Response下载文件

package com.xx.javaweb.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;

public class DownloadServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        ServletContext application = req.getServletContext();
        //获取下载文件的路径
        //String realPath = application.getRealPath("/bridge.jpg");
        String realPath = "E:\\java\\javacode\\javaweb\\target\\classes\\bridge.jpg";
        //获取下载文件名
        String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
        //设置响应头
        resp.setHeader("Content-Disposition", "attachment;filename" + URLEncoder.encode(fileName, "UTF-8"));
        //获取下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
        //创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];
        //获取OutputStream对象
        ServletOutputStream out = resp.getOutputStream();
        //将FileOutputStream流写入到buffer缓冲区,使用outputStream将缓冲区中的数据输出到客户端!
        while ((len=in.read(buffer)) != -1) {
            out.write(buffer, 0, len);
        }
        in.close();
        out.close();

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}