commons-fileupload-1.2.1实现文件上传

在java里实现文件上传的组件好多，如jspSmartUpload、commons-fileupload，但是jspSmartUpload差不多淘汰了。
在网上找了下 apache的commons-fileupload相关的使用，调通了程序，放在这里以后好直接使用。。
用到的jar包：（到www.apache.org下载即可）
commons-fileupload-1.2.1.jar
commons-io-1.4.jar
网上还有更详细的用法：
http://www.cnblogs.com/yyw84/archive/2007/06/27/797652.html
由于代码太多，如果大家有兴趣，可以自己去参考参考。

这是我自己机器上通过的简单的代码，放在下面：
web.xml<?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>
<servlet-name>FileUpload</servlet-name>
<servlet-class>FileUpload.FileUploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUpload</servlet-name>
<url-pattern>/servlet/FileUploadServlet</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>fileUpload.jsp</welcome-file>
</welcome-file-list>
</web-app>



FileUpload.javapackage FileUpload;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class FileUploadServlet extends HttpServlet {
public FileUploadServlet() {
super();
}
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
final String appRealPath = this.getServletContext().getRealPath("/"); //获取web app的物理路径
final long MAX_SIZE = 3 * 1024 * 1024;// 设置上传文件最大为 3M
final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",
"doc", "docx", "mp3", "wma", "m4a" }; // 允许上传的文件格式的列表
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8"); // 设置字符编码为UTF-8, 这样支持汉字显示
// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
DiskFileItemFactory dfif = new DiskFileItemFactory();
dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
dfif.setRepository(new File(appRealPath + "ImagesUploadTemp\\"));
// 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录
// 用以上工厂实例化上传组件
ServletFileUpload sfu = new ServletFileUpload(dfif);

sfu.setSizeMax(MAX_SIZE);// 设置最大上传尺寸
PrintWriter out = response.getWriter();

// 从request得到 所有 上传域的列表
List fileList = null;
try {
fileList = sfu.parseRequest(request);
} catch (FileUploadException e) {// 处理文件尺寸过大异常
if (e instanceof SizeLimitExceededException) {
out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");
out.println("<a href=\" " + request.getContextPath() + "/fileUpload.jsp" + " \" target=\"_top\">返回</a>");
return;
}
e.printStackTrace();
}
// 没有文件上传
if (fileList == null || fileList.size() == 0) {
out.println("请选择上传文件<p />");
out.println("<a href=\" " + request.getContextPath() + "/fileUpload.jsp" + " \" target=\"_top\">返回</a>");
return;
}
// 得到所有上传的文件
Iterator fileItr = fileList.iterator();
// 循环处理所有文件
while (fileItr.hasNext()) {
FileItem fileItem = null;
String path = null;
long size = 0;
// 得到当前文件
fileItem = (FileItem) fileItr.next();
// 忽略简单form字段而不是上传域的文件域(<input type="text" />等)
if (fileItem == null || fileItem.isFormField()) {
continue;
}
// 得到文件的完整路径
path = fileItem.getName();
// 得到文件的大小
size = fileItem.getSize();
if ("".equals(path) || size == 0) {
out.println("请选择上传文件<p />");
out.println("<a href=\" " + request.getContextPath() + "/fileUpload.jsp" + " \" target=\"_top\">返回</a>");
return;
}
// 得到去除路径的文件名
String t_name = path.substring(path.lastIndexOf("\\") + 1);
// 得到文件的扩展名(无扩展名时将得到全名)
String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
// 拒绝接受规定文件格式之外的文件类型
int allowFlag = 0;
int allowedExtCount = allowedExt.length;
for (; allowFlag < allowedExtCount; allowFlag++) {
if (allowedExt[allowFlag].equals(t_ext))
break;
}
if (allowFlag == allowedExtCount) {
out.println("请上传以下类型的文件<p />");
for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
out.println("*." + allowedExt[allowFlag]
+ "&nbsp;&nbsp;&nbsp;");
out
.println("<a href=\" " + request.getContextPath() + "/fileUpload.jsp" + " \" target=\"_top\">返回</a>");
return;
}
long now = System.currentTimeMillis();
// 根据系统时间生成上传后保存的文件名
String prefix = String.valueOf(now);
// 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
String u_name = appRealPath + "ImagesUploaded\\"
+ prefix + "." + t_ext;
try {
// 保存文件
fileItem.write(new File(u_name));
out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext
+ " &nbsp;&nbsp;文件大小: " + size + "字节<p />");
out.println("<a href=\" " + request.getContextPath() + "/fileUpload.jsp" + " \" target=\"_top\">继续上传</a>");
} catch (Exception e) {
e.printStackTrace();
}
}
}
public void init() throws ServletException {
// Put your code here
}
}




fileUpload.jsp<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'fileUpload.jsp' starting page</title>
</head>

<body>
<form action="<%= request.getContextPath() %>/servlet/FileUploadServlet" method="post" enctype="multipart/form-data" >
<input type="file" name="fileUpload" />
<input type="submit" value="upload" />
</form>
</body>
</html>



记得在上传的form里指明enctype="multipart/form-data"，具体的读一下FileUpload.java就清楚了。