【Java EE 学习 22 上】【文件上传】【目录打散】【文件重命名】

package com.kdyzm.servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadSingleFileServlet1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        //接收上传的请求，读取上传的文件
        //获取存放上传文件的上传文件夹
        String path=this.getServletContext().getRealPath("/upload");
        //第一步：声明一个磁盘文件项目工厂类，用于指定一个磁盘空间存放上传文件
        DiskFileItemFactory dfif=new DiskFileItemFactory();
        dfif.setRepository(new File(this.getServletContext().getRealPath("/temp")));//声明缓存目录
        dfif.setSizeThreshold(1024*10);//小于10KB留在内存，大于10KB保存到文件
        //第二步：声明ServletFileUpload接收上面的目录
        ServletFileUpload sfu=new ServletFileUpload(dfif);
        //第三步：解析Request
        try {
            List<FileItem>list=sfu.parseRequest(request);//解析请求HttpServletRequest
            //假设只有一个文件
            FileItem file=list.get(0);
            //获取文件名，改文件名带有路径
            String fileName=file.getName();
            fileName=fileName.substring(fileName.lastIndexOf("\")+1);
            //获取文件类型
            String fileType=file.getContentType();
            //获取输入字节流
            InputStream is=file.getInputStream();
            long fileSize=is.available();
            FileOutputStream fos =new FileOutputStream(new File(path+"/"+fileName));
            int length=-1;
            byte []buff=new byte[1024*1024];
            while((length=is.read(buff))!=-1)
            {
                fos.write(buff, 0, length);
            }
            fos.close();
            is.close();//这个流必须关闭，否则不能删除临时文件
            //删除临时文件的动作必须在流关闭之后。应当是文件占用的问题造成的失败。
            file.delete();
            PrintWriter pw=response.getWriter();
            pw.println("上传成功！<br/>文件名为："+fileName);
            pw.println("<br/>文件大小为："+fileSize+"Byte");
            pw.println("<br/>文件类型为："+fileType);
            //删除临时文件，伴随着FileItem对象的删除，实际存储在磁盘上的文件也被删除
        } catch (FileUploadException e) {
            e.printStackTrace();
        }
    }
}