验证码及文件上传
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2022-05-28 23:39:52
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servlet 验证码及文件上传案例
下面的代码块是生成验证码的工具类
package com.example.homework0525; /**
* @author 杨忠荣
* @create 2021-05-25-14:31
*/
import javax.imageio.ImageIO;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/checkServlet")
public class CheckServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//服务器通知浏览器不要缓存
response.setHeader("pragma","no-cache");
response.setHeader("cache-control","no-cache");
response.setHeader("expires","0");
//在内存中创建一个长80，宽30的图片，默认黑色背景
//参数一：长
//参数二：宽
//参数三：颜色
int width = 80;
int height = 30;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取画笔
Graphics g = image.getGraphics();
//设置画笔颜色为灰色7
g.setColor(Color.GRAY);
//填充图片
g.fillRect(0,0, width,height);
//产生4个随机验证码，12Ey
String checkCode = getCheckCode();
//将验证码放入HttpSession中
request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);
//设置画笔颜色为黄色
g.setColor(Color.YELLOW);
//设置字体的小大
g.setFont(new Font("黑体", Font.BOLD,24));
//向图片上写入验证码
g.drawString(checkCode,15,25);
//将内存中的图片输出到浏览器
//参数一：图片对象
//参数二：图片的格式，如PNG,JPG,GIF
//参数三：图片输出到哪里去
ImageIO.write(image,"PNG",response.getOutputStream());
}
private String getCheckCode() {
String base = "0123456789ABCDEFGHIJKLMNOPQRSTUVWYZabcdefghijklmnopqrstuvwxyz";
int size = base.length();
Random r = new Random();
StringBuffer sb = new StringBuffer();
for(int i=1;i<=4;i++){
//产生0到size-1的随机值
int index = r.nextInt(size);
//在base字符串中获取下标为index的字符
char c = base.charAt(index);
//将c放入到StringBuffer中去
sb.append(c);
}
return sb.toString();
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
前端页面调用servlet实现验证码
<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
<title>注册</title>
</head>
<script>
window.onload=function (){
let elementById = document.getElementById("imgs");
elementById.onclick=function (){
elementById.src="${pageContext.request.contextPath}/checkServlet?time="+new Date().getTime();
//加一个时间戳来改变src与上一次访问的servlet来区别
//post提交方式
}
}
</script>
//enctype="multipart/form-data"enctype="multipart/form-data"文件上传是以二进制转换进行传输，所有需要声明，
//后面userRegServlet用request.getParameter("");是获取不到文本框中的值的
// ${pageContext.request.contextPath} 获取项目的一个根目录
<body>
<form action="${pageContext.request.contextPath}/userRegServlet" method="post" enctype="multipart/form-data">
<table>
<tr>
<td>账号</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="pwd"></td>
</tr>
<tr>
<td>验证码</td>
<td><input type="text" name="yzm"></td>
<td><img src="checkServlet" id="imgs"></td><%-- 只要用户访问servlet就可以生成验证码--%>
</tr>
<tr>
<td>照片</td>
<td><input type="file" name="file"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="注册"></td>
</tr>
</table>
</form>
${msg}
</body>
</html>
文件上传
导jar包
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-xzyezfyl-1623238909112)(C:\Users\Administrator\Pictures\servlet\5.jpg)]
package com.example.homework0525; /**
* @author 杨忠荣
* @create 2021-05-25-18:27
*/
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.UUID;
@WebServlet("/userRegServlet")
public class UserRegServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//request.setCharacterEncoding("utf8");
//获取生成验证码
String checkcode_server = request.getSession().getAttribute("CHECKCODE_SERVER").toString();
//获取完成之后马上销毁验证码，以免对后面用户传递过来的验证码进行干扰
request.getSession().removeAttribute("CHECKCODE_SERVER");
//调用文件上传的jar包里面封装好的对象
DiskFileItemFactory disfilef=new DiskFileItemFactory();
//设置临时目录的值
disfilef.setRepository(new File("d:/"));
//设置临时文件的大小 4kb
disfilef.setSizeThreshold(4096);
//创建一个文件上传的对象
//StringBuffer stringBuffer=new StringBuffer();
ServletFileUpload servletFileUpload = new ServletFileUpload(disfilef);
try {
List<FileItem> fileItems = servletFileUpload.parseRequest(request);
for(int i=0;i<fileItems.size();i++){
if(fileItems.get(i).isFormField()){
//获取文本框用户名
// byte[] usernames = fileItems.get(0).getString().getBytes(StandardCharsets.UTF_8);
// for(int j=0;j<usernames.length;j++){
// stringBuffer.append(usernames[j]);
//
// }
String username = fileItems.get(0).getString();
//String username = stringBuffer.toString();
//获取文本框密码
String pwd=fileItems.get(1).getString();
//获取文本框验证码
String yzm = fileItems.get(2).getString();
// System.out.println(username);
// System.out.println(pwd);
// System.out.println(yzm);
if(!yzm.equalsIgnoreCase(checkcode_server)){
request.getSession().setAttribute("msg","验证码错误");
response.sendRedirect("index.jsp");
return;
}
if(username.equals("admin")&&pwd.equals("123456")){
//用户名 密码 验证码都正确 就上传文件
FileItem fileItem = fileItems.get(3);
request.getSession().setAttribute("username",username);
request.getSession().setAttribute("yzm",yzm);
String name = fileItem.getName();//获取文件的后缀
//获取服务器的根目录
String realPath = request.getServletContext().getRealPath("/");
//随机生成时间
// SimpleDateFormat sim=new SimpleDateFormat("yyyyMMddHHmmss");
// String format = sim.format(new Date());
String format= UUID.randomUUID().toString();
//获取文件的后缀名
String substring = name.substring(name.lastIndexOf("."));
File file=new File(realPath+format+substring);
// String uid = UUID.randomUUID().toString(); 或者是用这一行代码也可以生成唯一的标识名称
fileItem.write(file);
System.out.println("文件上传成功！！！");
response.sendRedirect("show.jsp");
return;
}else {
System.out.println(username);
System.out.println(pwd);
System.out.println(yzm);
request.getSession().setAttribute("msg","用户名或者密码错误，文件上传失败！");
response.sendRedirect("main.jsp");
return;
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}