Spring Cloud Alibaba (a) how to use the service registration and discovery nacos

Nacos Introduction

Nacos committed to helping you discover, configure, and micro-management services. Nacos provides a set of simple-to-use set of features that help you quickly realize dynamic service discovery, service configuration, service metadata and traffic management.

Nacos help you more quickly and easily build, deliver and manage micro-service platform. Nacos is to build a "service" as the center of modern application architectures (such as micro-service paradigm, cloud native paradigm) service infrastructure.

The key characteristic of Nacos

• Service discovery and health monitoring services
• Dynamic configuration services, with a management interface, support for rich configuration dimensions.
• Dynamic DNS Service
• Service and metadata management

Nacos download and deploy

Official description document: Nacos Quick Start or download zip package, deploy download

Windows environment problems encountered during deployment summary

jdk version requirements

Must pay attention to, jdk version requires 64bit JDK 1.8+

Run error

Run startup.cmd, fleeting. Open startup.cmd script, add a pause so that the error will not end immediately easy to see the error message in the last line, then find the following error message:

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/springfra
mework/boot/loader/PropertiesLauncher : Unsupported major.minor version 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
2)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

The cause of these problems is that I have some old projects on a computer using jdk 1.7, so the project is jdk1.7 and jdk1.8 crossed use. View version java -version output in cmd then there is 1.8.0_211 (only the highest output version)

solution

• Configuring java_home, increase jdk1.8 environment variables, how to add their own environment variables need to Baidu, the following posted my java environment variables

C:\Users\Administrator>set java_home
JAVA_HOME=D:\Program Files\Java\jdk1.7.0_71

C:\Users\Administrator>set java8_home
JAVA8_HOME=D:\Program Files\Java\jdk1.8.0_201

C:\Users\Administrator>

• Adjustment startup.cmd script, use java8_home variable, rather than allow it to call the correct jdk1.8 jdk1.7, the following adjustments are part of the code

if not exist "%JAVA8_HOME%\bin\java.exe" echo Please set the JAVA8_HOME variable in your environment, We need java(x64)! jdk8 or later is better! & EXIT /B 1
set "JAVA=%JAVA8_HOME%\bin\java.exe"

Here only to be replaced, the original JAVA_HOME planning to JAVA8_HOME, run startup.cmd, this time to run a proper service Nacos

View Interface

Successful start in the browser to visit: http: // localhost: 8848 / nacos, will jump to the login screen, the default login user name nacos, password is also nacos.

After the successful landing, you can operate the management interface

Use Nacos service registration and discovery

To use nacos, we need to add the necessary dependencies in pom.xml

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.1.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

Create a service registry and discovery sample code

In this case, the use of three service registered to the Nacos, respectively, for the service provider ali-nacos-provider and load balancing ribbon consumer ali-nacos-consumer-ribbon, declarative service call feign consumer ali-nacos-consumer -feign.

What is the ribbon and feign, using examples and are not repeated here introduced, you need to know you can see an example

Create a service provider ali-nacos-provider

Add nacos rely pom.xml

    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>

application.yml Configuration

server:
  port: 9000  #指定为9000端口

spring:
  application:
    name: ali-nacos-provider  #服务名
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848 #服务注册地址(nacos默认为8848端口)

management:
  endpoints:
    web:
      exposure:
        include: '*'

Start class increase @EnableDiscoveryClient comment

package com.easy.aliNacosProvider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class AliNacosProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(AliNacosProviderApplication.class, args);
    }
}

Write hello service interface HelloController.java

package com.easy.aliNacosProvider;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class HelloController {
    @GetMapping(value = "/hello/{str}", produces = "application/json")
    public String hello(@PathVariable String str) {
        log.info("-----------收到消费者请求-----------");
        log.info("收到消费者传递的参数：" + str);
        String result = "我是服务提供者，见到你很高兴==>" + str;
        log.info("提供者返回结果：" + result);
        return result;
    }
}

Create a service consumer ribbon

pom.xml and ribbon-dependent increase nocos

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

    </dependencies>

application.yml

server:
  port: 9100

spring:
  application:
    name: ali-nacos-consumer-ribbon
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

Service call HomeController.java

package com.easy.ancRibbon;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
@Slf4j
public class HomeController {
    @Autowired
    private RestTemplate restTemplate;

    @GetMapping(value = "/", produces = "application/json")
    public String home() {
        log.info("-----------------consumer调用开始-----------------");
        String param = "云天";
        log.info("消费者传递参数：" + param);
        String result = restTemplate.getForObject("http://ali-nacos-provider/hello/" + param, String.class);
        log.info("收到提供者响应：" + result);
        return "ribbon消费者，" + result;
    }
}

Enable class AncRibbonConsumerApplication.java

package com.easy.ancRibbon;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class AncRibbonConsumerApplication {

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

    public static void main(String[] args) {
        SpringApplication.run(AncRibbonConsumerApplication.class, args);
    }

}

Create a service consumer feign

pom.xml

    <dependencies>
        <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.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

application.yml

server:
  port: 9101

spring:
  application:
    name: ali-nacos-consumer-feign
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
  main:
    allow-bean-definition-overriding: true  #允许一样的beanName

Here is a pit next to note that if allow-bean-definition-overriding is set to true, run the following error will be reported:

错误： Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

There are problems in detail cause of the problem

Application Service HelloService.java

package com.easy.ancFeign;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient("ali-nacos-provider")
public interface HelloService {

    @RequestMapping(path = "hello/{str}")
    String hello(@RequestParam("str") String param);

}

Service call HomeController.java

package com.easy.ancFeign;

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

@RestController
@Slf4j
public class HomeController {

    @Autowired
    private HelloService helloService;

    @GetMapping(value = "/", produces = "application/json")
    public String home() {
        log.info("-----------------consumer调用开始-----------------");
        String param = "云天";
        log.info("消费者传递参数：" + param);
        String result = helloService.hello(param);
        log.info("收到提供者响应：" + result);
        return "feign消费者" + result;
    }
}

Start class AncFeignConsumerApplication.java

package com.easy.ancFeign;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients(basePackages = {"com.easy.ancFeign"})
public class AncFeignConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(AncFeignConsumerApplication.class, args);
    }
}

Examples of Use

The three existing projects are as follows

ali-nacos-provider: a service provider, service name: ali-nacos-provider, port: 9000
Ali-nacos-Consumer-Ribbon: Ribbon service consumers, service name: ali-nacos-consumer-ribbon , port: 9100
ali-nacos-consumer-feign: feign consumers, service name: ali-nacos-consumer-feign , port: 9101

Run the test

First to start the service registry nacos
Secondly, were started ali-nacos-provider, ali- nacos-consumer-ribbon, ali-nacos-consumer-feign three services

• Access address: http: // localhost: 9100 /, return: ribbon consumer, I am a service provider, nice to meet you ==> the sky, indicating the success of the ribbon consumption.
• Access address: http: // localhost: 9101 /, return: feign consumer I am a service provider, nice to meet you ==> the sky, indicating that consumer costs feign success.
• Access address: http: // localhost: 9000 / hello / yuntian, return: I am a service provider, nice to meet you ==> yuntian, description of the service provider access to success (PS: service providers generally are not of foreign public, how subtle the interface will be introduced in the next article)
• Access address: http: // localhost: 8848 / nacos / # / login, enter the user: nacos, password: nacos. Enter the service management interface in the service management - where you can see the list of services we run the three services.

data

• Spring Cloud Alibaba sample source code
• Nacos official website