Struts 2 custom interceptor

✔ 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



We can create a custom interceptor in struts 2. To create a custom interceptor implements the Interceptor interface. Interceptor interface provides the methods to create a custom interceptor.

Methods of Interceptor interface:

1. init(): It is used to initialize the interceptor. It is called only once by the web container.
Syntax: public void init()
2. intercept(ActionInvocation invocation): It is used to define the processing logic of the interceptor.
Syntax: public void intercept(ActionInvocation invocation) throws Exception
3. destroy(): It is used for clean-up process before destroying the interceptor.
Syntax: public void destroy()

Struts 2 custom interceptor example:

login.jsp
<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
 <head>
  <title>Struts 2 custom interceptor example</title>
 </head>
 <body>
  <h3>This is a custom interceptor example.</h3>
 
  <s:form action="Login">
   <s:textfield name="userName" label="UserName" />
   <s:submit value="Hello" 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">
 
  <interceptors>  
   <interceptor name="welcomeIntercepter" 
     class="com.javawithease.
      customintercepter.CustomIntercepter">
   </interceptor>  
  </interceptors> 
 
  <action name="Login" 
            class="com.javawithease.action.Login">
    <interceptor-ref name="defaultStack"/> 
    <interceptor-ref name="welcomeIntercepter"/>  
    <result name="success">/welcome.jsp</result>
  </action>
 </package>
 
</struts>
Login.java
/**
 * This class is used as an action class.
 * @author javawithease
 */
public class Login {
 //data members
 private String userName;
 
 //business logic
 public String execute(){
  System.out.println("Login's execute() " +
    "is called...");
  return "success"; 
 } 
 
 //getter setters
 public String getUserName() {
  return userName;
 }
 public void setUserName(String userName) {
  this.userName = userName;
 }
}
CustomIntercepter.java
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
import com.opensymphony.xwork2.util.ValueStack;
 
/**
 * This class is used for custom intercepter.
 * @author javawithease
 */
public class CustomIntercepter  implements Interceptor{
 
 public void init() {
   System.out.println("CustomIntercepter's " +
     "init methods is called.");
 }
 
 public String intercept(ActionInvocation 
   actionInvocation) throws Exception {
  System.out.println("Before " +
    "actionInvocation.invoke() called.");
   ValueStack stack = actionInvocation.getStack();  
      String userName = stack.findString("userName");            
      stack.set("userName","Hi " + userName + 
        ", welcome.");            
      String resultString = actionInvocation.invoke();   
      System.out.println("After " +
        "actionInvocation.invoke() called.");
      return resultString;
 }
 
 public void destroy() {
  System.out.println("CustomIntercepter's " +
    "destroy methods is called.");
 }
 
}
welcome.jsp
<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
 <head>
   <title>Struts 2 custom interceptor example</title>
 </head>
 <body>
   <h3>This is a custom interceptor example.</h3>
   <h4><s:property value="userName" /></h4>  
 </body>
</html>

Output:


 
Enter UserName.

 
Click on Hello button.

On Console:

CustomIntercepter's init methods is called.
Before actionInvocation.invoke() called.
Login's execute() is called...
After actionInvocation.invoke() called.

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