【Spring Boot】2. 整合Mybaits & Mybatis的逆向工程Demo

Spring Boot操作數據庫有jpa，但我們也可以引入Mybatis框架進行對數據庫的操作，而Mybatis的逆向工程可以方便我們進行開發。

1. 是什麼

Mybatis逆向工程，可以通過配置數據庫信息，配置對應參數，由數據庫表生成對應的Mapper接口跟mapper.xml文件，以及實體類Bean，方便我們進行開發，讓我們不用再去寫mapper.xml配置文件。

2. 使用過程

2.1 創建一個Spring Boot簡單Web工程

這裏引用另外一篇博客：簡單Spring Boot應用啓動Demo & 啓動類掃描範圍
按照博客先創建一個Spring Boot Demo

2.2 配置pom.xml

引入跟Mybatis逆向工程相關的包，以及Mysql相關的包：

	<dependencies>
        <!--MyBatis -->
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.2</version>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.41</version>
        </dependency>

		<!-- MBG -->
        <!-- https://mvnrepository.com/artifact/org.mybatis.generator/mybatis-generator-core -->
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.5</version>
        </dependency>
    </dependencies>

2.3 創建數據庫表

use mbg;
CREATE TABLE `people` (
  `id` int auto_increment,
  `age` int NOT NULL,
  `weight` double NOT NULL,
  `height` double NOT NULL,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

創建結果：

2.4 IDEA編寫配置文件

編寫mbg.xml與pom.xml放在同一目錄

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>

    <context id="DB2Tables" targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressAllComments" value="true" />
        </commentGenerator>
        <!-- 配置數據庫連接 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mbg" userId="root"
                        password="88888">
        </jdbcConnection>

        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- 指定javaBean生成的位置 -->
        <javaModelGenerator targetPackage="com.server.bean"
                            targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!--指定sql映射文件生成的位置 -->
        <sqlMapGenerator targetPackage="mapper" targetProject=".\src\main\resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <!-- 指定dao接口生成的位置，mapper接口 -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.server.dao" targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <!-- table指定每個表的生成策略 -->
        <table tableName="people" domainObjectName="People"/>
    </context>
</generatorConfiguration>

2.5 編寫生成代碼

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

public class Main {

    public static void main(String[] args) throws Exception {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        File configFile = new File("mbg.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config,
                callback, warnings);
        myBatisGenerator.generate(null);
    }
}

6. 執行

執行前：

執行後：

生成對應的mapper文件：

Mapper接口：

bean類：

3. 整合Mybatis：

3.1 配置數據源

注意需要配置數據源，以及mapper.xml文件的位置，application.yml文件：

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/mbg?useUnicode=true&characterEncoding=UTF-8&useSSL=false
    driverClassName: com.mysql.jdbc.Driver
    username: root
    password: 12345678

mybatis:
  mapper-locations: classpath:mapper/*.xml

3.2 更新pom.xml

當前的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.parallelline1996</groupId>
    <artifactId>springboot-mbg-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.22.RELEASE</version>
        <relativePath/>
    </parent>

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

        <!--MyBatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.41</version>
        </dependency>

        <!-- MBG -->
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.5</version>
        </dependency>

        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.0.2</version>
        </dependency>
    </dependencies>

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

3.3 對Mapper接口進行掃描

需要新增對Mapper接口進行掃描

同時，接口類上面也需要加入@Mapper的註解

4. 進行測試

編寫一個簡單的插入方法進行測試：

@RestController
public class MainController {

    private PeopleMapper peopleMapper;

    @Autowired
    MainController(PeopleMapper peopleMapper) {
        this.peopleMapper = peopleMapper;
    }

    @GetMapping("/addNewUser")
    public void addNewUser() {
        People people = new People(null, 12, 40.5, 153.4, "Tim");
        peopleMapper.insert(people);
    }
}

發送請求到 /addNewUser接口，執行後查看數據庫，發現插入成功：

Demo的github代碼：
https://github.com/Parallelline1996/Spring-Boot-Learning/tree/master/SpringBoot-Mybatis-MBG