带有@PathVariable的Spring MVC带注释的控制器接口

Question

有没有理由不将控制器映射为接口？

在所有示例和问题中，我看到周围的控制器，都是具体的类。是否有一个原因？我想将请求映射与实现分开。当我试图在我的具体课程中获得@PathVariable作为参数时，我碰壁了。

我的Controller界面如下所示：

@Controller
@RequestMapping("/services/goal/")
public interface GoalService {

    @RequestMapping("options/")
    @ResponseBody
    Map<String, Long> getGoals();

    @RequestMapping(value = "{id}/", method = RequestMethod.DELETE)
    @ResponseBody
    void removeGoal(@PathVariable String id);

}

实施班：

@Component
public class GoalServiceImpl implements GoalService {

    /* init code */

    public Map<String, Long> getGoals() {
        /* method code */
        return map;
    }

    public void removeGoal(String id) {
        Goal goal = goalDao.findByPrimaryKey(Long.parseLong(id));
        goalDao.remove(goal);
    }

}

getGoals()方法效果很好; removeGoal(String id)抛出异常

ExceptionHandlerExceptionResolver - Resolving exception from handler [public void
    todo.webapp.controllers.services.GoalServiceImpl.removeGoal(java.lang.String)]: 
    org.springframework.web.bind.MissingServletRequestParameterException: Required 
    String parameter 'id' is not present

如果我将@PathVariable注释添加到具体类中，一切都按预期工作，但为什么我必须在具体类中重新声明它？不应该由具有@Controller注释的任何内容处理吗？

Answer 1

显然，当请求模式通过@RequestMapping注释映射到方法时，它将映射到具体的方法实现。因此，与声明匹配的请求将直接调用GoalServiceImpl.removeGoal()，而不是最初声明@RequestMapping即GoalService.removeGoal()的方法。

由于接口，接口方法或接口方法参数上的注释不会延续到实现，因此Spring MVC无法将其识别为@PathVariable，除非实现类明确声明它。没有它，任何针对@PathVariable参数的AOP建议都不会被执行。

Answer 2

它适用于较新版本的Spring。

import org.springframework.web.bind.annotation.RequestMapping;
public interface TestApi {
    @RequestMapping("/test")
    public String test();
}

在Controller中实现接口

@RestController
@Slf4j
public class TestApiController implements TestApi {

    @Override
    public String test() {
        log.info("In Test");
        return "Value";
    }

}

它可以用作： Rest client

Answer 3

最近在Spring 5.1.5中实现了在接口上定义所有绑定的功能。

请查看此问题：https://github.com/spring-projects/spring-framework/issues/15682-这很艰难：）

现在您可以执行以下操作了：

@RequestMapping("/random")
public interface RandomDataController {

    @RequestMapping(value = "/{type}", method = RequestMethod.GET)
    @ResponseBody
    RandomData getRandomData(
            @PathVariable(value = "type") RandomDataType type, @RequestParam(value = "size", required = false, defaultValue = "10") int size);
}

@Controller
public class RandomDataImpl implements RandomDataController {

    @Autowired
    private RandomGenerator randomGenerator;

    @Override
    public RandomData getPathParamRandomData(RandomDataType type, int size) {
        return randomGenerator.generateRandomData(type, size);
    }
}

您甚至可以使用以下库：https://github.com/ggeorgovassilis/spring-rest-invoker

要获得基于该接口的客户端代理，类似于RestEasys客户端框架在JAX-RS领域中的工作方式。

Answer 4

最近我遇到了同样的问题。以下对我有用：

public class GoalServiceImpl implements GoalService {
    ...
    public void removeGoal(@PathVariableString id) {
    }
}

Answer 5

我解决了这个问题。

ON CLIENT SIDE：

我正在使用此库https://github.com/ggeorgovassilis/spring-rest-invoker/。该库从接口生成代理以调用spring rest服务。

我扩展了这个库：

我创建了一个注释和一个工厂客户端类：

确定Spring Rest服务

private void parseJson(String jsonString){
        ArrayList<String> legsDistanceList = new ArrayList<>();
        ArrayList<String> legStepsDistanceList = new ArrayList<>();
        try{
            JSONObject rootJson = new JSONObject(jsonString);
            if(rootJson.has("routes")) {
                JSONArray routesJsonArray = rootJson.getJSONArray("routes");
                for(int i=0;i<routesJsonArray.length();i++){
                    JSONObject routeJson = routesJsonArray.getJSONObject(i);
                    if(routeJson.has("legs")){
                        JSONArray legsJsonArray = routeJson.getJSONArray("legs");
                        for(int j=0;j<legsJsonArray.length();j++){
                            JSONObject legJson = legsJsonArray.getJSONObject(j);
                            if(legJson.has("distance")){
                                JSONObject distanceJson = legJson.getJSONObject("distance");
                                legsDistanceList.add(distanceJson.getString("text"));
                            }
                            if(legJson.has("steps")){
                                JSONArray stepsJsonArray = legJson.getJSONArray("steps");
                                for(int k=0;k<stepsJsonArray.length();k++){
                                    JSONObject stepJson = stepsJsonArray.getJSONObject(k);
                                    if(stepJson.has("distance")){
                                        JSONObject stepDistanceJson = stepJson.getJSONObject("distance");
                                        legStepsDistanceList.add(stepDistanceJson.getString("text"));
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }catch (Throwable e){
            e.printStackTrace();
        }

        Log.i("Legs Distance ",legsDistanceList.toString());
        Log.i("Legs Steps Distance ",legStepsDistanceList.toString());
    }

此类从接口

生成客户端休息

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SpringRestService {
    String baseUri();
}

我配置我的工厂：

public class RestFactory implements BeanFactoryPostProcessor,EmbeddedValueResolverAware  {

    StringValueResolver resolver;

    @Override
    public void setEmbeddedValueResolver(StringValueResolver resolver) {
        this.resolver = resolver;
    }
    private String basePackage = "com";

    public void setBasePackage(String basePackage) {
        this.basePackage = basePackage;
    }


    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        createBeanProxy(beanFactory,SpringRestService.class);
        createBeanProxy(beanFactory,JaxrsRestService.class);
    }

    private void createBeanProxy(ConfigurableListableBeanFactory beanFactory,Class<? extends Annotation> annotation) {
        List<Class<Object>> classes;
        try {
            classes = AnnotationUtils.findAnnotatedClasses(basePackage, annotation);
        } catch (Exception e) {
            throw new BeanInstantiationException(annotation, e.getMessage(), e);
        }
        BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
        for (Class<Object> classType : classes) {
            Annotation typeService = classType.getAnnotation(annotation);   
            GenericBeanDefinition beanDef = new GenericBeanDefinition();
            beanDef.setBeanClass(getQueryServiceFactory(classType, typeService));
            ConstructorArgumentValues cav = new ConstructorArgumentValues();
            cav.addIndexedArgumentValue(0, classType);
            cav.addIndexedArgumentValue(1, baseUri(classType,typeService));
            beanDef.setConstructorArgumentValues(cav);
            registry.registerBeanDefinition(classType.getName() + "Proxy", beanDef);
        }
    }

    private String baseUri(Class<Object> c,Annotation typeService){
        String baseUri = null;
        if(typeService instanceof SpringRestService){
            baseUri = ((SpringRestService)typeService).baseUri();  
        }else if(typeService instanceof JaxrsRestService){
            baseUri = ((JaxrsRestService)typeService).baseUri();
        }
        if(baseUri!=null && !baseUri.isEmpty()){
            return baseUri = resolver.resolveStringValue(baseUri);
        }else{
            throw new IllegalStateException("Impossibile individuare una baseUri per l'interface :"+c);
        }
    }

    private static Class<? extends FactoryBean<?>> getQueryServiceFactory(Class<Object> c,Annotation typeService){
        if(typeService instanceof SpringRestService){
            return it.eng.rete2i.springjsonmapper.spring.SpringRestInvokerProxyFactoryBean.class;  
        }else if(typeService instanceof JaxrsRestService){
            return it.eng.rete2i.springjsonmapper.jaxrs.JaxRsInvokerProxyFactoryBean.class;
        }
        throw new IllegalStateException("Impossibile individuare una classe per l'interface :"+c);
    }
}

关于REST服务签名

这是一个示例界面：

<bean class="it.eng.rete2i.springjsonmapper.factory.RestFactory">
    <property name="basePackage" value="it.giancarlo.rest.services" />
</bean>

关于REST服务实施

服务实施

package it.giancarlo.rest.services.spring;

import ...

@SpringRestService(baseUri="${bookservice.url}")
public interface BookService{

    @Override
    @RequestMapping("/volumes")
    QueryResult findBooksByTitle(@RequestParam("q") String q);

    @Override
    @RequestMapping("/volumes/{id}")
    Item findBookById(@PathVariable("id") String id);

}

要解析参数的注释，我创建了一个自定义RequestMappingHandlerMapping，它查找所有使用@SpringRestService注释的接口

@RestController
@RequestMapping("bookService")
public class BookServiceImpl implements BookService {
    @Override
    public QueryResult findBooksByTitle(String q) {
        // TODO Auto-generated method stub
        return null;
    }
    @Override
    public Item findBookById(String id) {
        // TODO Auto-generated method stub
        return null;
    }
}

我创建了一个配置类

public class RestServiceRequestMappingHandlerMapping extends RequestMappingHandlerMapping{


    public HandlerMethod testCreateHandlerMethod(Object handler, Method method){
        return createHandlerMethod(handler, method);
    }

    @Override
    protected HandlerMethod createHandlerMethod(Object handler, Method method) {
        HandlerMethod handlerMethod;
        if (handler instanceof String) {
            String beanName = (String) handler;
            handlerMethod = new RestServiceHandlerMethod(beanName,getApplicationContext().getAutowireCapableBeanFactory(), method);
        }
        else {
            handlerMethod = new RestServiceHandlerMethod(handler, method);
        }
        return handlerMethod;
    }


    public static class RestServiceHandlerMethod extends HandlerMethod{

        private Method interfaceMethod;


        public RestServiceHandlerMethod(Object bean, Method method) {
            super(bean,method);
            changeType();
        }

        public RestServiceHandlerMethod(Object bean, String methodName, Class<?>... parameterTypes) throws NoSuchMethodException {
            super(bean,methodName,parameterTypes);
            changeType();
        }

        public RestServiceHandlerMethod(String beanName, BeanFactory beanFactory, Method method) {
            super(beanName,beanFactory,method);
            changeType();
        }


        private void changeType(){
            for(Class<?> clazz : getMethod().getDeclaringClass().getInterfaces()){
                if(clazz.isAnnotationPresent(SpringRestService.class)){
                    try{
                        interfaceMethod = clazz.getMethod(getMethod().getName(), getMethod().getParameterTypes());
                        break;      
                    }catch(NoSuchMethodException e){

                    }
                }
            }
            MethodParameter[] params = super.getMethodParameters();
            for(int i=0;i<params.length;i++){
                params[i] = new RestServiceMethodParameter(params[i]);
            }
        }




        private class RestServiceMethodParameter extends MethodParameter{

            private volatile Annotation[] parameterAnnotations;

            public RestServiceMethodParameter(MethodParameter methodParameter){
                super(methodParameter);
            }


            @Override
            public Annotation[] getParameterAnnotations() {
                if (this.parameterAnnotations == null){
                        if(RestServiceHandlerMethod.this.interfaceMethod!=null) {
                            Annotation[][] annotationArray = RestServiceHandlerMethod.this.interfaceMethod.getParameterAnnotations();
                            if (this.getParameterIndex() >= 0 && this.getParameterIndex() < annotationArray.length) {
                                this.parameterAnnotations = annotationArray[this.getParameterIndex()];
                            }
                            else {
                                this.parameterAnnotations = new Annotation[0];
                            }
                        }else{
                            this.parameterAnnotations = super.getParameterAnnotations();
                        }
                }
                return this.parameterAnnotations;
            }

        }

    }

}

我配置了它

@Configuration
public class WebConfig extends WebMvcConfigurationSupport{

    @Bean
    public RequestMappingHandlerMapping requestMappingHandlerMapping() {
        RestServiceRequestMappingHandlerMapping handlerMapping = new RestServiceRequestMappingHandlerMapping();
        handlerMapping.setOrder(0);
        handlerMapping.setInterceptors(getInterceptors());
        handlerMapping.setContentNegotiationManager(mvcContentNegotiationManager());

        PathMatchConfigurer configurer = getPathMatchConfigurer();
        if (configurer.isUseSuffixPatternMatch() != null) {
            handlerMapping.setUseSuffixPatternMatch(configurer.isUseSuffixPatternMatch());
        }
        if (configurer.isUseRegisteredSuffixPatternMatch() != null) {
            handlerMapping.setUseRegisteredSuffixPatternMatch(configurer.isUseRegisteredSuffixPatternMatch());
        }
        if (configurer.isUseTrailingSlashMatch() != null) {
            handlerMapping.setUseTrailingSlashMatch(configurer.isUseTrailingSlashMatch());
        }
        if (configurer.getPathMatcher() != null) {
            handlerMapping.setPathMatcher(configurer.getPathMatcher());
        }
        if (configurer.getUrlPathHelper() != null) {
            handlerMapping.setUrlPathHelper(configurer.getUrlPathHelper());
        }
        return handlerMapping;
    }
}