java文件上传Demo(必看篇)
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2024-02-24 18:00:34
说到文件上传我们要做到：
1.引入两个包：commons-fileupload-1.2.1.jar和commons-io-1.3.2.jar
2.将form改为上传文件...
说到文件上传我们要做到：
1.引入两个包：commons-fileupload-1.2.1.jar和commons-io-1.3.2.jar
2.将form改为上传文件模式：enctype="multipart/form-data"
3.开始编写相关代码
这里会用到几个关键的类：磁盘文件工厂diskfileitemfactory ； 创建servlet文件上传类：servletfileupload
还有几个重要的方法：diskfileitemfactory类用于将以临时文件形式保存在磁盘上的存放目录的方法setrepository；
servletfileupload类得到表单中所有的数据，得到form表单中所有的元素方法：parserequest
下面看具体代码：
说明以这种方式上传文件是保存在服务器端的！
import java.io.file;
import java.io.ioexception;
import java.io.printwriter;
import java.util.arraylist;
import java.util.list;
import java.util.uuid;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
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 org.apache.commons.io.fileutils;
public class uploadservlet extends httpservlet {
/**
* constructor of the object.
*/
public uploadservlet() {
super();
}
/**
* destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // just puts "destroy" string in log
// put your code here
}
/**
* the doget method of the servlet. <br>
*
* this method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
this.dopost(request, response);
}
/**
* the dopost method of the servlet. <br>
*
* this method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
response.setcontenttype("text/html");
printwriter out = response.getwriter();
diskfileitemfactory sf= new diskfileitemfactory();//实例化磁盘被文件列表工厂
string path = request.getrealpath("/upload");//得到上传文件的存放目录
sf.setrepository(new file(path));//设置文件存放目录
sf.setsizethreshold(1024*1024);//设置文件上传小于1m放在内存中
string rename = "";//文件新生成的文件名
string filename = "";//文件原名称
string name = "";//普通field字段
//从工厂得到servletupload文件上传类
servletfileupload sfu = new servletfileupload(sf);
try {
list<fileitem> lst = sfu.parserequest(request);//得到request中所有的元素
for (fileitem fileitem : lst) {
if(fileitem.isformfield()){
if("name".equals(fileitem.getfieldname())){
name = fileitem.getstring("utf-8");
}
}else{
//获得文件名称
filename = fileitem.getname();
filename = filename.substring(filename.lastindexof("\\")+1);
string houzhui = filename.substring(filename.lastindexof("."));
rename = uuid.randomuuid()+houzhui;
fileitem.write(new file(path, rename));
}
}
} catch (exception e) {
// todo auto-generated catch block
e.printstacktrace();
}
system.out.println("普通字段"+name);
system.out.println("文件名称"+filename);
system.out.println("修改后生成的文件名称"+rename);
response.sendredirect("ok.jsp");
out.flush();
out.close();
}
/**
* initialization of the servlet. <br>
*
* @throws servletexception if an error occurs
*/
public void init() throws servletexception {
// put your code here
}
}
index.jsp页面：
<%@ page language="java" import="java.util.*" pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>文件测试界面</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
</head>
<body>
<div align="center">
<form action="uploadservlet" enctype="multipart/form-data" method="post">
名称：<input name="name" /> <br>
图片：<input name="img" type="file"/><br>
<input type="submit" value="提交" />
<input type="reset" value="重置" />
</form>
</div>
</body>
</html>
ok.jsp页面：
<body> <h1 align="center">上传文件成功!</h1> </body>
实现效果就不截图了，有需要自己那过去用！
以上这篇java文件上传demo(必看篇)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。
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