@interface

实际项目怎么用到一些自定义接口呢？

一个注册功能就用了三个自定义接口，看下面代码

@NonRepeatable
@ApiVersion(ApiVersionHolder.V1_1_0)
@ControllerLog(description = "注册")
@RequestMapping("/register")
@ResponseBody
public Result register() {
    LoginUserInfoResp info = userService.registerApp();
    Map<String, Object> resp = new HashMap<String, Object>();
    resp.put("user", info);
    return Result.success(resp);
}

@NonRepeatable

/**
 * 标记接口不能重复请求
 * 带这个注解的方法会缓存第一次请求的响应结果
 */
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface NonRepeatable {

}

@ApiVersion(ApiVersionHolder.V1_1_0)

/**
 * 标识接口版本号
 */
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Mapping
public @interface ApiVersion {

    int value();
}

@ControllerLog(description = “注册”)

/**  
 *  自定义注解 拦截controller
 */   
@Retention(RetentionPolicy.RUNTIME)    
@Documented
public @interface ControllerLog {
    String description()  default "";
}

这是上面的自定义注解创建好了，这时候可以使用到面向切面编程技术把它们使用上，每次看培训课都强调面向切面编程都会提到日志，我们前面@ControllerLog(description = “注册”)这个注解就是拿来做日志收集，表达不好代码来凑。其余两个用法我在以前开发过程中和下面用法差不多思路

@Aspect
@Component
public class SystemLogAspect {

    private static final Logger LOGGER = LoggerFactory.getLogger(SystemLogAspect.class);

    private ThreadLocal<Long> startTimeLocal = new ThreadLocal<>();

    /**
     * 获取注解中对方法的描述信息 用于Controller层注解
     *
     * @param joinPoint 切点
     * @return 方法描述
     */
    public static String getControllerMethodDescription(JoinPoint joinPoint) throws Exception {
        String targetName = joinPoint.getTarget().getClass().getName();
        String methodName = joinPoint.getSignature().getName();
        Object[] arguments = joinPoint.getArgs();
        Class<?> targetClass = Class.forName(targetName);
        Method[] methods = targetClass.getMethods();
        String description = "";
        for (Method method : methods) {
            if (method.getName().equals(methodName)) {
                Class<?>[] clazzs = method.getParameterTypes();
                if (clazzs.length == arguments.length) {
                    description = method.getAnnotation(SystemControllerLog.class).description();
                    break;
                }
            }
        }
        return description;
    }

    //Controller层, 日志记录切点
    @Pointcut("@annotation(com.luogong.common.annotation.SystemControllerLog)")
    public void controllerAspect() {
    }

    /**
     * 前置通知 用于拦截Controller层记录用户的操作
     *
     * @param joinPoint 切点
     */
    @Before("controllerAspect()")
    public void doBefore(JoinPoint joinPoint) {
        try {
            startTimeLocal.set(System.currentTimeMillis());

            HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
            LOGGER.info("*****************************************Controller Start:"
                    + request.getRequestURI() + "*********************************************");
            String methodName = (joinPoint.getTarget().getClass().getName() + "." + joinPoint.getSignature().getName());
            LOGGER.info("请求方法:" + methodName);
            LOGGER.info("方法描述:" + getControllerMethodDescription(joinPoint));

            //打印请求参数等信息
            HttpUtils.logRequest(request);
        } catch (Throwable e) {
            LogUtils.printException(LOGGER, e, "执行前异常");
        }
    }

    @After("controllerAspect()")
    public void doAfter(JoinPoint joinPoint) {
        try {
            HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
            String methodName = (joinPoint.getTarget().getClass().getName() + "." + joinPoint.getSignature().getName());
            LOGGER.trace(methodName + " : finished!" );

            long end = System.currentTimeMillis();
            long start = startTimeLocal.get();
            LOGGER.info("*****************************************Controller End:"
                    + request.getRequestURI()
                    + ",cost:" + (end - start) + "ms" +
                    "********************************************");
        } catch (Throwable e) {
            LogUtils.printException(LOGGER, e, "执行后异常");
        }
    }
}