springcloud服务与服务之间的调用（Feign）
2020-04-19 21:15
525 查看
-
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。
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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。
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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。
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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：
[code]<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：
[code]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。
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服务端1（被调用端1）
创建一个springboot项目：
pom文件：
[code]<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
[code]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
[code]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;
}
}
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服务端2（被调用端2）
新建一个springboot项目：
pom文件：
[code]<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
[code]eureka: client: serviceUrl: defaultZone: http://localhost:8769/eureka/ server: port: 8763 spring: application: name: service-hi
启动类：
[code]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;
}
}
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客服端（调用端）
新建一个springboot项目
pom配置文件：
[code]<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
[code]eureka: client: serviceUrl: defaultZone: http://localhost:8769/eureka/ server: port: 8765 spring: application: name: service-feign feign: hystrix: enabled: true
controller类：
[code]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：
[code]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：
[code]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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