Struts2 the method in which the action receives the parameter: properties, Model,modeldriver

There are three main methods of action receiving parameters in Struts2:
1. Receive parameters using the properties of the action:
A. Definition: Define attributes in the action class, create get and set methods;
B. Receive: Receive parameters through attributes, such as: UserName;
C. Send: Use property name to pass parameters, such as: USER1!ADD?USERNAME=MAGCI;
2. Use Domainmodel to receive parameters:
A. Definition: Define the Model class, define the object of the model class (without new) in the action, and create the Get and set methods of the object;
B. Receive: Parameters are received through the properties of the object, such as: User.getusername ();
C. Send: Use the properties of the object to pass parameters, such as: USER2!ADD?USER.USERNAME=MGC;
3. Use Modeldriven to receive parameters:
A. Definition: The action implements the Modeldriven generic interface, defines the object of the model class (must be New), and returns the object through the Getmodel method;
B. Receive: Parameters are received through the properties of the object, such as: User.getusername ();
C. Send: Pass parameters directly using attribute names, such as: USER2!ADD?USERNAME=MGC

Struts2 Action gets table conveys value
1. Through property-driven
Jsp:

<form action= "Sys/login.action" method= "POST" >
  <input type= "text" name= "username" >
  <input Type= "Submit" value= "Submit" >
 </form>

Action: Gets directly through the get, set method.

public class Sysaction extends actionsupport{
 private String username;

 Public String Login () throws Exception {
  System.out.println (username);
  return SUCCESS;
 }

 Public String GetUserName () {return
  username;
 }
 public void Setusername (String username) {
  this.username= username;
 }
}

2. Model-driven mode, the Modeldriven<t> interface must be implemented. Inconvenient for the second way to pass in multiple model
Jsp:

<form action= "Sys/login.action" method= "POST" >
  <input type= "text" name= "username" >
  <input Type= "Submit" value= "Submit" >
 </form>

Action: The Getmodel () method must be implemented

public class Sysaction extends Actionsupport implements modeldriven<user>{
 Private user user;

 Public String Login () throws Exception {
  System.out.println (Getmodel (). GetUserName ());
  return SUCCESS;
 }

 Public User Getmodel () {
  if (null = = user) {return
   user = new User ();
  }
  return user;
 }

3. The third Way is to not implement MODELDRIVEN<T> at all, or to use the properties of multiple model objects.
Jsp:

<form action= "Sys/login.action" method= "POST" >
  <input type= "text" name= "User.username" >
  < Input type= "text" name= "Teacher.level" >
  <input type= "Submit" value= "Submit" >
 </form>

Action: The set method must be supplied

public class Sysaction extends private user user;

 Private Teacher Teacher;
  Public String Login () throws Exception {System.out.println (User.getusername ());
  System.out.println (Teacher.getlevel ());
 return SUCCESS;
 public void SetUser (user user) {this.user = user;
 public void Setteacher (Teacher Teacher) {this.teacher = Teacher; }
}