Spring Cloud（二） Ribbon
Spring Cloud RibbonRibbon参考及原理
- 环境及工具
- maven 3.5.3
- jdk1.8
- Intellij Idea
- spring boot 2.0
使用Idea创建项目
– pom.xml文件
<?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>cn.qx</groupId>
<artifactId>spring-cloud-ribbon</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>spring-cloud-ribbon</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.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>
<spring-cloud.version>Finchley.M8</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-openfeign</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</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>${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>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
- application.yml
spring:
application:
name: ribbon-test
server:
port: 9006
ribbon:
# Max number of retries on the same server (excluding the first try)
MaxAutoRetries: 1
# Max number of next servers to retry (excluding the first server)
MaxAutoRetriesNextServer: 1
# Whether all operations can be retried for this client
OkToRetryOnAllOperations: true
# Interval to refresh the server list from the source
ServerListRefreshInterval: 2000
# Connect timeout used by Apache HttpClient
ConnectTimeout: 3000
# Read timeout used by Apache HttpClient
ReadTimeout: 3000
# Initial list of servers, can be changed via Archaius dynamic property at runtime
#listOfServers: www.microsoft.com:80,www.yahoo.com:80,www.google.com:80
#EnablePrimeConnections: true
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8001/eureka/- 主要项目结构
- 关键代码块
- SpringCloudRibbonApplication
@EnableDiscoveryClient
@SpringBootApplication
public class SpringCloudRibbonApplication {
/** * @see * RestTemplate实例化 * @Bean注入到spring容器， * 通过@LoadBalanced开启均衡负载能力 * @return restTemplate */
@Bean
@LoadBalanced
public static RestTemplate restTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(SpringCloudRibbonApplication.class, args);
}
}- RibboController 为web端提供接口
@RestController
public class RibbonController {
@Autowired
RibbonService ribbonService;
@RequestMapping("/ribbon/{id}")
public User findUser(@PathVariable Long id){
System.out.println("----------------------------------进入ribbon------findUser---------------------------------------------");
return ribbonService.findUserById(id);
}
@GetMapping("/ribbon/{id}/{name}")
public User findUserByIdAndName(@PathVariable Long id,@PathVariable String name){
System.out.println("----------------------------------进入ribbon---findUserByIdAndName---------------------------------------");
return ribbonService.findUserByIdAndName(id,name);
}
}- RibbonService
- 注意： http://demo-clent/ 这里的demo-client为服务提供端的spring.application. name = demo-clent;必须用服务名开头，后面跟上接口名以及参数;否则会报：java.lang.IllegalStateException: No instances available for *异常*
@Service
public class RibbonService {
@Autowired
RestTemplate restTemplate;
/** * @see findUserById 单个参数 * @param id * @return */
public User findUserById(Long id){
return restTemplate.getForObject("http://demo-clent/"+ id ,User.class);
}
/** * @see findUserByIdAndName 多个参数,getForObject可以换位其它的方法，比如postForObject * @param id * @param name * @return */
public User findUserByIdAndName(Long id,String name){
return restTemplate.getForObject("http://demo-clent/findUserByIdAndName/"+ id + "/" + name ,User.class);
}
}- 接下来是服务提供者相关内容：
- 服务提供者的名称为： spring.application. name = demo-clent，可以多个，ribbon提供了均衡负载，直接访问即可
- 都注册到同一个注册中心Eureka-Server上
- 服务提供者项目结构图
- 主要代码RibbonController
@RestController
public class RibbonController {
@GetMapping("{id}")
public User findUserById(@PathVariable Long id ){
User u = new User();
u.setId(id);
u.setAge(100);
u.setUsername("demo-client1--长寿人");
return u;
}
@GetMapping("/findUserByIdAndName/{id}/{name}")
public User findUserByIdAndName(@PathVariable Long id, @PathVariable String name ){
User u = new User();
u.setId(id);
u.setAge(110);
u.setUsername("demo-client1--不死人： "+ name);
return u;
}
}测试Ribbon
浏览器输入
http://localhost:9006/ribbon/25/小明
前面加了@LoadBalanced 注解，ribbon会开启均衡负载；结果如下
到此完成ribbon的访问测试代码；
GitHub完整ribbon代码示例
GitHub服务提供者代码示例
- 遇到的问题：
- 问题：java.lang.IllegalStateException: No instances available for 异常
- 解决： http://demo-clent/ 这里的demo-client为服务提供端的spring.application. name = demo-clent;必须用服务名开头，后面跟上接口名以及参数;否则会报上述一次
