Javaweb中的ServletContext对象

ServletContext对象

概念：代表整个Web应用，可以和程序的容器（服务器）来通信
获取

1. 通过request对象获取
      req.getServletContext()
   2.通过HttpServlet获取
   this.getServletContext();
   代码实现

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        ServletContext servletContext = req.getServletContext();
        System.out.println(servletContext);
        ServletContext servletContext1 = this.getServletContext();
        System.out.println(servletContext1);
        System.out.println(servletContext==servletContext1);

    }

功能

• 获取MIME类型
     MIME类型：在互联网通信过程中定义的一中文本数据类型
     格式： 大类型/小类型    text/html    image/jpeg
  代码实现

     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
        
    ServletContext servletContext = req.getServletContext();
    File file = new File("a.txt");
    String filename="a.jpg";
    String mimeType = servletContext.getMimeType(filename);
    System.out.println(mimeType);
  }
  

• 域对象：共享数据
  getAttribute(String name)
  setAttribute(String name,Object value)
  removeAttribute(String name)
  对象范围：所有对象请求的所有数据
• 获取文本真实（服务器）路径
  context.getRealPath();