Spring Cloud总览

概述

服务提供者：服务的被调用发，为其他服务提供服务的服务

服务消费者：服务的调用方，即依赖其他服务的服务

示例

场景描述

围绕该场景，需要两个微服务

用户微服务，作为服务提供者为电影微服务提供服务
电影微服务，作为消费者调用用户微服务提供的服务

用户微服务

Spring Boot 2.1.1

Spring Data JPA

lombok简化编码

新建Spring Boot服务

项目结构

pom.xml

<?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.artisan</groupId>
  <artifactId>micorservice-simple-provider-user</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>micorservice-simple-provider-user</name>
  <description>Demo project for Spring Cloud</description>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.1.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>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>com.h2database</groupId>
      <artifactId>h2</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.4</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

用户库表

简单起见，我们使用H2数据库

schema.sql

drop table user if exists;
create table user(
  id bigint generated by default as identity,
  username varchar(40),
  name varchar(20),
  age int(3),
  balance decimal(10,2), 
  primary key(id)
);

data.sql

insert into user(id,username, name, age, balance) values(1,'user1', '张三', 20, 100.00);
insert into user(id,username, name, age, balance) values(2,'user2', '李四', 20, 100.00);
insert into user(id,username, name, age, balance) values(3,'user3', '王五', 20, 100.00);
insert into user(id,username, name, age, balance) values(4,'user4', '马六', 20, 100.00);

Model

为了简化代码，使用了lombok的@Data注解

package com.artisan.microservice.model;
import java.io.Serializable;
import java.math.BigDecimal;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import lombok.Data;
@Entity
@Data
public class User implements Serializable {
  private static final long serialVersionUID = 226695758444267342L;
  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  private Long id ;
  @Column
  private String username;
  @Column
  private String name;
  @Column
  private Integer age;
  @Column
  private BigDecimal balance;
}

Dao层

使用Spring Data JPA操作数据库

package com.artisan.microservice.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.artisan.microservice.model.User;
@Repository
public interface UserRepository extends JpaRepository<User,Long>{
}

Service

按道理都应该有Service层，这里demo比较简单，省略也可以，直接在Controller层调用Dao层

Controller 暴露Rest API

package com.artisan.microservice.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Example;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import com.artisan.microservice.model.User;
import com.artisan.microservice.repository.UserRepository;
@RestController
public class UserController {
  @Autowired
  private UserRepository userRepository;
  @GetMapping("/user/{id}")
  public User findById(@PathVariable Long id) {
    User user = new User();
      user.setId(id);
      User user2 = new User();
      user2.setName("no this user");
      // 我们使用的spring boot2.1.1版本中关联使用的spring data jpa不再支持findone(id)方法,改成如下写法
      return userRepository.findOne(Example.of(user)).orElse(user2); 
  }
}

配置文件application.yml

server:
  port: 7900
spring:
  jpa:
    generate-ddl: false
    show-sql: true
    hibernate:
      ddl-auto: none
  datasource:
    platform: h2
    schema: classpath:schema.sql
    data: classpath:data.sql
logging:
  level:
    root: INFO
    org.hibernate: INFO
    org.hibernate.type.descriptor.sql.BasicBinder: TRACE
    org.hibernate.type.descriptor.sql.BasicExtractor: TRACE
    com.artisan: DEBUG

测试

package com.artisan.microservice;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class MicorserviceSimpleProviderUserApplication {
  public static void main(String[] args) {
    SpringApplication.run(MicorserviceSimpleProviderUserApplication.class, args);
  }
}

右键–Run As --Spring Boot App,启动成功后

访问数据库中存在的用户

http://localhost:7900/user/1

{"id":1,"username":"user1","name":"张三","age":20,"balance":100.00}

http://localhost:7900/user/2

{"id":2,"username":"user2","name":"李四","age":20,"balance":100.00}

http://localhost:7900/user/3

{"id":3,"username":"user3","name":"王五","age":20,"balance":100.00}

http://localhost:7900/user/4

{"id":4,"username":"user4","name":"马六","age":20,"balance":100.00}

访问数据库中不存在的一个用户

http://localhost:7900/user/66

{"id":null,"username":null,"name":"no this user","age":null,"balance":null}

电影微服务

新建Spring Boot服务

如用户微服务，只不过我们这里仅仅作为消费者，仅使用web即可。

项目结构

pom.xml

<?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.artisan</groupId>
  <artifactId>micorservice-simple-consumer-movie</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>micorservice-simple-consumer-movie</name>
  <description>Demo project for Spring Cloud</description>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.1.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>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.4</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

Controller通过 RestTemplate 调用用户微服务提供的服务

因为仅仅作为服务消费者，所有只要在Controller层调用对应的rest接口即可

package com.artisan.microservice.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import com.artisan.microservice.model.User;
@RestController
public class MovieController {
  @Autowired
  private RestTemplate restTemplate;
  @Value("${user.userServicePath}")
  private String userServicePath;
  @GetMapping("/movie/{id}")
  public User findById(@PathVariable Long id) {
    return this.restTemplate.getForObject(this.userServicePath + id, User.class);
  }
}

用到了User类，新建个User.java

package com.artisan.microservice.model;
import java.io.Serializable;
import java.math.BigDecimal;
import lombok.Data;
@Data
public class User implements Serializable {
  private static final long serialVersionUID = 8912111288470833198L;
  private Long id;
  private String username;
  private String name;
  private Integer age;
  private BigDecimal balance;
}

启动类入口处，通过@Bean实例化RestTemplate

通过@Bean实例化RestTemplate

package com.artisan.microservice;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
public class MicorserviceSimpleConsumerMovieApplication {
  @Bean
  public RestTemplate restTemplate(){
    return new RestTemplate();
  }
  public static void main(String[] args) {
    SpringApplication.run(MicorserviceSimpleConsumerMovieApplication.class, args);
  }
}

配置文件 application.yml

配置端口及用户微服务的地址

server:
  port: 7901
user: 
  userServicePath: http://localhost:7900/user/

测试

启动用户微服务，访问7901

访问数据库中存在的用户

http://localhost:7901/movie/1

{"id":1,"username":"user1","name":"张三","age":20,"balance":100.00}

http://localhost:7901/movie/2

{"id":2,"username":"user2","name":"李四","age":20,"balance":100.00}

http://localhost:7901/movie/3

{"id":3,"username":"user3","name":"王五","age":20,"balance":100.00}

http://localhost:7901/movie/4

{"id":4,"username":"user4","name":"马六","age":20,"balance":100.00}

访问数据库中不存在的一个用户

http://localhost:7901/movie/66

{"id":null,"username":null,"name":"no this user","age":null,"balance":null}

成功调用到了用户微服务对外提供的服务。

示例的缺点

不难发现，虽然我们把用户微服务对外提供的接口地址配置在了配置文件中，然后通过@Value的方式去加载该属性，但是一旦用户微服务修改了地址，电影微服务作为消费者也要修改对应的地址，多了的话，也是很难管理

第二个原因，如果存在多个用户微服务，如何进行负载？ nginx固然可以，如果这种服务比较多，依赖nginx, 增加节点还是需要修改nginx配置文件，比较头疼

所以接下来我们来看下服务发现与服务注册，这里主要说的是Spring Cloud支持比较好的Eureka

Spring Cloud【Finchley】-01服务提供者与服务消费者

Spring Cloud总览

概述

示例

场景描述

用户微服务

新建Spring Boot服务

项目结构

用户库表

Model

Dao层

Service

Controller 暴露Rest API

配置文件application.yml

测试

电影微服务

新建Spring Boot服务

项目结构

Controller通过 RestTemplate 调用用户微服务提供的服务

启动类入口处，通过@Bean实例化RestTemplate

配置文件 application.yml

测试

示例的缺点

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Spring Cloud【Finchley】-01服务提供者与服务消费者

Spring Cloud总览

概述

示例

场景描述

用户微服务

新建Spring Boot服务

项目结构

用户库表

Model

Dao层

Service

Controller 暴露Rest API

配置文件application.yml

测试

电影微服务

新建Spring Boot服务

项目结构

Controller通过 RestTemplate 调用用户微服务提供的服务

启动类入口处，通过@Bean实例化RestTemplate

配置文件 application.yml

测试

示例的缺点

热门文章

最新文章

相关课程

相关电子书