Response下载文件

1.首先在maven项目下创建java class 类 ，然后继承HttpServlet接口。 重写doGet方法。
2.代码如下

点击查看代码

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;

public class response extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取文件下载路径
       // String realPath = this.getServletContext().getRealPath("/1.png");
        String realPath="F:\\demo\\maven01\\response01\\target\\classes\\1.png";
        //2.下载文件命是啥
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
        //3.设置想办法让浏览器能够(Content-Disposition)支持下载我们需要的东西
        resp.setHeader("Content-Disposition","attachment;filename="+filename);
        //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buffer缓冲区
        while((len=in.read(buffer))>0){
            out.write(buffer,0,len);
        }
        in.close();
        out.close();
    }
}

3.运行成功会自动下载