Spring-AOP五种注解的区别和联系
文章目录
- @Before
- @After
- @AfterReturning
- @AfterThrowing
- @Around
导入AOP的jar包
配置xml文件
<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/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd">
<context:component-scan base-package="com.wl.calculater">context:component-scan>
<aop:aspectj-autoproxy proxy-target-class="false">aop:aspectj-autoproxy>
beans>
目标类
@Service
public class CalculatorService implements ICalculatorService {
@Override
public int mul(int a, int b) {
int result = a*b;
return result;
}
@Override
public int div(int a, int b) {
int result = a/b;
return result;
}
}
@Before
- 前置增强
@Aspect
@Component
public class CalculatorAspect {
@Before("execution(* com.jd.calculater.CalculatorService.mul(..))")
public void before(JoinPoint joinPoint) {
System.out.println("前置增强");
Object target = joinPoint.getTarget();
Object[] args = joinPoint.getArgs();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0] + ","
+ args[1] + "]");
}
测试类
public class Test {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
ICalculatorService calculatorService = context.getBean(ICalculatorService.class);
System.out.println(calculatorService.getClass());
int result = calculatorService.mul(1, 1);
System.out.println("结果为："+result);
}
}
结果
class com.sun.proxy.$Proxy8
前置增强
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
结果为：1
上面可以看出对mul方法进行了增强，并且是以JDK动态代理的方式
@After
- 后置增强
切面类
@Aspect
@Component
public class CalculatorAspect {
@Before("execution(public int mul(int,int))")
public void before(JoinPoint joinPoint) {
System.out.println("前置增强");
Object target = joinPoint.getTarget();
Object[] args = joinPoint.getArgs();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0] + ","
+ args[1] + "]");
}
@After("execution(public int mul(int,int))")
public void after(JoinPoint joinPoint) {
System.out.println("后置增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：The " + name + " method ends.");
}
}
测试类
public class Test {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
ICalculatorService calculatorService = context.getBean(ICalculatorService.class);
System.out.println(calculatorService.getClass());
int result = calculatorService.mul(1, 1);
System.out.println("结果为："+result);
}
}
结果
class com.sun.proxy.$Proxy9
前置增强
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
结果为：1
@AfterReturning
- 返回增强，可以获得方法的返回值
@Aspect
@Component
public class CalculatorAspect {
@Before("execution(public int mul(int,int))")
public void before(JoinPoint joinPoint) {
System.out.println("前置增强");
Object target = joinPoint.getTarget();
Object[] args = joinPoint.getArgs();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0] + ","
+ args[1] + "]");
}
//这里需要注意注解中多了一个参数returning，下面参数列表中的参数名和返回值类型要对应起来
@AfterReturning(value = "execution(public int mul(int,int))", returning = "result")
public void afterReturning(JoinPoint joinPoint, Integer result) {
System.out.println("返回增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Result of the " + name + " method：" + result);
}
@After("execution(public int mul(int,int))")
public void after(JoinPoint joinPoint) {
System.out.println("后置增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：The " + name + " method ends.");
}
}
测试类
public class Test {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
ICalculatorService calculatorService = context.getBean(ICalculatorService.class);
System.out.println(calculatorService.getClass());
int result = calculatorService.mul(1, 1);
System.out.println("结果为："+result);
}
}
结果
class com.sun.proxy.$Proxy10
前置增强
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
返回增强
com.wl.calculater.CalculatorService：Result of the mul method：1
结果为：1
@AfterThrowing
- 异常增强
@Aspect
@Component
public class CalculatorAspect {
@Before("execution(public int mul(int,int))")
public void before(JoinPoint joinPoint) {
System.out.println("前置增强");
Object target = joinPoint.getTarget();
Object[] args = joinPoint.getArgs();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0] + ","
+ args[1] + "]");
}
@AfterReturning(value = "execution(public int mul(int,int))", returning = "result")
public void afterReturning(JoinPoint joinPoint, Integer result) {
System.out.println("返回增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：Result of the " + name + " method：" + result);
}
@After("execution(public int mul(int,int))")
public void after(JoinPoint joinPoint) {
System.out.println("后置增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println(target.getClass().getName() + "：The " + name + " method ends.");
}
//throwing对应的值要和参数列表中的参数名对应
@AfterThrowing(value = "execution(public int mul(int,int))", throwing = "exception")
public void afterThrowing(JoinPoint joinPoint, RuntimeException exception) {
System.out.println("异常增强");
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
System.out.println("There is an RuntimeException in " + name + ":" + exception.getMessage());
}
测试类
public class Test {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
ICalculatorService calculatorService = context.getBean(ICalculatorService.class);
System.out.println(calculatorService.getClass());
int result = calculatorService.mul(1, 1);
System.out.println("结果为："+result);
}
}
结果
class com.sun.proxy.$Proxy11
前置增强
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
返回增强
com.wl.calculater.CalculatorService：Result of the mul method：1
结果为：1
只有出现异常的情况话，才会出现异常增强，在CalculatorService中添加代码
@Service
public class CalculatorService implements ICalculatorService {
@Override
public int mul(int a, int b) {
int result = a*b;
//当a,b互为倒数的时候抛出异常
if(result == 1) {
throw new RuntimeException("a和b互为倒数");
}
return result;
}
@Override
public int div(int a, int b) {
int result = a/b;
return result;
}
}
结果
class com.sun.proxy.$Proxy11
前置增强
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
异常增强
There is an RuntimeException in mul:a和b互为倒数
Exception in thread "main" java.lang.RuntimeException: a和b互为倒数
@Around
- 环绕增强，环绕增强可以实现@Before，@After，@AfterReturning和@AfterThrowing增强效果
@Aspect
@Component
public class CalculatorAspect {
// @Before("execution(public int mul(int,int))")
// public void before(JoinPoint joinPoint) {
// System.out.println("前置增强");
// Object target = joinPoint.getTarget();
// Object[] args = joinPoint.getArgs();
// String name = joinPoint.getSignature().getName();
// System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0] + ","
// + args[1] + "]");
// }
//
// @AfterReturning(value = "execution(public int mul(int,int))", returning = "result")
// public void afterReturning(JoinPoint joinPoint, Integer result) {
// System.out.println("返回增强");
// Object target = joinPoint.getTarget();
// String name = joinPoint.getSignature().getName();
// System.out.println(target.getClass().getName() + "：Result of the " + name + " method：" + result);
// }
//
// @After("execution(public int mul(int,int))")
// public void after(JoinPoint joinPoint) {
// System.out.println("后置增强");
// Object target = joinPoint.getTarget();
// String name = joinPoint.getSignature().getName();
// System.out.println(target.getClass().getName() + "：The " + name + " method ends.");
// }
// @AfterThrowing(value = "execution(public int mul(int,int))", throwing = "exception")
// public void afterThrowing(JoinPoint joinPoint, RuntimeException exception) {
// System.out.println("异常增强");
// Object target = joinPoint.getTarget();
// String name = joinPoint.getSignature().getName();
// System.out.println("There is an RuntimeException in " + name + ":" + exception.getMessage());
// }
@Around("execution(public int mul(int,int))")
public Object around(ProceedingJoinPoint joinPoint) {
Integer result = 0;
Object target = joinPoint.getTarget();
String name = joinPoint.getSignature().getName();
Object[] args = joinPoint.getArgs();
try {
try {
System.out.println("前置增强");
System.out.println(target.getClass().getName() + "：The " + name + " method begins.");
System.out.println(target.getClass().getName() + "：Parameters of the " + name + " method： [" + args[0]
+ "," + args[1] + "]");
result = (Integer) joinPoint.proceed();
} finally {
System.out.println("后置增强");
System.out.println(target.getClass().getName() + "：The " + name + " method ends.");
}
System.out.println("返回增强");
System.out.println(target.getClass().getName() + "：Result of the " + name + " method：" + result);
return result;
} catch (Throwable e) {
System.out.println("异常增强");
System.out.println("There is an RuntimeException in " + name + ":" + e.getMessage());
e.printStackTrace();
return null;
}
}
}
测试类
public class Test {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
ICalculatorService calculatorService = context.getBean(ICalculatorService.class);
System.out.println(calculatorService.getClass());
int result = calculatorService.mul(1, 1);
System.out.println("结果为："+result);
}
}
出现异常的结果
class com.sun.proxy.$Proxy8
前置增强
com.wl.calculater.CalculatorService：The mul method begins.
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,1]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
异常增强
There is an RuntimeException in mul:a和b互为倒数
java.lang.RuntimeException: a和b互为倒数
不出现异常的结果
class com.sun.proxy.$Proxy8
前置增强
com.wl.calculater.CalculatorService：The mul method begins.
com.wl.calculater.CalculatorService：Parameters of the mul method： [1,2]
后置增强
com.wl.calculater.CalculatorService：The mul method ends.
返回增强
com.wl.calculater.CalculatorService：Result of the mul method：2
结果为：2
- 注意当前置增强，后置增强，返回增强，异常增强同时出现的时候，如果出现异常，发挥增强不会执行，后置增强一定会执行（因为在finally代码块中）