前言
微服务开发需要用到服务间的调用Feign、也可以选择dubbo，但是dubbo上手有点难度，可参考另一篇文章//www.greatytc.com/p/e11ff097424b
至于他们的优缺点，一个是rpc一个是http rest。Feign较带宽资源，对我们来说这点带宽还不是事，下面基于Feign来实现负载均衡和熔断，我们拿一个user的服务为例子。
第一篇-使用：//www.greatytc.com/p/7af37be1bedb
第二篇-熔断限流：//www.greatytc.com/p/2945c88950d9
源码：https://github.com/xcocean/spring-cloud-feign-demo
Feign的调用总结就是我开启feign调用另一个服务的接口(controller)，另一个服务不需要feign，只需要注册在一起的集群下。
技术栈
1、负载均衡：spring boot 2.1.x+nacos注册中心+Feign
2、熔断：
关于spring boot的版本，我们先选择现在最新稳定的2.1.102020年2月22日
2.2.x可能有点坑，先不用它。
一、创建聚合项目
parent(root)
|__dependencies：依赖
|__user-service：服务提供者
|__user-feign：服务调用者（调用一方使用feign）
创一个文件夹：spring-cloud-feign-demo使用idea打开，在创建pom.xml：如下：
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.10.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.qbccn</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<url>http://www.qbccn.com</url>
<description>spring cloud feign 演示demo</description>
<modules>
<module>dependencies</module>
<module>user-service</module>
<module>user-feign</module>
</modules>
<properties>
<java.version>1.8</java.version>
<maven.compiler.source>${java.version}</maven.compiler.source>
<maven.compiler.target>${java.version}</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.qbccn</groupId>
<artifactId>dependencies</artifactId>
<version>${project.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<profiles>
<profile>
<id>default</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
<properties>
<spring-javaformat.version>0.0.12</spring-javaformat.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>io.spring.javaformat</groupId>
<artifactId>spring-javaformat-maven-plugin</artifactId>
<version>${spring-javaformat.version}</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<!-- 设置默认跳过测试 -->
<includes>
<include>**/*Tests.java</include>
</includes>
<excludes>
<exclude>**/Abstract*.java</exclude>
</excludes>
<systemPropertyVariables>
<java.security.egd>file:/dev/./urandom</java.security.egd>
<java.awt.headless>true</java.awt.headless>
</systemPropertyVariables>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<executions>
<execution>
<id>enforce-rules</id>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<rules>
<bannedDependencies>
<excludes>
<exclude>commons-logging:*:*</exclude>
</excludes>
<searchTransitive>true</searchTransitive>
</bannedDependencies>
</rules>
<fail>true</fail>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<configuration>
<skip>true</skip>
</configuration>
<inherited>true</inherited>
</plugin>
</plugins>
</build>
</profile>
</profiles>
<repositories>
<repository>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestone</id>
<name>Spring Milestone</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-snapshot</id>
<name>Spring Snapshot</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestone</id>
<name>Spring Milestone</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-snapshot</id>
<name>Spring Snapshot</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>
在spring-cloud-feign-demo下创建dependencies，pom.xml如下：
<?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>
<groupId>com.qbccn</groupId>
<artifactId>dependencies</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<url>http://www.qbccn.com</url>
<properties>
<spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>
<spring-cloud-alibaba.verion>0.9.0.RELEASE</spring-cloud-alibaba.verion>
<spring-cloud-starter-feign.version>1.4.7.RELEASE</spring-cloud-starter-feign.version>
<spring-cloud-starter-alibaba-nacos-discovery.version>0.9.0.RELEASE
</spring-cloud-starter-alibaba-nacos-discovery.version>
<spring-cloud-starter-alibaba-sentinel.version>2.1.1.RELEASE</spring-cloud-starter-alibaba-sentinel.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-alibaba-dependencies</artifactId>
<version>${spring-cloud-alibaba.verion}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
<version>${spring-cloud-starter-feign.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
<version>${spring-cloud-starter-alibaba-nacos-discovery.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
<version>${spring-cloud-starter-alibaba-sentinel.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<repositories>
<repository>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestone</id>
<name>Spring Milestone</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-snapshot</id>
<name>Spring Snapshot</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestone</id>
<name>Spring Milestone</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-snapshot</id>
<name>Spring Snapshot</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>
二、创建服务生产者
接着创建服务提供者user-service，pom.xml如下：
<?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>
<parent>
<groupId>com.qbccn</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>user-service</artifactId>
<packaging>jar</packaging>
<url>http://www.qbccn.com</url>
<inceptionYear>2020-Now</inceptionYear>
<dependencies>
<!-- Spring Boot Begin -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- Spring Boot End -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
application.yml
server:
port: 10000
spring:
application:
name: user-service
main:
allow-bean-definition-overriding: true
jackson:
time-zone: GMT+8
date-format: yyyy-MM-dd HH:mm:ss
cloud:
nacos:
discovery:
server-addr: 192.168.112.1:8848 # 注意改成你的nacos地址
UserServiceApplication如下：
package com.qbccn.userservice;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient //注册服务
public class UserServiceApplication {
public static void main(String[] args) {
SpringApplication.run(UserServiceApplication.class, args);
}
}
编写普通的controller、service和实现接口
package com.qbccn.userservice.controller;
import com.qbccn.userservice.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @author linke
* @date 2020-02-21 下午 22:59
* @description
*/
@RestController
@RequestMapping("user")
public class UserController {
@Autowired
private UserService userService;
@GetMapping("info")
public Object info() {
return userService.getInfo();
}
}
package com.qbccn.userservice.service;
public interface UserService {
/**
* 获取用户信息
*/
Object getInfo();
}
package com.qbccn.userservice.service.impl;
import com.qbccn.userservice.service.UserService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import java.util.HashMap;
import java.util.Map;
@Component //交给spring托管
public class UserServiceImpl implements UserService {
// 用于显示负载均衡，端口区分
@Value("${server.port}")
private int port;
@Override
public Object getInfo() {
System.out.println("被调用！当前端口：" + port);
Map<String, Object> map = new HashMap<>();
map.put("name", "张三");
map.put("age", 23);
map.put("sex", "男");
map.put("port", port);
return map;
}
}
1、然后启动项目，
2、勾选上，然后修改application的端口为10000，再启动一次项目
image.png
image.png
3、登陆nacos可以看到已经被注册上：
image.png
三、创建服务消费者(Feign)
spring-cloud-feign-demo下创建文件夹user-feign，pom.xml如下：
<?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>
<parent>
<groupId>com.qbccn</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>user-feign</artifactId>
<packaging>jar</packaging>
<url>http://www.qbccn.com</url>
<inceptionYear>2020-Now</inceptionYear>
<dependencies>
<!-- Spring Boot Begin -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- Spring Boot End -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
</dependencies>
</project>
application.yml配置如下
spring:
application:
name: user-feign
main:
allow-bean-definition-overriding: true
jackson:
time-zone: GMT+8
date-format: yyyy-MM-dd HH:mm:ss
cloud:
nacos:
discovery:
server-addr: 192.168.112.1:8848
application.java需要开启feign：
package com.qbccn.userfeign;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableDiscoveryClient //注册服务
@EnableFeignClients //开启feign客户端
public class UserFeignApplication {
public static void main(String[] args) {
SpringApplication.run(UserFeignApplication.class, args);
}
}
接着是controller：
package com.qbccn.userfeign.controller;
import com.qbccn.userfeign.feign.UserServiceFeign;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("user")
public class UserFeignController {
@Autowired
private UserServiceFeign userServiceFeign;
@GetMapping("info")
@ResponseBody
public Object info() {
return userServiceFeign.GetInfo();
}
}
feign，自行看包路径创建
package com.qbccn.userfeign.feign;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
/**
* 说明一下，这个user-service是指服务提供者，注册到nacos上的，不区分大小写
* path 表示是user-service服务下的 /user/info 这个路径
*/
@FeignClient(value = "user-service", path = "user")
public interface UserServiceFeign {
@GetMapping(value = "info")
Object GetInfo();
}
然后启动服务，访问http://localhost:8080/user/info，不断刷新效果如下：
GIF.gif
可以看出这是一个轮询机制，可以配置权重
实现熔断
像这样开发，如果10000端口的服务突然网络震荡，请求失败了，我们需要使用熔断来返回失败结果，由于篇幅，我将在下一篇文章说明
