spring mvc bean scope singleton seem not work properly - spring-mvc

Question

Please help me
I am new spring mvc user. In controller i call a singleton bean like that:
#RequestMapping(value = "/student", method = RequestMethod.GET)
public ModelAndView student(#RequestParam(required = false) String name) {
ApplicationContext context =
new ClassPathXmlApplicationContext(new String[] { "mvc-dispatcher-servlet.xml" });
Student student = (Student) context.getBean("student");
if (name != null && name.length() > 1) {
student.setName(name);
}
System.out.println("name:" + student.getName());
return new ModelAndView("result", "student", student);
}
The first time, i enter url in browser: http://localhost:8080/example/student?name=myname
The system print result like that: name:myname=> it's ok
The second time, i enter url in browser: http://localhost:8080/example/student
The system print result like that: name:null
Why? you said that a single bean instance be created for every request?
So the first time the name of student was set is "myname". The second time, when i request again, if a single bean instance was created, the name of student must be "myname", because it was set in first time request?But in my case, the second time request, seem that a new bean instance be created? So the name value is null
Thanks very much

Answer 1

Spring is doing what you have exactly asked for.
ApplicationContext context =
new ClassPathXmlApplicationContext(new String[] { "mvc-dispatcher-servlet.xml" });
Everytime you are making a request, you are creating a new instance of parent context. And hence you are not getting the bean with a singleton scope.
When you use ,
#Autowired private Student student
you are not creating context for every request. Hence your bean is getting created with a singleton scope.

Answer 2

Singleton instance means through out the applications only single instance of bean will be created by the spring containers like BeanFactory or ApplicationContext.
When ever you supplied your *.xml configuration file to BeanFactory or ApplicationContext containers then they will read specified bean declarations and starts instantiate them as singleton by default.
In your case you are specifying your *.xml to containers for each request to "/student" so, for every request of "/student" instances will be created.
study this link to configure your xml files to spring container for web applications
http://docs.spring.io/autorepo/docs/spring/3.2.x/spring-framework-reference/html/mvc.html