struts2学习笔记（六）文件上传与下载（上）jspServlet的文件上传与下载_struts中文件上传与servlet中的文件上传-优快云博客

本文链接：https://blog.youkuaiyun.com/renlei0109/article/details/21085611

本文介绍了一个使用Java Servlet和Apache Commons FileUpload库实现的文件上传功能。该Servlet能够处理多部分表单数据，支持同时上传多个文件，并将文件保存到服务器指定目录。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

相应的servlet

package org.lei.servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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;

/**
* Servlet implementation class UploadServlet
*/

@WebServlet("/UploadServlet")

public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public UploadServlet() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//一个工厂类的对象,该对象有下面两个比较好的属性
DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();
//设置一个临时的存储目录，当文件比较大的时候先存储在这个（磁盘）临时目录里面，当比较小的时候就放在内存中
String path = request.getRealPath("/upload");
//表示小于这个大小一兆就放在内存中，其他的放在刚才指定的那个目录
diskFileItemFactory.setSizeThreshold(1024*1024*1024);

ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
try {
List <FileItem>list = servletFileUpload.parseRequest(request);

for(FileItem item :list){
//判断是否是文件类型的，如果为真则表示不是文件类型的
if(item.isFormField()){
//获得表单的名字
String name = item.getFieldName();
String value = item.getString("gbk");
request.setAttribute(name, value);

}

else {
//获取form中文件的名字
String name = item.getFieldName();
//获取世纪文件的名字，根据浏览器的不同所的得到的值不同，大多数浏览器不包括路径
String value = item.getName();
/**
* 截取真正的文件的名字
*/
//获取最后一个\的位置
int start = value.lastIndexOf("\\");
String fileName = value.substring(start+1);
request.setAttribute(name, fileName);

/**
* 将文件存储（加载）到服务器端
*/
OutputStream os = new FileOutputStream(new File(path,fileName));
InputStream is = item.getInputStream();
byte []buffer = new byte[400];
int length = 0;
while((length = is.read(buffer))>0){
os.write(buffer,0,length);
}
os.close();
is.close();

}
}

} catch (FileUploadException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

request.getRequestDispatcher("upload/result2.jsp").forward(request, response);
}

}

jsp中的代码

<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
</head>
<body>	
	<form action="/struts007fileupload01/UploadServlet" method="post"  enctype="multipart/form-data">
		username:<input type="text" name = "username"><br>
		password:<input type="password" name = "password"><br>
		file1:<input type="file" name="file1"><br>
		file2:<input type="file" name="file2">
		<input type="submit"  value="提交">
	</form>
</body>
</html>