文件下载

package com.lsgjzhuwei.servlet.response;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

/**
 * Servlet implementation class ServletDownload
 */
@WebServlet(asyncSupported = true, urlPatterns = { "/ServletDownload" })
public class ServletDownload extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public ServletDownload() {
        super();
        // TODO Auto-generated constructor stub
    }

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

        //获得请求文件名
        String filename = request.getParameter("filename");
        System.out.println(filename);

        //设置文件MIME类型
        response.setContentType(getServletContext().getMimeType(filename));
        //设置Content-Disposition
        response.setHeader("Content-Disposition", "attachment;filename="+filename);
        //读取目标文件，通过response将目标文件写到客户端
        //获取目标文件的绝对路径
        String fullFileName = getServletContext().getRealPath("/download/" + filename);
        //System.out.println(fullFileName);
        //读取文件
        InputStream in = new FileInputStream(fullFileName);
        OutputStream out = response.getOutputStream();

        //写文件
        int b;
        while((b=in.read())!= -1)
        {
            out.write(b);
        }

        in.close();
        out.close();
    }

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

}