springcloud服务与服务之间的调用（Feign）

其他 2020-03-28 10:56:47 阅读次数: 0

  • springcloud是什么？

           Spring Cloud为开发人员提供了快速构建分布式系统中一些常见模式的工具（例如配置管理，服务发现，断路器，智能路由，控制总微代理，线，一次性令牌，全局锁定，领导选举，分布式会话，集群状态）。分布式系统的协调导致锅炉板模式，使用Spring Cloud开发人员可以快速站起来实现这些模式的服务和应用程序。它们适用于任何分布式环境，包括开发人员自己的笔记本电脑，裸机数据中心和Cloud Foundry等托管平台。

  • 什么分布式系统？

         分布式就是将一个系统拆分成很多的子系统，比如淘宝系统，他有许许多多的子系统：会员系统、订单系统、积分系统等等，这样已拆分就大大的减轻了服务器的压力，如果想深入了解分布式的架构，还请百度分布式架构，这里不多做说明。

  • 什么是Feign

          既然一个系统被拆分成了无数个子系统，那系统之间是如何进行通信的呢？假如我现在在订单系统中想获取到会员的信息，此时，你能怎么做？

          可能你会说用外链接查询，这个也没啥错，但是正规的分布式系统都是将对应的表分给了对应的库，所以这里链接查询是走不通的，这时，你可能在想，要是我能直接调用会员服务的方法那该多好，Feign就来了，他解决了服务与服务之间的通讯。

          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,类似于Dubbo的RPC。

  •  eureka

        如果想实现服务与服务之前的调用，那么必须要有eureka这个注册中心，eureka在这里不多做解释，直接看代码：

      1.创建一个eureka-service的springboot项目。

                    
       2.maven依赖：     

<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>
	<groupId>com.ymy</groupId>
	<artifactId>sprintcloud</artifactId>
	<version>0.0.1-SNAPSHOT</version>

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </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>
        <!--eureka server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
        <!-- spring boot test -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.RC1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
</project>

不需要的jar可以不引用。

3.添加配置文件：

server:
  port: 8769
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

这样eureka服务算是大功告成。

  • 服务端1（被调用端1）

      创建一个springboot项目：

                     

       pom文件：
            

<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>
  <groupId>com.ymy.client1</groupId>
  <artifactId>cloud-client1</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>boot1</name>
	<description>Demo project for Spring Boot</description>
 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </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.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.RC1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
  
  
  
</project>

    新建配置文件：application.yml

       

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8769/eureka/
server:
  port: 8762
spring:
  application:
    name: service-hi

启动类：我将controller直接写在了启动类了，你们可以新建一个controller包

package com.ymy;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@EnableEurekaClient
@SpringBootApplication
@RestController
@RequestMapping("c")
public class App1 {
	
	public static void main(String[] args) {
		SpringApplication.run(App1.class, args);
	}
	
	@Value("${server.port}")
	String port;
	@GetMapping("hello")
	public String hello(@RequestParam String name){
		
		return "hello "+name+" 我的服务端口是："+port;
	}
}

  • 服务端2（被调用端2）

      新建一个springboot项目：

           

        pom文件：
 

<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>
  <groupId>com.ymy.client1</groupId>
  <artifactId>cloud-client1</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </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.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.RC1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
  
  
</project>

新建配置文件：application.yml

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8769/eureka/
server:
  port: 8763
spring:
  application:
    name: service-hi

启动类：

    

package com.ymy;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@EnableEurekaClient
@SpringBootApplication
@RestController
@RequestMapping("c")
public class App2 {
	
	public static void main(String[] args) {
		SpringApplication.run(App2.class, args);
	}
	
	@Value("${server.port}")
	String port;
	@GetMapping("hello")
	public String hello(@RequestParam String name){
		
		return "hello "+name+" 我的服务端口是："+port;
	}
}

  • 客服端（调用端）

新建一个springboot项目

     

pom配置文件：
 

<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>
	<groupId>com.ymy.client3</groupId>
	<artifactId>cloud-client3</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.2.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</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.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-feign</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<!-- 断路器 -->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-hystrix</artifactId>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>Dalston.RC1</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
	</repositories>



</project>

新建application.yml文件
    

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8769/eureka/
server:
  port: 8765
spring:
  application:
    name: service-feign
feign:
  hystrix:
    enabled: true

controller类：

package com.ymy.controller;

import javax.inject.Inject;

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

import com.ymy.feign.ClientFeign;
import com.ymy.feign.HystrixClientFeign;
@RestController
public class MyController {

	@Inject
	private ClientFeign clientFeign;
//	@Autowired
//	private HystrixClientFeign hystrixClientFeign;
	
	
	@GetMapping("hi")
	public String hi(@RequestParam String name){
		return clientFeign.getHello(name);
	}
	
	/*@GetMapping("hihi")
	public String hihi(@RequestParam String name){
		System.out.println("哈哈哈哈");
		return hystrixClientFeign.hello(name);
	}*/
}

重点来了，Feign的运用:

ClientFeign类：

package com.ymy.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;


@FeignClient(value = "service-hi", fallback = HystrixClientFeign.class)
public interface ClientFeign {
	@GetMapping("c/hello")
	String getHello(@RequestParam(value = "name") String name);
}

HystrixClientFeign类：

  

package com.ymy.feign;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@Component
public class HystrixClientFeign implements ClientFeign{

//	@Autowired
//	private RestTemplate  restTemplate;
	
	
//	@HystrixCommand(defaultFallback="hiError")
//	public String hello(String name){
//		return restTemplate.getForObject("http://service-hi/hello?name="+name, String.class);
//	}
	
	/*public String hiError(String name) {
        return "hi," + name + ",sorry,error!";
    }*/

	@Override
	public String getHello(String name) {
		return "hello " + name + ", error!";
	}
}

代码已经贴的差不多了，下面我们来看运行结果：

两个服务端我做的是集群，客服端以轮询的方式访问，有兴趣的小伙伴可以试试哦，需要源码的可以留言哦。

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