（四十六）java版spring cloud微服务架构b2b2c电子商务平台-Feign自定义注解翻译器

一 新建自定义注解MyUrl

package org.crazyit.cloud.contract;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

//这个注解只能定义方法
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyUrl {
   //为注解配置两个属性
   String url();
   String method();
}

二 新建接口，使用MyUrl注解

package org.crazyit.cloud.contract;
 
public interface ContractClient {
 
    @MyUrl(url = "/hello", method = "GET")
    public String hello();
}

三 定义注解翻译器

package org.crazyit.cloud.contract;
 
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
 
import feign.Contract.BaseContract;
import feign.MethodMetadata;
 
public class MyContract extends BaseContract {
 
    @Override
    protected void processAnnotationOnClass(MethodMetadata data, Class<?> clz) {
        // 处理类级别注解
 
    }
 
    @Override
    protected void processAnnotationOnMethod(MethodMetadata data,
            Annotation annotation, Method method) {
        // 注解是MyUrl类型的，才处理
        if(MyUrl.class.isInstance(annotation)) {
            MyUrl myUrl = method.getAnnotation(MyUrl.class);
            String url = myUrl.url();
            String httpMethod = myUrl.method();
            data.template().method(httpMethod);
            data.template().append(url);
        }
    }
 
    @Override
    protected boolean processAnnotationsOnParameter(MethodMetadata data,
            Annotation[] annotations, int paramIndex) {
        // 处理参数级别注解
        return false;
    }
 
}

四 测试类

package org.crazyit.cloud.contract;
 
import org.crazyit.cloud.jaxrs.RsClient;
 
import feign.Feign;
import feign.jaxrs.JAXRSContract;
 
public class ContractMain {
 
    public static void main(String[] args) {
        ContractClient client = Feign.builder()
                .contract(new MyContract())
                .target(ContractClient.class,
                "http://localhost:8080");
        String result = client.hello();
        System.out.println(result);
    }
 
}