SpringCloud的学习记录(5)

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这一章节讲如何使用ribbon和hystrix.

在我们生成的Demo项目上右键点击New->Module->spring Initializr, 然后next, 填写Group和Artifact等信息，

这里Artifact填写ribbonconsumer, 再次next,

这里选择如下图:

最后在Module Name中填写ribbon-consumer.

生成的pom.xml文件如下:

<?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>2.1.3.RELEASE</version>
<relativePath/> 
</parent>
<groupId>com.xum</groupId>
<artifactId>ribbon-consumer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>ribbon-consumer</name>
<description>Demo project for Spring Boot</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.RELEASE</spring-cloud.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-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.netflix.hystrix</groupId>
<artifactId>hystrix-javanica</artifactId>
<version>RELEASE</version>
<scope>compile</scope>
</dependency>
</dependencies>
<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>
</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>
</repository>
</repositories>
</project>

在src->main->resources下建立application.yml文件, 内容如下

eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8771
spring:
application:
name: ribbon-consumer
management:
endpoint:
health:
show-details: always
endpoints:
web:
exposure:
include: '*'

在RibbonConsumerApplication.java里的内容如下, 要加上@EnableCircuitBreaker
@EnableHystrixDashboard
@EnableDiscoveryClient这三个注解.

package com.xum.ribbonconsumer;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;@EnableCircuitBreaker
@EnableHystrixDashboard
@EnableDiscoveryClient
@SpringBootApplication
public class RibbonConsumerApplication { @Bean
@LoadBalanced // 这里是加载平衡, 我这里使用RestTemplate
RestTemplate restTemplate () {
return new RestTemplate();
} public static void main(String[] args) {
SpringApplication.run(RibbonConsumerApplication.class, args);
}
}

然后在RibbonConsumerApplication.java文件夹同级目录下建立Controller文件夹, 里面写一个RibbonConsumerController.java, 内容如下:

package com.xum.ribbonconsumer.controller;import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;@RestController
@RequestMapping(value = "/ribbonconsumer")
public class RibbonConsumerController {
private static final Logger LOG = LoggerFactory.getLogger(RibbonConsumerController.class); @Autowired
RestTemplate restTemplate; @RequestMapping(value = "/test")
@HystrixCommand(fallbackMethod = "testConsumer_ribbon") // 这里是HystrixCommand注解, 如果eureka-client项目没有启动, 那么就会转到本项目的fallbackMethod方法,即testConsumer_ribbon(), 就是下面的方法
public String testConsumer() { // 这里是通过getForEntity属性来调用eureka-client里的testone/test这条api
LOG.info("RibbonConsumerController=>testConsumer");
return restTemplate.getForEntity("http://eureka-client/testone/test",String.class).getBody();
}
// 这里就是熔断器(Hystrix)自我保护的方法,其实是自定义的方法.
public String testConsumer_ribbon() {
LOG.info("RibbonConsumerController=>testConsumer_ribbon");
return "testConsumer_ribbon";
}
}

下面是eureka-client项目下testone/test的api返回内容, 这里是简写了,具体的内容可以回看前面eureka-client项目搭建.

@RequestMapping(value = "/test")
public String test(@RequestParam(value = "name", required = false, defaultValue = "testOneClient")String name) {
String info = "Hi " + name + ", this is EurekaClient, port is " + port;
return info;
}

最后顺序启动如下项目: