Spring Cloud学习笔记---Spring Cloud Sleuth--新建两个互相调用的服务测试zipkin（简单易懂一看就会）（2018-08-10）

之前已经介绍了如何手动搭建一个zipkin，但是那个是很久之前的东西了，没啥技术含量还浪费时间，所以今天就来一个有意思的，好玩的，其实这个也没啥技术含量。２３３３３３
https://zipkin.io/pages/quickstart.html
这个是zipkin的官网，我们可以进行下载它的jar包，直接运行。

启动成功后，zipkin默认是在9411端口的，访问
http://localhost:9411/zipkin/
就可以看到zipkin的追踪界面

---

接下来，我们写两个互相调用的小的demo。
首先是我们的serviceThree.
其整个demo的目录结构如下

pom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>

    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>serviceThree</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.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.SR1</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-zipkin</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>${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>


</project>

然后就是application.yml

spring:
  application:
    name: serviceThree
  zipkin:
    base-url: http://localhost:9411


#eureka:
#  client:
#    serviceUrl:
#      defaultZone: http://localhost:9999/eureka/

server:
  port: 7779

注释掉注册中心的原因是，zipkin进行服务追踪的时候并不需要注册中心。

为了方便我就直接在入口函数写了

package com.example.demo;

import brave.sampler.Sampler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;


@RestController
@SpringBootApplication
public class ServiceThreeApplication {

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


    @Autowired
    private RestTemplate restTemplate;

    @Bean
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }

    @RequestMapping("/getInfo")
    public String info(){
        return "I'm serviceThree";
    }

    @RequestMapping("/callServiceFour")
    public String callServiceTwo(){
        return restTemplate.getForObject("http://localhost:7780/getInfo",String.class)
                +"form serviceThree";
    }
    @Bean
    public Sampler defaultSampler() {
        return Sampler.ALWAYS_SAMPLE;
    }

}

---

接下来就是serviceFour，这次为了稍微规范一点，改了一下目录结构，这个无所谓的。

然后是pom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>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>serviceFour</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.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.SR1</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-zipkin</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>${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>


</project>

然后就是配置文件

spring.application.name=serviceFour
spring.zipkin.base-url=http://localhost:9411
server.port=7780
#eureka.client.service-url.defaultZone=http://localhost:9999/eureka/

之后就是写的测试调用

package com.example.demo.controller;

import brave.sampler.Sampler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * Created by chenzhen on 2018/8/7.
 */
@RestController
public class xxxController {

    private Logger logger = LoggerFactory.getLogger(xxxController.class);

    @Autowired
    RestTemplate restTemplate;

    @Bean
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }

    @RequestMapping("/getInfo")
    public String getInfo(){
        return "I'm serviceFour";
    }

    @RequestMapping("/callServiceThree")
    public String callServiceThree(){
        return restTemplate.getForObject("http://localhost:7779/getInfo",String.class)
                +" form serviceFour";
    }
    @Bean
    public Sampler defaultSampler() {
        return Sampler.ALWAYS_SAMPLE;
    }
}

---

两个都写完之后，访问
http://localhost:7780/callServiceThree
http://localhost:7779/callServiceFour
之后再打开zipkin的追踪页面就会发现
http://localhost:9411/zipkin/dependency/

---

至此，整个小demo的服务依赖关系已经追踪完毕。

但是就目前来看，用zipkin来进行服务链路追踪，对代码有入侵，比如
代码中加的如下的代码就很重要。

@Bean
    public Sampler defaultSampler() {
        return Sampler.ALWAYS_SAMPLE;
    }

还有就是配置文件中需要配置zipkin的url,

spring.zipkin.base-url=http://localhost:9411

以及在pom中要引入zipkin依赖

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

以上三者缺一不可。