package org.shengke.servlet;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

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

/**
 * 文件批量下载
 */
public class BatchDownloadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doPost(req,resp);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//设置文件头，类型为下载类型
		resp.setContentType("application/x-msdownload");
		//下载时浏览器提示用户保存的文件名filename=test.zip
		resp.setHeader("Content-Disposition", "attachment;filename=test.zip");
//		String path = getServletContext().getRealPath("/") + "images/";
		//设置下载文件的路径,文件在服务器上的位置
		String path = "/home/shengke/workspace/wenjianSCXZ/WebContent/images/";
		//初始化一个String数组，来存放下载文件名序列
		String[] filenames  = req.getParameterValues("filename");
		String str = "";
		//为了偷懒
		String rt = "\r\n";
//		文件压缩，这是批量文件下载的关键，如果不对多个下载文件进行统一打包的话，下载时浏览器会弹出多个提示下载框，个用户体验不好
		//使用zip方式压缩文件序列
		ZipOutputStream zos = new ZipOutputStream(resp.getOutputStream());
		for(String filename : filenames){
			str += filename + rt;
			File file = new File(path + filename);
			zos.putNextEntry(new ZipEntry(filename));
			FileInputStream fis = new FileInputStream(file);
			//读取文件
			byte b[] = new byte[1024];
			int n = 0;
			while((n = fis.read(b)) != -1){
				zos.write(b, 0, n);
			}
			zos.flush();
			fis.close();
		}
		zos.setComment("download success:" + rt + str);
		zos.flush();
		zos.close();
	}

}