Servlet实现文件上传-优快云博客

本文介绍了一种利用Servlet实现文件上传的方法。通过下载commons-fileupload和commons-io库，并配置到项目中，可以轻松地实现多文件上传功能。文章提供了完整的JSP页面和Servlet代码示例。

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做系统，有时会需要实现文件上传的功能，在这里我用servlet来实现文件的http://上传，为了开发方便，我们需要下载两个文件：commons-fileupload.jar；commons-io-2.3前一个需要依赖后一个，所以两个都要下载，配置好后就可以编写代码了。

首先编写jsp文件：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</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">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  	<form action="UploadServlet" method="post" enctype="multipart/form-data">
  		username:<input type="text" name="username"/><br/>
  		file: <input type="file" name="file" /><br/>
  		file: <input type="file" name="file2"/><br/>
  		<input type="submit" value="ok"/>
  	</form>
  </body>
</html>

这里需要说明的是：form表单一点要有enctype属性并且其值为：multipart/form-data。

然后是编写servlet了，很简单：

package com.nine.upload.action;

import java.io.File;
import java.io.IOException;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadServlet extends HttpServlet {
	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		DiskFileItemFactory factory = new DiskFileItemFactory();
		
		String path = request.getRealPath("/upload");
		
		factory.setRepository(new File(path));
		factory.setSizeThreshold(1024 * 1024);
		ServletFileUpload upload = new ServletFileUpload(factory);
		//设置上传文件大小
		upload.setSizeMax(2 * 1024 * 1024);
		
		try {
			List<FileItem> list = (List<FileItem>) upload.parseRequest(request);
			for (FileItem item : list) {
				String name = item.getFieldName();
				if (item.isFormField()) {
					//文本域
					String value = item.getString();
					System.out.println("name ----> " + name);
					System.out.println("value ----> " + value);
					request.setAttribute(name, value);
				} else {
					//文件本身
					String value = item.getName();
					System.out.println("value ----> " + value);
					int start = value.lastIndexOf("\\");
					String fileName = value.substring(start + 1);
					request.setAttribute(name, value);
					
					item.write(new File(path, fileName));
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		request.getRequestDispatcher("uploadresult.jsp").forward(request, response);
		
	}

}

就这样了，文件上传就实现了