javaweb-番外篇-Commons-FileUpload组件上传文件

一、Commons-FileUpload简介

Commons-FileUpload组件

　　Commons是Apache开放源代码组织的一个Java子项目，其中的FileUpload是用来处理HTTP文件上传的子项目

Commons-FileUpload组件特点

　　使用简单：可以方便地嵌入到JSP文件中，编写少量代码即可完成文件的上传功能能够全程控制上传内容能够对上传文件的大小、类型进行控制

获取Commons-FileUpload组件的方式

　　http://commons.apache.org/fileupload下载Commons-FileUpload组件

　　　　Commons-FileUpload组件类库：commons-fileupload-1.2.2.jar

　　　　Commons-FileUpload组件的API文档： apidocs

　　http://commons.apache.org/io下载Commons-IO组件 Commons-IO组件

　　　　类库：commons-io-2.4.jar

　　　　Commons-IO组件的API文档： commons-io-2.4docs

二、Commons-FileUpload组件的API

三、Commons-FileUpload组件应用

四、代码

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    <title>上传</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
  </head>
  
  <body>
   <form action="DoUpLoadServlet" enctype="multipart/form-data" method="post">
           <p>选择图片：<input type="file" name="nfile"></p> 
           <p><input type="submit" value="提交"></p>
   </form>
  </body>
</html>

DoUpLoadServlet

package com.qj.servlet;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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.FileUploadBase;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class DoUpLoadServlet
 */
@WebServlet("/DoUpLoadServlet")
public class DoUpLoadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DoUpLoadServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uploadFileName = ""; //上传的文件名
        String fieldName = "";  //表单字段元素的name属性值
        PrintWriter out = response.getWriter();//获取out对象
        //请求信息中的内容是否是multipart类型
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        //上传文件的存储路径（服务器文件系统上的绝对文件路径）
        String uploadFilePath = request.getSession().getServletContext().getRealPath("upload/" );
        //创建临时文件目录路径
        File tempPatchFile=new File("d:\temp\buffer\");
        if(!tempPatchFile.exists())  //判断文件或目录是否存在
            tempPatchFile.mkdirs();   //创建指定的目录，包括所有必需但不存在的父目录
        if (isMultipart) {
            DiskFileItemFactory factory=new DiskFileItemFactory();
            //设置缓冲区大小4kb
            factory.setSizeThreshold(4096);   
            //设置上传文件用到临时文件存放路径
            factory.setRepository(tempPatchFile);   
            ServletFileUpload upload = new ServletFileUpload(factory);
            //设置单个文件的最大限制
            upload.setSizeMax(1024*30);   
            try {
                //解析form表单中所有文件
                List<FileItem> items = upload.parseRequest(request);
                Iterator<FileItem> iter = items.iterator();
                while (iter.hasNext()) {   //依次处理每个文件
                    FileItem item = (FileItem) iter.next();
                    if (!item.isFormField()){  //文件表单字段
                        String fileName = item.getName();
                        //通过Arrays类的asList()方法创建固定长度的集合
                        List<String> filType=Arrays.asList("gif","bmp","jpg");
                        String ext=fileName.substring(fileName.lastIndexOf(".")+1);
                        if(!filType.contains(ext))  //判断文件类型是否在允许范围内
                                out.print("上传失败，文件类型只能是gif、bmp、jpg");
                        else{
                            if (fileName != null && !fileName.equals("")) {
                                File fullFile = new File(item.getName());
                                File saveFile = new File(uploadFilePath, fullFile.getName());
                                item.write(saveFile);
                                uploadFileName = fullFile.getName();
                                out.print("上传成功后的文件名是："+uploadFileName+
                                "，文件大小是："+item.getSize()+"bytes!");
        
                            }        
                        }
                    }
                }
            }catch(FileUploadBase.SizeLimitExceededException ex){
                out.print("上传失败，文件太大，单个文件的最大限制是："+upload.getSizeMax()+"bytes!");    
            }catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}