本文通过实例来介绍如何使用commons-fileupload.jar，Apache的commons-fileupload.jar可方便的实现文件的上传功能，具体内容如下
将Apache的commons-fileupload.jar放在应用程序的WEB-INFlib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-INFlib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:tempbuffer"); 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:tempbuffer"; // 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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