commons-fileupload实现文件上传(1)

Apache Commons fileUpload实现文件上传

 

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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: [url]http://zhangjunhd.blog.51cto.com/[/url]

    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 >

    < meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

    < 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 >

       < input type = "text" name = "name" size = "15" >< br >

       File: < br >

       < input type = "file" name = "myfile" >< br >

       < br >

       < input type = "submit" name = "submit" value = "Commit" >

    </ 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 >

    < meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

    < 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 >

    < meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

    < title > File upload </ title >

</ head >

< body >

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

       enctype = "multipart/form-data" >

       File1: < br >

       < input type = "file" name = "myfile" >< br >

       File2: < br >

       < input type = "file" name = "myfile" >< br >

       < br >

       < input type = "submit" name = "submit" value = "Commit" >

    </ 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 >

< meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

< 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 >

    < meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

    < title > File upload </ title >

</ head >

< body >

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

       enctype = "multipart/form-data" >

       File: < br >

       < input type = "file" name = "myfile" >< br >

       < br >

       < input type = "submit" name = "submit" value = "Commit" >

    </ 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 >

< meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

< 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" )

public class 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" )

    public void 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();

       }

    }

 

    public void 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 >

    < meta http-equiv = "Content-Type" content = "text/html; charset=GB18030" >

    < 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 >

       < input type = "file" name = "myfile" >< br >

       < br >

       < input type = "submit" name = "submit" value = "Commit" >

    </ form >

</ body >

</ html >

 

web.xml

< servlet >

    < 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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