是否为struts2动作类提供了任何init方法？

Question

Is there any init method provided for struts 2 action class that can be called before every method of that action class?

For example, I have an action class for struts 2 as given below

import com.opensymphony.xwork2.ActionSupport;

public class EmployeeAction extends ActionSupport{

    private  DepartmentDaoService deptService = new DepartmentDaoService() ;
    private  EmployeeDaoService empService = new EmployeeDaoService();
    private Employee employee;
    private List<Employee> employees;
    private List<Department> departments;

       public void init()
       {
          //Do initialization stuff here
       }

       public String getAllEmployees(){
          employees = empService.getAllEmployees();
          return "success";
       }

       public String deleteEmployee(){
        empService.deleteEmployee(employee.getEmployeeId());
        return "success";
       }
}

Now in above code when struts action for getAllEmployees() and deleteEmplyee() is called I want init() method to execute first. We can run it by calling it from both functions.

But is there any provision given in struts 2 that will run init method automatically on each call or struts 2 provides any such method for action clases?

Please tell me if anyone knows.

Thanks.

Answer 1

看看Preparable接口和Prepare Interceptor 。

Answer 2

Yes there is:

First of all, your action class must implement the Preparable interface . Then, your action must implement Preparable.prepare() method. Struts 2 will execute prepare() everytime before it invokes your action method.

Cheers.

Answer 3

Prepare Interceptor is way to go. If your action is using default interceptor stack just rename your init() method to prepare() .

If your action class has multiple action methods (like createEmployee() or deleteEmployee()) you can do specific preparation for concrete method with method named prepare<*ActionMethodName*>() (eg prepareDeleteEmployee() ).

Answer 4

Yes

init() 

Called after an interceptor is created, but before any requests are processed using intercept , giving the Interceptor a chance to initialize any needed resources.

See this