springboot的自定义注解使用

1.自定义注解配合拦截器

// 自定义注解
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation {// 自定义注解的属性
}// 控制器类
@RestController
public class MyController {@GetMapping("/myEndpoint")@MyAnnotation // 使用自定义注解public String myEndpoint() {return "Hello, World!";}
}// 自定义拦截器
@Component
public class MyInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {// 判断请求方法上是否有自定义注解if (handler instanceof HandlerMethod) {HandlerMethod handlerMethod = (HandlerMethod) handler;MyAnnotation myAnnotation = handlerMethod.getMethod().getAnnotation(MyAnnotation.class);if (myAnnotation != null) {// 在这里处理自定义注解的逻辑System.out.println("Intercepted request with MyAnnotation");}}return true;}// 省略postHandle()和afterCompletion()方法
}// 注册拦截器
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {private final MyInterceptor myInterceptor;public InterceptorConfig(MyInterceptor myInterceptor) {this.myInterceptor = myInterceptor;}@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(myInterceptor).addPathPatterns("/**");}
}

2. 自定义注解与过滤器(需要前端约定好一个属性，不推荐)

// 自定义注解
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation {// 自定义注解的属性
}// 控制器类
@RestController
public class MyController {@GetMapping("/myEndpoint")@MyAnnotation // 使用自定义注解public String myEndpoint() {return "Hello, World!";}
}// 自定义过滤器
@Component
public class MyFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {// 初始化方法}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {HttpServletRequest httpRequest = (HttpServletRequest) request;HttpServletResponse httpResponse = (HttpServletResponse) response;/** 判断请求方法上是否有自定义注解过滤器在请求到达DispatchServlet之前执行，可以用于对请求进行预处理和过滤。DispatchServlet负责处理请求的分发和后续的处理逻辑。HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE属性是在DispatchServlet的请求处理阶段赋值的，它存储了最佳匹配的处理器信息。只有当请求到达DispatchServlet并且经过HandlerMapping的匹配过程后，才会有该属性的值。在过滤器(Filter)中，默认情况下是无法直接获取到	HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE属性的。如果在过滤器中需要获取HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE属性，一种可行的方式是在过滤器中将该属性保存到请求的属性中，然后在后续的处理环节中再进行获取。具体的做法可以通过自定义的HttpServletRequestWrapper或者自定义的Filter来实现。*/HandlerMethod handlerMethod = (HandlerMethod) httpRequest.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);if (handlerMethod != null) {MyAnnotation myAnnotation = handlerMethod.getMethod().getAnnotation(MyAnnotation.class);if (myAnnotation != null) {// 在这里处理自定义注解的逻辑System.out.println("Filtered request with MyAnnotation");}}// 继续处理请求chain.doFilter(request, response);}@Overridepublic void destroy() {// 销毁方法}
}// 注册过滤器
@Configuration
public class FilterConfig {private final MyFilter myFilter;public FilterConfig(MyFilter myFilter) {this.myFilter = myFilter;}@Beanpublic FilterRegistrationBean<MyFilter> myFilterRegistration() {FilterRegistrationBean<MyFilter> registration = new FilterRegistrationBean<>(myFilter);registration.addUrlPatterns("/*");return registration;}
}