Interceptor is an object which intercepts an action dynamically. It executed before and after the action execution. It Allows the developers to write a code which can execute and after the action. It executed before and after the code. It can prevent an action before executing.
The mapping of interceptor is done as follows
<interceptors> <interceptor name="Name Of the Interceptor" class="interceptor class path with full package " /> <interceptor name="Name Of the 2nd Interceptor" class="interceptor class path with full package " /> </interceptors>
<action name="actionName" class="actionClass"> <interceptor-ref name="defaultStack"> <param name="validation.excludeMethods">MyValidationMethod</param> </interceptor-ref> </action>
Consider an example of Struts interceptor given bellowADS_TO_REPLACE_1
Login.jsp
<%@ taglib prefix="s" uri="/struts-tags"%> <head> <title>Login Page</title> </head> <body bgcolor="lightblue"> <s:head/> <br> <center><h2><u>Please Login</u></h2></center> <s:form action="doLogin"> <table border=0 align="center"> <tr> <td><s:textfield name="userName" label="User Name" /></td> </tr> <tr> <td><s:submit align="center" value="login" /></td> </tr> </table> </s:form> </body>
Welcome.jsp
<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <%@page import="javax.xml.crypto.Data"%> <%@page import="java.util.Date"%><html> <head> <title>Welcome</title> <link href="<s:url value="/css/examplecss"/>" rel="stylesheet" type="text/css"/> </head> <body> <h1 align="center">You Are Welcome</h1> </body> </html>
error.jspADS_TO_REPLACE_2
<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <html> <head> <title>Error Page</title> </head> <body> <h2>Error Page</h2> Go to <a href="<s:url action="loginPage"></s:url>">Login</a> </body> </html>
LoginModel.java
package net.roseindia.model;
import java.io.Serializable;
public class LoginModel implements Serializable{
private static final long serialVersionUID = -5995468832791791552L;
private String userName;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
}
MyLoginInterCeptor.java
package net.roseindia.interceptor;
import java.util.Date;
import javax.servlet.http.HttpServletRequest;
import net.roseindia.model.LoginModel;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class MyLoginInterCeptor implements Interceptor {
private static final long serialVersionUID = 1L;
String result = null;
String className = null;
long startingTime = 0;
long endingTime = 0;
final HttpServletRequest request = (HttpServletRequest) ActionContext
.getContext().get(ServletActionContext.HTTP_REQUEST);
@Override
public void destroy() {
// TODO Auto-generated method stub
System.out.println("Destroying Interceptor");
}
@Override
public void init() {
// TODO Auto-generated method stub
System.out.println("Intialising Interceptor");
}
@Override
public String intercept(ActionInvocation invocation) throws Exception {
// TODO Auto-generated method stub
className = invocation.getAction().getClass().getName();
startingTime = System.currentTimeMillis();
System.out
.println("Interceptor Starting Time" + new Date(startingTime));
result = invocation.invoke();
System.out.println(result);
endingTime = System.currentTimeMillis();
System.out.println("Interceptor Enging Time " + new Date(endingTime));
System.out.println("Time Taken by the Interceptor "
+ new Date(endingTime - startingTime));
return result;
}
}
LoginAction.javaADS_TO_REPLACE_3
package net.roseindia.action;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import net.roseindia.model.LoginModel;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction extends ActionSupport {
private static final long serialVersionUID = 1L;
ActionContext context = ActionContext.getContext();
HttpServletRequest request = (HttpServletRequest) context
.get(ServletActionContext.HTTP_REQUEST);
HttpSession session;
@Override
public String execute() throws Exception {
return SUCCESS;
}
}LoginAction-validation.xml
<!DOCTYPE validators PUBLIC "-//OpenSymphony Group//XWork Validator 1.0.2//EN" "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd"> <validators> <field name="userName"> <field-validator type="requiredstring"> <message key="requiredstring" /> </field-validator> </field> <field name="password"> <field-validator type="requiredstring"> <message key="requiredstring" /> </field-validator> </field> </validators>
LoginAction.properties
userName = User Name
password = Password
requiredstring = ${getText(fieldName)} is Requiredstruts.xmlADS_TO_REPLACE_4
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="false" /> <package name="roseindia" namespace="/" extends="struts-default"> <interceptors> <interceptor name="loginInterceptor" class="net.roseindia.interceptor.MyLoginInterCeptor" /> </interceptors> <global-results> <result name="error" type="freemarker">/resources/Login.jsp</result> </global-results> <action name="loginPage" method="displayForm" class="net.roseindia.model.LoginModel"> <result name="input">/resources/Login.jsp</result> </action> <action name="doLogin" class="net.roseindia.action.LoginAction"> <interceptor-ref name="loginInterceptor"/> <interceptor-ref name="logger" /> <result name="success">/resources/Welcome.jsp</result> <result name="input">/resources/Login.jsp</result> <result name="error">/resources/error.jsp</result> </action> </package> </struts>
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