1.获取ServletContext对象

• 两种方式
  1.通过request获取
  ServletContext servletContext = request.getServletContext();
  2.通过HttpServlet获取
  ServletContext servletContext = this.getServletContext();
• 代码

@WebServlet("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //通过request获取
        ServletContext servletContext = request.getServletContext();
        //通过HttpServlet获取
        ServletContext servletContext1 = this.getServletContext();
    }
}

2.功能

2.1 获取MIME对象

servletContext.getMimeType();

• 步骤
  1.通过HttpServlet获取ServletContext对象
  2.定义文件名称
  3.获取MIME类型

@WebServlet("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //通过HttpServlet获取
        ServletContext servletContext = this.getServletContext();
        //定义文件名称
        String filename = "a.jpg";
        //获取MIME类型
        String mimeType = servletContext.getMimeType(filename);
        System.out.println(mimeType);
    }
}

• 结果：image/jpeg

2.2 域对象:共享数据

1. setAttribute(string name,object value)
2. getAttribute( string hame)
3. removeAttribute(string name)

• 作用范围
  Servletcontext对象范围:所有用户所有请求的数据

2.3 获取文件真实路径（服务器路径）

• String getRealPath(String path)