基于注解的AOP 方式
1.加入jar包
com.springsource.org.aopalliance-1.0.0.jar
com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
commons-logging-1.1.3.jar
spring-aop-4.1.0.RELEASE.jar
spring-aspects-4.1.0.RELEASE.jar
spring-beans-4.1.0.RELEASE.jar
spring-context-4.1.0.RELEASE.jar
spring-core-4.1.0.RELEASE.jar
spring-expression-4.1.0.RELEASE.jar
2.在配置文件中加入AOP的命名空间
3.基于注解的方式
①在配置文件中加入如下配置
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
②把横切关注点的代码抽象到切面的类中
切面首先是一个IOC中的bean，即加入@Component注解
切面还需要加入@Aspect注解
③在类中声明各种通知
@Before 前置通知，在方法执行之前执行
@After 后置通知，在方法执行之后执行
@AfterRunning 返回通知，在方法返回结果之后执行
@AfterThrowing 异常通知，在方法抛出异常之后执行
@Around 环绕通知，围绕着方法执行
③在方法中声明一个类型为JoinPoint的参数就可以访问链接细节
ArithmeticCalculator接口
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package com.spring.aop.impl;
public interface ArithmeticCalculator {
public int add(int i, int j);
public int sub(int i, int j);
public int mul(int i, int j);
public int div(int i, int j);
} |
接口实现类 ArithmeticCalculatorImpl.java
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package com.spring.aop.impl;
import org.springframework.stereotype.Component;
@Componentpublic class ArithmeticCalculatorImpl implements ArithmeticCalculator{
@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;
}
} |
切面类 LoggingAspect.java
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package com.spring.aop.impl;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
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.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
//指定切面的优先级，当有多个切面时，数值越小优先级越高@Order(1)
//把这个类声明为一个切面：需要把该类放入到IOC容器中。再声明为一个切面.@Aspect@Componentpublic class LoggingAspect {
/**
* 声明切入点表达式，一般在该方法中不再添加其他代码。
* 使用@Pointcut来声明切入点表达式。
* 后面的通知直接使用方法名来引用当前的切入点表达式。
*/
@Pointcut("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))")
public void declareJoinPointExpression() {}
/**
*前置通知，在目标方法开始之前执行。
*@Before("execution(public int com.spring.aop.impl.ArithmeticCalculator.add(int, int))")这样写可以指定特定的方法。
* @param joinpoint
*/
@Before("declareJoinPointExpression()")
//这里使用切入点表达式即可。后面的可以都改成切入点表达式。如果这个切入点表达式在别的包中，在前面加上包名和类名即可。
public void beforeMethod(JoinPoint joinpoint) {
String methodName = joinpoint.getSignature().getName();
List<Object>args = Arrays.asList(joinpoint.getArgs());
System.out.println("前置通知：The method "+ methodName +" begins with " + args);
}
/**
*后置通知，在目标方法执行之后开始执行，无论目标方法是否抛出异常。
*在后置通知中不能访问目标方法执行的结果。
* @param joinpoint
*/
@After("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(int, int))")
public void afterMethod(JoinPoint joinpoint) {
String methodName = joinpoint.getSignature().getName();
//List<Object>args = Arrays.asList(joinpoint.getArgs()); 后置通知方法中可以获取到参数
System.out.println("后置通知：The method "+ methodName +" ends ");
}
/**
*返回通知，在方法正常结束之后执行。
*可以访问到方法的返回值。
* @param joinpoint
* @param result 目标方法的返回值
*/
@AfterReturning(value="execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))", returning="result")
public void afterReturnning(JoinPoint joinpoint, Object result) {
String methodName = joinpoint.getSignature().getName();
System.out.println("返回通知：The method "+ methodName +" ends with " + result);
}
/**
*异常通知。目标方法出现异常的时候执行，可以访问到异常对象，可以指定在出现特定异常时才执行。
*假如把参数写成NullPointerException则只在出现空指针异常的时候执行。
* @param joinpoint
* @param e
*/
@AfterThrowing(value="execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))", throwing="e")
public void afterThrowing(JoinPoint joinpoint, Exception e) {
String methodName = joinpoint.getSignature().getName();
System.out.println("异常通知：The method "+ methodName +" occurs exception " + e);
}
/**
* 环绕通知类似于动态代理的全过程，ProceedingJoinPoint类型的参数可以决定是否执行目标方法。
* @param point 环绕通知需要携带ProceedingJoinPoint类型的参数。
* @return 目标方法的返回值。必须有返回值。
*/
/*不常用
@Around("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))")
public Object aroundMethod(ProceedingJoinPoint point) {
Object result = null;
String methodName = point.getSignature().getName();
try {
//前置通知
System.out.println("The method "+ methodName +" begins with " + Arrays.asList(point.getArgs()));
//执行目标方法
result = point.proceed();
//翻译通知
System.out.println("The method "+ methodName +" ends with " + result);
} catch (Throwable e) {
//异常通知
System.out.println("The method "+ methodName +" occurs exception " + e);
throw new RuntimeException(e);
}
//后置通知
System.out.println("The method "+ methodName +" ends");
return result;
}
*/
} |
applicationContext.xml
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<?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"
xmlns:context="http://www.springframework.org/schema/context"
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-4.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
<!-- 配置自动扫描包 -->
<context:component-scan base-package="com.spring.aop.impl"></context:component-scan>
<!-- 使AspectJ注解起作用：自动为匹配的类生产代理对象 -->
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
</beans>
|
Main.java
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package com.spring.aop.impl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
//创建spring IOC容器
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
//从IOC容器中获取bean实例
ArithmeticCalculator arithmeticCalculator = applicationContext.getBean(ArithmeticCalculator.class);
int result = arithmeticCalculator.add(4, 6);
System.out.println(result);
result = arithmeticCalculator.sub(4, 6);
System.out.println(result);
System.out.println(result);
result = arithmeticCalculator.mul(4, 6);
System.out.println(result);
System.out.println(result);
result = arithmeticCalculator.div(4, 0);
System.out.println(result);
}} |
基于配置文件的AOP 方式
引入的jar包与基于注解的方式引入的jar包相同
ArithmeticCalculator接口
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package com.spring.aop.impl.xml;
public interface ArithmeticCalculator {
public int add(int i, int j);
public int sub(int i, int j);
public int mul(int i, int j);
public int div(int i, int j);
} |
接口实现类 ArithmeticCalculatorImpl.java
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package com.spring.aop.impl.xml;
public class ArithmeticCalculatorImpl implements ArithmeticCalculator{
@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;
}
} |
切面类 LoggingAspect.java
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package com.spring.aop.impl.xml;
import java.util.Arrays;
import java.util.List;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
public class LoggingAspect {
public void beforeMethod(JoinPoint joinpoint) {
String methodName = joinpoint.getSignature().getName();
List<Object>args = Arrays.asList(joinpoint.getArgs());
System.out.println("前置通知：The method "+ methodName +" begins with " + args);
}
public void afterMethod(JoinPoint joinpoint) {
String methodName = joinpoint.getSignature().getName();
//List<Object>args = Arrays.asList(joinpoint.getArgs()); 后置通知方法中可以获取到参数
System.out.println("后置通知：The method "+ methodName +" ends ");
}
public void afterReturnning(JoinPoint joinpoint, Object result) {
String methodName = joinpoint.getSignature().getName();
System.out.println("返回通知：The method "+ methodName +" ends with " + result);
}
public void afterThrowing(JoinPoint joinpoint, Exception e) {
String methodName = joinpoint.getSignature().getName();
System.out.println("异常通知：The method "+ methodName +" occurs exception " + e);
}
public Object aroundMethod(ProceedingJoinPoint point) {
Object result = null;
String methodName = point.getSignature().getName();
try {
//前置通知
System.out.println("The method "+ methodName +" begins with " + Arrays.asList(point.getArgs()));
//执行目标方法
result = point.proceed();
//翻译通知
System.out.println("The method "+ methodName +" ends with " + result);
} catch (Throwable e) {
//异常通知
System.out.println("The method "+ methodName +" occurs exception " + e);
throw new RuntimeException(e);
}
//后置通知
System.out.println("The method "+ methodName +" ends");
return result;
}
} |
切面类 ValidationAspect.java
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package com.spring.aop.impl.xml;
import java.util.Arrays;
import org.aspectj.lang.JoinPoint;
public class ValidationAspect {
public void validateArgs(JoinPoint joinPoint) {
System.out.println("validate:" + Arrays.asList(joinPoint.getArgs()));
}
} |
applicationContext-xml.xml
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<?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-4.1.xsd">
<!-- 配置bean -->
<bean id="arithmeticCalculator" class="com.spring.aop.impl.xml.ArithmeticCalculatorImpl"></bean>
<!-- 配置切面的bean -->
<bean id="loggingAspect" class="com.spring.aop.impl.xml.LoggingAspect"></bean>
<bean id="validationAspect" class="com.spring.aop.impl.xml.ValidationAspect"></bean>
<!-- 配置AOP -->
<aop:config>
<!-- 配置切点表达式 -->
<aop:pointcut expression="execution(* com.spring.aop.impl.xml.ArithmeticCalculator.*(..))" id="pointcut"/>
<!-- 配置切面及通知，使用order指定优先级 -->
<aop:aspect ref="loggingAspect" order="1">
<!-- 环绕通知 -->
<!--
<aop:around method="aroundMethod" pointcut-ref="pointcut"/>
-->
<!-- 前置通知 -->
<aop:before method="beforeMethod" pointcut-ref="pointcut"/>
<!-- 后置通知 -->
<aop:after method="afterMethod" pointcut-ref="pointcut"/>
<!-- 异常通知 -->
<aop:after-throwing method="afterThrowing" pointcut-ref="pointcut" throwing="e"/>
<!-- 返回通知 -->
<aop:after-returning method="afterReturnning" pointcut-ref="pointcut" returning="result"/>
</aop:aspect>
<aop:aspect ref="validationAspect" order="2">
<!-- 前置通知 -->
<aop:before method="validateArgs" pointcut-ref="pointcut"/>
</aop:aspect>
</aop:config>
</beans>
|
Main.java
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package com.spring.aop.impl.xml;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
//创建spring IOC容器
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext-xml.xml");
//从IOC容器中获取bean实例
ArithmeticCalculator arithmeticCalculator = applicationContext.getBean(ArithmeticCalculator.class);
int result = arithmeticCalculator.add(4, 6);
System.out.println(result);
result = arithmeticCalculator.sub(4, 6);
System.out.println(result);
System.out.println(result);
result = arithmeticCalculator.mul(4, 6);
System.out.println(result);
System.out.println(result);
result = arithmeticCalculator.div(4, 0);
System.out.println(result);
}}
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AOP 与动态代理混合使用已添加log逻辑
AOP前传之动态代理
假设有如下需求：
写一个计算器类，里面包含加减乘除四个方法。在每个方法开始前打印出该方法开始的消息，在每个方法结束前打印出该方法结束的消息和计算的结果。
普通方法，先写一个接口，然后在接口里实现四个方法。在每个方法里加上要打印的语句。实现代码如下。
ArithmeticCalculator接口
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package com.spring.aop.helloworld;
public interface ArithmeticCalculator {
int add(int i, int j);
int sub(int i, int j);
int mul(int i, int j);
int div(int i, int j);
} |
ArithmeticCalculatorLoggingImpl.java 实现上面的接口
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package com.spring.aop.helloworld;
public class ArithmeticCalculatorLoggingImpl implements ArithmeticCalculator{
@Override
public int add(int i, int j) {
System.out.println("The method add begins with [" + i + ", " + j + "]");
int result = i + j;
System.out.println("The method add end with " + result);
return result;
}
@Override
public int sub(int i, int j) {
System.out.println("The method sub begins with [" + i + ", " + j + "]");
int result = i - j;
System.out.println("The method sub end with " + result);
return result;
}
@Override
public int mul(int i, int j) {
System.out.println("The method mul begins with [" + i + ", " + j + "]");
int result = i * j;
System.out.println("The method mul end with " + result);
return result;
}
@Override
public int div(int i, int j) {
System.out.println("The method div begins with [" + i + ", " + j + "]");
int result = i / j;
System.out.println("The method div end with " + result);
return result;
}
} |
Main.java
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ArithmeticCalculator arithmeticCalculator = new ArithmeticCalculatorLoggingImpl();
arithmeticCalculator.add(1, 5);
System.out.println("----------");
arithmeticCalculator.sub(5, 3);
System.out.println("----------");
arithmeticCalculator.mul(3, 7);
System.out.println("----------");
arithmeticCalculator.div(9, 3);
|
程序运行结果：
The method add begins with [1, 5]
The method add end with 6
----------
The method sub begins with [5, 3]
The method sub end with 2
----------
The method mul begins with [3, 7]
The method mul end with 21
----------
The method div begins with [9, 3]
The method div end with 3
可见，上面的代码中间存在这大量相似的代码。而面向对象编程又不能很好地解决这个问题，下面采用动态代理的方法来解决上面的问题。
接口不变。写一个实现类ArithmeticCalculatorImpl.java 这个实现类只关注业务，没有需要打印的内容
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package com.spring.aop.helloworld;
public class ArithmeticCalculatorImpl implements ArithmeticCalculator{
@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;
}
} |
ArithmeticCaculatorLogginProxy.java
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package com.spring.aop.helloworld;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
public class ArithmeticCaculatorLogginProxy {
//要代理的对象
private ArithmeticCalculator target;
public ArithmeticCaculatorLogginProxy(ArithmeticCalculator target){
this.target = target;
}
public ArithmeticCalculator getLoggingProxy() {
ArithmeticCalculator proxy = null;
//代理对象由哪一个类加载器负责加载
ClassLoader loader = target.getClass().getClassLoader();
//代理对象的类型，即其中有哪些方法
Class[] interfaces = new Class[]{ArithmeticCalculator.class};
//当调用代理对象其中的方法时，该执行的代码
InvocationHandler h = new InvocationHandler() {
/**
* proxy:正在返回的代理对象，一般情况下，在invoke方法中都不适用该对象
* method：正在被调用的方法
* args：调用方法时，传入的参数
*/
@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
//下面这句执行的时候又会调用invoke方法，所以会出现死循环导致内存溢出
//System.out.println(proxy.toString());
String methodName = method.getName();
//日志
System.out.println("The method " + methodName + " begins with" + Arrays.asList(args));
System.out.println("Invoke...");
//执行方法
Object result = method.invoke(target, args);
//日志
System.out.println("The method" + methodName + " ends with " + result);
return result;
}
};
proxy = (ArithmeticCalculator) Proxy.newProxyInstance(loader, interfaces, h);
return proxy;
}
} |
main方法
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ArithmeticCalculator target = new ArithmeticCalculatorImpl();
ArithmeticCalculator proxy = new ArithmeticCaculatorLogginProxy(target).getLoggingProxy();
proxy.add(1, 5);
System.out.println("----------");
proxy.sub(5, 3);
System.out.println("----------");
proxy.mul(3, 7);
System.out.println("----------");
proxy.div(9, 3);
|
程序运行结果 ：
The method add begins with[1, 5]
Invoke...
The methodadd ends with 6
----------
The method sub begins with[5, 3]
Invoke...
The methodsub ends with 2
----------
The method mul begins with[3, 7]
Invoke...
The methodmul ends with 21
----------
The method div begins with[9, 3]
Invoke...
The methoddiv ends with 3