SpringBoot AOP使用笔记

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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