Mybatis——逆向工程

前言

什么是逆向工程: 根据数据库的表，由我们的Mybatis反向生成资源
包括Java类、Mapper接口、以及我们的映射文件

正向工程: 先创建Java实体类 由Mybatis生成数据库表。

一、创建逆向工程步骤

①导入依赖和插件

<?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.tyf</groupId>
    <artifactId>Mybatis_MBG</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!-- 依赖MyBatis核心包 -->
    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.32</version>
        </dependency>
        <!--Mybatis核心包-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
        </dependency>
    </dependencies>
    <!-- 控制Maven在构建过程中相关配置 -->
    <build>
        <!-- 构建过程中用到的插件 -->
        <plugins>
            <!-- 具体插件，逆向工程的操作是以构建过程中插件形式出现的 -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.0</version>
                <!-- 插件的依赖 -->
                <dependencies>
                    <!-- 逆向工程的核心依赖 -->
                    <dependency>
                        <groupId>org.mybatis.generator</groupId>
                        <artifactId>mybatis-generator-core</artifactId>
                        <version>1.3.2</version>
                    </dependency>
                    <!-- 数据库连接池 -->
                    <dependency>
                        <groupId>com.mchange</groupId>
                        <artifactId>c3p0</artifactId>
                        <version>0.9.2</version>
                    </dependency>
                    <!-- MySQL驱动 -->
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>5.1.8</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>


</project>

②创建核心配置文件

<?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>
    <properties resource="jdbc.properties"/>

    <typeAliases>
        <package name="com.xxx.mybatis.bean"/>
    </typeAliases>

    <plugins>
        <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
    </plugins>
    
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.Driver}"/>
                <property name="url" value="${jdbc.Url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/xxx/mybatis/mapper/EmpMapper.xml"/>
    </mappers>
</configuration>

③创建逆向工程的配置文件

文件名必须是generatorConfig.xml

<?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>
    <!--
    targetRuntime: 执行生成的逆向工程的版本
    MyBatis3Simple: 生成基本的CRUD（清新简洁版）
    MyBatis3: 生成带条件的CRUD（奢华尊享版）
    -->
    <context id="DB2Tables" targetRuntime="MyBatis3">
        <!-- 数据库的连接信息 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mybatis"
                        userId="root"
                        password="123">
        </jdbcConnection>
        <!-- javaBean的生成策略-->
        <javaModelGenerator targetPackage="com.xxx.mybatis.bean"
                            targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        <!-- SQL映射文件的生成策略 -->
        <sqlMapGenerator targetPackage="com.xxx.mybatis.mapper"
                         targetProject=".\src\main\resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>
        <!-- Mapper接口的生成策略 -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.xxx.mybatis.mapper" targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>
        <!-- 逆向分析的表 -->
        <!-- tableName设置为*号，可以对应所有表，此时不写domainObjectName -->
        <!-- domainObjectName属性指定生成出来的实体类的类名 -->
        <table tableName="emp" domainObjectName="Emp"/>
        <table tableName="dept" domainObjectName="Dept"/>
    </context>
</generatorConfiguration>

④执行插件

二、QBC查询

@Test 
public void testMBG() throws IOException {
    
     
	InputStream is = Resources.getResourceAsStream("mybatis-config.xml"); 
	SqlSession sqlSession = new SqlSessionFactoryBuilder().build(is).openSession(true); 
	EmpMapper mapper = sqlSession.getMapper(EmpMapper.class); 
	EmpExample empExample = new EmpExample(); 
    //创建条件对象，通过andXXX方法为SQL添加查询添加，每个条件之间是and关系 
    empExample.createCriteria().andEnameLike("a").andAgeGreaterThan(20).andDidIsNot Null(); 
    //将之前添加的条件通过or拼接其他条件 
    empExample.or().andSexEqualTo("男"); 
    List list = mapper.selectByExample(empExample); 
    for (Emp emp : list) {
    
     System.out.println(emp); } 
}