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Spring Boot 基于@Transaction思想实现日志功能

通过之前对@Transaction原理分析，可以得出实现事务的要点如下：

需要定义一个后置处理器，用来拦截bean
需要定义一个切面
需要定义切面的切点
需要定义切面的通知，用作代理处理

基于以上思想，我们来实现一个类似的功能：系统日志

系统日志实现

实现是以Spring Boot为基础，需要添加如下依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>
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按照如上提到的要点依次定义

定义bean后置处理器，特别注意，如果项目中使用到了事务特性，就不需要重复定义

/**
 * 一定要声明InfrastructureAdvisorAutoProxyCreator，用于实现bean的后置处理
 *
 * @return
 */
@Bean
public InfrastructureAdvisorAutoProxyCreator infrastructureAdvisorAutoProxyCreator() {
    return new InfrastructureAdvisorAutoProxyCreator();
}
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定义切面

public class BeanFactorySystemLogAdvisor extends AbstractBeanFactoryPointcutAdvisor {

    /**
     * 定义切点
     */
    private final SystemLogPointcut point = new SystemLogPointcut();

    @Override
    public Pointcut getPointcut() {
        return this.point;
    }
}
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定义切点

public class SystemLogPointcut extends StaticMethodMatcherPointcut {

    @Override
    public boolean matches(Method method, Class<?> targetClass) {
        AnnotationAttributes attributes = AnnotatedElementUtils.findMergedAnnotationAttributes(
                targetClass, SystemLog.class, false, false);
        if (Objects.nonNull(attributes)) {
            return true;
        }

        attributes = AnnotatedElementUtils.findMergedAnnotationAttributes(
                method, SystemLog.class, false, false);
        return Objects.nonNull(attributes);
    }
}
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定义通知

@Slf4j
public class SystemLogInterceptor implements MethodInterceptor, Serializable {

    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        Method method = invocation.getMethod();
        String className = method.getDeclaringClass().getSimpleName();
        String methodName = method.getName();
        log.info("======[" + className + "#" + methodName + " method begin execute]======");
        Arrays.stream(invocation.getArguments()).forEach(argument -> log.info("======[execute method argument：" + argument + "]======"));
        Long time1 = Clock.systemDefaultZone().millis();
        Object result = invocation.proceed();
        Long time2 = Clock.systemDefaultZone().millis();
        log.info("======[method execute time：" + (time2 - time1) + "]======");
        return result;
    }
}
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自动配置

@Configuration
public class ProxySystemLogConfiguration {

    /**
     * 定义切面
     * 此处一定要指定@Role注解
     *
     * @return
     */
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    @Bean
    public BeanFactorySystemLogAdvisor beanFactorySystemLogAdvisor() {
        BeanFactorySystemLogAdvisor advisor = new BeanFactorySystemLogAdvisor();
        advisor.setAdvice(systemLogInterceptor());
        return advisor;
    }

    /**
     * 定义通知
     *
     * @return
     */
    @Bean
    public SystemLogInterceptor systemLogInterceptor() {
        return new SystemLogInterceptor();
    }

    /**
     * 一定要声明InfrastructureAdvisorAutoProxyCreator，用于实现bean的后置处理
     *
     * @return
     */
    @Bean
    public InfrastructureAdvisorAutoProxyCreator infrastructureAdvisorAutoProxyCreator() {
        return new InfrastructureAdvisorAutoProxyCreator();
    }
}
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定义注解

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SystemLog {
}
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集成到业务

定义控制器

@RestController
public class SystemLogController {

    @Autowired
    private SystemLogService systemLogService;

    @GetMapping("/log")
    public String hello(@RequestParam("name") String name) throws InterruptedException {
        return systemLogService.log(name);
    }
}
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定义业务方法

@Slf4j
@Service
public class SystemLogService {

    @SystemLog
    public String log(String name) throws InterruptedException {
        log.info("执行业务方法");
        TimeUnit.SECONDS.sleep(1);
        return "hello " + name;
    }
}
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定义启动类

@SpringBootApplication
public class TransactionImitateApplication {

    public static void main(String[] args) {
        SpringApplication.run(TransactionImitateApplication.class, args);
    }
}
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访问http://localhost:8080/log?name=advisor
查看控制台

2019-08-23 11:13:36.029  INFO 23227 --- [nio-8080-exec-1] c.b.example.config.SystemLogInterceptor  : ======[SystemLogService#log method begin execute]======
2019-08-23 11:13:36.030  INFO 23227 --- [nio-8080-exec-1] c.b.example.config.SystemLogInterceptor  : ======[execute method argument：advisor]======
2019-08-23 11:13:36.038  INFO 23227 --- [nio-8080-exec-1] c.boot.example.service.SystemLogService  : 执行业务方法
2019-08-23 11:13:37.038  INFO 23227 --- [nio-8080-exec-1] c.b.example.config.SystemLogInterceptor  : ======[method execute time：1004]======
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可以看到通过模拟@Transaction注解的实现方式，完成了日志切面功能

原文 https://juejin.im/post/5d64a48ef265da03cb1248bb

正文到此结束