第一种：一般类，带有public String execute()方法。

另外一种：继承LoginActionInterface implements Action接口的类。

第三种：继承LoginActionSupport extends ActionSupport抽象类的类。

结构图

三个类的详细写法，也贴上来供大家參考

package com.test.action;

import com.test.dao.UserCheck;
import com.test.vo.User;

public class LoginAction {
	private String username;
	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	private String password;
	
	public String execute()
	{
		User u=new User();
		u.setUsername(this.getUsername());
		u.setPassword(this.getPassword());
		
		/*调用业务逻辑层代码*/
		UserCheck check=new UserCheck();
		if(check.login(u))
		{
			return "login_ok";
		}
		else
		{
			return "login_fail";
		}
		
	}
}

package com.test.action;

import com.opensymphony.xwork2.Action;
import com.test.dao.UserCheck;
import com.test.vo.User;

public class LoginActionInterface implements Action{
	private String username;
	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	private String password;
	
	public String execute()
	{
		User u=new User();
		u.setUsername(this.getUsername());
		u.setPassword(this.getPassword());
		
		/*调用业务逻辑层代码*/
		UserCheck check=new UserCheck();
		if(check.login(u))
		{
			return "login_ok";
		}
		else
		{
			return "login_fail";
		}
		
	}
}

package com.test.action;

import com.opensymphony.xwork2.ActionSupport;
import com.test.dao.UserCheck;
import com.test.vo.User;

public class LoginActionSupport extends ActionSupport{
	
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	public LoginActionSupport()
	{
		System.out.println("LoginActionSupport");
	}
	private String username;
	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	private String password;
	
	public String execute()
	{
		User u=new User();
		u.setUsername(this.getUsername());
		u.setPassword(this.getPassword());
		
		/*调用业务逻辑层代码*/
		UserCheck check=new UserCheck();
		if(check.login(u))
		{
			return "login_ok";
		}
		else
		{
			return "login_fail";
		}
		
	}
}

事实上我们发现。仅仅要具有public String execute()这种方法即可了。还要注意，在继承ActionSupport的时候。默认的execute()是返回success。