1. 启用AOP
a. 在类上添加@Aspect注解
b. 注入该类, 可以使用@Component进行注入到Spring容器中
2. 通过PointCut对象创建切入点
a. 在某个方法使用类似下面的方法进行注入
@Pointcut("execution(* com.sguess.service.IAOPService.*(..))")
private void pointcut() {
}
i. 其中,execution表达式为
execution(modifiers-pattern? ret-type-pattern declaring-type-pattern? name-pattern(param-pattern)throws-pattern?)
ii. 注意, pointcut()方法名是后面切入的时候需要使用的
iii. 方法内可以什么也不写, 写了也调不到
iv. 也可以创建多个PointCut,例如再创建一个
@Pointcut("execution(* com.sguess.service.IAOPService.fun1(..))")
private void pointcut2() {
}
这个的方法名就位pointcut2, 方法名不一样.
b. 创建After方法,Before方法
@After(value = "pointcut()")
public void doAfter() {
System.out.println("Do AOP After function 01");
}
i. After方法是指, 在配置了的切入点被执行后, 执行该方法.
ii. value中的pointcut() 是我们前面在创建@Pointcut中的方法名. 也就是说,是通过方法名和切入点进行匹配的.
iii. 这个的方法名可以随便起.
iv. Before方法同理
c. 带Return的After方法,
@AfterReturning(returning = "str", pointcut = "pointcut()")
public void doAfterReturning(String str) throws Exception {
System.out.println("Return value is: " + str);
}
i. AfterReturn是指在被切入的方法执行后, 获取其返回值, 再执行该方法. 注意关键, 这个可以进行操作返回值.
ii. returning = "str",是指, 假设切入方法的返回的值变量名为str
doAfterReturning(String str)方法的参数变量名必须和和returning保持一致, 这里也叫作str. 然后才能在方法体中使用.
iii. pointcut = "pointcut()"同样是指前面声明的pointcut方法名
3. 通过注解, 使用切入点
a. 监听方法参数
@Before("execution(public int com.sguess.service.*(int, int))")
public void beforMethod(JoinPoint point) {
String methodName = point.getSignature().getName();
List<Object> args = Arrays.asList(point.getArgs());
System.out.println("Before FunctionName：" + methodName + ",ParameterName：" + args);
}
@After("execution(public int com.sguess.service.*(int, int))")
public void afterMethod(JoinPoint point) {
String methodName = point.getSignature().getName();
List<Object> args = Arrays.asList(point.getArgs());
System.out.println("After FunctionName：" + methodName + ",ParameterName：" + args);
}
4. 执行顺序:
a.Around的方法优先于Before/After执行,After优先于AfterReturn.
i. 代码
@Before("execution(public int com.sguess.service.*.*(int, int))")
public void beforMethod(JoinPoint point) {
System.out.println("Before function");
}
@After("execution(public int com.sguess.service.*.*(int, int))")
public void afterMethod(JoinPoint point) {
System.out.println("After function");
}
@AfterReturning("execution(public int com.sguess.service.*.*(int, int))")
public void afterReturnMethod(JoinPoint point) {
System.out.println("AfterReturn function");
}
@AfterThrowing(value = "execution(public int com.sguess.service.*.*(int, int))", throwing = "e")
public void afterReturningThrowing(JoinPoint point, Exception e) {
System.out.println("AfterReturnThrowing function");
}
@Around("execution(public int com.sguess.service.*.*(int, int))")
public Object aroundMethod(ProceedingJoinPoint pdj) {
System.out.println("Start AroundFunction");
Object result = null;
try {
System.out.println("Around process start");
result = pdj.proceed();
System.out.println("Around process end");
} catch (Throwable e) {
System.out.println("Around process exception");
}
System.out.println("After Around process");
return result;
}
}
执行结果:
Start AroundFunction
Around process start
Before function
Around process end
After Around process
After function
AfterReturn function
5.小结:
@AfterReturning(returning = "str", pointcut = "pointcut()")
public void doAfterReturning(String str) throws Exception {
System.out.println("Return value is: " + str);
}
@Before("execution(public int com.sguess.service.*.*(int, int))")
public void beforMethod(JoinPoint point) {
String methodName = point.getSignature().getName();
List<Object> args = Arrays.asList(point.getArgs());
System.out.println("Before FunctionName：" + methodName + ",ParameterName：" + args);
}
@After("execution(public int com.sguess.service.*.*(int, int))")
public void afterMethod(JoinPoint point) {
String methodName = point.getSignature().getName();
List<Object> args = Arrays.asList(point.getArgs());
System.out.println("After FunctionName：" + methodName + ",ParameterName：" + args);
}
@AfterThrowing(value = "execution(public int com.sguess.service.*.*(int, int))", throwing = "e")
public void afterReturningThrowing(JoinPoint point, Exception e) {
String methodName = point.getSignature().getName();
List<Object> args = Arrays.asList(point.getArgs());
System.out.println("AfterReturningThrowing FunctionName：" + methodName + ",ParameterName：" + args + ",Exception：" + e);
}
@Around("execution(public int com.sguess.service.*.*(int, int))")
public Object aroundMethod(ProceedingJoinPoint pdj) {
System.out.println("Start AroundFunction");
Object result = null;
try {
System.out.println("Around process start");
result = pdj.proceed();
System.out.println("Around process end");
} catch (Throwable e) {
System.out.println("Around process exception");
}
System.out.println("After Around process");
return result;
}
总结
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