Struts 2 Zero Configuration by annotation approach

✔ STRUTS 2 CHAPTERS:-

1. Struts2 Overview
2. Struts2 Architecture
3. Struts2 Configuration Files
4. Action in Struts2
5. Action in Struts2 by using Pojo Class
6. Action in struts2 by Implementing Action Interface
7. Action in Struts2 by Extending Action Support Class
8. Struts2 Hello World Example
9. Multiple Configuration File in Struts2
10. OGNL in Struts2
11. Value Stack in Struts2
12. Interceptors in Struts2
13. Struts2 Execandwait Interceptor
14. Struts2 Custom Interceptor
15. Struts2 Result type
16. Struts2 Redirect result type
17. Struts2 Validation Framework
18. Struts2 Validation by Built in validators
19. Struts2 i18n
20. Struts2 Zero Configuration by convention approach
21. Struts2 Zero Configuration by annotation Approach
22. Dispatch Action Functionality in Struts2
23. Dynamic method invocation in Struts2
24. Struts2 UI Tags
25. Struts2 Control Tags
26. Struts2 Data Tags
27. Struts2 and tiles integration
28. Struts2 and Quartz2 Schedular
29. Struts2 Interview Questions and Answers

As we discussed how to create a struts application using struts.xml file. Struts framework also provides a way to create a struts application without using struts.xml file. Struts framework provides the annotation to achieve this. A struts application without using struts.xml file is also known as application with Zero Configuration.

Some useful annotations.

1. @Action: It is used for action mapping for execute method or marking a class as action class.

2. @Result: It is used to specify the view screen based on the outcome of execute method.

3. @Results: It is used to define multiple results for an action. It is a collection of results.

4. @RequiredFieldValidator: It is used to perform required validation on the field.

Struts 2 Zero Configuration by annotation approach example:

login.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
       <head>
  <title>Struts 2 zero configuration by
                                 annotation approach example</title>
 </head>
 <body>
  <h3>This is a zero configuration by 
                                    annotation approach 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>

Login.java

import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Result;
import com.opensymphony.xwork2.ActionSupport;
 
/**
 * This class is used as an action class.
 * @author javawithease
 */
@Action(value="login", results={
 @Result(name="success",location="/welcome.jsp"),
 @Result(name="error",location="/login.jsp")
})
public class Login extends ActionSupport{
 //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;
 }
}

login-error.jsp

<jsp:include page="/login.jsp"></jsp:include>

login-error.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
 <head>
  <title>Struts 2 zero configuration by 
                            annotation approach example</title>
 </head>
 <body>
  <h3>This is a zero configuration by 
                              annotation approach example.</h3>
 
  <s:property value="message" />
 
 </body>
</html>