Mybatis学习之查询

╰+攻爆jí腚メ 2022-06-08 07:18 168阅读 0赞

## MyBatis架构图 ##

![这里写图片描述][SouthEast]

## MyBatis核心配置文件 ##

<?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="development">
            <environment id="development">
                
                <transactionManager type="JDBC" />
                
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver" />
                    <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
                    <property name="username" value="root" />
                    <property name="password" value="1000" />
                </dataSource>
            </environment>
        </environments>
    
        
        <mappers>
            <mapper resource="User.xml" />
        </mappers>
    </configuration>

## MyBatis核心代码 ##

@Test
    public void testName() throws IOException {
        //加载核心配置文件，需要放在classpath下
        InputStream stream = Resources.getResourceAsStream("sqlMapConfig.xml");
        //创建SqlSessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(stream);
        //创建SqlSession
        SqlSession sqlSession = sessionFactory.openSession();
        //执行sql语句
        ...
    }

*  查询一个

//参数1是User.xml中配置的id，参数2是查询的条件
    User user = sqlSession.selectOne("com.xanthuim.pojo.User.selectById", 1);

*  查询多个

List<User> users = sqlSession.selectList("com.xanthuim.pojo.User.selectByName", "张");
    for (User user : users) {
        System.out.println(user);
    }

[SouthEast]: /images/20220608/ea5a62d91a6441ff96767ff0032a6aea.png