response 文件下载-2023-2-28

public class FileLoad extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
        //1.获得下载对象的下载地址
        String realPath = "E:\\JAVA\\JavaWeb\\MyServlet\\target\\MyServlet\\WEB-INF\\classes\\飞剑.png";
        //2.获得下载对象的名称,非常精妙
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
        //3.想办法让浏览器支持我们能下载
        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buffer
        int len =0;
        byte[] buffer = new byte[1024];
        //6.获取OutputStream对象
        ServletOutputStream out = resp.getOutputStream();
        //7.写入到buffer,将缓冲区的数据输出到客户端
        while ((len=in.read(buffer))>0){
           out.write(buffer,0,len);
        }
        //8.关闭资源
        in.close();
        out.close();
    }