Mybatis入门

Posted 2020-11-26 荒野猛兽

pom.xml

<packaging>jar</packaging>

<dependencies>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.5</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.6</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.12</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.1</version>
    </dependency>
</dependencies>

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>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///eesy"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="com/company/dao/IAcountMapper.xml"></mapper>
    </mappers>
</configuration>


IAcountMapper.xml

<?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.company.dao.IAccountMapper">
    <select id="findAll" resultType="com.company.domain.Account">
        SELECT * FROM account
    </select>
</mapper>

MyBatisTest.java

public static void main(String[] args) throws Exception {
    //1.读取配置文件
    InputStream in= Resources.getResourceAsStream("SqlMapConfig.xml");
    //2.创建SqlSessionFactory工厂(构建者模式：隐藏对象的创建细节，使用者只需调用方法即可拿到对象)
    SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
    SqlSessionFactory factory=builder.build(in);
    //3.使用工厂对象获取SqlSession对象（工厂模式：创建对象的最佳方式，使用一个共同的接口来指向新创建的对象）
    SqlSession session = factory.openSession();
    //4.使用SqlSession对象创建Dao接口的代理对象（动态代理模式：不修改原有代码的情况下对已有方法进行增强）
    IAccountMapper mapper = session.getMapper(IAccountMapper.class);
    //5.使用代理对象执行方法
    List<Account> all = mapper.findAll();
    System.out.println(all);
    //6.释放资源
    session.close();
    in.close();
}