Apache commons fileupload文件上传实例讲解

文件上传的方法主要目前有两个常用的,一个是SmartUpload,一个是Apache的Commons fileupload.

我们这里主要介绍下第二个的用法,首先要上传文件,注意几个问题:

  1 form表单内,要添加空间<input type="file" name="myfile">

  2 form表单的内容格式要定义成multipart/form-data格式

  3 需要类库:1 commons-io.jar 2commons-fileupload-1.3.1.jar

接下来我们看下用法。

首先阅读Apache commons fileupload的官方文档可以发现下面几个常用的函数:

1 创建文件解析对象

代码如下:
DiskFileUpload diskFileUpload = new DiskFileUpload();

2 进行文件解析后放在List中,因为这个类库支持多个文件上传,因此把结果会存在List中。

代码如下:
List<FileItem> list = diskFileUpload.parseRequest(request);

3 获取上传文件,进行分析(不是必须)

代码如下:
File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

4 创建新对象,进行流拷贝

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());

file1.getParentFile().mkdirs();

file1.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file1);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");

}finally{

ous.close();

ins.close();

}

这样我们就完成了文件的上传。

fileUpload.html

<form action="servlet/UploadServlet" method="post" enctype="multipart/form-data">

<div align="center">

<fieldset style="width:80%">

<legend>上传文件</legend><br/>

<div align="left">上传文件1</div>

<div align="left">

<input type="file" name="file1"/>

</div>

<div align="left">上传文件2</div>

<div align="left">

<input type="file" name="file2"/>

</div>

<div>

<div align='left'>上传文件说明1</div>

<div align='left'><input type="text" name="description1"/></div>

</div>

<div>

<div align='left'>上传文件说明2</div>

<div align='left'><input type="text" name="description2"/></div>

</div>

<div>

<div align='left'>

<input type='submit' value="上传文件"/>

</div>

</div>

</fieldset>

</div>

</form>

web.xml

<servlet>

<servlet-name>UploadServlet</servlet-name>

<servlet-class>com.test.hello.UploadServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>UploadServlet</servlet-name>

<url-pattern>/servlet/UploadServlet</url-pattern>

</servlet-mapping>

UploadServlet.java

package com.test.hello;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.PrintWriter;

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.DiskFileUpload;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadException;

public class UploadServlet extends HttpServlet {

/**

* Constructor of the object.

*/

public UploadServlet() {

super();

}

/**

* Destruction of the servlet. <br>

*/

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

// Put your code here

}

/**

* The doGet method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to get.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setCharacterEncoding("UTF-8");

response.getWriter().println("请以POST方式上传文件");

}

/**

* The doPost method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to post.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

@SuppressWarnings({ "unchecked", "deprecation" })

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

File file1 = null,file2=null;

String description1 = null,description2 = null;

response.setCharacterEncoding("UTF-8");

request.setCharacterEncoding("UTF-8");

response.setContentType("text/html");

PrintWriter out = response.getWriter();

DiskFileUpload diskFileUpload = new DiskFileUpload();

try{

List<FileItem> list = diskFileUpload.parseRequest(request);

out.println("遍历所有的FileItem...<br/>");

for(FileItem fileItem : list){

if(fileItem.isFormField()){

if("description1".equals(fileItem.getFieldName())){

out.println("遍历到description1 ... <br/>");

description1 = new String(fileItem.getString().getBytes(),"UTF-8");

}

if("description2".equals(fileItem.getFieldName())){

out.println("遍历到description2 ... <br/>");

description2 = new String(fileItem.getString().getBytes(),"UTF-8");

}

}else{

if("file1".equals(fileItem.getFieldName())){

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

out.println("遍历到file1...<br/>");

out.println("客户端文件位置:"+remoteFile.getAbsolutePath()+"<br/>");

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());

file1.getParentFile().mkdirs();

file1.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file1);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");

}finally{

ous.close();

ins.close();

}

}

if("file2".equals(fileItem.getFieldName())){

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

out.println("遍历到file2...<br/>");

out.println("客户端文件位置:"+remoteFile.getAbsolutePath()+"<br/>");

file2 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());

file2.getParentFile().mkdirs();

file2.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file2);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file2.getAbsolutePath()+"<br/>");

}finally{

ous.close();

ins.close();

}

}

}

out.println("Request 解析完毕<br/><br/>");

}

}catch(FileUploadException e){}

out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");

out.println("<HTML>");

out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");

out.println(" <BODY>");

if(file1 != null){

out.println("<div>");

out.println(" <div align='left'>file1;</div>");

out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+

file1.getName()+"'target=_blank>"+file1.getName()+"</a>");

out.println("</div>");

out.println("</div>");

}

if(file2 != null){

out.println("<div>");

out.println(" <div align='left'>file2;</div>");

out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+

file2.getName()+"'target=_blank>"+file2.getName()+"</a>");

out.println("</div>");

out.println("</div>");

}

out.println("<div>");

out.println(" <div align='left'>description1:</div>");

out.println(" <div align='left'>");

out.println(description1);

out.println("</div>");

out.println("</div>");

out.println("<div>");

out.println(" <div align='left'>description2:</div>");

out.println(" <div align='left'>");

out.println(description2);

out.println("</div>");

out.println("</div>");

out.println(" </BODY>");

out.println("</HTML>");

out.flush();

out.close();

}

/**

* Initialization of the servlet. <br>

*

* @throws ServletException if an error occurs

*/

public void init() throws ServletException {

// Put your code here

}

}

运行示例

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