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

　　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

复制代码 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。

复制代码 代码如下:List list = diskFileUpload.parseRequest(request);

3 获取上传文件，进行分析（不是必须）

复制代码 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()+"
");
     }finally{
ous.close();
ins.close();
     }

这样我们就完成了文件的上传。

fileUpload.html

web.xml

  UploadServlet
  com.test.hello.UploadServlet
 

  UploadServlet
  /servlet/UploadServlet
 

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 {

  
  public UploadServlet() {
    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 {

    response.setCharacterEncoding("UTF-8");
    response.getWriter().println("请以POST方式上传文件");
  }

  
  @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 list = diskFileUpload.parseRequest(request);
      
      out.println("遍历所有的FileItem...
");
      for(FileItem fileItem : list){
 if(fileItem.isFormField()){
   if("description1".equals(fileItem.getFieldName())){
     out.println("遍历到description1 ... 
");
     description1 = new String(fileItem.getString().getBytes(),"UTF-8");
   }
   if("description2".equals(fileItem.getFieldName())){
     out.println("遍历到description2 ... 
");
     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...
");
     out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"
");
     
     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()+"
");
     }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...
");
     out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"
");
     
     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()+"
");
     }finally{
ous.close();
ins.close();
     }
   }
 }
 out.println("Request 解析完毕

");
      }
    }catch(FileUploadException e){}
    
    out.println("");
    out.println("");
    out.println(" ");
    out.println(" ");
    
    if(file1 != null){
      out.println("");
      out.println(" file1;");
      out.println(" "+file1.getName()+"");
      out.println("");
      out.println("");
    }
    if(file2 != null){
      out.println("");
      out.println(" file2;");
      out.println(" "+file2.getName()+"");
      out.println("");
      out.println("");
    }
    out.println("");
    out.println(" description1:");
    out.println(" ");
    out.println(description1);
    out.println("");
    out.println("");
    
    out.println("");
    out.println(" description2:");
    out.println(" ");
    out.println(description2);
    out.println("");
    out.println("");
    
    out.println(" ");
    out.println("");
    out.flush();
    out.close();
  }

  
  public void init() throws ServletException {
    // Put your code here
  }

}

运行示例

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