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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