Apache Commons fileUpload文件上传多个示例分享

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-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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