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

Spring Boot操作数据库有jpa，但我们也可以引入Mybatis框架进行对数据库的操作，而Mybatis的逆向工程可以方便我们进行开发。

1. 是什么

Mybatis逆向工程，可以通过配置数据库信息，配置对应参数，由数据库表生成对应的Mapper接口跟mapper.xml文件，以及实体类Bean，方便我们进行开发，让我们不用再去写mapper.xml配置文件。

2. 使用过程

2.1 创建一个Spring Boot简单Web工程

这里引用另外一篇博客：简单Spring Boot应用启动Demo & 启动类扫描范围
按照博客先创建一个Spring Boot Demo

2.2 配置pom.xml

引入跟Mybatis逆向工程相关的包，以及Mysql相关的包：

	<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 创建数据库表

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;

创建结果：

2.4 IDEA编写配置文件

编写mbg.xml与pom.xml放在同一目录

<?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>
        <!-- 配置数据库连接 -->
        <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指定每个表的生成策略 -->
        <table tableName="people" domainObjectName="People"/>
    </context>
</generatorConfiguration>

2.5 编写生成代码

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. 执行

执行前：

执行后：

生成对应的mapper文件：

Mapper接口：

bean类：

3. 整合Mybatis：

3.1 配置数据源

注意需要配置数据源，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

当前的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 对Mapper接口进行扫描

需要新增对Mapper接口进行扫描

同时，接口类上面也需要加入@Mapper的注解

4. 进行测试

编写一个简单的插入方法进行测试：

@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);
    }
}

发送请求到 /addNewUser接口，执行后查看数据库，发现插入成功：

Demo代码的github链接：
https://github.com/Parallelline1996/Daily-Learning/tree/master/SpringBoot/code-repository/SpringBoot-Mybatis-MBG