package com.aojie.web.download;

import com.aojie.web.utils.DownLoadUtils;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;

/**
 * @author aojie
 * @fuction
 * @create 2020-04-20 21:45
 */
@WebServlet("/servletDownload")
public class ServletDownload extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求参数
        String filename = request.getParameter("filename");
        //使用字节输入流把文件加载进内存
            //找到文件服务器路径
            //使用字节流关联
        ServletContext servletContext = this.getServletContext();
        String realPath = servletContext.getRealPath("/imge/" + filename);
        FileInputStream fis=new FileInputStream(realPath);
        String mimeType = servletContext.getMimeType(filename);
        //解决中文文件名问题
        String header = request.getHeader("user-agent");
        filename = DownLoadUtils.getFileName(header, filename);
        //设置response响应头类型和打开方式
        response.setHeader("content-type",mimeType);
        response.setHeader("content-disposition","attachment;filename="+filename);
        //将输入流写出到输出流
        ServletOutputStream outputStream = response.getOutputStream();
        byte[] buff=new byte[1024];
        int len=0;
        while((len=fis.read(buff))!=-1){
                outputStream.write(buff,0,len);
        }

    }

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