Here we have taken the logging aspect as a cross cutting concern.
Created LoginAspect.java and made it aspect using @Aspect and written advice using
@Before("execution(public String getName())")
The two object classes we have used is Circle and Triangle, where both having simple attribute name with getter and setter.
So we need to log it whenever the getter called.
We have created ShapeService class to get the object, for better standard way to present.
AppMain.java is used to test the application.
1. create AOP - simple maven app
2. create xml - spring.xml
need to have name spaces with aop , search for xml with aspectj-autoproxy
<aop:aspectj-autoproxy />
3. create service class ShapeService
4. create model, dto class Triangle,Circle
just add one variable name;
ShapeService add reference to model
5. let's create bean definition for Triangle
<bean name="triangle" class="org.aop.model.Triangle">
<property name="name" value="Traingle name"></property>
</bean>
<bean name="circle" class="org.aop.model.Circle">
<property name="name" value="Circle name"></property>
</bean>
<bean name="shapeService" class="org.aop.service.ShapeService"
autowire="byName"></bean>
6. Test bean creation with main method
public class AppMain {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"spring.xml");
// you need to cast if not use second parameter ShapeService.class
ShapeService shapeService = ctx.getBean("shapeService",
ShapeService.class);
System.out.println(shapeService.getCircle().getName());
}
}
Once you run main method output will be
===============
Circle name
=====================
7. for AOP you need below dependencies
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.7.3</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.11</version>
</dependency>
8. Use case we are discussing is adding log.
First thing = we need to write Aspect = LoginAspect
public class LoginAspect {
public void loginAdvice() {
System.out.println("Login advice run::get method called");
}
}
9. Aspect may contain more than once advice. This is standard terminology.
Next we need to convert the std class for Aspect.
use annotation @Aspect
10. Now we have advice
need to tell spring , congiure that logging need to happen when getName() called
For this moment , I need to run before
Then we have to tell before what
1. So we include:: @Before
2. say when:: "execution"
3. tell execution which method:: public String getName()
@Before("execution(public String getName())")
@Aspect
public class LoginAspect {
@Before("execution(public String getName())")
public void loginAdvice() {
System.out.println("Login advice run::get method called");
}
}
11. Now we need to give bean definition.
<bean name="loginAspect" class="org.aop.aspect.LoginAspect"></bean>
12. Run and get the output
=====================================
Login advice run::get method called
Circle name
===================================
So what happens if we run for Triangle
public class AppMain {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"spring.xml");
// you need to cast if not use second parameter ShapeService.class
ShapeService shapeService = ctx.getBean("shapeService",
ShapeService.class);
System.out.println(shapeService.getTriangle().getName());
}
}
=====================================
Login advice run::get method called
Traingle name
===================================
Note : We have not code inside objects. Spring framework does the work for us.
Final coding
POM.XML this include more dependencies , more than needed
----------------------------------------------------------------------------------------
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.test</groupId>
<artifactId>AOP</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>AOP</name>
<description>Aspect Oriented Programming</description>
<properties>
<jdk.version>1.6</jdk.version>
<spring.version>3.2.8.RELEASE</spring.version>
<spring.security.version>3.2.3.RELEASE</spring.security.version>
<jstl.version>1.2</jstl.version>
<javax.servlet.version>3.1.0</javax.servlet.version>
<mysql.connector.version>5.1.30</mysql.connector.version>
</properties>
<dependencies>
<!-- Spring 3 dependencies -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- spring jdbc -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- Spring Security -->
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-web</artifactId>
<version>${spring.security.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-config</artifactId>
<version>${spring.security.version}</version>
</dependency>
<!-- AOP -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.7.3</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.11</version>
</dependency>
<!-- connect to mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.connector.version}</version>
</dependency>
</dependencies>
</project>
----------------------------------------------------------------------------------------
spring.xml - bean definition
----------------------------------------------------------------------------------------
<?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:aspectj-autoproxy />
<bean name="triangle" class="org.aop.model.Triangle">
<property name="name" value="Traingle name"></property>
</bean>
<bean name="circle" class="org.aop.model.Circle">
<property name="name" value="Circle name"></property>
</bean>
<bean name="shapeService" class="org.aop.service.ShapeService"
autowire="byName"></bean>
<bean name="loginAspect" class="org.aop.aspect.LoginAspect"></bean>
</beans>
----------------------------------------------------------------------------------------
Circle.java
----------------------------------------------------------------------------------------
package org.aop.model;
public class Circle {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Triangle.java
----------------------------------------------------------------------------------------
package org.aop.model;
public class Triangle {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
ShapeService .java
----------------------------------------------------------------------------------------
package org.aop.service;
import org.aop.model.Circle;
import org.aop.model.Triangle;
public class ShapeService {
private Circle circle;
private Triangle triangle;
public Circle getCircle() {
return circle;
}
public void setCircle(Circle circle) {
this.circle = circle;
}
public Triangle getTriangle() {
return triangle;
}
public void setTriangle(Triangle triangle) {
this.triangle = triangle;
}
}
LoginAspect .java
----------------------------------------------------------------------------------------
package org.aop.aspect;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
@Aspect
public class LoginAspect {
@Before("execution(public String getName())")
public void loginAdvice() {
System.out.println("Login advice run::get method called");
}
}
AppMain .java
--------------------------------------------------------------------------------------------------------------------------
package org.aop.main;
import org.aop.service.ShapeService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppMain {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"spring.xml");
// you need to cast if not use second parameter ShapeService.class
ShapeService shapeService = ctx.getBean("shapeService",
ShapeService.class);
System.out.println(shapeService.getTriangle().getName());
}
}
No comments:
Post a Comment