Java Web——文件上传

最新推荐文章于 2025-07-25 17:28:41 发布

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本文介绍了如何使用Apache Commons库中的FileUpload组件处理文件上传请求，包括创建FileItem工厂、设置内存和磁盘阈值、解析请求数据并保存文件。

给予Apache提供的两个Jar包

commons-fileupload-1.3.1.jar

commons-io-2.4.jar

package com.jabnih.Upload;

import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

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;

public class FileUploadServlet extends HttpServlet {

	private int memSize = 4*1024;
	private int thresold = 1024*1024;
	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//判断表单中的enctype 是否为 multipart/form-data
		if (!ServletFileUpload.isMultipartContent(request) ) {
			response.getWriter().println("no file to upload");
			return;
		}
		
		/*	创建一个FileIterm工厂类	*/
		DiskFileItemFactory factory = new DiskFileItemFactory();
		/*	设置最大存在于内存文件的大小，超出这个范围将写到磁盘中	*/
		factory.setSizeThreshold(memSize);
		/*	设置存放临时文件的文件夹	*/
		factory.setRepository(new File("F:\\"));
		//此类用于将request对象中的数据解析封装为FileItem类
		ServletFileUpload upload = new ServletFileUpload(factory);
		//设置接收文件的最大值
		upload.setFileSizeMax(thresold);
	
		try {
			/*	解析表单提交的数据	*/
			List<FileItem> items = upload.parseRequest(request);

			Iterator<FileItem> iterator = items.iterator();
			while( iterator.hasNext() ) {
				FileItem item = iterator.next();
				/*	将表单中的数据写入到文件中	*/
				item.write(new File("F:\\" + item.getName()));
			}
			response.getWriter().println("Upload successfully");
		}catch (Exception e) {
			e.printStackTrace();
		}
	}
}

upload.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'upload.jsp' starting page</title>
  </head>
  <body>
    <fieldset>
    	<legend>Upload</legend>
    	<%-- 注意： 一定要填写属性  enctype --%>
    	<form action="/MyDay01/upload" method="post" enctype="multipart/form-data">
    	<table>
    		<tr>
    			<td>
    				选择文件:
    			</td>
    			<td><input type="file" name="upload"/></td>
    		</tr>
    		<tr>
     			<td colspan="2"><input type="submit" value="上传"/></td>
    		</tr>
    	</table>
    	</form>
    </fieldset>
  </body>
</html>