MyBatis入門之 逆向工程 MyBatis Generator代碼生成

Mybatis 提供了逆向工程,通過逆向工程,可以幫助程序員根據單表來生成pojo類,mappper映射文件、mapper接口。

  1. 新建maven項目,在pom中添加如下依賴:

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.0</version>
        </dependency>

        <!-- mysql驅動包 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.6</version>
        </dependency>
    </dependencies>


    <build>

        <resources>
            <resource>
                <directory>src/main/resources/</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>



        <plugins>
            <!-- mybatis-generator自動生成代碼插件 -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.6</version>
            </plugin>
        </plugins>
    </build>

  1. 在resource config目錄下新建 generatorConfig.xml文件:
<?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="mybatisGenerator" targetRuntime="MyBatis3">
        <commentGenerator>
            <!-- 是否去除自動生成的註釋 true:是 : false:否 -->
            <property name="suppressAllComments" value="true" />
        </commentGenerator>

        <!-- 拉取表信息的數據庫鏈接URL、驅動類、用戶名、密碼 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC"
                        userId="root"
                        password="rhwl1234,">
        </jdbcConnection>

        <!-- 默認false,把JDBC DECIMAL 和 NUMERIC 類型解析爲 Integer,爲 true時把JDBC DECIMAL 和
            NUMERIC 類型解析爲java.math.BigDecimal -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- targetProject:指定javaBean的生成策略
          targetPackage :目標包名
          targetProject: 目標工程
        -->
        <javaModelGenerator targetPackage="com.diligentkong.mybatis.bean"
                            targetProject="./src/main/java">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
            <!-- 從數據庫返回的值被清理前後的空格 -->
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!--
        對應的mapper.xml文件
        sqlMapGenerator:sql映射生成策略
        targetProject:mapper映射文件生成的位置 -->
        <sqlMapGenerator targetPackage="mapper"
                         targetProject="./src/main/resources">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
        </sqlMapGenerator>

        <!-- javaClientGenerator:指定mapper接口所在的位置
            targetPackage:mapper接口生成的位置
         -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.diligentkong.mybatis.mapper"
                             targetProject="./src/main/java">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
        </javaClientGenerator>
        <!--指定逆向分析哪些表  根據表要創建javaBean -->
        <table tableName="employee" domainObjectName="Employee"></table>
        <table tableName="dept" domainObjectName="Department"></table>



    </context>
</generatorConfiguration>
  1. 運行函數:
public static void main(String[] args) throws Exception{
    List<String> warnings = new ArrayList<String>();
    boolean overwrite = true;
    File configFile = new File("src/main/resources/config/generationConfig.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);

}

項目生成目錄如下:
在這裏插入圖片描述

  1. 項目測試代碼:
public SqlSessionFactory getSqlSeeionFactory() throws IOException {
    String resource = "config/mybatis-config.xml";
    InputStream inputStream = Resources.getResourceAsStream(resource);
    return new SqlSessionFactoryBuilder().build(inputStream);

}

@Test
public void myTestif() throws IOException {
    // 1.獲取sqlSessionFactory對象
    SqlSessionFactory sqlSessionFactory = getSqlSeeionFactory();
    // 2、獲取sqlSession對象
    SqlSession openSession = sqlSessionFactory.openSession(true);

    try {
        // 3、獲取接口的實現類對象
        //會爲接口自動的創建一個代理對象,代理對象去執行增刪改查方法

        EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
        // XXXExample就是封裝查詢條件,相當於where後面部分
       EmployeeExample example = new EmployeeExample();
       // 創建一個Criteria,這個Criteria就是拼裝查詢條件
        //select id,username,age,email from employee where (username like "%k%" and age = 20)  or eamil like "%e%"
       EmployeeExample.Criteria criteria = example.createCriteria();
        criteria.andUserNameLike("%k%");
        criteria.andAgeEqualTo(20);

        EmployeeExample.Criteria criteria2 = example.createCriteria();
        criteria2.andEmailLike("%e%");
        example.or(criteria2);
        List<Employee> list = mapper.selectByExample(example);
        for (Employee employee : list){
            System.out.println(employee.getId());
        }

    } finally {
        openSession.close();
    }
}
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