在我们的web开发中，很多的时候都需要把本机的一些文件上传到web服务器上面去。
如：一个BBS系统，当用户使用这是系统的时候，能把本机的一些图片，文档上传到服务器上面去。然后其他用户可以去下载这些文件，那么这样的话，我们可以自己编程实现文件的上传
但是更好的方式是使用一些已有的组件帮助我们实现这种上传功能。
常用的上传组件：
Apache 的 Commons FileUpload
JavaZoom的UploadBean
jspSmartUpload
upload.jsp
代码；
<%@ page language="java" contentType="text/html; charset=UTF-8"%><html><head><title>using commons Upload to upload file </title></head><style>* { font-family: "宋体"; font-size: 14px }</style><body><p align="center"> 请您选择需要上传的文件</p><form id="form1" name="form1" method="post" action="servlet/fileServlet" enctype="multipart/form-data"> <table align="center"> <tr> <td>上传人：</td> <td> <input name="name" type="text" id="name" size="20" ></td> </tr> <tr> <td>上传文件：</td> <td><input name="file" type="file" size="20" ></td> </tr> <tr> <td></td><td> <input type="submit" name="submit" value="提交" > <input type="reset" name="reset" value="重置" > </td> </tr> </table></form></body></html>FileUploadServlet.java代码：
/** * */package com.b510.example;import java.io.File;import java.io.IOException;import java.util.*;import javax.servlet.ServletConfig;import javax.servlet.ServletContext;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;/** * * @author XHW * * @date 2011-7-26 * */public class FileUploadServlet extends HttpServlet { private static final long serialVersionUID = -7744625344830285257L; private ServletContext sc; private String savePath; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void init(ServletConfig config) { // 在web.xml中设置的一个初始化参数 savePath = config.getInitParameter("savePath"); sc = config.getServletContext(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); DiskFileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory); try { List items = upload.parseRequest(request); Iterator itr = items.iterator(); while (itr.hasNext()) { FileItem item = (FileItem) itr.next(); if (item.isFormField()) { System.out.println("表单参数名:" + item.getFieldName() + "，表单参数值:" + item.getString("UTF-8")); } else { if (item.getName() != null && !item.getName().equals("")) { System.out.println("上传文件的大小:" + item.getSize()); System.out.println("上传文件的类型:" + item.getContentType()); // item.getName()返回上传文件在客户端的完整路径名称 System.out.println("上传文件的名称:" + item.getName()); File tempFile = new File(item.getName()); ／／上传文件的保存路径 File file = new File(sc.getRealPath("/") + savePath, tempFile.getName()); item.write(file); request.setAttribute("upload.message", "上传文件成功！"); }else{ request.setAttribute("upload.message", "没有选择上传文件！"); } } } }catch(FileUploadException e){ e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); request.setAttribute("upload.message", "上传文件失败！"); } request.getRequestDispatcher("/uploadResult.jsp").forward(request, response); }}uploadResult.jsp代码：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>uploadResult</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" rel="external nofollow" > --> </head> <body> ${requestScope['upload.message'] } <a href="/upload/uploadFile.jsp" rel="external nofollow" >上传文件</a> </body></html>web.xml
<servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>FileUploadServlet</servlet-name> <servlet-class>com.b510.example.FileUploadServlet</servlet-class> ＜！--设置初始化参数--＞ <init-param> <param-name>savePath</param-name> <param-value>uploads</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>FileUploadServlet</servlet-name> <url-pattern>/servlet/fileServlet</url-pattern> </servlet-mapping>
本文已被整理到了《Java上传操作技巧汇总》，欢迎大家学习阅读。
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