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: 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>     <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>

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