前言
最近有个新需求，是对用户的某些操作进行监控，操作记录要写入数据库，首先想到了使用Filter过滤器和Spring的Interceptor(拦截器)，这两种都需要复杂的配置（能用代码解决的问题绝不上手），于是灵机一动想到了基于注解实现AOP,在要进行监控的Action加上该注解，完美，开始！
编写自定义注解
package com.asiainfo.annotation;
import java.lang.annotation.*;
/**
* @description: 自动以注解
* @author: Mr-box
* @create: 2019-05-23 10:00
**/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
public @interface EagleEye {
String desc() default "";
}
复制代码- 定义注解的生命周期为运行时
- 定义注解的作用于为方法
- 标记注解可以被JavaDoc记录
- 定义注解为EagleEye（鹰眼）
- 定义desc，用来描述被修饰的方法
定义AOP切面
package com.asiainfo.aspect;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import javax.servlet.http.HttpServletRequest;
import java.util.Arrays;
/**
* @description: 定义AOP切面
* @author: Mr-box
* @create: 2019-05-23 10:00
**/
@Aspect
@Component
public class LogAspect {
// 定义切点
@Pointcut("@annotation(com.asiainfo.annotation.EagleEye)")
public void eagleEye() {
}
// 利用环绕增强来实现我们的功能
@Around("eagleEye()")
public Object surroundInform(ProceedingJoinPoint proceedingJoinPoint) {
System.out.println("环绕通知开始...");
ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
HttpServletRequest request = attributes.getRequest();
System.out.println("请求路径 : " + request.getRequestURL());
System.out.println("请求方式 : " + request.getMethod());
System.out.println("方法名 : " + proceedingJoinPoint.getSignature().getName());
System.out.println("类路径 : " + proceedingJoinPoint.getSignature().getDeclaringTypeName());
System.out.println("参数 : " + Arrays.toString(proceedingJoinPoint.getArgs()));
try {
// 真实业务代码，这里是伪代码
Object o = proceedingJoinPoint.proceed();
System.out.println("方法环绕proceed，结果是 :" + o);
return o;
} catch (Throwable e) {
e.printStackTrace();
return null;
}
}
}
复制代码注解的使用
- 在方法上加入@EagleEye(desc = "测试接口")注解即可实现
package com.asiainfo.action;
import com.asiainfo.annotation.EagleEye;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @description: 定义AOP切面
* @author: Mr-box
* @create: 2019-05-23 10:00
**/
@RestController
public class TestAction {
@EagleEye(desc = "测试接口")
@RequestMapping(value = "/sayHello")
public String test(String params)throws Exception{
System.out.println("参数:" + params);
return "hello "+ params;
}
}
复制代码启动测试
浏览器调用：http://127.0.0.1:8081/aop-demo/sayHello?params=lala 观察日志输出：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.2.5.RELEASE)
2019-05-23 10:00 INFO 3183 --- [ main] com.asiainfo.SpringAopDemoApplication : Starting SpringAopDemoApplication on zhangdsdeiMac.local with PID 3183 (/Users/zhangds/Development/code/spring-aop-demo/target/classes started by zhangds in /Users/zhangds/Development/code/spring-aop-demo)
2019-05-23 10:00 INFO 3183 --- [ main] com.asiainfo.SpringAopDemoApplication : No active profile set, falling back to default profiles: default
2019-05-23 10:00 INFO 3183 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8081 (http)
2019-05-23 10:00 INFO 3183 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2019-05-23 10:00 INFO 3183 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.31]
2019-05-23 10:00 INFO 3183 --- [ main] o.a.c.c.C.[.[localhost].[/aop-demo] : Initializing Spring embedded WebApplicationContext
2019-05-23 10:00 INFO 3183 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 627 ms
2019-05-23 10:00 INFO 3183 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2019-05-23 10:00 INFO 3183 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8081 (http) with context path '/aop-demo'
2019-05-23 10:00 INFO 3183 --- [ main] com.asiainfo.SpringAopDemoApplication : Started SpringAopDemoApplication in 1.115 seconds (JVM running for 1.654)
2019-05-23 10:00 INFO 3183 --- [nio-8081-exec-1] o.a.c.c.C.[.[localhost].[/aop-demo] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2019-05-23 10:00 INFO 3183 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2019-05-23 10:00 INFO 3183 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 4 ms
请求路径 : http://127.0.0.1:8081/aop-demo/sayHello
请求方式 : GET
方法名 : test
类路径 : com.asiainfo.action.TestAction
参数 : [lala]
环绕通知开始...
参数:lala
方法环绕proceed，结果是 :hello lala
复制代码总结
- 要比配置切点用execution表达式灵活性要高，execution表达式具有一定的局限性。
- 自定义注解灵活性比较高，但这只是自定义注解的小用法而已。