一、依赖

 1 <dependency>
 2     <groupId>org.springframework.boot</groupId>
 3     <artifactId>spring-boot-starter-web</artifactId>
 4 </dependency>
 5 
 6 <!-- aop -->
 7 <dependency>
 8     <groupId>org.springframework.boot</groupId>
 9     <artifactId>spring-boot-starter-aop</artifactId>
10 </dependency>

二、注解

 1 @Target(ElementType.METHOD)
 2 @Retention(RetentionPolicy.RUNTIME)
 3 @Documented
 4 public @interface Limiter {
 5     /**
 6      * 使用spel表达式获取限流的key
 7      * @return
 8      */
 9     String value();
10 }

三、AOP切面的应用

 1 @Aspect
 2 @Component
 3 public class LimiterAspect {
 4     private ExpressionParser parser = new SpelExpressionParser();
 5     private LocalVariableTableParameterNameDiscoverer discoverer = new LocalVariableTableParameterNameDiscoverer();
 6 
 7     @Pointcut("@annotation(limiter)")
 8     public void pointcut(Limiter limiter) {
 9     }
10 
11     @Around("pointcut(limiter)")
12     public Object around(ProceedingJoinPoint pjp, Limiter limiter) throws Throwable {
13         Method method = this.getMethod(pjp);
14         String methodName = method.toString();
15 
16         //获取方法的参数值
17         Object[] args = pjp.getArgs();
18         EvaluationContext context = this.bindParam(method, args);
19 
20         //根据spel表达式获取值
21         Expression expression = parser.parseExpression(limiter.value());
22         Object key = expression.getValue(context);
23         //打印
24         System.out.println(key);
25         
26         return pjp.proceed();
27     }
28 
29     /**
30      * 获取当前执行的方法
31      *
32      * @param pjp
33      * @return
34      * @throws NoSuchMethodException
35      */
36     private Method getMethod(ProceedingJoinPoint pjp) throws NoSuchMethodException {
37         MethodSignature methodSignature = (MethodSignature) pjp.getSignature();
38         Method method = methodSignature.getMethod();
39         Method targetMethod = pjp.getTarget().getClass().getMethod(method.getName(), method.getParameterTypes());
40         return targetMethod;
41     }
42 
43     /**
44      * 将方法的参数名和参数值绑定
45      *
46      * @param method 方法,根据方法获取参数名
47      * @param args   方法的参数值
48      * @return
49      */
50     private EvaluationContext bindParam(Method method, Object[] args) {
51         //获取方法的参数名
52         String[] params = discoverer.getParameterNames(method);
53 
54         //将参数名与参数值对应起来
55         EvaluationContext context = new StandardEvaluationContext();
56         for (int len = 0; len < params.length; len++) {
57             context.setVariable(params[len], args[len]);
58         }
59         return context;
60     }

四、Controller

 1 @RestController
 2 public class TestController {
 3 
 4     //获取名为id的参数
 5     @Limiter("#id")
 6     @GetMapping("test")
 7     public String test(Long id){
 8         return "hello";
 9     }
10 }

五、获取对象(补充)

1、注解

1 @Limter(value = "#testObj")
2 public JSONObject test01(TestObj  testObj){
3       // ......      
4 }

多个切点同时获取

 1 /**
 2  * 设置操作日志切入点 记录操作日志 在注解的位置切入代码
 3  */
 4 //@Pointcut("@annotation(com.test.Limter)")
 5 @Pointcut("@annotation(limter)")
 6 public void operLogPointCut(Limter limter) {
 7 }
 8 
 9 @Pointcut("execution(public * com.test.aaa..*.*(..))")
10 public void operLogPointMethod() {
11 }

线程变量的使用,当前切面类中使用线程变量存储变量

 1 @Aspect
 2 @Component
 3 public class LogAspect {
 4 
 5     @Autowired
 6     private LogsService logsService;
 7     // 线程变量
 8     private ThreadLocal<String> threadLocal = new ThreadLocal<>();
 9 
10     /**
11      * 设置操作日志切入点 记录操作日志 在注解的位置切入代码
12      */

方法体中存入数据

public void savaData(){
    threadLocal.set("asdf");
}

在另一个方法体中获取当前线程数据

public void savaData(){
    String value = threadLocal.get();
}

切点多条件限制 &&

 1 @AfterReturning(value = "operLogPointCut(limter) && operLogPointMethod()", returning = "returnValue")
 2     public void saveOperLog(JoinPoint joinPoint, Limter limter, Object returnValue) {
 3         Object[] args = joinPoint.getArgs();
 4         // 从切面织入点处通过反射机制获取织入点处的方法
 5         MethodSignature signature = (MethodSignature) joinPoint.getSignature();
 6         // 获取切入点所在的方法
 7         Method method = signature.getMethod();
 8         EvaluationContext context = this.bindParam(method, args);
 9         Expression expression = parser.parseExpression(limter.value());
10 
11         TestObj testObj= expression.getValue(context, TestObj.class);
12         // ......
13         new Thread(() -> logsService.saveLogs(Obj...)).start();
14 
15         // 存入数据库后移除当前线程变量
16         threadLocal.remove();
17     }

 参考:

https://blog.csdn.net/weixin_45052750/article/details/105742934

 其他参考:

https://www.codeleading.com/article/30952452765/

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