java mybatis 使用步骤

Posted 2020-11-30 monkey-K

1. Pom 文件依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.monkey</groupId>
    <artifactId>java_mybatis_01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <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>4.12</version>
        </dependency>
    </dependencies>


</project>

2.1  sql 配置

<?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">
<!--mybatis 的主配置文件-->
<configuration>
    <environments default="mysql">
        <!--mysql配置-->
        <environment id="mysql">
            <!--配置事务类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源（连接池）-->
            <dataSource type="POOLED">
                <!--配置连接数据库的4要素-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="cn/monkey/dao/UserDao.xml"></mapper>
    </mappers>

</configuration>

2.2 mapper 配置文件

<?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="cn.monkey.dao.UserDao">
    <select id="findAll" resultType="cn.monkey.domain.User">
        SELECT * FROM USER
    </select>
</mapper>

3. 创建 javaBean 和 Dao 层的 interface

4. 调用 java api 调用

public void test1 () throws IOException {
        // 1. 读取配置文件
        InputStream is = Resources.getResourceAsStream("sqlMapConfig.xml");
        // 2. 创建 SqlSessionFactory 工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(is);
        // 3. 使用工厂类创建 SqlSesson 对象
        SqlSession session = factory.openSession();
        // 4. 使用 sqlSession 对象创建 Dao 层的代理对象
        UserDao userDao = session.getMapper(UserDao.class);
        // 5. 使用代理对象执行方法
        List<User> users = userDao.findAll();
        for (User user : users) {
            System.out.println(user);
        }
        // 6. 释放资源
        session.close();
        is.close();
    }