Java工具类之@RequestMapping注解

@RestController
@RequestMapping("say")
public class SayController {

    @Autowired
    private SayService sayService;


    @RequestMapping("hello")
    public String hello() {
        return sayService.hello();
    }
}

// 自定义分发注解
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestRouter {
    String[] value() default "";
}

package com.kingfish.springjdbcdemo.config;

import lombok.SneakyThrows;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.mvc.condition.PatternsRequestCondition;
import org.springframework.web.servlet.mvc.method.RequestMappingInfo;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;

import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * @Author : kingfish
 * @Email : kingfishx@163.com
 * @Data : 2021/4/21 16:47
 * @Desc : 路由 HandlerMapping 的实现
 */
@Component("handlerMapping")
public class RouterRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
	
	// 在将 方法封装成 HandlerMethod 时会调用此方法
    @SneakyThrows
    @Override
    protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
    	// 获取 RequestRouter 注解
     	RequestRouter requestRouter = method.getAnnotation(RequestRouter.class);
        if (requestRouter == null) {
            requestRouter = handlerType.getAnnotation(RequestRouter.class);
            if (requestRouter == null) {
                for (Class<?> handlerTypeInterface : handlerType.getInterfaces()) {
                    if ((requestRouter = handlerTypeInterface.getAnnotation(RequestRouter.class)) != null) {
                        break;
                    }
                }
            }
        }
		// 调用父类，生成 RequestMappingInfo 
        RequestMappingInfo mappingForMethod = super.getMappingForMethod(method, handlerType);
        if (requestRouter != null) {
        	// 如果 requestRouter 不为空，则进行路径处理
            String[] requestRouterValue = requestRouter.value();
            PatternsRequestCondition condition = mappingForMethod.getPatternsCondition();
            // 获取当前方法匹配的路径，随即进行添加处理。
            Set<String> patterns = condition.getPatterns();
            Set<String> routerPatterns = patterns.stream()
            		// 拼接 请求路径。这里可以自定义处理策略
                    .flatMap(pattern -> Arrays.stream(requestRouterValue).map(val -> "/" + val + pattern))
                    .collect(Collectors.toSet());
            // 将拼接后的路径添加到 RequestMappingInfo 中
            patterns.addAll(routerPatterns);
        }
        return mappingForMethod;
    }
}

@Configuration
public class SpringConfig {

    @Bean
    public DispatcherServlet dispatcherServlet(){
        DispatcherServlet dispatcherServlet = new DispatcherServlet();
        // 禁止加载所有的handlerMapper，而只加载beanName  为  handlerMapper 的bean
        dispatcherServlet.setDetectAllHandlerMappings(false);
        return dispatcherServlet;
    }
}

@RestController
@RequestMapping("say")
public class SayController {

    @Autowired
    private SayService sayService;

    @RequestRouter(value = {"a", "b"})
    @RequestMapping("hello")
    public String hello() {
        return sayService.hello();
    }
}