> HttpServletResponse response<span class="token punctuation">)</span> <span class="token keyword">throws</span> ServletException<span class="token punctuation">,</span> IOException <span class="token punctuation">{</span> <span class="token keyword">try</span> <span class="token punctuation">{</span> request<span class="token punctuation">.</span><span class="token function">setCharacterEncoding</span><span class="token punctuation">(</span><span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String realPath <span class="token operator">=</span> <span class="token function">getServletContext</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">getRealPath</span><span class="token punctuation">(</span><span class="token string">"/upload"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> File uploadDir <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">File</span><span class="token punctuation">(</span>realPath<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>uploadDir<span class="token punctuation">.</span><span class="token function">exists</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> uploadDir<span class="token punctuation">.</span><span class="token function">mkdir</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment">//我们使用Apache提供的commons-io和commons-fileupload两个jar包</span> DiskFileItemFactory factory <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">DiskFileItemFactory</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> ServletFileUpload servletFileUpload <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ServletFileUpload</span><span class="token punctuation">(</span>factory<span class="token punctuation">)</span><span class="token punctuation">;</span> List<span class="token generics function"><span class="token punctuation"><</span>FileItem<span class="token punctuation">></span></span> fileItems <span class="token operator">=</span> servletFileUpload<span class="token punctuation">.</span><span class="token function">parseRequest</span><span class="token punctuation">(</span>request<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">for</span> <span class="token punctuation">(</span>FileItem item <span class="token operator">:</span> fileItems<span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>item<span class="token punctuation">.</span><span class="token function">isFormField</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">//判断是否是普通表单项</span> String fieldName <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getFieldName</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>fieldName<span class="token punctuation">)</span><span class="token punctuation">;</span> String fieldValue <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getString</span><span class="token punctuation">(</span><span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>fieldValue<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span> <span class="token comment">//这个分支是文件表单项</span> String fieldName <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getFieldName</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>fieldName<span class="token punctuation">)</span><span class="token punctuation">;</span> String name <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getName</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//文件名</span> <span class="token keyword">long</span> size <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getSize</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"上传的"</span> <span class="token operator">+</span> name <span class="token operator">+</span> <span class="token string">"文件大小为："</span> <span class="token operator">+</span> size <span class="token operator">+</span> <span class="token string">"B"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String contentType <span class="token operator">=</span> item<span class="token punctuation">.</span><span class="token function">getContentType</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"文件类型为："</span> <span class="token operator">+</span> contentType<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//将文件保存到服务器</span> File file <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">File</span><span class="token punctuation">(</span>uploadDir<span class="token punctuation">,</span> UUID<span class="token punctuation">.</span><span class="token function">randomUUID</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">"-"</span> <span class="token operator">+</span> name<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//当文件名相同时容易造成覆盖，生成唯一的方法</span> <span class="token comment">//1、System.currentTimeMillis()</span> <span class="token comment">//2、UUID</span> item<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span>file<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">Exception</span> e<span class="token punctuation">)</span> <span class="token punctuation">{</span> e<span class="token punctuation">.</span><span class="token function">printStackTrace</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token annotation punctuation">@Override</span> <span class="token keyword">protected</span> <span class="token keyword">void</span> <span class="token function">doGet</span><span class="token punctuation">(</span>HttpServletRequest request<span class="token punctuation">,</span> HttpServletResponse response<span class="token punctuation">)</span> <span class="token keyword">throws</span> ServletException<span class="token punctuation">,</span> IOException <span class="token punctuation">{</span> <span class="token function">doPost</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> response<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>
<p>
<img onerror="this.src='/statics/superweb999/images/image_error.jpg'"src="/default/index/img?u=aHR0cDovL2ltYWdlczUuMTBxaWFud2FuLmNvbS8xMHFpYW53YW4vMjAyMDA4MjgvYl8wXzIwMjAwODI4MTQxNTI1OTg2NS5qcGc=" alt="Javaweb文件上传和下载、UUID、注解案例" title="Javaweb文件上传和下载、UUID、注解案例"></p>
<h2>
<a id="UUID_116" target="_blank" rel="nofollow" href="/default/index/url?u=aHR0cHM6Ly93d3cuMTBxaWFud2FuLmNvbQ=="></a>UUID
</h2>
<blockquote>
<p>
System.currentTimeMillis()
</p>
</blockquote>
<p>
long类型的时间戳
</p>
<blockquote>
<p>
UUID
</p>
</blockquote>
<pre><code class="prism language-java">String string <span class="token operator">=</span> UUID<span class="token punctuation">.</span><span class="token function">randomUUID</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>string<span class="token punctuation">)</span><span class="token punctuation">;</span> </code></pre>
<p>
bb384e27-22a5-4191-b1ec-9b23789064bc
</p>
<p>
be871b39-0a1f-4bdc-8475-23ce01a9d8a7
</p>
<p>
3575b2a7-4a56-449c-9029-8f65ac17534c
</p>
<h2>
<a id="_137" target="_blank" rel="nofollow" href="/default/index/url?u=aHR0cHM6Ly93d3cuMTBxaWFud2FuLmNvbQ=="></a>文件下载
</h2>
<p>
前台页面
</p>
<pre><code class="prism language-jsp"><%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>文件下载</title>
</head>
<body>
<a href="${pageContext.request.contextPath}/download?filename=3f05.jpeg">图片下载</a>
<hr>
<a href="${pageContext.request.contextPath}/download?filename=乌兹.jpeg">乌兹图片下载</a>
</body>
</html> </code></pre>
<p>
后台处理逻辑
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>demo<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>commons<span class="token punctuation">.</span>io<span class="token punctuation">.</span>IOUtils<span class="token punctuation">;</span> <span class="token keyword">import</span> sun<span class="token punctuation">.</span>misc<span class="token punctuation">.</span>BASE64Encoder<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>ServletException<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>ServletOutputStream<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>WebServlet<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServlet<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServletRequest<span class="token punctuation">;</span> <span class="token keyword">import</span> javax<span class="token punctuation">.</span>servlet<span class="token punctuation">.</span>http<span class="token punctuation">.</span>HttpServletResponse<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>File<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>FileInputStream<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>IOException<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>net<span class="token punctuation">.</span>URLEncoder<span class="token punctuation">;</span> <span class="token comment">/**
* @author lwj
* @date 2020/8/25 10:33
*/</span> <span class="token annotation punctuation">@WebServlet</span><span class="token punctuation">(</span>name <span class="token operator">=</span> <span class="token string">"DownServlet"</span><span class="token punctuation">,</span> value <span class="token operator">=</span> <span class="token string">"/download"</span><span class="token punctuation">)</span> <span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">DownServlet</span> <span class="token keyword">extends</span> <span class="token class-name">HttpServlet</span> <span class="token punctuation">{</span> <span class="token annotation punctuation">@Override</span> <span class="token keyword">protected</span> <span class="token keyword">void</span> <span class="token function">doPost</span><span class="token punctuation">(</span>HttpServletRequest request<span class="token punctuation">,</span> HttpServletResponse response<span class="token punctuation">)</span> <span class="token keyword">throws</span> ServletException<span class="token punctuation">,</span> IOException <span class="token punctuation">{</span> String realPath <span class="token operator">=</span> <span class="token function">getServletContext</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">getRealPath</span><span class="token punctuation">(</span><span class="token string">"/img"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String filename <span class="token operator">=</span> request<span class="token punctuation">.</span><span class="token function">getParameter</span><span class="token punctuation">(</span><span class="token string">"filename"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>filename<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//3f05.jpeg</span> <span class="token comment">//乌兹.jpeg</span> FileInputStream fis <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">FileInputStream</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">File</span><span class="token punctuation">(</span>realPath<span class="token punctuation">,</span> filename<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> ServletOutputStream outputStream <span class="token operator">=</span> response<span class="token punctuation">.</span><span class="token function">getOutputStream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//如果图片中包含中文，那么将图片名称传递给浏览器之前需要编码图片名称</span> String agent <span class="token operator">=</span> request<span class="token punctuation">.</span><span class="token function">getHeader</span><span class="token punctuation">(</span><span class="token string">"user-agent"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>agent<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"MSIE"</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// IE浏览器</span> filename <span class="token operator">=</span> URLEncoder<span class="token punctuation">.</span><span class="token function">encode</span><span class="token punctuation">(</span>filename<span class="token punctuation">,</span> <span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> filename <span class="token operator">=</span> filename<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token string">"+"</span><span class="token punctuation">,</span> <span class="token string">" "</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>agent<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"Firefox"</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// 火狐浏览器</span> BASE64Encoder base64Encoder <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BASE64Encoder</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> filename <span class="token operator">=</span> <span class="token string">"=?utf-8?B?"</span> <span class="token operator">+</span> base64Encoder<span class="token punctuation">.</span><span class="token function">encode</span><span class="token punctuation">(</span>filename<span class="token punctuation">.</span><span class="token function">getBytes</span><span class="token punctuation">(</span><span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">"?="</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>agent<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"Chrome"</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// google浏览器</span> filename <span class="token operator">=</span> URLEncoder<span class="token punctuation">.</span><span class="token function">encode</span><span class="token punctuation">(</span>filename<span class="token punctuation">,</span> <span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span> <span class="token comment">// 其它浏览器</span> filename <span class="token operator">=</span> URLEncoder<span class="token punctuation">.</span><span class="token function">encode</span><span class="token punctuation">(</span>filename<span class="token punctuation">,</span> <span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> response<span class="token punctuation">.</span><span class="token function">setHeader</span><span class="token punctuation">(</span><span class="token string">"content-disposition"</span><span class="token punctuation">,</span> <span class="token string">"attachment;filename="</span> <span class="token operator">+</span> filename<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//设置文件的类型</span> response<span class="token punctuation">.</span><span class="token function">setHeader</span><span class="token punctuation">(</span><span class="token string">"content-type"</span><span class="token punctuation">,</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">getServletContext</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">.</span><span class="token function">getMimeType</span><span class="token punctuation">(</span>filename<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//设置响应头，告诉浏览器不要默认打开，而是弹出一个下载框</span> IOUtils<span class="token punctuation">.</span><span class="token function">copy</span><span class="token punctuation">(</span>fis<span class="token punctuation">,</span> outputStream<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//通过commons-io包下的工具类进行流的拷贝</span> <span class="token punctuation">}</span> <span class="token annotation punctuation">@Override</span> <span class="token keyword">protected</span> <span class="token keyword">void</span> <span class="token function">doGet</span><span class="token punctuation">(</span>HttpServletRequest request<span class="token punctuation">,</span> HttpServletResponse response<span class="token punctuation">)</span> <span class="token keyword">throws</span> ServletException<span class="token punctuation">,</span> IOException <span class="token punctuation">{</span> <span class="token function">doPost</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> response<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>
<p>
<img onerror="this.src='/statics/superweb999/images/image_error.jpg'"src="/default/index/img?u=aHR0cDovL2ltYWdlczUuMTBxaWFud2FuLmNvbS8xMHFpYW53YW4vMjAyMDA4MjgvYl8wXzIwMjAwODI4MTQxNTI2OTcwOS5qcGc=" alt="Javaweb文件上传和下载、UUID、注解案例" title="Javaweb文件上传和下载、UUID、注解案例"></p>
<p>
在请求后台的图片时，浏览器默认会将请求URL中的中文进行URL编码。
</p>
<p>
URL编码
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>demo<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>io<span class="token punctuation">.</span>UnsupportedEncodingException<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>net<span class="token punctuation">.</span>URLEncoder<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>nio<span class="token punctuation">.</span>charset<span class="token punctuation">.</span>StandardCharsets<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>Arrays<span class="token punctuation">;</span> <span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">MyTest4</span> <span class="token punctuation">{</span> <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span>String<span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token keyword">throws</span> UnsupportedEncodingException <span class="token punctuation">{</span> String str <span class="token operator">=</span> <span class="token string">"乌兹"</span><span class="token punctuation">;</span> <span class="token keyword">byte</span><span class="token punctuation">[</span><span class="token punctuation">]</span> bytes <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">getBytes</span><span class="token punctuation">(</span>StandardCharsets<span class="token punctuation">.</span>UTF_8<span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>bytes<span class="token punctuation">.</span>length<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//6 utf-8编码，每个中文3个字节</span> String<span class="token punctuation">[</span><span class="token punctuation">]</span> strs <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">[</span>bytes<span class="token punctuation">.</span>length<span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">int</span> index <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">byte</span> b <span class="token operator">:</span> bytes<span class="token punctuation">)</span> <span class="token punctuation">{</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>Integer<span class="token punctuation">.</span><span class="token function">toBinaryString</span><span class="token punctuation">(</span>b <span class="token operator">&</span> <span class="token number">0xff</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//11100100</span> <span class="token comment">//10111001</span> <span class="token comment">//10001100</span> <span class="token comment">//11100101</span> <span class="token comment">//10000101</span> <span class="token comment">//10111001</span> <span class="token comment">//高24位置0，低8位保持不变</span> strs<span class="token punctuation">[</span>index<span class="token operator">++</span><span class="token punctuation">]</span> <span class="token operator">=</span> Integer<span class="token punctuation">.</span><span class="token function">toHexString</span><span class="token punctuation">(</span>b <span class="token operator">&</span> <span class="token number">0xff</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>Arrays<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span>strs<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//[e4, b9, 8c, e5, 85, b9]</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>URLEncoder<span class="token punctuation">.</span><span class="token function">encode</span><span class="token punctuation">(</span><span class="token string">"乌兹"</span><span class="token punctuation">,</span> <span class="token string">"utf-8"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//%E4%B9%8C%E5%85%B9</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>Integer<span class="token punctuation">.</span><span class="token function">toBinaryString</span><span class="token punctuation">(</span><span class="token number">0xe4</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//11100100</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>Integer<span class="token punctuation">.</span><span class="token function">toBinaryString</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">127</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//11111111111111111111111110000001</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>
<h1>
<a id="jdbcproperties_278" target="_blank" rel="nofollow" href="/default/index/url?u=aHR0cHM6Ly93d3cuMTBxaWFud2FuLmNvbQ=="></a>注解代替jdbc.properties
</h1>
<p>
在前面学习JDBC获取连接时都是读取.properties配置文件来获取value。
</p>
<p>
现在使用注解来实现。
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>demo<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>lang<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>ElementType<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>lang<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>Retention<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>lang<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>RetentionPolicy<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>lang<span class="token punctuation">.</span>annotation<span class="token punctuation">.</span>Target<span class="token punctuation">;</span> <span class="token comment">/**
* @author lwj
* @date 2020/8/25 13:56
*/</span> <span class="token annotation punctuation">@Retention</span><span class="token punctuation">(</span>value <span class="token operator">=</span> RetentionPolicy<span class="token punctuation">.</span>RUNTIME<span class="token punctuation">)</span> <span class="token annotation punctuation">@Target</span><span class="token punctuation">(</span>value <span class="token operator">=</span> <span class="token punctuation">{</span>ElementType<span class="token punctuation">.</span>METHOD<span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token keyword">public</span> @<span class="token keyword">interface</span> <span class="token class-name">JDBCAnno</span> <span class="token punctuation">{</span> String <span class="token function">driverClass</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">default</span> <span class="token string">"com.mysql.jdbc.Driver"</span><span class="token punctuation">;</span> String <span class="token function">url</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String <span class="token function">username</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">default</span> <span class="token string">"root"</span><span class="token punctuation">;</span> String <span class="token function">password</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">default</span> <span class="token string">"xxxxxx"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> </code></pre>
<p>
JDBCUtil.java
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>util<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>demo<span class="token punctuation">.</span>JDBCAnno<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>lang<span class="token punctuation">.</span>reflect<span class="token punctuation">.</span>Method<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>sql<span class="token punctuation">.</span>Connection<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>sql<span class="token punctuation">.</span>DriverManager<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>sql<span class="token punctuation">.</span>SQLException<span class="token punctuation">;</span> <span class="token comment">/**
* @author lwj
* @date 2020/8/25 13:55
*/</span> <span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">JDBCUtil</span> <span class="token punctuation">{</span> <span class="token keyword">private</span> <span class="token function">JDBCUtil</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span> <span class="token annotation punctuation">@JDBCAnno</span><span class="token punctuation">(</span>url <span class="token operator">=</span> <span class="token string">"jdbc:mysql:///javaweb?useSSL=false"</span><span class="token punctuation">)</span> <span class="token keyword">public</span> <span class="token keyword">static</span> Connection <span class="token function">getConnection</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">throws</span> NoSuchMethodException<span class="token punctuation">,</span> ClassNotFoundException<span class="token punctuation">,</span> SQLException <span class="token punctuation">{</span> <span class="token comment">//使用反射获取注解的值</span> Method method <span class="token operator">=</span> JDBCUtil<span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">.</span><span class="token function">getDeclaredMethod</span><span class="token punctuation">(</span><span class="token string">"getConnection"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//获取方法对象</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>method<span class="token punctuation">.</span><span class="token function">isAnnotationPresent</span><span class="token punctuation">(</span>JDBCAnno<span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> JDBCAnno annotation <span class="token operator">=</span> method<span class="token punctuation">.</span><span class="token function">getDeclaredAnnotation</span><span class="token punctuation">(</span>JDBCAnno<span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//获取方法上的注解</span> String driverClass <span class="token operator">=</span> annotation<span class="token punctuation">.</span><span class="token function">driverClass</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String url <span class="token operator">=</span> annotation<span class="token punctuation">.</span><span class="token function">url</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String username <span class="token operator">=</span> annotation<span class="token punctuation">.</span><span class="token function">username</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> String password <span class="token operator">=</span> annotation<span class="token punctuation">.</span><span class="token function">password</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//获取连接</span> Class<span class="token punctuation">.</span><span class="token function">forName</span><span class="token punctuation">(</span>driverClass<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">return</span> DriverManager<span class="token punctuation">.</span><span class="token function">getConnection</span><span class="token punctuation">(</span>url<span class="token punctuation">,</span> username<span class="token punctuation">,</span> password<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token keyword">return</span> null<span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>
<p>
测试类
</p>
<pre><code class="prism language-java"><span class="token keyword">package</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>test<span class="token punctuation">;</span> <span class="token keyword">import</span> org<span class="token punctuation">.</span>westos<span class="token punctuation">.</span>util<span class="token punctuation">.</span>JDBCUtil<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>sql<span class="token punctuation">.</span>Connection<span class="token punctuation">;</span> <span class="token keyword">import</span> java<span class="token punctuation">.</span>sql<span class="token punctuation">.</span>SQLException<span class="token punctuation">;</span> <span class="token comment">/**
* @author lwj
* @date 2020/8/25 14:07
*/</span> <span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">MyTest</span> <span class="token punctuation">{</span> <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span>String<span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">try</span> <span class="token punctuation">{</span> Connection connection <span class="token operator">=</span> JDBCUtil<span class="token punctuation">.</span><span class="token function">getConnection</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>connection<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//com.mysql.jdbc.JDBC4Connection@4b9af9a9</span> <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">NoSuchMethodException</span> <span class="token operator">|</span> ClassNotFoundException <span class="token operator">|</span> SQLException e<span class="token punctuation">)</span> <span class="token punctuation">{</span> e<span class="token punctuation">.</span><span class="token function">printStackTrace</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>
<p>
本文地址：https://blog.csdn.net/ShawnYue_08/article/details/108236131
</p> </div>
<div class="tags">
相关标签： <a href="/t/Java/" target="_blank">
Java </a>
<a href="/t/Web/" target="_blank">
Web </a>
</div>
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SpringMVC文件的上传 </a>
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