struts2 action interface

Action interface defines five constants and one no-argument method.

Action interface.

public interface Action {
   public static final String SUCCESS = "success";
   public static final String NONE = "none";
   public static final String ERROR = "error";
   public static final String INPUT = "input";
   public static final String LOGIN = "login";
   public String execute() throws Exception;
}

Example:

login.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
	<head>
	 <title>Struts 2 action interface implementation example</title>
	</head>
	<body>
	     <h3>This is a action interface implementation example.</h3>
 
		<s:property value="message" /> <br/>
 
		<s:form action="Login">
			<s:textfield name="userName" label="UserName" />
			<s:password name="password" label="Password" />
			<s:submit value="login" align="center"/>
		</s:form>
 
	</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 
 
 	<filter>
		<filter-name>struts2</filter-name>
		<filter-class>
        	org.apache.struts2.dispatcher.ng.
        	filter.StrutsPrepareAndExecuteFilter
        </filter-class>
	</filter>
 
	<filter-mapping>
		<filter-name>struts2</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
 
	<welcome-file-list>
	  <welcome-file>login.jsp</welcome-file>
	</welcome-file-list>
 
</web-app>

struts.xml

<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
 
<struts>
 
 <package name="user" extends="struts-default">
   <action name="Login" class="com.w3schools.action.Login">
	  <result name="success">/welcome.jsp</result>
	  <result name="error">/login.jsp</result>
   </action>
  </package>
 
</struts>

Login.java

import com.opensymphony.xwork2.Action;
 
/**
 * This class is used as an action class 
 * and implements Action interface.
 * @author w3schools
 */
public class Login implements Action{
	//data members
	private String userName;
	private String password;
	private String message;
 
	//business logic
	public String execute(){
		if(userName.equals("jai") && 
				password.equals("1234")){
			setMessage("Hello " +userName + ", " +
				"You are successfully logged in.");
			return SUCCESS;
		}else{
			setMessage("Invalid username or password.");
			return ERROR;
		}		
	}	
 
	//getter setters
	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;
	}
	public String getMessage() {
		return message;
	}
	public void setMessage(String message) {
		this.message = message;
	}
}

welcome.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
   <head>
	<title>Struts 2 action interface implementation example</title> 
   </head>
   <body>
	<h3>This is a action interface implementation example.</h3>
	<s:property value="message" />	 
   </body>
</html>

Output:

struts 3 login

Enter UserName: jai , Password: 1234
struts 3 value

Click on login button.
struts 3 final

Download this example.

Next Topic: Action in struts 2 by extending ActionSupport class with example.
Previous Topic: Action in struts 2 by using POJO class with example.