Apache Commons fileUpload实现文件上传

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 "-//W 3C //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 "-//W 3C //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 "-//W 3C //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 >