springCloud4---feign

JAX-WS : soap是遵循这个标准。

JAX-RS ： 标准，jersey框架遵循这个标准。

Feign是一个声明式的web service客户端。Feign使用的负载均衡也是ribbon，Feign整合了Ribbon和Eureka。

package com.itmuch.cloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients  //Feign的客户端
public class ConsumerMovieFeignApplication {
  public static void main(String[] args) {
    SpringApplication.run(ConsumerMovieFeignApplication.class, args);
  }
}
package com.itmuch.cloud.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.itmuch.cloud.entity.User;
import com.itmuch.cloud.feign.UserFeignClient;

@RestController
public class MovieController {

  @Autowired
  private UserFeignClient userFeignClient;

/*  原来是通过restTemplate来调用
  @GetMapping("/movie/{id}")
  public User findById(@PathVariable Long id) {
        return this.restTemplate.getForObject(this.userServicePath + id, User.class);
  }*/
  
  @GetMapping("/movie/{id}")
  public User findById(@PathVariable Long id) {
    return this.userFeignClient.findById(id);
  }

  @GetMapping("/test")
  public User testPost(User user) {
    return this.userFeignClient.postUser(user);
  }

  @GetMapping("/test-get")
  public User testGet(User user) {
    return this.userFeignClient.getUser(user);
  }
}
package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.itmuch.cloud.entity.User;

@FeignClient("microservice-provider-user")  //请求microservice-provider-user服务
public interface UserFeignClient {
  @RequestMapping(value = "/simple/{id}", method = RequestMethod.GET)//microservice-provider-user服务的/simple/{id}
  public User findById(@PathVariable("id") Long id); // 两个坑：1. @GetMapping不支持   2. @PathVariable得设置value

  @RequestMapping(value = "/user", method = RequestMethod.POST) //post对象
  public User postUser(@RequestBody User user);

  // 该请求不会成功，只要参数是复杂对象，即使指定了是GET方法，feign依然会以POST方法进行发送请求。可能是我没找到相应的注解或使用方法错误。
  // 如勘误，请@lilizhou2008  eacdy0000@126.com
  @RequestMapping(value = "/get-user", method = RequestMethod.GET)
  public User getUser(User user);
}
spring:
  application:
    name: microservice-consumer-movie  #本服务的名字
server:
  port: 7905
eureka:
  client:
    healthcheck:
      enabled: true
    serviceUrl:
      defaultZone: http://user:password123@localhost:8761/eureka  #注册到的eureka的地址
  instance:
    prefer-ip-address: true
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>microservice-consumer-movie-feign</artifactId>
    <packaging>jar</packaging>

    <parent>
        <groupId>com.itmuch.cloud</groupId>
        <artifactId>microservice-spring-cloud</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!-- 引入feign依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>
</project>

复写feign的默认配置，

package com.itmuch.cloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
//默认只扫描这个类所在的包和子包
public class ConsumerMovieFeignApplication {
  public static void main(String[] args) {
    SpringApplication.run(ConsumerMovieFeignApplication.class, args);
  }
}
package com.itmuch.cloud.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.itmuch.cloud.entity.User;
import com.itmuch.cloud.feign.FeignClient2;
import com.itmuch.cloud.feign.UserFeignClient;

@RestController
public class MovieController {

  @Autowired
  private UserFeignClient userFeignClient;

  @Autowired
  private FeignClient2 feignClient2;

  @GetMapping("/movie/{id}")
  public User findById(@PathVariable Long id) {
    return this.userFeignClient.findById(id);
  }

  @GetMapping("/{serviceName}")
  public String findServiceInfoFromEurekaByServiceName(@PathVariable String serviceName) {
    return this.feignClient2.findServiceInfoFromEurekaByServiceName(serviceName);
  }
}
package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import com.itmuch.config.Configuration2;

//Configuration2作为他的配置文件
@FeignClient(name = "xxxx", url = "http://localhost:8761/", configuration = Configuration2.class)
public interface FeignClient2 {
  @RequestMapping(value = "/eureka/apps/{serviceName}")
  public String findServiceInfoFromEurekaByServiceName(@PathVariable("serviceName") String serviceName);
}
package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;

import com.itmuch.cloud.entity.User;
import com.itmuch.config.Configuration1;

import feign.Param;
import feign.RequestLine;

//Configuration1作为他的配置文件
@FeignClient(name = "microservice-provider-user", configuration = Configuration1.class)
public interface UserFeignClient {
  @RequestLine("GET /simple/{id}")
  public User findById(@Param("id") Long id);
}
package com.itmuch.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import feign.Contract;
import feign.Logger;

@Configuration
public class Configuration1 {
  @Bean
  public Contract feignContract() {
    return new feign.Contract.Default();
  }

  @Bean
  Logger.Level feignLoggerLevel() {
    return Logger.Level.FULL;
  }
}
package com.itmuch.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import feign.auth.BasicAuthRequestInterceptor;

@Configuration
public class Configuration2 {
  @Bean
  public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
    return new BasicAuthRequestInterceptor("user", "password123");
  }
}
spring:
  application:
    name: microservice-consumer-movie
server:
  port: 7901
eureka:
  client:
    healthcheck:
      enabled: true
    serviceUrl:
      defaultZone: http://user:password123@localhost:8761/eureka
  instance:
    prefer-ip-address: true
logging:
  level:
    com.itmuch.cloud.feign.UserFeignClient: DEBUG   #日志是debug级别

# 解决第一次请求报超时异常的方案：
# hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000
# 或者：
# hystrix.command.default.execution.timeout.enabled: false
# 或者：
feign.hystrix.enabled: false ## 索性禁用feign的hystrix

# 超时的issue：https://github.com/spring-cloud/spring-cloud-netflix/issues/768
# 超时的解决方案： http://stackoverflow.com/questions/27375557/hystrix-command-fails-with-timed-out-and-no-fallback-available
# hystrix配置： https://github.com/Netflix/Hystrix/wiki/Configuration#execution.isolation.thread.timeoutInMilliseconds
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>microservice-consumer-movie-feign-customizing</artifactId>
    <packaging>jar</packaging>

    <parent>
        <groupId>com.itmuch.cloud</groupId>
        <artifactId>microservice-spring-cloud</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>
</project>
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原文地址：https://www.cnblogs.com/yaowen/p/9129068.html