Spring Tutorials

In this chapter we will see that Implementation of AOP based on XML Schema. Before using the AOP we have to add namespaces of AOP to the configuration file as following.Within your Spring configurations, all aspect and advisor elements must be placed within an <aop:config> element .

An <aop:config> element can contain pointcut, advisor, and aspect elements. To use the aop namespace tags described in this section, you need to import the spring-aop schema as described below:

Configuration

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">
<!-- Bean definition & AOP specific configuration -->
</beans>

Within your Spring configurations, all aspect and advisor elements must be placed within an <aop:config> element (you can have more than one <aop:config> element in an application context configuration). An <aop:config> element can contain pointcut, advisor, and aspect elements .

Now You will need the following AspectJ libraries on the classpath of your application. These libraries are available in the 'lib' directory of an AspectJ installation, otherwise you can download them from the internet.

aspectjrt.jar
aspectjweaver.jar
aspectj.jar

Technologies used to run this Application.

Spring 3.0
Eclipse IDE
JDK 1.6

XML Schema Based AOP Example

Let us have working Eclipse IDE in place and follow the following steps to create a Spring application:

Step1. Now you create a simple Java Project using Eclipse IDE. Follow the option File -> New -> Project and finally select Java Project wizard from the wizard list. Now name your project as XmlSchemaBasedAop using the wizard window as given below.

Add spring jar files

Step2. Now add spring jar in your project, To do this, right click on your project name XmlSchemaBasedAop and then follow the following option available in context menu: Build Path -> Configure Build Path to display the Java Build Path window as given below. There are some jar files required to run this application, To load the jar files in eclipse IDE, Right click on your project - Build Path - Add external archives - select all the required jar files - finish. and add the above three jars.

antlr-runtime-3.0.1
org.springframework.aop-3.1.0
org.springframework.asm-3.1.0.
org.springframework.aspects-3.1.0.
org.springframework.beans-3.1.0.
org.springframework.context.support-3.1.0.
org.springframework.context-3.1.0.
org.springframework.core-3.1.0.
org.springframework.expression-3.1.0.
commons-logging-1.1.1

Create Java class file

Step3. Now you create simply java file with any name. First we need to create a package with any name like com.r4r. To do this, Right click on src in package explorer section and follow the option : New -> Package. and then Right click on package(com.r4r) - New - class - Write the class name e.g. Employee - finish. Write the following code:

package com.r4r;
public class Employee {
	private Integer id;
	private String name;
	public void setId(Integer id)
	{
	this.id = id;
	}
	public Integer getId()
	{
	System.out.println("Id : " + id );
	return id;
	}
	public void setName(String name)
	{
	this.name = name;
	}
	public String getName()
	{
	System.out.println("Name : " + name );
	return name;
	}
	public void printThrowException()
	{
	System.out.println("Exception Occurred");
	throw new IllegalArgumentException();
	}
}

Step4. Now you create another Java class named Login.java.

package com.r4r;
public class Login {
	public void beforeAdvice()
	{
	System.out.println("Knowing the Employee Information.");
	}
	public void afterAdvice()
	{
	System.out.println("Finish the Employee Information.");
	}
	public void afterReturningAdvice(Object retVal)
	{
	System.out.println("Returning:" + retVal.toString() );
	}
	public void AfterThrowingAdvice(IllegalArgumentException ex)
	{
	System.out.println("An exception is: " + ex.toString());
	}
}

Step5. Now create the xml file click on src- new -file -give the file name like Beans.xml then finish.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
  http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
  http://www.springframework.org/schema/aop
  http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">
  
<aop:config>
<aop:aspect id="log" ref="login">
<aop:pointcut id="selectAll" expression="execution(* com.r4r.*.*(..))"/>
<aop:before pointcut-ref="selectAll" method="beforeAdvice"/>
<aop:after pointcut-ref="selectAll" method="afterAdvice"/>
<aop:after-returning pointcut-ref="selectAll" 
returning="retVal" method="afterReturningAdvice"/>
<aop:after-throwing pointcut-ref="selectAll" 
throwing="ex" method="AfterThrowingAdvice"/>
</aop:aspect>
</aop:config>

<!-- Definition for employee bean -->
<bean id="employee" class="com.r4r.Employee">
<property name="name" value="John" />
<property name="id" value="01"/>
</bean>
<!-- Definition for login aspect -->
<bean id="login" class="com.r4r.Login"/>
</beans>

Step6.Now Create the java Main class (MainApp.java).

package com.r4r;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.
ClassPathXmlApplicationContext;

public class MainApp {
public static void main(String[] args) {
ApplicationContext context = 
	new ClassPathXmlApplicationContext("Beans.xml");
Employee employee = (Employee) context.getBean("employee");
employee.getName();
employee.getId();
employee.printThrowException();
}
}

Run Application

Now run the Application you see the following output

Knowing the Employee Information.
Name : John
Finish the Employee Information.
Returning: John
Knowing the Employee Information.
Id : 01
Finish the Employee Information.
Returning:01
Knowing the Employee Information.
Exception Occurred
Finish the Employee Information.
An exception is : java.lang.IllegalArgumentException

R4R Topics