1. 啓用AOP
a. 在類上添加@Aspect註解
b. 注入該類, 可以使用@Component進行注入到Spring容器中
2. 通過PointCut對象創建切入點
a. 在某個方法使用類似下面的方法進行注入
@Pointcut("execution(* com.sguess.service.IAOPService.*(..))")
private void pointcut() {
}
i. 其中,execution表達式爲
execution(modifiers-pattern? ret-type-pattern declaring-type-pattern? name-pattern(param-pattern)throws-pattern?)
ii. 注意, pointcut()方法名是後面切入的時候需要使用的
iii. 方法內可以什麼也不寫, 寫了也調不到
iv. 也可以創建多個PointCut,例如再創建一個
@Pointcut("execution(* com.sguess.service.IAOPService.fun1(..))")
private void pointcut2() {
}
這個的方法名就位pointcut2, 方法名不一樣.
b. 創建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, 在配置了的切入點被執行後, 執行該方法.
ii. value中的pointcut() 是我們前面在創建@Pointcut中的方法名. 也就是說,是通過方法名和切入點進行匹配的.
iii. 這個的方法名可以隨便起.
iv. Before方法同理
c. 帶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執行後, 獲取其返回值, 再執行該方法. 注意關鍵, 這個可以進行操作返回值.
ii. returning = "str",是指, 假設切入方法的返回的值變量名爲str
doAfterReturning(String str)方法的參數變量名必須和和returning保持一致, 這裏也叫作str. 然後才能在方法體中使用.
iii. pointcut = "pointcut()"同樣是指前面聲明的pointcut方法名
3. 通過註解, 使用切入點
a. 監聽方法參數
@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. 執行順序:
a. Around的方法優先於Before/After執行, After優先於AfterReturn.
i. 代碼
@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;
}
}
執行結果:
• Start AroundFunction
• Around process start
• Before function
• Around process end
• After Around process
• After function
• AfterReturn function
5. 總結:
@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;
}