Response文件下载

package com.hui.servlet;

import javax.servlet.Servlet;
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.net.URLEncoder;

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1 获取下载的路径
        String realPath = "D:\\idea\\javaweb-01-servlet\\target\\classes\\王小慧.png";
        System.out.println("下载文件的路径：" + realPath);
//        2 下载的文件名称
        String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
//        3 设置想办法让浏览器能够支持（Content-disposition)来下载,我们需要东西中文文件名     URLEncoder.encode编码，否则可能乱码

        resp.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
//        4 获取下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
//        5 创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];
//        6 获取OutputStream对象
        ServletOutputStream out = resp.getOutputStream();
//        7 将FileOutputStream流写入到buffer缓冲区，使用OutputStream将缓冲区的数据输出到客户端
        while ((len = in.read(buffer)) > 0) {
            out.write(buffer, 0, len);
        }
        in.close();
        out.close();
    }

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