使用MyBatis Generator逆向生成数据库读写代码

4-12 后端 magicwt 2,546 views

使用MyBatis Generator逆向生成数据库读写代码

4-12 2,546 views

简介

MyBatis（前身是iBATIS）是一个基于Java的持久层框架，而MyBatis Generator (MBG，http://www.mybatis.org/generator/)是一个根据数据库表结构为MyBatis和iBATIS逆向生成相关Java代码和配置文件的工具。
MBG可以生成：
1）Java POJO，与数据库表结构对应；
2）MyBatis和iBATIS规范的SQL映射配置文件，每个配置文件包含对一个表实现简单CRUD操作的SQL语句；
3）MyBatis和iBATIS规范的Java客户端接口，提供对数据的增、删、查、改方法。

示例数据库

示例数据库包含3张表：
1）课程表（course），存储课程名称、学分信息，主键为自增整数；
2）学生表（student），存储学生姓名、性别、年龄等信息，主键为自增整数；
3）得分表（score），存储某位学生某门课程的分数，使用课程id和学生id作为联合主键。

使用MBG逆向生成代码

使用MBG生成代码时，需要指定配置文件（generatorConfig.xml），如下所示，其中指定了数据库连接方式，Java POJO、SQL映射配置文件、Java客户端接口的生成方式和生成路径等：

<?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>
	<classPathEntry location="/Users/tao/develop/mysql-connector-java-5.1.12.jar" />
	<context id="test" targetRuntime="MyBatis3">
		<commentGenerator>
			<property name="suppressAllComments" value="true" />
		</commentGenerator>
		<jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://xxx.xxx.xxx.xxx:3306/test" userId="xxx" password="xxx">
		</jdbcConnection>
		<javaTypeResolver>
			<property name="forceBigDecimals" value="false" />
		</javaTypeResolver>
		<javaModelGenerator targetPackage="com.magicwt.bean" targetProject="/Users/tao/develop/test/src">
			<property name="enableSubPackages" value="false" />
			<property name="trimStrings" value="true" />
		</javaModelGenerator>
		<sqlMapGenerator targetPackage="com.magicwt.mapper" targetProject="/Users/tao/develop/test/src">
			<property name="enableSubPackages" value="false" />
		</sqlMapGenerator>
		<javaClientGenerator type="XMLMAPPER" targetPackage="com.magicwt.dao" targetProject="/Users/tao/develop/test/src">
			<property name="enableSubPackages" value="false" />
		</javaClientGenerator>
		<table tableName="%" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>	
	</context>
</generatorConfiguration>

<?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">

</commentGenerator>

</jdbcConnection>

</javaTypeResolver>

</javaModelGenerator>

</sqlMapGenerator>

</javaClientGenerator>

</context>

</generatorConfiguration>

指定配置文件后，MBG支持以下4种生成代码方式：
1）使用命令行生成代码；
2）作为Ant任务生成代码；
3）作为Maven插件生成代码；
4）使用Java接口编程生成代码。
这里使用命令行方式，从https://github.com/mybatis/generator/releases下载jar包，命令行下执行jar包：

java -jar mybatis-generator-core-1.3.2.jar -configfile generatorConfig.xml

执行成功后，便会生成如下代码：
1）Java POJO：Course.java，Student.java，ScoreKey.java，Score.java，其中Course.java对应于course表，如下所示：

package com.magicwt.bean;

public class Course {
    private Integer id;

    private String name;

    private Byte credit;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public Byte getCredit() {
        return credit;
    }

    public void setCredit(Byte credit) {
        this.credit = credit;
    }
}

package com.magicwt.bean;

public class Course {

private Integer id;

private String name;

private Byte credit;

public Integer getId() {

return id;

}

public void setId(Integer id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name == null ? null : name.trim();

}

public Byte getCredit() {

return credit;

}

public void setCredit(Byte credit) {

this.credit = credit;

}

2）SQL映射配置文件：CourseMapper.xml，StudentMapper.xml，ScoreMapper.xml，其中CourseMapper.xml包含对course表实现CRUD操作的SQL语句，如下所示：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.magicwt.dao.CourseMapper" >
  <resultMap id="BaseResultMap" type="com.magicwt.bean.Course" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="name" property="name" jdbcType="VARCHAR" />
    <result column="credit" property="credit" jdbcType="TINYINT" />
  </resultMap>
  <sql id="Base_Column_List" >
    id, name, credit
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from course
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from course
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.magicwt.bean.Course" >
    insert into course (id, name, credit
      )
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{credit,jdbcType=TINYINT}
      )
  </insert>
  <insert id="insertSelective" parameterType="com.magicwt.bean.Course" >
    insert into course
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="name != null" >
        name,
      </if>
      <if test="credit != null" >
        credit,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="credit != null" >
        #{credit,jdbcType=TINYINT},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.magicwt.bean.Course" >
    update course
    <set >
      <if test="name != null" >
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="credit != null" >
        credit = #{credit,jdbcType=TINYINT},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.magicwt.bean.Course" >
    update course
    set name = #{name,jdbcType=VARCHAR},
      credit = #{credit,jdbcType=TINYINT}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >

</resultMap>

id, name, credit

</sql>

select

from course

where id = #{id,jdbcType=INTEGER}

</select>

delete from course

where id = #{id,jdbcType=INTEGER}

</delete>

insert into course (id, name, credit

)

values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{credit,jdbcType=TINYINT}

)

</insert>

insert into course

id,

</if>

name,

</if>

credit,

</if>

</trim>

#{id,jdbcType=INTEGER},

</if>

#{name,jdbcType=VARCHAR},

</if>

#{credit,jdbcType=TINYINT},

</if>

</trim>

</insert>

update course

<set >

name = #{name,jdbcType=VARCHAR},

</if>

credit = #{credit,jdbcType=TINYINT},

</if>

</set>

where id = #{id,jdbcType=INTEGER}

</update>

update course

set name = #{name,jdbcType=VARCHAR},

credit = #{credit,jdbcType=TINYINT}

where id = #{id,jdbcType=INTEGER}

</update>

</mapper>

3）Java客户端接口，CourseMapper.java，StudentMapper.java，ScoreMapper.java，其中CourseMapper.java提供对Course对象的增、删、查、改方法，如下所示：

package com.magicwt.dao;

import com.magicwt.bean.Course;

public interface CourseMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(Course record);

    int insertSelective(Course record);

    Course selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(Course record);

    int updateByPrimaryKey(Course record);
}

package com.magicwt.dao;

import com.magicwt.bean.Course;

public interface CourseMapper {

int deleteByPrimaryKey(Integer id);

int insert(Course record);

int insertSelective(Course record);

Course selectByPrimaryKey(Integer id);

int updateByPrimaryKeySelective(Course record);

int updateByPrimaryKey(Course record);

}

使用所生成代码读写数据库

示例工程使用Maven构建，并使用Spring管理上下文，代码目录如图所示：

除MBG生成的代码和配置文件外，还需要context.xml和configuration.xml分别配置Spring和MyBatis，context.xml和configuration.xml如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.2.xsd">

    <!-- 配置数据库连接池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver" />
        <property name="jdbcUrl" value="jdbc:mysql://123.57.154.17:3306/test?characterEncoding=UTF-8&amp;autoReconnect=true" />
        <property name="user" value="server_test" />
        <property name="password" value="4abE9r4Imx12" />
        <property name="initialPoolSize" value="1" />
    </bean>

    <!-- 配置会话工厂 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:configuration.xml" />
    </bean>
    
    <bean id="courseDao" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
        <property name="mapperInterface" value="com.magicwt.dao.CourseMapper" />
    </bean>

    <bean id="studentDao" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
        <property name="mapperInterface" value="com.magicwt.dao.StudentMapper" />
    </bean>

    <bean id="scoreDao" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
        <property name="mapperInterface" value="com.magicwt.dao.ScoreMapper" />
    </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="

http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.2.xsd">

</bean>

</bean>

</bean>

</bean>

</bean>

</beans>

<?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>

    <typeAliases>
        <typeAlias alias="Course" type="com.magicwt.bean.Course"/>
        <typeAlias alias="Student" type="com.magicwt.bean.Student"/>
        <typeAlias alias="Score" type="com.magicwt.bean.Score"/>
    </typeAliases>

    <mappers>
        <mapper resource="com/magicwt/mapper/CourseMapper.xml"/>
        <mapper resource="com/magicwt/mapper/StudentMapper.xml"/>
        <mapper resource="com/magicwt/mapper/ScoreMapper.xml"/>
    </mappers>

</configuration>

<?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">

</typeAliases>

</mappers>

</configuration>

编写测试类对course表执行插入操作：

public class DaoTest {

    private ApplicationContext context;

    @Before
    public void prepare() {
        context = new ClassPathXmlApplicationContext(new String[] {"context.xml"});
    }

    @Test
    public void test() {
        CourseMapper courseDao = (CourseMapper) context.getBean("courseDao");
        Course course = new Course();
        course.setName("微积分");
        course.setCredit(new Byte("4"));
        courseDao.insert(course);
    }

}

public class DaoTest {

private ApplicationContext context;

@Before

public void prepare() {

context = new ClassPathXmlApplicationContext(new String[] {"context.xml"});

}

@Test

public void test() {

CourseMapper courseDao = (CourseMapper) context.getBean("courseDao");

Course course = new Course();

course.setName("微积分");

course.setCredit(new Byte("4"));

courseDao.insert(course);

}

执行后，在course表中成功插入一条记录：

版权属于: 我爱我家

原文地址: http://magicwt.com/2015/04/12/%e4%bd%bf%e7%94%a8mybatis-generator%e7%94%9f%e6%88%90%e4%bb%a3%e7%a0%81/

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