RestTemplate体验远程调用

为SpringCloud学习作准备

RestTemplate使用的是http方式，缺点比RPC略慢，优点不限定语言，灵活。

Dubbo使用的是RPC（Remote Procedure Call远程过程调用），优点速度比http略快，缺点限定语言

idea创建maven父工程cloud-demo

不使用骨架

父工程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.company</groupId>
    <artifactId>cloud-demo</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <modules>
        <module>user-service</module>
        <module>consumer-demo</module>
    </modules>
    <packaging>pom</packaging>


    <!--SpringBoot启动器作为父工程-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2.RELEASE</version>
        <relativePath/>
    </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>
        <mapper.start.version>2.1.5</mapper.start.version>
        <mysql.version>5.1.6</mysql.version>
    </properties>
    <!--在dependencyManagement标签中的内容，子工程需要引用才能用（无需指定版本）-->
    <dependencyManagement>
        <dependencies>
            <!--springCloud-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--通用mapper启动器-->
            <dependency>
                <groupId>tk.mybatis</groupId>
                <artifactId>mapper-spring-boot-starter</artifactId>
                <version>${mapper.start.version}</version>
            </dependency>
            <!--mysql驱动-->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <!--在dependencyManagement标签外的内容，子工程可以直接使用-->
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

再创建两个子工程user-service和consumer-demo

在父工程上右键新建Module

不使用骨架，默认父工程就是cloud-demo

user-service

　　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>cloud-demo</artifactId>
        <groupId>com.company</groupId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>user-service</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
　　　　

　　　　<!--通用Mapper，会依赖导入MyBatis启动器和jdbc启动器

　　　　参考https://www.cnblogs.com/zou-rong/p/12566257.html
　　　　-->

      <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
        </dependency>
    </dependencies>
</project>

　　application.yaml配置文件

server:
    servlet:
      #拦截路径
      context-path: /
    #端口
    port: 8088
  logging:
    level:
      #日志级别，目录: 级别
      com.company: debug

#配置com.zaxxer:HikariCP:3.4.1连接池
  spring:
    datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT
      username: root
      password: yourPassword

#整合mybatis
  mybatis:
    #启用别名
    type-aliases-package: com.company.pojo

　　UserApplication启动类

package com.company;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import tk.mybatis.spring.annotation.MapperScan;

@SpringBootApplication
@MapperScan("com.company.mapper")
public class UserApplication {

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

　　实体类

　　

package com.company.pojo;

import lombok.Data;
import tk.mybatis.mapper.annotation.KeySql;

import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;
import java.util.Date;
@Data
@Table(name="tb_user")
public class User {
    @Id//主键
    @KeySql(useGeneratedKeys = true)//自动增长
    private Long id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    //1男，2女
    private Integer sex;
    private Date birthday;
    private String note;
    private Date created;
//    @Transient 忽略该字段
    private Date updated;
}

　　UserMapper

package com.company.mapper;

import com.company.pojo.User;
import tk.mybatis.mapper.common.Mapper;

public interface UserMapper extends Mapper<User>{
}

　　UserServiceImpl(接口略)

package com.company.service.impl;

import com.company.mapper.UserMapper;
import com.company.pojo.User;
import com.company.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service("userService")
public class UserServiceImpl implements UserService{
    @Autowired
    private UserMapper userMapper;
    @Override
    public User findOne(Long id) {
        return userMapper.selectByPrimaryKey(id);
    }

    @Override
    @Transactional
    public void insert(User user) {
        user.setUserName("test5");
        user.setPassword("test5");
        user.setName("ceshi5");
        userMapper.insert(user);
//        int i=10/0;
    }
}

　　UserController

package com.company.web;

import com.company.pojo.User;
import com.company.service.UserService;
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;

@RequestMapping("/user")
@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping("/{id}")
    public User getUser(@PathVariable("id") Long id){
        return userService.findOne(id);
    }

    @RequestMapping("/add")
    public String addUser(){
        userService.insert(new User());
        return "ok";
    }
}

接下来是consumer-demo

　　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>cloud-demo</artifactId>
        <groupId>com.company</groupId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>consumer-demo</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

　　启动类ConsumerApplication

package com.company;

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 ConsumerApplication {

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

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

　　ConsumerController

package com.company.controller;

import com.company.pojo.User;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
@RequestMapping("/consumer")
public class ConsumerController {

    @Autowired
    private RestTemplate template;

    @GetMapping("/{id}")
    public User getUserById(@PathVariable("id")Long id){
        return template.getForObject("http://localhost:8088/user/"+id,User.class);
    }
}

　　实体类

package com.company.pojo;

import lombok.Data;

import java.util.Date;

@Data
public class User {
    private Long id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    //1男，2女
    private Integer sex;
    private Date birthday;
    private String note;
    private Date created;
    private Date updated;
}

　　接下来刷新maven

　　

 　　右下角会提示

　　

　　点开

　　

 　　很方便统一管理

　　

　　把两个子项目都启动，然后访问consumer-demo的http://localhost:8080/consumer/1

　　id为1的用户就被user-service项目所查询出来

　　

 　　与直接访问http://localhost:8088/user/1一致。