servlet实现文件下载

描述

servlet实现文件下载很简单的，只需要如下代码。

首先，配置servlet环境（配置一下Tomcat服务器即可）
然后，重写doGet()方法
就完成了

环境

项目目录
controller

@WebServlet("/download")
public class downloadController extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1、获得下载文件的路径
        String realPath = "/Users/mac/Desktop/servlet/web/学习进度建议.png";
        //2、下载文件的文件名？
        String fileName = realPath.substring(realPath.lastIndexOf("/") + 1);
        //3、设置type，让浏览器支持下载
        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
        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();
    }
}