RestTemplate_resttemplate驱动-优快云博客

这篇博客介绍了如何在Java应用中使用RestTemplate作为消费者发送远程HTTP请求。作者首先阐述了使用RestTemplate的原因，然后详细说明了创建消费者的过程，包括设置数据库、配置文件、依赖管理、Bean注入和Controller编写等步骤。文章最后提到测试了部分方法，并鼓励读者指正错误，共同学习。

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前言

为什么使用?
我们经常做的事情是生产者做的事情，而一个系统中使用消费者的
RestTemplie是发送远程http请求,作为消费者来使用

使用

官网:https://docs.spring.io/spring-framework/docs/4.3.7.RELEASE/javadoc-api/org/springframework/web/client/RestTemplate.html
由于是消费者，所以无service层
我们需要做好一个生产者做的事情
1.准备数据库
在这里插入图片描述
2.使用idea编写代码，设计结构等等

3.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>demo1</artifactId>
        <groupId>com.yan</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>demo-procider-dept-8001</artifactId>

    <dependencies>
        <dependency><!-- 引入自己定义的api通用包，可以使用Dept部门pojo -->
            <groupId>com.yan</groupId>
            <artifactId>demo-api</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--单元测试支持-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <!--mysql数据库支持-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--阿里巴巴druid数据源管理-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <!--日志logback-->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>
        <!--mybatis整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--使用boot的jetty服务器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jetty</artifactId>
        </dependency>
        <!--boot的web组件-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--boot的测试组件-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <!-- 修改后立即生效，热部署 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>


</project>

4.application.xml

```java
server:
  port: 8001

mybatis:
  config-location: classpath:mybatis/mybatis.xml        # mybatis配置文件所在路径
  type-aliases-package: com.yan.cloudapi.pojo               # 所有Entity别名类所在包
  mapper-locations:
  - classpath:mybatis/mapper/**/*.xml                       # mapper映射文件

spring:
   application:
    name: democloud-dept
   datasource:
    type: com.alibaba.druid.pool.DruidDataSource            # 当前数据源操作类型
    driver-class-name: com.mysql.cj.jdbc.Driver           # mysql驱动包
    url: jdbc:mysql://localhost:3306/cloudDB01?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT             # 数据库名称
    username: root
    password: 123456
    dbcp2:
      min-idle: 5                                           # 数据库连接池的最小维持连接数
      initial-size: 5                                       # 初始化连接数
      max-total: 5                                          # 最大连接数
      max-wait-millis: 200                                  # 等待连接获取的最大超时时间

5.mybatis.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>

    <settings>
        <setting name="cacheEnabled" value="true"/><!-- 二级缓存开启 -->
    </settings>

</configuration>


6.dao

```java
package com.yan.cloud.dao;

import com.yan.cloudapi.pojo.Dept;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 10:47 2020/3/1
 */
@Mapper
public interface DeptDao {

    public boolean addDept(Dept dept);

    public Dept findById(Long id);

    public List<Dept> findAll();
}

7.DeptMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.yan.cloud.dao.DeptDao">

    <select id="findById" resultType="Dept" parameterType="Long">
        select deptno,dname,db_source from dept where deptno=#{deptno};
    </select>
    <select id="findAll" resultType="Dept">
        select deptno,dname,db_source from dept;
    </select>
    <insert id="addDept" parameterType="Dept">
        INSERT INTO dept(dname,db_source) VALUES(#{dname},DATABASE());
    </insert>


</mapper>

8.service

package com.yan.cloud.service;

import com.yan.cloudapi.pojo.Dept;

import java.util.List;

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 10:52 2020/3/1
 */
public interface DeptService {
    public boolean add(Dept dept);

    public Dept get(Long id);

    public List<Dept> list();
}

9.serviceimpl

package com.yan.cloud.service.impl;

import com.yan.cloud.dao.DeptDao;
import com.yan.cloud.service.DeptService;
import com.yan.cloudapi.pojo.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 11:03 2020/3/1
 */
@Service
public class DeptServiceImpl implements DeptService {

    @Autowired
    private DeptDao dao;

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

    @Override
    public Dept get(Long id) {
        return dao.findById(id);
    }

    @Override
    public List<Dept> list() {
        return dao.findAll();
    }
}

10.controller

package com.yan.cloud.controller;

import com.yan.cloud.service.DeptService;
import com.yan.cloudapi.pojo.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 11:08 2020/3/1
 */
@RestController
public class DeptController {

    @Autowired
    private DeptService service;

    @RequestMapping(value = "/dept/add", method = RequestMethod.POST)
    public boolean add(@RequestBody Dept dept) {
        return service.add(dept);
    }

    @RequestMapping(value = "/dept/get/{id}", method = RequestMethod.GET)
    public Dept get(@PathVariable("id") Long id) {
        return service.get(id);
    }

    @RequestMapping(value = "/dept/list", method = RequestMethod.GET)
    public List<Dept> list() {
        return service.list();
    }

}

11.主启动类

package com.yan.cloud;

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

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 11:18 2020/3/1
 */
@SpringBootApplication
public class DeptProvider8001_App {
    public static void main(String[] args) {
        SpringApplication.run(DeptProvider8001_App.class, args);
    }
}

至此，生产者完成且测试也完成,ok没问题

建立消费者
新建工程，结构如下图：
在这里插入图片描述
1.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>demo1</artifactId>
        <groupId>com.yan</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>demo-consumer-dept-80</artifactId>
    <description>部门消费者</description>

    <dependencies>
        <dependency><!-- 自己定义的api -->
            <groupId>com.yan</groupId>
            <artifactId>demo-api</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- 修改后立即生效，热部署 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

</project>

2.application.xml

server:
  port: 80

3.将RestTemplate注入spring容器中

package com.yan.demo.cloud.cfgbeans;

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

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 20:47 2020/3/1
 */
@Configuration
public class ConfigBean {

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

4.编写controller

package com.yan.demo.cloud.comtroller;

import com.yan.cloudapi.pojo.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.List;

/**
 * @Author: 闫明辉
 * @Description: RestTemplate提供了多种便捷访问远程Http服务的方法，
 * 是一种简单便捷的访问restful服务模板类，是Spring提供的用于访问Rest服务的客户端模板工具集
 * RestTemplate官网:https://docs.spring.io/spring-framework/docs/4.3.7.RELEASE/javadoc-api/org/springframework/web/client/RestTemplate.html
 * @Date: Create in 20:54 2020/3/1
 */
@RestController
public class DeptController_Consumer {

//    (url, requestMap, ResponseBean.class)
//    REST请求地址、请求参数、HTTP响应转换被转换成的对象类型。

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

    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping(value = "/consumer/dept/add")
    public boolean add(Dept dept) {
        return restTemplate.postForObject(REST_URL_PREFIX + "/dept/add", dept, Boolean.class);
    }

    @RequestMapping(value = "/consumer/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id) {
        return restTemplate.getForObject(REST_URL_PREFIX + "/dept/get/" + id, Dept.class);
    }

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

5.主启动类

package com.yan.demo.cloud;

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

/**
 * @Author: 闫明辉
 * @Description:
 * @Date: Create in 21:01 2020/3/1
 */
@SpringBootApplication
public class DeptConsumer80_App {

    public static void main(String[] args) {
        SpringApplication.run(DeptConsumer80_App.class, args);
    }
}