Spring AOP面向切面

AOP面向切面，通过预编译和运行期动态代理实现程序功能的统一维护

AOP可以使业务各个部分隔离，使业务耦合降低，提升重用性和开发效率

面向接口编程

public interface StudentService {

	public void addStudent(String name);
}

实现类

public class StudentServiceImpl implements StudentService{

	@Override
	public void addStudent(String name) {
		// System.out.println("开始添加学生"+name);
		System.out.println("添加学生"+name);
		// System.out.println("完成学生"+name+"的添加");
	}

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
	
	<bean id="studentService" class="com.java.service.impl.StudentServiceImpl"></bean>
	
</beans>

接口多态

父类的引用直接指向具体的实现

接口调用add方法

public class T {

	private ApplicationContext ac;

	@Before
	public void setUp() throws Exception {
		ac=new ClassPathXmlApplicationContext("beans.xml");
	}

	@Test
	public void test1() {
		StudentService studentService=(StudentService)ac.getBean("studentService");
		studentService.addStudent("张三");
	}
	

}

日志记录

前置通知，后置通知，环绕通知，返回通知，异常通知

前置通知执行方法前执行操作

public class StudentServiceAspect {
public void doBefore(JoinPoint jp){
		System.out.println("类名:"+jp.getTarget().getClass().getName());
		System.out.println("方法名："+jp.getSignature().getName());
		System.out.println("开始添加学生："+jp.getArgs()[0]);
	}
}

aop:aspect 定义切面类

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aop:pointcut spring的切点定义到方法 (返回值 包路径 *.*(类和方法名) 方法的参数）

<?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.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
	
	<bean id="studentServiceAspect" class="com.java.advice.StudentServiceAspect"></bean>

	<aop:config>
		<aop:aspect id="studentServiceAspect" ref="studentServiceAspect">
			<aop:pointcut expression="execution(* com.java.service.*.*(..))" id="businessService"/>
			<aop:before method="doBefore" pointcut-ref="businessService"/>
			<aop:after method="doAfter" pointcut-ref="businessService"/>
			<aop:around method="doAround" pointcut-ref="businessService"/>
			<aop:after-returning method="doAfterReturning" pointcut-ref="businessService"/>
			<aop:after-throwing method="doAfterThrowing" pointcut-ref="businessService" throwing="ex"/>
		</aop:aspect> 
	</aop:config>
</beans>

上面的配置已经把service都扫描进去，在执行addService的时候通过配置aop;before 通过代理先执行doBefore方法

​public class StudentServiceImpl implements StudentService{

	@Override
	public void addStudent(String name) {
		System.out.println("添加学生"+name);
		System.out.println(1/0);
	}

}

​

切面类的其他通知

环绕通知doAround有返回值为addStudent方法的返回值，当要执行方法时候先执行proceed调用代理执行业务的方法

返回通知 方法要返回return之前的通知，方法还没有执行完

异常通知 Throwable 异常解析

	public void doAfter(JoinPoint jp){
		System.out.println("类名:"+jp.getTarget().getClass().getName());
		System.out.println("方法名："+jp.getSignature().getName());
		System.out.println("学生添加完成："+jp.getArgs()[0]);
	}
	
	public Object doAround(ProceedingJoinPoint pjp) throws Throwable{
		System.out.println("添加学生前");
		Object retVal=pjp.proceed();
		System.out.println(retVal);
		System.out.println("添加学生后");
		return retVal;
	}
	
	public void doAfterReturning(JoinPoint jp){
		System.out.println("返回通知");
	}
	
	public void doAfterThrowing(JoinPoint jp,Throwable ex){
		System.out.println("异常通知");
		System.out.println("异常信息："+ex.getMessage());
	}