Spring Learning (7)-enhancement class and spring Learning Enhancement class

Spring Learning (7)-enhancement class and spring Learning Enhancement class

Spring cut point

What is a cut point? Pointcut, each program class has multiple connection points, for example, a class with two methods, both methods are connection points, that is, the connection points are objective things in the program class. But how can we locate a certain number of connection points from multiple connection points? AOP locates a specific connection point through a "cut point. The concept of database query can be used to understand the relationship between the cut point and the connection point. The connection point is equivalent to the record in the database, and the cut point is equivalent to the query condition.

Pre-enhancement

Org. springframework. aop. BeforeAdvice indicates the pre-enhancement. Because spring only supports method-level enhancement, MethodBeforeAdvice is currently available and indicates that the pre-enhancement is implemented before the target method is executed.

• Post Enhancement

Org. springframework. aop. AfterAdvice indicates post-enhancement, indicating that the target method is enhanced after execution.

• Surround Enhancement

Org. springframework. aop. MethodInterceptor indicates enhanced surround, indicating enhanced implementation before and after the target method is executed.

• Exception throw Enhancement

Org. springframework. aop. ThrowsAdvice indicates that the exception is thrown and the enhancement is performed after the target method throws an exception.

• Introduction Enhancement

Org. springframework. aop. IntroductionInterceptor indicates introduction enhancement, indicating adding some new methods and attributes to the target class. Pre-enhancement and post-enhancementWaiter interface Waiter. java

package com.paic.zhangqi.spring.aop;  public interface Waiter {      void greetTo(String name);      void serveTo(String name); }

Waiter interface implementation class NaiveWaiter. java

package com.paic.zhangqi.spring.aop;  public class NaiveWaiter implements Waiter {       @Override      public void greetTo(String name) {          System.out.println(greet to +name+...);      }       @Override      public void serveTo(String name) {          System.out.println(serving +name+...);      } }

 

package com.paic.zhangqi.spring.aop;  import java.lang.reflect.Method; import org.springframework.aop.MethodBeforeAdvice;  public class GreetingBeforeAdvice implements MethodBeforeAdvice {            @Override      public void before(Method method, Object[] args, Object obj) throws Throwable {          String clientName = (String)args[ 0 ];          System.out.println(How are you！Mr.+clientName+.);      } }

The post-enhancement class GreetingAfterAdvice. java is executed after the target class method is called.

package com.paic.zhangqi.spring.aop; import java.lang.reflect.Method;import org.springframework.aop.AfterReturningAdvice; public class GreetingAfterAdvice implements AfterReturningAdvice {     @Override    public void afterReturning(Object arg0, Method arg1, Object[] arg2,            Object arg3) throws Throwable {        System.out.println(Please enjoy yourself!);    }}

Test class TestAdvice. java

Package com. paic. zhangqi. spring. aop; import org. springframework. aop. afterAdvice; import org. springframework. aop. beforeAdvice; import org. springframework. aop. framework. proxyFactory; public class TestAdvice {public static void main (String [] args) {Waiter target = new NaiveWaiter (); BeforeAdvice beforeAdvice = new GreetingBeforeAdvice (); afterAdvice afterAdvice = new GreetingAfterAdvice (); // The proxy factory ProxyFactory pf provided by spring = new ProxyFactory (); // sets the proxy target pf. setTarget (target); // Add an enhanced pf for the proxy target. addAdvice (beforeAdvice); pf. addAdvice (afterAdvice); // generate the proxy instance Waiter proxy = (Waiter) pf. getProxy (); proxy. greetTo (John); proxy. serveTo (Tomcat );}}

Output result

How are you！Mr.John.greet to John...Please enjoy yourself!How are you！Mr.Tomcat.serving Tomcat...Please enjoy yourself!

Use the configuration file to configure beans. xml

<beans beans="" http:="" schema="" spring-beans-3.0.xsd="" www.springframework.org="" 
xmlns="http://www.springframework.org/schema/beans" xmlns:p="http://www.springframework.org/schema/p" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://www.springframework.org/schema/beans">　　　　　　<bean class="com.paic.zhangqi.spring.aop.GreetingBeforeAdvice"  id="greetingBefore" />　　　　　　<bean class="com.paic.zhangqi.spring.aop.GreetingAfterAdvice" id="greetingAfter"  />　　　　　　<bean class="com.paic.zhangqi.spring.aop.NaiveWaiter" id="target"  /> </beans>                    

Corresponding test class SpringConfigTest. java

package com.paic.zhangqi.spring.aop; import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; public class SpringConfigTest {     public static void main(String[] args) {        String configPath = com/paic/zhangqi/spring/aop/beans.xml;        ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath);        Waiter waiter = (Waiter) ctx.getBean(waiter);        waiter.greetTo(John);        waiter.serveTo(Tomcat);    }}

Same output

How are you！Mr.John.greet to John...Please enjoy yourself!How are you！Mr.Tomcat.serving Tomcat...Please enjoy yourself!