ServletContext获取以及ServletContext获取MIME类型

ServletContext获取

获取：

　　1、通过request对象获取

request.getServletContext();

　　2、通过HttpServlet获取

this.getServletContext();

 

 

@WebServlet("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /**
         * ServletContext对象获取：
         * 　　1、通过request对象获取
         *      request.getServletContext();
         * 　　2、通过HttpServlet获取
         *      this.getServletContext();
         */

        //通过request对象获取
        ServletContext servletContext = req.getServletContext();
        //通过HttpServlet获取
        ServletContext servletContext1 = this.getServletContext();

        System.out.println(servletContext);
        System.out.println(servletContext1);

        System.out.println(servletContext==servletContext1);

    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
}

 

 

 

 

 

 

 

 

 

ServletContext获取MIME类型

获取MIME类型：

　　MIME类型：在互联网通信过程中定义的一种文件数据类型

　　　　格式：大类型/小类型      text/html     image/jpeg

　　获取：String getMimeType(String file)

@WebServlet("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /**
         * 获取MIME类型：
         * 　　MIME类型：在互联网通信过程中定义的一种文件数据类型
         * 　　　　格式：大类型/小类型      text/html     image/jpeg
         * 　　获取：String getMimeType(String file)
         */
        //通过HttpServlet获取
        ServletContext context = this.getServletContext();

        //定义文件名称
        String filename = "a.jpg";

        //获取MIME类型
        String mimeType = context.getMimeType(filename);
        System.out.println(mimeType);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
}