SpringCloud:Rest Api~~基于http的远程调用解决方案

什么是Rest

REST是Representational State Transfer的缩写，它是由罗伊·菲尔丁（Roy Fielding）提出的，是用来描述创建HTTP API的标准方法的，他发现这四种常用的行为（查看（view），创建（create），编辑（edit）和删除（delete））都可以直接映射到HTTP 中已实现的GET,POST,PUT和DELETE方法。

在实际应用上就是在controller层根据访问不同业务，去指定请求类型，如常用的post，get

什么是Api

全称Application Programming Interface（应用程序j接口）

什么是Rest Api

基于上述两个知识点就很好理解了，就是一个http的远程调用解决方案，它提供restTemplate等接口

目的：在微服务架构中的作用是让各微服务之间产生联系，方便调用

本质：基于http的具备restful风格的远程调用的接口，

什么是远程调用：建议看我的dubbo原理篇博客！！！

下面开始去做一个基于rest api的微服务架构

 

Rest学习环境搭建与测试

建一个maven（不要模板）项目，作为父项目

目的：将所有子项目的依赖到导入父项目中，控制各依赖项目的版本，解决了分布式项目中依赖版本不兼容问题

导入相关依赖

<?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.king</groupId>
    <artifactId>SpringCloudLearns</artifactId>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>springcloud-api</module>
        <module>springcloud-provider-dept-8001</module>
        <module>springcloud-consumer-dept-80</module>
    </modules>

    <!--打包方式pom，默认的是jar-->
    <packaging>pom</packaging>

    <!--配置-->
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <junit.version>4.12</junit.version>
    <!--    <lombok.version>1.8.10</lombok.version>-->
        <log4j.version>1.2.17</log4j.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!--springCloud的依赖-->
            <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-dependencies -->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!--springboot-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.1.4.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!--数据库-->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.15</version>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>1.2.3</version>
            </dependency>

            <!--SpringBoot启动器-->
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>1.3.2</version>
            </dependency>

            <!--日志测试-->
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>1.2.3</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.16</version>
            </dependency>
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>${log4j.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

建立各业务模块

每个模块都是独立的一个微服务，通过改port，让他们能在一个tomcat中独立运行

涉及到的模块：

1.api（关注pojo）

导入相关依赖

<?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">
    <parent>
        <artifactId>SpringCloudLearns</artifactId>
        <groupId>com.king</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springcloud-api</artifactId>

    <!--导入的是父类的已有的依赖，用的是<dependencyManagement>所以要自己导-->
    <!--微服务架构中尽量在父项目中导依赖，为了版本一致-->
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

</project>

实体类

//所有分布式架构的实体类都要先序列化
@Data
@NoArgsConstructor
@Accessors(chain = true) //链式写法
/*链式编程例子
* Dept dept = new Dept
* dept.setdname('11').setdeptno(1);
* */
public class Dept implements Serializable {

    private Long deptno;
    private String dname;

    //记录数据库来源，一个服务对应一个数据库
    private String db_source;


    //第一个主键自增，第三个数据库函数，数据库自动获取，自动生成
    public Dept(String dme) {
        this.dname = dname;
    }

}

2.服务端（关注点：业务~model）

相关依赖

<?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">
    <parent>
        <artifactId>SpringCloudLearns</artifactId>
        <groupId>com.king</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springcloud-provider-dept-8001</artifactId>

    <dependencies>
        <!--需要拿到实体类，所以需要配置api module-->
        <dependency>
            <groupId>com.king</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--jetty-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jetty</artifactId>
        </dependency>
        <!--热部署工具-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

    </dependencies>


</project>

yaml 配置（数据库，mybatis，port配置）

server:
  port: 8001

#mybatis配置
mybatis:
  mapper-locations: classpath*:mybatis/mapper/*.xml
  type-aliases-package: com.king.springcloud.pojo


#spring配置
spring:
  application:
    name: springcloud-provider-dept
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springcloudlearns?useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8
    username: root
    password: 123456

mapper

@Mapper
@Repository
public interface DeptMapper {

    boolean addDept(Dept dept);

    Dept queryById(@Param("deptno") Long id);

    List<Dept> queryAll();

}

mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.king.springcloud.mapper.DeptMapper">

    <insert id="addDept" parameterType="Dept">
        insert into dept (dname,db_source)
        values (#{dname},database())
    </insert>

    <select id="queryById" parameterType="Long" resultType="Dept">
        select * from dept where deptno=#{deptno};
    </select>

    <select id="queryAll" resultType="Dept">
        select * from dept;
    </select>


</mapper>

service接口

public interface DeptService {

    boolean addDept(Dept dept);

    Dept queryById(Long id);

    List<Dept> queryAll();

}

serviceImpl

@Service
public class DeptServiceImpl implements DeptService{

    @Autowired
    private DeptMapper deptMapper;

    @Override
    public boolean addDept(Dept dept) {
        return deptMapper.addDept(dept);
    }

    @Override
    public Dept queryById(Long id) {
        return deptMapper.queryById(id);
    }

    @Override
    public List<Dept> queryAll() {
        return deptMapper.queryAll();
    }
}

创建主启动类

@SpringBootApplication
public class DeptProvider_8001 {
    public static void main(String[] args) {
        SpringApplication.run(DeptProvider_8001.class,args);
    }
}

3.客户端（关注点：view~controller）重要

maven依赖

<?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">
    <parent>
        <artifactId>SpringCloudLearns</artifactId>
        <groupId>com.king</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springcloud-consumer-dept-80</artifactId>

    <!--实体类+web-->
    <dependencies>
        <dependency>
            <groupId>com.king</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>


</project>

配置端口号：80（）客户端一般都是80

RestTemplate不是spring的组件所以要去配置（@Bean）

//@Configuration,相当于spring中的applicationContext.xml
@Configuration
public class ConfigBean {

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

}

controller

@RestController
public class DeptConsumerController {

    //理解：消费者不应该又service层~,那么怎么去调用其他服务器端的服务呢？
    //解决：远程调用，RestTemplate基于http的远程调用接口服务，注册到spring中
    //(url,实体：Map，class<T>responseType)
    @Autowired
    private RestTemplate restTemplate;

    private static final String REST_URL_PREFIX = "http://localhost:8001";

    @RequestMapping("/consumer/dept/add/{dname}")
    public Boolean add(@PathVariable("dname") String dname){
        System.out.println(dname);
        Dept dept = new Dept();
        dept.setDname(dname);
        return restTemplate.postForObject(REST_URL_PREFIX+"dept/add",dept,Boolean.class);
    }

    //http://localhost:8001/dept/get/{id}
    @RequestMapping("/consumer/dept/get/{id}")
    public Dept get(@PathVariable("id")Long id){
        //远程调用，
        return restTemplate.getForObject(REST_URL_PREFIX+"/dept/get/"+id,Dept.class);
    }

    @RequestMapping("/consumer/dept/list")
    public List<Dept> list(){
        return restTemplate.getForObject(REST_URL_PREFIX+"/dept/list",List.class);
    }


}

创建主启动类

@SpringBootApplication
public class DeptConsumer_80 {
    public static void main(String[] args) {
        SpringApplication.run(DeptConsumer_80.class,args);
    }
}

总结：

本次客户端远程调用服务端测试采用的是aop思想；