AOP(切面、通知、切入点、切面优先级)
示例：
1.项目目录
2.MathI.java(接口)
package com.atguigu.spring.aop;
public interface MathI {
int add(int i, int j);
int sub(int i, int j);
int mul(int i, int j);
int div(int i, int j);
}
3.MathImpl.java（实现类）
package com.atguigu.spring.aop;
import org.springframework.stereotype.Component;
@Component
public class MathImpl implements MathI{
@Override
public int add(int i, int j) {
int result = i + j;
return result;
}
@Override
public int sub(int i, int j) {
int result = i - j;
return result;
}
@Override
public int mul(int i, int j) {
int result = i * j;
return result;
}
@Override
public int div(int i, int j) {
int result = i / j;
return result;
}
}
4.MyLoggerAspect.java（切面–>日志）
package com.atguigu.spring.aop;
import java.util.Arrays;
import org.aopalliance.intercept.Joinpoint;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
@Component
@Aspect//标注当前类为切面
@Order(1)
public class MyLoggerAspect {
//AspectJ支持的5种类型的通知注解
//重用切入点定义
@Pointcut(value="execution(* com.atguigu.spring.aop.*.*(..))")
public void test(){
}
/**
* @Before：将方法指定为前置通知
* 必须设置value,其值为切入点表达式
* 前置通知：作用于方法执行之前
*/
//前置通知
// @Before(value = "execution(public int com.atguigu.spring.aop.MathImpl.add(int, int))")
// @Before(value = "execution(public int com.atguigu.spring.aop.MathImpl.*(int,int))")
// @Before(value = "execution(* com.atguigu.spring.aop.MathImpl.*(int,int))")
// @Before(value = "execution(* com.atguigu.spring.aop.*.*(int,int))")
// @Before(value = "execution(* com.atguigu.spring.aop.*.*(..))")
@Before(value = "test()")
public void beforeMethod(JoinPoint joinPoint){
Object[] args = joinPoint.getArgs();//获取方法的参数
String methodName = joinPoint.getSignature().getName();//获取方法名
System.out.println("method:" + methodName + ",arguments:" + Arrays.toString(args));
}
/**
* @After:将方法标注为后置通知
* 后置通知：作用于方法的finally语句块，即不管有没有异常都会执行
*/
//后置通知
//@After(value = "execution(* com.atguigu.spring.aop.*.*(..))")
@After(value = "test()")
public void afterMethod(){
System.out.println("后置通知");
}
/**
* @AfterReturning：将方法标注为返回通知
* 返回通知：作用于方法执行之后
* 要通过returning设置接收方法返回值的变量名
* 要向在方法中使用，必须在方法的形参中设置和变量名相同的参数名的参数
*/
@AfterReturning(value = "execution(* com.atguigu.spring.aop.*.*(..))",returning="result")
public void afterReturing(JoinPoint joinPoint, Object result){
String methodName = joinPoint.getSignature().getName();
System.out.println("method:" + methodName + ",result:" + result);
}
/**
* @AfterThrowing：将方法标注为异常通知（例外通知）
* 异常通知：作用于方法抛出异常时
* 可通过throwing设置接受方法返回的异常信息
* 在参数列表中可通过具体的异常类型，来对指定的异常信息进行操作
*/
@AfterThrowing(value = "execution(* com.atguigu.spring.aop.*.*(..))", throwing="ex")
public void afterThrowing(Exception ex){
System.out.println("有异常了,messages"+ex);
}
//处理特定异常
// @AfterThrowing(value = "execution(* com.atguigu.spring.aop.*.*(..))", throwing="ex")
// public void afterThrowing(NullPointerException ex){
// System.out.println("有异常了,messages"+ex);
// }
/**
* @Around：
*/
@Around(value = "execution(* com.atguigu.spring.aop.*.*(..))")
public Object aroundMethod(ProceedingJoinPoint joinPoint){
Object result = null;
try {
//前置通知
System.out.println("前置通知");
result = joinPoint.proceed();//执行方法
//返回通知
System.out.println("返回通知");
return result;
} catch (Throwable e) {
// TODO Auto-generated catch block
e.printStackTrace();
//异常通知
System.out.println("异常通知");
}finally{
//后置通知
System.out.println("后置通知");
}
return -1;
}
}
5.TestHandler.java
package com.atguigu.spring.aop;
import org.springframework.stereotype.Component;
@Component
public class TestHandler {
public void test(){
System.out.println("测试切入点表达式");
}
}
6.TestAspect.java（切面–>另一个切面，用来测试切面优先级）
package com.atguigu.spring.aop;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
@Component
@Aspect
@Order(0)//定义切面作用的优先级，值越小优先级越高，默认值为int的最大值
public class TestAspect {
@Before(value="execution(* com.atguigu.spring.aop.*.*(..))")
public void before(){
System.out.println("TestAspect====>前置通知");
}
}
7.Test.java（测试类）
package com.atguigu.spring.aop;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml");
MathI math = ac.getBean("mathImpl", MathI.class);
int i = math.div(1, 1);
System.out.println(i);
// TestHandler bean = ac.getBean("testHandler", TestHandler.class);
// bean.test();
}
}