FileUpload实现文件上传（包含多文件）

package com.hzml.serve;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
import javax.servlet.ServletContext;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

@WebServlet("/FileUploadServlet")
public class FileUploadServlet extends HttpServlet {
    private String filePath;    // 文件存放目录
    private String tempPath;    // 临时文件目录
    // 初始化
    public void init() throws ServletException
    {
        super.init();
        // 从配置文件中获得初始化参数
        ServletContext context = getServletContext();
        filePath = context.getRealPath("/") + "/hzmlFile";
        tempPath = context.getRealPath("/") + "/hzmlFile";
        System.out.println("文件存放目录、临时文件目录准备完毕 ...");
    }  

    private void process(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException{
         res.setContentType("text/plain;charset=gbk");
         PrintWriter pw = res.getWriter();
         try{
             DiskFileItemFactory diskFactory = new DiskFileItemFactory();
             // threshold 极限、临界值，即硬盘缓存 1M
             diskFactory.setSizeThreshold(4 * 1024);
             // repository 贮藏室，即临时文件目录
             diskFactory.setRepository(new File(tempPath));  

             ServletFileUpload upload = new ServletFileUpload(diskFactory);
             // 设置允许上传的最大文件大小 4M
             upload.setSizeMax(4 * 1024 * 1024);
             // 解析HTTP请求消息头
             List fileItems = upload.parseRequest(req);
             Iterator iter = fileItems.iterator();
             while(iter.hasNext())
             {
                 FileItem item = (FileItem)iter.next();
                 if(item.isFormField())
                 {
                     System.out.println("处理表单内容 ...");
                     processFormField(item, pw);
                 }else{
                     System.out.println("处理上传的文件 ...");
                     processUploadFile(item, pw);
                 }
             }// end while()  

             pw.close();
         }catch(Exception e){
             System.out.println("使用 fileupload 包时发生异常 ...");
             e.printStackTrace();
         }// end try ... catch ...
    }

    public void doPost(HttpServletRequest req, HttpServletResponse res)
        throws IOException, ServletException  {
        process(req, res);
    }

    protected void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        process(req, res);
    }

    // 处理表单内容
    private void processFormField(FileItem item, PrintWriter pw)
        throws Exception
    {
        String name = item.getFieldName();
        String value = item.getString();
        pw.println(name + " : " + value + "\r\n");
    }  

    // 处理上传的文件
    private void processUploadFile(FileItem item, PrintWriter pw)
        throws Exception
    {
        // 此时的文件名包含了完整的路径，得注意加工一下
        String filename = item.getName();
        System.out.println("完整的文件名：" + filename);
        int index = filename.lastIndexOf("\\");
        filename = filename.substring(index + 1, filename.length());  

        long fileSize = item.getSize();  

        if("".equals(filename) && fileSize == 0)
        {
            System.out.println("文件名为空 ...");
            return;
        }
        pw.println(filePath);
        File uploadFile = new File(filePath + "/" + filename);
        item.write(uploadFile);
        pw.println(filename + " 文件保存完毕 ...");
        pw.println("文件大小为 ：" + fileSize + "\r\n");
    }
}