文件下载

DownloadServlet.java

package com.kaishengit.web;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DownloadServlet extends HttpServlet {

  private static final long serialVersionUID = 1L;
	
	private static Map<String,String> mimeMap=new HashMap<String, String>();
	static{
		mimeMap.put("zip", "application/zip");
		mimeMap.put("pdf", "application/pdf");
		mimeMap.put("jpg", "image/jpeg");
		mimeMap.put("png", "image/png");
		mimeMap.put("doc", "application/msword");
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");
		File file=new File("E:/upload");
		String fileName=request.getParameter("f");
		fileName=new String(fileName.getBytes("ISO8859-1"),"UTF-8");
		File downloadFile=new File(file,fileName);
		if(!downloadFile.exists()){
			response.sendError(404);
			return;
		}
		
		String extName=fileName.substring(fileName.lastIndexOf(".")+1);
		//设置文件下载的类型
		response.setContentType(mimeMap.get(extName));
		//添加对进度条的支持
		response.setContentLength(new Long(downloadFile.length()).intValue());
		//对被下载文件的中文文件名进行转码操作
		fileName=new String(fileName.getBytes("UTF-8"),"ISO8859-1");
		//改变浏览器接收到的文件的名字
		response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
		
		InputStream inputStream=new FileInputStream(downloadFile);
		OutputStream outputStream=response.getOutputStream();
		BufferedInputStream bis=new BufferedInputStream(inputStream);
		BufferedOutputStream bos=new BufferedOutputStream(outputStream);
		byte[] buffer=new byte[4096];
		int len=-1;
		while((len=bis.read(buffer))!=-1){
			bos.write(buffer, 0, len);
		}
		bos.flush();
		bos.close();
		bis.close();
		
	}

	

}