Apache Commons fileUpload实现文件上传

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本文详细介绍如何使用Apache的commons-fileupload.jar实现文件上传功能。包括简单上传、上传至指定目录、限定文件大小及使用Servlet实现文件上传等示例。

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Apache的commons-fileupload.jar可方便的实现文件的上传功能，本文通过实例来介绍如何使用commons-fileupload.jar。

@author:ZJ 07-2-22

Blog: http://zhangjunhd.blog.51cto.com/

将Apache的commons-fileupload.jar放在应用程序的WEB-INF/lib下，即可使用。下面举例介绍如何使用它的文件上传功能。

所使用的fileUpload版本为1.2，环境为Eclipse3.3+MyEclipse6.0。FileUpload 是基于 Commons IO的，所以在进入项目前先确定Commons IO的jar包（本文使用commons-io-1.3.2.jar）在WEB-INF/lib下。

此文作示例工程可在文章最后的附件中下载。

示例1

最简单的例子，通过ServletFileUpload静态类来解析Request，工厂类FileItemFactory会对mulipart类的表单中的所有字段进行处理，不只是file字段。getName（）得到文件名，getString（）得到表单数据内容，isFormField（）可判断是否为普通的表单项。

demo1.html

<html>

<head>

<title>File upload</title>

</head>

<body>

//必须是multipart的表单数据。

<form name="myform" action="demo1.jsp" method="post"

enctype="multipart/form-data">

Your name: <br>

File:<br>

<br>

</form>

</body>

</html>

demo1.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"

pageEncoding="GB18030"%>

<%@ page import="org.apache.commons.fileupload.*"%>

<%@ page import="org.apache.commons.fileupload.servlet.*"%>

<%@ page import="org.apache.commons.fileupload.disk.*"%>

<%@ page import="java.util.*"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

boolean isMultipart = ServletFileUpload.isMultipartContent(request);//检查输入请求是否为multipart表单数据。

if (isMultipart == true) {

FileItemFactory factory = new DiskFileItemFactory();//为该请求创建一个DiskFileItemFactory对象，通过它来解析请求。执行解析后，所有的表单项目都保存在一个List中。

ServletFileUpload upload = new ServletFileUpload(factory);

List<FileItem> items = upload.parseRequest(request);

Iterator<FileItem> itr = items.iterator();

while (itr.hasNext()) {

FileItem item = (FileItem) itr.next();

//检查当前项目是普通表单项目还是上传文件。

if (item.isFormField()) {//如果是普通表单项目，显示表单内容。

String fieldName = item.getFieldName();

if (fieldName.equals("name")) //对应demo1.html中type="text" name="name"

out.print("the field name is" + item.getString());//显示表单内容。

out.print("<br>");

} else {//如果是上传文件，显示文件名。

out.print("the upload file name is" + item.getName());

out.print("<br>");

}

} else {

out.print("the enctype must be multipart/form-data");

}

<html>

<head>

<title>File upload</title>

</head>

<body>

</body>

</html>

结果：

the field name isjeff the upload file name isD:/C语言考试样题/作业题.rar

示例2

上传两个文件到指定的目录。

demo2.html

<html>

<head>

<title>File upload</title>

</head>

<body>

<form name="myform" action="demo2.jsp" method="post"

enctype="multipart/form-data">

File1:<br>

File2:<br>

<br>

</form>

</body>

</html>

demo2.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"

pageEncoding="GB18030"%>

<%@ page import="org.apache.commons.fileupload.*"%>

<%@ page import="org.apache.commons.fileupload.servlet.*"%>

<%@ page import="org.apache.commons.fileupload.disk.*"%>

<%@ page import="java.util.*"%>

<%@ page import="java.io.*"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<%String uploadPath="D://temp";

boolean isMultipart = ServletFileUpload.isMultipartContent(request);

if(isMultipart==true){

try{

FileItemFactory factory = new DiskFileItemFactory();

ServletFileUpload upload = new ServletFileUpload(factory);

List<FileItem> items = upload.parseRequest(request);//得到所有的文件

Iterator<FileItem> itr = items.iterator();

while(itr.hasNext()){//依次处理每个文件

FileItem item=(FileItem)itr.next();

String fileName=item.getName();//获得文件名，包括路径

if(fileName!=null){

File fullFile=new File(item.getName());

File savedFile=new File(uploadPath,fullFile.getName());

item.write(savedFile);

}

out.print("upload succeed");

}

catch(Exception e){

e.printStackTrace();

}

else{

out.println("the enctype must be multipart/form-data");

}

<html>

<head>

<title>File upload</title>

</head>

<body>

</body>

</html>

结果：

upload succeed

此时，在"D:/temp"下可以看到你上传的两个文件。

示例3

上传一个文件到指定的目录，并限定文件大小。

demo3.html

<html>

<head>

<title>File upload</title>

</head>

<body>

<form name="myform" action="demo3.jsp" method="post"

enctype="multipart/form-data">

File:<br>

<br>

</form>

</body>

</html>

demo3.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"

pageEncoding="GB18030"%>

<%@ page import="org.apache.commons.fileupload.*"%>

<%@ page import="org.apache.commons.fileupload.servlet.*"%>

<%@ page import="org.apache.commons.fileupload.disk.*"%>

<%@ page import="java.util.*"%>

<%@ page import="java.io.*"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

File uploadPath = new File("D://temp");//上传文件目录

if (!uploadPath.exists()) {

uploadPath.mkdirs();

}

// 临时文件目录

File tempPathFile = new File("d://temp//buffer//");

if (!tempPathFile.exists()) {

tempPathFile.mkdirs();

}

try {

// Create a factory for disk-based file items

DiskFileItemFactory factory = new DiskFileItemFactory();

// Set factory constraints

factory.setSizeThreshold(4096); // 设置缓冲区大小，这里是4kb

factory.setRepository(tempPathFile);//设置缓冲区目录

// Create a new file upload handler

ServletFileUpload upload = new ServletFileUpload(factory);

// Set overall request size constraint

upload.setSizeMax(4194304); // 设置最大文件尺寸，这里是4MB

List<FileItem> items = upload.parseRequest(request);//得到所有的文件

Iterator<FileItem> i = items.iterator();

while (i.hasNext()) {

FileItem fi = (FileItem) i.next();

String fileName = fi.getName();

if (fileName != null) {

File fullFile = new File(fi.getName());

File savedFile = new File(uploadPath, fullFile

.getName());

fi.write(savedFile);

}

out.print("upload succeed");

} catch (Exception e) {

e.printStackTrace();

}

<html>

<head>

<title>File upload</title>

</head>

<body>

</body>

</html>

示例4

利用Servlet来实现文件上传。

Upload.java

package com.zj.sample;

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.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

@SuppressWarnings("serial")

publicclass Upload extends HttpServlet {

private String uploadPath = "D://temp"; // 上传文件的目录

private String tempPath = "d://temp//buffer//"; // 临时文件目录

File tempPathFile;

@SuppressWarnings("unchecked")

publicvoid doPost(HttpServletRequest request, HttpServletResponse response)

throws IOException, ServletException {

try {

// Create a factory for disk-based file items

DiskFileItemFactory factory = new DiskFileItemFactory();

// Set factory constraints

factory.setSizeThreshold(4096); // 设置缓冲区大小，这里是4kb

factory.setRepository(tempPathFile);// 设置缓冲区目录

// Create a new file upload handler

ServletFileUpload upload = new ServletFileUpload(factory);

// Set overall request size constraint

upload.setSizeMax(4194304); // 设置最大文件尺寸，这里是4MB

List<FileItem> items = upload.parseRequest(request);// 得到所有的文件

Iterator<FileItem> i = items.iterator();

while (i.hasNext()) {

FileItem fi = (FileItem) i.next();

String fileName = fi.getName();

if (fileName != null) {

File fullFile = new File(fi.getName());

File savedFile = new File(uploadPath, fullFile.getName());

fi.write(savedFile);

}

System.out.print("upload succeed");

} catch (Exception e) {

// 可以跳转出错页面

e.printStackTrace();

}

publicvoid init() throws ServletException {

File uploadFile = new File(uploadPath);

if (!uploadFile.exists()) {

uploadFile.mkdirs();

}

File tempPathFile = new File(tempPath);

if (!tempPathFile.exists()) {

tempPathFile.mkdirs();

}

demo4.html

<html>

<head>

<title>File upload</title>

</head>

<body>

// action="fileupload"对应web.xml中<servlet-mapping>中<url-pattern>的设置.

<form name="myform" action="fileupload" method="post"

enctype="multipart/form-data">

File:<br>

<br>

</form>

</body>

</html>

web.xml

<servlet-name>Upload</servlet-name>

<servlet-class>com.zj.sample.Upload</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>Upload</servlet-name>

<url-pattern>/fileupload</url-pattern>

</servlet-mapping>

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