一文详解SpringBoot中控制器的动态注册与卸载

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DynamicControllerApplication {
    public static void main(String[] args) {
        SpringApplication.run(DynamicControllerApplication.class, args);
    }
}

// 动态控制器注解
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DynamicController {

    // 启动时注册
    boolean startupRegister() default true;

}

// 测试控制器
package com.example.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/demo")
@DynamicController(startupRegister = false)
public class DemoController {

    @GetMapping("/hello")
    public String hello() {
        return "Hello from Dynamic Controller!";
    }

}

package com.example.controller;

import cn.hutool.core.util.ReflectUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.mvc.method.RequestMappingInfo;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

@Component
@Slf4j
public class DynamicControllerRegistry {

    @Autowired
    private ApplicationContext applicationContext;

    @Autowired
    private RequestMappingHandlerMapping requestMappingHandlerMapping;

    private final Map<String, String> registeredControllers = new HashMap<>();

    public String registerController(Object controller,String methodName) {
        Class<?> controllerClass = controller.getClass();
        String key = key(controllerClass,methodName);
        String url = "";
        if (!registeredControllers.containsKey(key)) {
            Method method = ReflectUtil.getMethod(controllerClass,methodName);
            RequestMapping methodMapping = AnnotatedElementUtils.findMergedAnnotation(method, RequestMapping.class);
            RequestMapping requestMapping = controllerClass.getAnnotation(RequestMapping.class);

            url = getMethodUrl(requestMapping,methodMapping);
            // 注册控制器
            requestMappingHandlerMapping.registerMapping(
                    RequestMappingInfo.paths(url).methods(methodMapping.method()).build(),
                    controller,method
            );
            registeredControllers.put(key,url);
        }else{
            url = registeredControllers.get(key);
            log.warn("controller already registered:{}",url);
        }
        return url;
    }

    public String unregisterController(Class<?> controllerClass,Method method) {
        RequestMapping methodMapping = AnnotatedElementUtils.findMergedAnnotation(method, RequestMapping.class);
        RequestMapping requestMapping = controllerClass.getAnnotation(RequestMapping.class);
        String url = getMethodUrl(requestMapping,methodMapping);
        RequestMappingInfo mappingInfo = RequestMappingInfo.paths(url).methods(methodMapping.method()).build();
        requestMappingHandlerMapping.unregisterMapping(mappingInfo);
        registeredControllers.remove(key(controllerClass,method.getName()));
        log.info("unregister controller:{}", url);
        return url;
    }

    public String unregisterController(Class<?> controllerClass,String methodName) {
        Method method = ReflectUtil.getMethod(controllerClass,methodName);
        return unregisterController(controllerClass,method);
    }

    private String key(Class<?> controllerClass, String method){
        return controllerClass.getName() + "." + method;
    }

    private String getMethodUrl(RequestMapping requestMapping,RequestMapping methodMapping){
        String baseUrl = "";
        String url = "";
        if(requestMapping != null){
            baseUrl = requestMapping.value()[0];
        }
        if(methodMapping != null) {
            String[] values = methodMapping.value();
            if (values.length > 0) {
                url = baseUrl + values[0];
            }
        }
        return url;
    }

}

package com.example.config;

import cn.hutool.core.util.ClassUtil;
import com.example.controller.DynamicController;
import com.example.controller.DynamicControllerRegistry;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.web.bind.annotation.RequestMapping;

import java.lang.reflect.Method;
import java.util.Map;
import java.util.Set;

@Configuration
@Slf4j
public class WebConfig {

    @Autowired
    private DynamicControllerRegistry dynamicControllerRegistry;

    @Bean
    public Void unregisterDynamicController() {
        Set<Class<?>> classes = ClassUtil.scanPackageByAnnotation("com.example", DynamicController.class);
        for(Class<?> clazz : classes) {
            DynamicController dynamicController = clazz.getAnnotation(DynamicController.class);
            boolean needRegister = dynamicController.startupRegister();
            if(needRegister) {
                continue;
            }

            // 默认不需要注册的controller，需要在启动时注销掉
            RequestMapping requestMapping = clazz.getAnnotation(RequestMapping.class);
            Method[] methods = clazz.getDeclaredMethods();
            for(Method method : methods) {
                dynamicControllerRegistry.unregisterController(clazz,method);
            }
        }

        return null;
    }
}

package com.example.controller;

import cn.hutool.extra.spring.SpringUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/controller")
public class ControllerManagement {

    @Autowired
    private DynamicControllerRegistry dynamicControllerRegistry;

    @PostMapping("/register")
    public String registerController(@RequestParam String controllerBeanName, @RequestParam String methodName) {
        Object controller = SpringUtil.getBean(controllerBeanName);
        String url = dynamicControllerRegistry.registerController(controller, methodName);
        return "Controller registered at: " + url;
    }

    @DeleteMapping("/unregister")
    public String unregisterController(@RequestParam String controllerBeanName, @RequestParam String methodName) {
        Object controller = SpringUtil.getBean(controllerBeanName);
        String url = dynamicControllerRegistry.unregisterController(controller.getClass(),methodName);
        return "Controller unregistered from: " + url;
    }
}