背景
微服务重构,使用Spring全家桶.JSON数据传输为了兼容接口规范对Feign进行了定制
启用Feign
加入Feign的Spring starter依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
Applicaiton中加上注解
@SpringBootApplication
@EnableFeignClients
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class);
}
}
定义一个和使用客户端
package com.tourscool.passport;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient(name="authorize" ,url="http://authorize.dev.philo.in/api/v1/",configuration = FeignConfiguration.class)
public interface AuthorizeClient {
@RequestMapping(value = "/auth/verify-get", method = RequestMethod.GET)
PermInfo verifyAndGet(@RequestParam String token, @RequestParam long applicationId);
}
在 AuthorizeClient 这个接口中我们定义了一个verifyAndGet的方法,用于进行TOKEN的验证.
@FeignClient(name="authorize" ,url="http://authorize.dev.philo.in/api/v1/",configuration = FeignConfiguration.class)
这个注解启用 Feign客户端. name字段在启用了服务发现之后会从服务发现中获取到你所要调用的
服务的真实地址.调试时可以设置url来指定你的地址.
configuration 则用于指定该客户端在发送HTTP 请求的一些行为.通过这个class我们可以对Feign进行深度的定制.
@RestController
public class Endpoint {
@Value("${application.name:passport}")
private String name;
@Autowired
private AuthorizeClient client;
@GetMapping("/")
public HashMap<String,Object> info(String token)
{
PermInfo info = client.verifyAndGet(token,1);
}
定义好接口之后我们可以直接进行使用.Feign会帮我们创建实例.
定制
Feign 的定制通过指定configuration 类来实现.非常方便.也可以使用spring扫描配置来应用到全局.
旧的规范我们定义了接口的结构如下,
{
"code": 0,
"msg": "success",
"data": {
"name" : "vincent",
"salary" : 800
}
}
异常情况
{
"code": 600403,
"msg": "Access Deny",
"data": null
}
我们希望在Feign使用中,发现异常情况直接抛出异常,而如果执行正常则需要直接返回实际的数据结构.
因此我们需要自己实现一个Feign的Decoder用于将Feign返回的内容转换成对象.
代码如下: 处理了泛型数据
package com.tourscool.passport;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.vnzmi.commons.exception.BusinessException;
import feign.Logger;
import feign.Types;
import feign.Util;
import feign.codec.Decoder;
import org.springframework.context.annotation.Bean;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
public class FeignConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
@Bean
public Decoder decoder(){
return (response, type) -> {
String bodyText = Util.toString(response.body().asReader(StandardCharsets.UTF_8));
ObjectMapper mapper = new ObjectMapper();
JsonNode root = mapper.readTree(bodyText);
JsonNode codeNode = root.get("code");
JsonNode msgNode = root.get("msg");
if(codeNode == null || codeNode == null)
{
throw new BusinessException(400,"unsupported rest format");
}
int code = codeNode.asInt();
String message = msgNode.asText();
if (code != 0) {
throw new ApiException(code, message).setData(dataNode.asText());
} else {
Class rawType = Types.getRawType(type);
if (type instanceof ParameterizedType){
ParameterizedType type1 = (ParameterizedType) type;
//log.info("{} - > {} ->{}",type1.getRawType().getTypeName(),type1.getActualTypeArguments()[0].getClass(),dataNode);
try {
List<Class> params = new ArrayList<>();
for (Type e : type1.getActualTypeArguments()) {
Class<?> aClass = Class.forName(e.getTypeName());
params.add(aClass);
}
JavaType resultType = mapper.getTypeFactory().constructParametricType(
Class.forName(type1.getRawType().getTypeName()),
params.toArray(new Class[params.size()]));
return mapper.readValue(dataNode.toString(),resultType);
} catch (ClassNotFoundException e) {
e.printStackTrace();
throw new ApiException(e);
}
}else{
return mapper.treeToValue(dataNode,rawType);
}
}
};
}
}
另外 Feign 写的 ‘‘‘Types.getRawType’‘‘还挺好用 ;)
public static Class<?> getRawType(Type type) {
if (type instanceof Class) {
return (Class)type;
} else if (type instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType)type;
Type rawType = parameterizedType.getRawType();
if (!(rawType instanceof Class)) {
throw new IllegalArgumentException();
} else {
return (Class)rawType;
}
} else if (type instanceof GenericArrayType) {
Type componentType = ((GenericArrayType)type).getGenericComponentType();
return Array.newInstance(getRawType(componentType), 0).getClass();
} else if (type instanceof TypeVariable) {
return Object.class;
} else if (type instanceof WildcardType) {
return getRawType(((WildcardType)type).getUpperBounds()[0]);
} else {
String className = type == null ? "null" : type.getClass().getName();
throw new IllegalArgumentException("Expected a Class, ParameterizedType, or GenericArrayType, but <" + type + "> is of type " + className);
}
}
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