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。
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常用的上传组件：
Apache 的 Commons FileUpload
JavaZoom的UploadBean
jspSmartUpload
--------------------------------------------------------------------------------------------------
FileUpload下载地址：
http://commons.apache.org/fileupload/
下载：commons-fileupload-1.2.2-bin.zip 得到：commons-fileupload-1.2.2.jar
下载：commons-io-1.4-bin.zip 得到：commons-io-1.4.jar
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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 border="0" 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>
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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);
}
}
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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">
-->
</head>
<body>
${requestScope['upload.message'] }
<a href="/upload/uploadFile.jsp">上传文件</a>
</body>
</html>
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web.xml
代码：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<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>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
<welcome-file>uploadFile.jsp</welcome-file>
</welcome-file-list>
</web-app>
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