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Struts2 Interceptor Example

February 12, 2017 Leave a comment

In Struts2 interceptor are called one after other one in a configured order for each invocation of an action class. So with interceptor we can do some perform task like logging, validation before action is called.
In this tutorial it shows how to create an own interceptor in Struts2 (Login and Loggin Interceptor). Sumary steps below.

  • Create a class that implements com.opensymphony.xwork2.interceptor.Interceptor interface and override the intercept(ActionInvocation invocation), init, destroy method.

Interceptor class (AuthInterceptor.java)

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

/**
* The Class AuthInterceptor.
*/
public class AuthInterceptor implements Interceptor {

/** The Constant serialVersionUID. */
private static final long serialVersionUID = 1L;

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#destroy()
*/
public void destroy() {
System.out.println("destroy Auth");
}

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#init()
*/
public void init() {
System.out.println("init Auth");
}

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#intercept(com.opensymphony.xwork2.ActionInvocation)
*/
public String intercept(ActionInvocation invoke) throws Exception {
SessionMap sessionMap = (SessionMap) ActionContext.getContext().getSession();
if(sessionMap.get("user") == null){
return Action.LOGIN;
} else {
return invoke.invoke();
}
}
}

Interceptor class (LogInterceptor.java)

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
/**
* The Class LogInterceptor.
*/
public class LogInterceptor implements Interceptor {

/** The Constant serialVersionUID. */
private static final long serialVersionUID = 1L;

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#destroy()
*/
public void destroy() {
System.out.println("destroy Log");
}

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#init()
*/
public void init() {
System.out.println("init Log");
}

/* (non-Javadoc)
* @see com.opensymphony.xwork2.interceptor.Interceptor#intercept(com.opensymphony.xwork2.ActionInvocation)
*/
public String intercept(ActionInvocation invoke) throws Exception {
String className = invoke.getAction().getClass().getName();
long startTime = System.currentTimeMillis();
System.out.println("Before calling action: " + className);

String result = invoke.invoke();

long endTime = System.currentTimeMillis();
System.out.println("After calling action: " + className + " Time taken: " + (endTime - startTime) + " ms");
return result;
}
}

If any intercept method in interceptor class decides action should not executed,
it can return a string value and response will be created from global result that same name in struts config file.

  • Configure the interceptor in the struts.xml.
<interceptors>
<interceptor name="authentication" class="strutshelloworld.net.ren.struts2.interceptors.AuthInterceptor">
</interceptor>

<interceptor name="logging" class="strutshelloworld.net.ren.struts2.interceptors.LogInterceptor">
</interceptor>

<interceptor-stack name="authStack">
<interceptor-ref name="authentication" />
<interceptor-ref name="logging" />
<interceptor-ref name="defaultStack" />
</interceptor-stack>
</interceptors>
<default-interceptor-ref name="defaultStack"></default-interceptor-ref>
  • Add global result
<action name="index">
<interceptor-ref name="authStack"></interceptor-ref>
<result type="redirect">/home.html</result>
</action>
  • Add interceptor in action
<action name="home" class="strutshelloworld.net.ren.struts2.actions.UserAction">
<interceptor-ref name="authStack"></interceptor-ref>
<result name="success">/WEB-INF/jsp/Welcome.jsp</result>
</action>

For complete code, you can get it in here.
Fyi, I used project in this post as basis.

Thank you. 🙂

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