The struts 2 framework is a web framework, and provides the function of data subpackage

Data encapsulation property driven encapsulation

set method provided by property driven encapsulation (not commonly used)

Let's take an example to explain:
Let's start with a simple user form submission page

Key jsp code:

 <form action="${pageContext.request.contextPath}/userAction.action" method="post">
name: <input type="text" name="firstname"><br>
password: <input type="password" name="lastname"><br>
age: <input type="text" name="age"><br>
birthday:<input  type="text" name="birthday"><br>
salary:<input  type="text" name="salary"><br>
<input  type="submit" value="Submission">
</form>

Write Action main code

//We use the second way to inherit
public  Class UserAction extends ActionSupport {
	private String username;
	private String password;
	private Integer age;
	private Date birthday;
	private Double salary;
	//Their set method
	....
	public String execute() throws Exception{
		//Encapsulated data
		User user = new User();// Database User table and User class need to be established -- hbt is not the focus of this time
		user.setUsername(username);
		user.setPassword(password);
		user.setAge(age);
		user.setBirthday(birthday);
		user.Salary(salary);
		return NONE;

How to submit expression in property driven page

Key jsp code

 <form action="${pageContext.request.contextPath}/userAction.action" method="post">
name: <input type="text" name="user.firstname"><br>
password: <input type="password" name="user.lastname"><br>
age: <input type="text" name="user.age"><br>
birthday:<input  type="text" name="user.birthday"><br>
salary:<input  type="text" name="user.salary"><br>
<input  type="submit" value="Submission">
</form>

Action key code

public class UserAction extends ActionSupport{
private User user;//1. Provide a user object
//2. Providing the set and get method interceptors will create this object and encapsulate it in your, so you must give the set method
...

Model driven (most commonly used)

Key jsp

 <form action="${pageContext.request.contextPath}/userAction.action" method="post">
name: <input type="text" name="firstname"><br>
password: <input type="password" name="lastname"><br>
age: <input type="text" name="age"><br>
birthday:<input  type="text" name="birthday"><br>
salary:<input  type="text" name="salary"><br>
<input  type="submit" value="Submission">
</form>

Writing Action

public class UserAction extends ActionSuppert implements ModelDriven<User>{
//Create objects manually
private User user = new User();
//2. Provide getModel method
public User getModel(){
	return user;
	}
	//It's self-contained
}

Disadvantage: only one object can be encapsulated at the same time
But the second one can encapsulate multiple objects (supplementary)