HttpResonse类

HttpResonse类

常见应用

• 向浏览器输出消息

• 下载文件

  • 获取下载文件的路径（绝对路径）

  • 获取下载文件名

  • 设置浏览器支持下载

  • 获取下载文件的输入流，将所要下载文件读入到输入流中

  • 创建缓冲区

  • 获取outputstream对象

  • 将输入流中内容读到缓冲区中

  • 使用outputstream对象将缓冲区中内容输出到客户端！

代码展示：

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String realPath = "D:\\javaweb-sevlet\\response\\src\\main\\resources\\m.png";
        System.out.println(realPath);
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
        resp.setHeader("Content-disposition","attachment;filename="+ URLEncoder.encode(filename,"UTF-8"));
        FileInputStream in = new FileInputStream(realPath);
        int len=0;
        byte[] buffer = new byte[1024];
        ServletOutputStream out = resp.getOutputStream();
        while ((len=in.read(buffer))>0){
            out.write(buffer,0,len);
        }
        in.close();
        out.close();
    }

<servlet>
  <servlet-name>down</servlet-name>
  <servlet-class>com.zhou.servlet.FileServlet</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>down</servlet-name>
  <url-pattern>/down</url-pattern>
</servlet-mapping>