1、需求

调用微信接口之前：统一权限校验及异常处理。

2、思路

提供自定义注解，可配置需要的参数
aop拦截自定义注解，方法执行前校验权限，拦截并过滤方法抛出的异常

3、核心代码

3.1、自定义注解@WxFuncAuth

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WxFuncAuth {
    /**
     * 方法权限列表
     *
     * @return 方法权限列表
     */
    String[] funcs() default {};

    /**
     * 微信认证状态，默认：认证
     * 有些接口不需要微信认证即可调用
     *
     * @return 微信认证状态
     */
    boolean isVerify() default true;

    /**
     * appId
     *
     * @return appId
     */
    String appId() default "";
}

3.2、微信方法权限注解拦截WxFuncAuthAspect

@Aspect
@Component
@Slf4j
public class WxFuncAuthAspect {
    /**
     * 用于SpEL表达式解析.
     */
    private final SpelExpressionParser parser = new SpelExpressionParser();
    /**
     * 用于获取方法参数定义名字.
     */
    private final ParameterNameDiscoverer nameDiscoverer = new DefaultParameterNameDiscoverer();

    @AfterThrowing(throwing = "ex", value = "@annotation(wxFuncAuth)")
    public void wxFuncAuth(JoinPoint joinPoint, Throwable ex, WxFuncAuth wxFuncAuth) {
        //获取appId
        String appId = generateKeyBySpringEL(wxFuncAuth.appId(), joinPoint);
        log.info("After throwing appId:{},message:{}", appId, ex.getMessage());
        if (ex instanceof WxServiceException) {
            //微信返回的48001异常
            if (((WxServiceException) ex).getErrorCode() == WxMaErrorMsgEnum.CODE_48001.getCode()) {
                //自定义处理
            }
        }
    }

    @Before(value = "@annotation(wxFuncAuth)")
    public void wxFuncAuth(JoinPoint joinPoint, WxFuncAuth wxFuncAuth) {
        //获取appId
        String appId = generateKeyBySpringEL(wxFuncAuth.appId(), joinPoint);
        log.info("annotation WxFuncAuth Before appId:{}", appId);
        if (StringUtils.isBlank(appId)) {
            throw new WxServiceException("appId不存在");
        }
        log.info("annotation WxFuncAuth Before funcs:{}", JSON.toJSONString(wxFuncAuth.funcs()));

        //配置了接口权限集，才需要校验
        if (wxFuncAuth.funcs().length > 0) {
            //校验微信权限信息
        }

    }

    /**
     * 根据el表达式字符串生成key
     *
     * @param elString  el表达式字符串
     * @param joinPoint joinPoint
     * @return key
     */
    private String generateKeyBySpringEL(String elString, JoinPoint joinPoint) {
        MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
        Method targetMethod = AopUtils.getMostSpecificMethod(methodSignature.getMethod(), AopUtils.getTargetClass(joinPoint.getTarget()));
        Expression expression = parser.parseExpression(elString);
        EvaluationContext context = new MethodBasedEvaluationContext(new Object(), targetMethod, joinPoint.getArgs(), nameDiscoverer);
        return Objects.requireNonNull(expression.getValue(context)).toString();
    }
}

3.3、测试

@Component
public class WxFuncAuthAnnotationCaller {
    /***
     * 正常场景测试
     * @param appId appId
     * @return String
     */
    @WxFuncAuth(appId = "#appId", funcs = {"1", "2"})
    public String callNormal(String appId) {
        return appId + ": I'm very good";
    }

    /***
     * 异常场景测试
     * @param appId appId
     */
    @WxFuncAuth(appId = "#appId", funcs = {"1", "2"})
    public void callError(String appId) {
        throw new WxServiceException(appId+"权限不足",48001);
    }
}