JavaWeb——ServletContext

1. Concept: representative of the web application, the container may program (server) to communicate

2. Get:

1. Get the request object

  ServletContext context1 = request.getServletContext();

2. Get through HttpServlet

 ServletContext context2 = this.getServletContext();

3. Function:

1. Obtain the MIME type

MIME types: a definition file in Internet communication process data type

• Format: Large type / small type text / html image / jpeg
• Gets:
  String getMimeType (String File);

For example:

 //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);//image/jpeg
        System.out.println(mimetype);

2. domain objects: data sharing

1.setAttribute(String name,Object value)
2.getAttribute(String name)
3.removeAttribute(String name)

ServletContext 对象范围：所有用户所有请求的数据

3. Get real files (server) path

method:

String   getRealPath(String path)

image.png

Reproduced in: https: //www.jianshu.com/p/197b52c9e8c0