SpringCloud（二）—— RestTemplate客户端对象 服务调用

RestTemplate简介

spring框架提供的RestTemplate类可用于在应用中调用rest服务，它简化了与http服务的通信方式，统一了RESTful的标准，封装了http链接， 我们只需要传入url及返回值类型即可。相较于之前常用的HttpClient，RestTemplate是一种更优雅的调用RESTful服务的方式。

RestTemplate 服务调用

使用版本号：

• jdk11.0.10
• springboot 2.2.3.RELEASE
• springcloud Hoxton.SR8

中文文档：https://springcloud.cc/spring-cloud-netflix.html
中文API文档：https://springcloud.cc/spring-cloud-dalston.html
SpringCloud中国社区 http://springcloud.cn/
SpringCloud中文网 https://springcloud.cc
对应版本依赖:https://docs.spring.io/spring-cloud/docs/Hoxton.SR8/reference/htmlsingle/

一、新建一个普通的maven项目删除src目录

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1、编写pom.xml文件,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>org.study</groupId>
    <artifactId>SpringCloud</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--打包方式 pom-->
    <packaging>pom</packaging>
	<!--加群1025684353一起吹水聊天-->
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <junit.version>4.12</junit.version>
        <lombok.version>1.18.18</lombok.version>
        <log4j.version>1.2.17</log4j.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!--SpringCloud-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR8</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--Springboot-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.3.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--数据库-->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.47</version>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>1.2.6</version>
            </dependency>
            <!--Springboot启动器-->
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.4</version>
            </dependency>
            <!--log4j-->
            <!--加群1025684353一起吹水聊天-->
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>${log4j.version}</version>
            </dependency>
            <!--junit-->
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
            </dependency>
            <!--lombok-->
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${lombok.version}</version>
            </dependency>
            <!--logback:日志测试-->
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>1.3.0-alpha4</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

SpringCloud的父工程导入依赖时，发现jar包无法下载下来到本地库。而且pom文件报红

• 原因：<dependencyManagement>只是用于父工程管理依赖的，用于统一管理jar的版本。子工程需要使用相应的jar引入依赖即可，这时才真正的使用到相应jar，才会去下载。
• 解决：先将<dependencyManagement>删除，下载jar包，下载完成后在重新使用<dependencyManagement>

提供者服务

二、新建一个子模块

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1、编写子模块的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">
    <parent>
        <artifactId>SpringCloud</artifactId>
        <groupId>org.study</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
	<!--加群1025684353一起吹水聊天-->
    <artifactId>springcloud-api</artifactId>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

    <!--当前的Module自己需要的依赖，如果父工程中已经配置了版本。这里就不用再写版本-->
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
</project>

2、创建一个数据库：DB01

CREATE TABLE dept(
deptno BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,
dname VARCHAR(60),
db_source VARCHAR(60)
);

INSERT INTO dept(dname,db_source) VALUES('开发部',DATABASE());
INSERT INTO dept(dname,db_source) VALUES('人事部',DATABASE());
INSERT INTO dept(dname,db_source) VALUES('财务部',DATABASE());
INSERT INTO dept(dname,db_source) VALUES('市场部',DATABASE());
INSERT INTO dept(dname,db_source) VALUES('运维部',DATABASE());

SELECT * FROM dept;

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3、子项目连接数据库

4、创建实体类

package com.study.springcloud.pojo;

import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;

import java.io.Serializable;

//实体类必须要序列化 Serializable
@Data
@NoArgsConstructor
@Accessors(chain = true)//链式写法
public class Dept implements Serializable {
	//加群1025684353一起吹水聊天
    private Long deptno;
    private String dname;
    //这个数据是存在哪个数据库的字段，微服务：一个服务对应一个数据库，同一个信息可能存在不同的数据库
    private String db_source;

    public Dept(String dname) {
        this.dname = dname;
    }
}

三、新建springcloud-provider-dept-8001子模块

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1、编写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">
    <parent>
        <artifactId>SpringCloud</artifactId>
        <groupId>org.study</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
	<!--加群1025684353一起吹水聊天-->
    <artifactId>springcloud-provider-dept-8001</artifactId>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

    <dependencies>
        <!--我们需要拿到实体类,所以要配置api module-->
        <dependency>
            <groupId>org.study</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!--junit-->
        <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>
        <!--加群1025684353一起吹水聊天-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--springboot-test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
            <version>2.3.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.3.3.RELEASE</version>
        </dependency>
        <!--jetty-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jetty</artifactId>
            <version>2.3.3.RELEASE</version>
        </dependency>
        <!--热部署-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <version>2.3.3.RELEASE</version>
        </dependency>
    </dependencies>

</project>

2、在resources包下新建mybatis/mapper包,新建mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
	<!--加群1025684353一起吹水聊天-->
    <settings>
        <!--开启二级缓存-->
        <setting name="cacheEnabled" value="true"/>
    </settings>
</configuration>

3、新建application.yaml文件

server:
  port: 8001

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

#spring配置
spring:
  application:
    name: springcloud-provider-dept
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db01?useUnicode=true&characherEncoding=utf-8
    username: root
    password: 123456

4、编写mapper层

package com.study.springcloud.mapper;

import com.study.springcloud.pojo.Dept;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper
@Repository
public interface DeptMapper {
    boolean addDept(Dept dept);
	//加群1025684353一起吹水聊天
    Dept queryById(Long id);

    List<Dept> queryAll();
}

5、编写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.study.springcloud.mapper.DeptMapper">
    <insert id="addDept" parameterType="Dept">
        insert into dept( dname, db_source)
        values (#{dname},DATABASE())
    </insert>

    <select id="queryById" resultType="com.study.springcloud.pojo.Dept" parameterType="Long">
        select * from dept where deptno = #{deptno};
    </select>
	<!--加群1025684353一起吹水聊天-->
    <select id="queryAll" resultType="com.study.springcloud.pojo.Dept">
        select * from dept;
    </select>

</mapper>

6、编写Service层

package com.study.springcloud.service;

import com.study.springcloud.pojo.Dept;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface DeptService {
    boolean addDept(Dept dept);
	//加群1025684353一起吹水聊天
    Dept queryById(Long id);

    List<Dept> queryAll();
}

7、编写service接口实现类

package com.study.springcloud.service;

import com.study.springcloud.mapper.DeptMapper;
import com.study.springcloud.pojo.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class ServiceImpl implements DeptService{

    @Autowired
    private DeptMapper deptMapper;

    @Override
    public boolean addDept(Dept dept) {
        return deptMapper.addDept(dept);
    }
		//加群1025684353一起吹水聊天
    @Override
    public Dept queryById(Long id) {
        return deptMapper.queryById(id);
    }

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

8、编写controller

package com.study.springcloud.controller;

import com.study.springcloud.pojo.Dept;
import com.study.springcloud.service.DeptService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

//提供Restful服务！
@RestController
public class DeptController {
    @Autowired
    DeptService deptService;

    @PostMapping("/dept/add")
    public boolean addDept(Dept dept){
        return deptService.addDept(dept);
    }

    @GetMapping("/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id){
        return deptService.queryById(id);
    }
	//加群1025684353一起吹水聊天
    @GetMapping("/dept/list")
    public List<Dept> queryAll(){
        return deptService.queryAll();
    }
}

9、编写提供者dept的启动类

package com.study.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

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10、运行测试

项目目录结构!

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消费者服务

四、新建消费者模块 springcloud-consumer-dept-80

1、导入相关依赖

<!--实体类+web，主要根前端打交道-->
<dependencies>
    <dependency>
    <!--加群1025684353一起吹水聊天-->
        <groupId>org.study</groupId>
        <artifactId>springcloud-api</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.3.3.RELEASE</version>
    </dependency>
    <dependency>
    <!--加群1025684353一起吹水聊天-->
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <version>2.3.3.RELEASE</version>
    </dependency>
</dependencies>

2、编写application.yaml

server:
  port: 80

3、编写config层

package com.study.springcloud.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class ConfigBean {   //相当于spring里面的applicationContext.xml
    @Bean
    public RestTemplate getRestTemplate(){
    //加群1025684353一起吹水聊天
        return new RestTemplate();
    }
}

4、编写controller

package com.study.springcloud.controller;

import com.study.springcloud.pojo.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.client.RestTemplate;

import java.util.List;

@RestController
public class DeptConsumerController {
    //消费者不应该有service层，怎么才能拿到service层?
    //RestTemplate,注册到spring中
    @Autowired
    private RestTemplate restTemplate;//提供多种便捷访问远程http服务器的方法,简单的Restful服务模板

    //访问地址是localhost:8081开头，所以直接提取出来
    private static final String REST_URL_PREFIX = "localhost:8081/";
	//加群1025684353一起吹水聊天
    @RequestMapping("consumer/dept/add")
    private boolean add(Dept dept){
        //getForObject三个主要参数URI url, Class<T> responseType
        return restTemplate.postForObject(REST_URL_PREFIX+"/dept/add",dept,Boolean.class);
    }

    @RequestMapping("/consumer/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id){
        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);
    }
}

5、编写启动类

package com.study.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

模块目录结构

五、启动测试

1、启动springcloud-provider-dept-8001测试

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2、再启动springcloud-consumer-dept-80测试

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核心代码部分

最后，祝大家早日学有所成，拿到满意offer，快速升职加薪，走上人生巅峰。 可以的话请给我一个三连支持一下我哟，我们下期再见

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