微服务之springCloud-docker-feign(四)

简介

上一节，我们讨论了怎么通过，restTemlate调用cloud的生产者，实现起来还是比较复杂的，尤其是在消费复杂的Restful服务的时候，还需要进行一系列的转换，编解码等，使用Feign就完全不用考虑这个问题.。

一、feinn介绍

Feign是一种声明式、模板化的HTTP客户端。在Spring Cloud中使用Feign, 我们可以做到使用HTTP请求远程服务时能与调用本地方法一样的编码体验，开发者完全感知不到这是远程方法，更感知不到这是个HTTP请求，这整个调用过程和Dubbo的RPC非常类似。开发起来非常的优雅。

二、创建模块（microservice-consumer-movie-feign）

项目结构如下：

三、pom.xml

<?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">
    <parent>
        <artifactId>microservice-spring-cloud</artifactId>
        <groupId>com.jacky</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

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

    <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>

        <!--<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-oauth2</artifactId>
        </dependency>-->
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>com.spotify</groupId>
                <artifactId>docker-maven-plugin</artifactId>
                <executions>
                    <!--设置在执行maven 的install时构建镜像-->
                    <execution>
                        <id>build-image</id>
                        <phase>install</phase>
                        <goals>
                            <goal>build</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <!--安装了docker的主机，并且打开了api remote接口设置-->
                    <dockerHost>http://192.168.6.130:5678</dockerHost>
                    <pushImage>true</pushImage><!--设置上传镜像到私有仓库，需要docker设置指定私有仓库地址-->
                    <!--镜像名称-->
                    <imageName>${docker.repostory}/${docker.image.prefix}/${project.artifactId}:${project.version}</imageName>
                    <!--镜像的基础版本-->
                    <baseImage>java:openjdk-8-jdk-alpine</baseImage>
                    <!--镜像启动参数-->
                    <entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint>
                    <resources>
                        <resource>
                            <targetPath>/</targetPath>
                            <directory>${project.build.directory}</directory>
                            <include>${project.build.finalName}.jar</include>
                        </resource>
                    </resources>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

四、配置文件application.yml

spring:
  application:
    name: microservice-consumer-movie-feign
server:
  port: 7901
eureka:
  client:
    healthcheck:
      enabled: true
    serviceUrl:
      defaultZone: http://jacky:admin@peer1:8761/eureka/,http://jacky:admin@peer2:8762/eureka/,http://jacky:admin@peer3:8763/eureka/
  instance:
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${spring.cloud.client.ipAddress}:${spring.application.instance_id:${server.port}}

五、MovieController.java

package com.jacky.cloud.controller;

import com.jacky.cloud.entity.User;
import com.jacky.cloud.feign.UserFeignClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * Created by jacky on 2017/7/14.
 */
@RestController
public class MovieController {

    @Autowired
    private UserFeignClient userFeignClient;

    @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);
    }
}

六、实体类User.java

package com.jacky.cloud.entity;

import java.math.BigDecimal;

public class User {
  private Long id;

  private String username;

  private String name;

  private Short age;

  private BigDecimal balance;

  public Long getId() {
    return this.id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getUsername() {
    return this.username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

  public String getName() {
    return this.name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Short getAge() {
    return this.age;
  }

  public void setAge(Short age) {
    this.age = age;
  }

  public BigDecimal getBalance() {
    return this.balance;
  }

  public void setBalance(BigDecimal balance) {
    this.balance = balance;
  }

}

七、UserFeignClient.java

package com.jacky.cloud.feign;

import com.jacky.cloud.entity.User;
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;

/**
 * Created by jacky on 2017/7/14.
 */
@FeignClient("microservice-provider-user")
public interface UserFeignClient {
    /**
     * 根据Id获得User
     * 两个坑：1. @GetMapping不支持   2. @PathVariable得设置value
     * @param id
     * @return
     */
    @RequestMapping(value = "/simple/{id}", method = RequestMethod.GET)
    public User findById(@PathVariable("id") Long id);

    @RequestMapping(value = "/user", method = RequestMethod.POST)
    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。
    // 也就是说复杂对象，feign一定要post的请求方式
    @RequestMapping(value = "/get-user", method = RequestMethod.GET)
    public User getUser(User user);
}

八、启动类(MicroserviceSimpleConsumerMovieApplication.java)

package com.jacky.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;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

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