mybatis整合spring原始dao开发

一、开发框架结构

1、引入jar包

2、配置文件

3、po

4、dao

　　

二、编写dao接口和接口实现类

public interface UserDao {
    public User findUserById(int id);

　　dao实现类

public class UserDaoImpl implements UserDao {
    
    @Override
    public User findUserById(int id) {
    //1、获取SqlSession
    SqlSession sqlSession= null;
    //2、通过SqlSession的方法执行statement
    User user=sqlSession.selectOne("",id);
    //3、返回执行结果
    return user;
    }

　　1、获取statement的id

　　　　1.1、新建一个Mapper.xml（User.xml）用于配置操作数据库的statement

<?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="test">
    <select id="findUserById" parameterType="Integer" resultType="com.xxx.mybatis.spring.po.User">
        SELECT * FROM
        T_USER WHERE ID=#{ID}
    </select>
</mapper>

　　　　1.2、配置核心配置文件SqlMapConfig.xml

<?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>
    <mappers>
        <mapper resource="User.xml"/>
    </mappers>
</configuration>

　　2、获取SqlSession对象

　　　　2.1、让UserDaoImpl实现类继承SqlSessionDaoSupport，SqlSessionDaoSupport可以获得SqlSession对象

public abstract class SqlSessionDaoSupport extends DaoSupport {

  private SqlSessionTemplate sqlSessionTemplate;


  public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
    if (this.sqlSessionTemplate == null || sqlSessionFactory != this.sqlSessionTemplate.getSqlSessionFactory()) {
      this.sqlSessionTemplate = createSqlSessionTemplate(sqlSessionFactory);
    }
  }

　　　　2.2、SqlSession对象需要sqlSessionFactory对象创建的，sqlSessionFactory对象要通过spring创建，spring创建sqlSessionFactory，就需要数据源和mybatis核心配置文件

    <!-- 1、引入数据库连接属性文件 -->
    <context:property-placeholder location="classpath:jdbc.properties" />

    <!-- 2、配置C3P0连接池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driverClass}" />
        <property name="jdbcUrl" value="${jdbc.url}" />
        <property name="user" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
    </bean>

    <!-- 3、spring创建sqlSessionFactory对象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 加载mybatis的配置文件 -->
        <property name="configLocation" value="mybatis/SqlMapConfig.xml" />
        <!-- 数据源 -->
        <property name="dataSource" ref="dataSource" />
    </bean>
    
    <!-- 4、spring创建userDao对象，并将sqlSessionFactory对象注入到userDao对象的sqlSessionFactory属性中-->
    <bean id="userDao" class="com.xxx.mybatis.spring.dao.impl.UserDaoImpl">
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
    </bean>

以上就解决了SqlSession和statement的获取，dao的实现类的代码如下：

public class UserDaoImpl extends SqlSessionDaoSupport implements UserDao {
    
    @Override
    public User findUserById(int id) {
    //1、获取SqlSession
    SqlSession sqlSession= this.getSqlSession();
    //2、通过SqlSession的方法执行statement
    User user=sqlSession.selectOne("test.findUserById",id);
    //3、返回执行结果
    return user;
    }

三、测试

    ApplicationContext applicationContext;

    @BeforeEach
    void setUp() throws Exception {
    applicationContext=new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
    }

    @Test
    void testFindUserById() {
    UserDao userDao=(UserDao) applicationContext.getBean("userDao");//userDao是spring管理Bean的id
    User user=userDao.findUserById(1);
    System.out.println(user);
    }