HttpResonse類

常見應用

• 向瀏覽器輸出訊息

• 下載檔案

  • 獲取下載檔案的路徑（絕對路徑）

  • 獲取下載檔名

  • 設定瀏覽器支援下載

  • 獲取下載檔案的輸入流，將所要下載檔案讀入到輸入流中

  • 建立緩衝區

  • 獲取outputstream物件

  • 將輸入流中內容讀到緩衝區中

  • 使用outputstream物件將緩衝區中內容輸出到客戶端！

程式碼展示：

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>