轻松集成Mybatis框架

众所周知，Mybatis是一个JAVA轻量级（相对于Hibernate与）的数据库处理框架,支持xml映射文件、动态SQL。对于习惯了写复杂SQL语句的开发人员来说，是非常方便的，他摒除了jdbc的冗长写法，极大地减少了代码行数。不同于Hibernate繁琐的配置，Mybatis的集成是非常容易的。
1.新建新建实体类：

public Class User{        public String user_id;        public String user_name;}

2.新建映射接口:com.company.mapInterface.UserMapper

public interface UserMapper {     public User findByUserId(String userId);  }

3.新建xml映射文件com/company/mappers/UserMapping.xml,内容如下:

<?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">  <!--这块等于dao接口的实现 namespace必须和接口的类路径一样-->  <mapper namespace="com.company.mapInterface.UserMapper">   <!-- findByUserId必须和接口中的方法名一样 返回一个User就是刚才的别名-->   <select id="findByUserId" parameterType="HashMap" resultType="User">      select * from user_data where user_id=#{userId}      </select>  </mapper>  

4.在com.company.config下新建batis配置文件mybatis.xml,内容如下：

<?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>        <!—作用：该包下所有实体类自动使用别名 -->        <package name="com.company.bean"/>    </typeAliases>    <!--数据源配置 使用mysql数据库 -->    <environments default="development">        <environment id="development">            <transactionManager type="jdbc" />            <dataSource type="POOLED">            <!--Mysql写法-->                <!-- <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis" /> -->                <!--Oracle写法-->                 <property name="driver" value="oracle.jdbc.OracleDriver"></property>                 <property name=" url"value="jdbc:oracle:thin:@XXX"></property>                <!--账号/密码-->                <property name="username" value="test" />                <property name="password" value="psw" />            </dataSource>        </environment>    </environments>    <mappers>        <!--userMapper.xml装载进来 同等于把“dao”的实现装载进来 -->        <mapper resource="com/company/mappers/UserMapping.xml" />    </mappers></configuration>  

其中dataSource 的配置也可以使用占位符，如下：

<?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>        <!—作用：该包下所有实体类自动使用别名 -->        <package name="com.company.bean"/>    </typeAliases>    <properties resource="org/mybatis/example/config.properties">     <property name="driver" value="oracle.jdbc.OracleDriver"/>      <property name="url" value="jdbc:oracle:thin:@XXX"/>      <property name="username" value="test"/>      <property name="password" value="psw"/>    </properties>    <!--数据源配置 使用mysql数据库 -->    <environments default="development">        <environment id="development">            <transactionManager type="jdbc" />            <dataSource type="POOLED">                <!--Oracle写法-->                <property name="driver" value="${driver}"></property>                <property name="url" value="${url}"></property>                <!--账号/密码-->                <property name="username" value="${username}" />                <property name="password" value="${password}" />            </dataSource>        </environment>    </environments>    <mappers>        <!--userMapper.xml装载进来 同等于把“dao”的实现装载进来 -->        <mapper resource="com/company/mappers/UserMapping.xml" />    </mappers></configuration> 

还可以使用配置文件，如下：

<?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>        <!—作用：该包下所有实体类自动使用别名 -->        <package name="com.company.bean"/>    </typeAliases>    <properties resource="jdbc.properties"></properties>    <!--数据源配置 使用mysql数据库 -->    <environments default="development">        <environment id="development">            <transactionManager type="jdbc" />            <dataSource type="POOLED">            <!--Mysql写法-->                <!-- <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis" /> -->                <!--Oracle写法-->                 <property name="driver" value="${driver}"></property>                 <property name="url" value="${url}"></property>                <!--账号/密码-->                <property name="username" value="${username}" />                <property name="password" value="${password}" />            </dataSource>        </environment>    </environments>    <mappers>        <!--userMapper.xml装载进来 同等于把“dao”的实现装载进来 -->        <mapper resource="com/company/mappers/UserMapping.xml" />    </mappers></configuration> 

然后同路径下新建jdbc.properties文件

driver=oracle.jdbc.OracleDriverurl=jdbc:oracle:thin:@XXXusername=testpassword=psw

5.最后一步，测试:
(1)新建工具类:

public class BatisUtil {    public static SqlSessionFactory getSessionFactory() {        SqlSessionFactory sessionFactory = null;        String resource = "com/company/config/mybatis.xml";        try {         sessionFactory = new SqlSessionFactoryBuilder().build(Resources           .getResourceAsReader(resource));        } catch (IOException e) {         // TODO Auto-generated catch block         e.printStackTrace();        }        return sessionFactory;  

(2)新建测试类:

public class MyBatisTest {     public static void main(String[] args) {            SqlSession sqlSession = BatisUtil.getSessionFactory().openSession();            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);            User user = userMapper.findByUserId("1455");            System.out.println(user.user_name);       }  }

执行,正确打印出数据库中的user_name值，完成。