Maven中使用Mybaits

记录一下在Maven中使用Mybaits

单纯的Mybatis,没有整合spring
首先在pom中导入依赖

点击查看代码

 <dependencies>
<!--    单元测试-->
      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.12</version>
          <scope>test</scope>
      </dependency>
      <dependency>
          <groupId>org.junit.jupiter</groupId>
          <artifactId>junit-jupiter</artifactId>
          <version>RELEASE</version>
          <scope>compile</scope>
      </dependency>
<!--    MyBatis核心-->
      <dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>3.5.10</version>
      </dependency>
<!--    MySql驱动-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.35</version>
    </dependency>
<!--    log4j日志-->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.17</version>
    </dependency>
  </dependencies>

使用MyBatis需要在resource文件夹中创建一个xml进行一下全局配置
MyBatis的xml约束头
右键new -> file
文件以.xml结尾

点击查看代码

<?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">

在Mybatis的全局配置中，重要的配置是数据库配置，和映射配置文件

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<?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">

    <!--配置信息的顺序-->
    <!--The content of element type "configuration" must match "(
    properties?,settings?,typeAliases?,typeHandlers?,
    objectFactory?,objectWrapperFactory?,reflectorFactory?,
    plugins?,environments?,databaseIdProvider?,mappers?)".-->

    <!--引入jdbc.properties数据库配置文件-->
    <!--使用配置信息 ${key}-->
    <properties resource="jdbc.properties" />

<configuration>
    <environments default="testDataSource">
        <environment id="testDataSource">
            <transactionManager type="jdbc"></transactionManager>
            <dataSource type="pooled">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///test?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
        <environment id="testDataSource2">
            <transactionManager type="jdbc"></transactionManager>
            <dataSource type="pooled">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///test?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
        <package name=""/>
    </mappers>
</configuration>

environments标签的default属性为子标签environment的Id
default是那个id就会使用那个数据库配置

mappers标签为映射配置文件的路径
标签有两种：
mapper 属性 resource 路径具体到文件名
package 属性 name 路径具体到放置文件的包名

typeAliases标签为取别名

映射配置文件UserMapper.xml

点击查看代码

<?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.wz.mapper.UserMapper">
    <select id="queryList" resultType="com.wz.pojo.User">
        select * from t_user
    </select>

</mapper>

namespace属性为对应的接口类。
select标签代表查询，insert标签代表新增等等
resultType属性为返回值类型，如果全局配置中没有配置别名的话这里要写全限定类名，如果配置了别名写别名就可以了

接口类UserMapper

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public interface UserMapper {
    public List<User> queryList();
}

映射文件的名字必须与接口类名一致 sql标签的id也必须与方法名一致

方法类

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public class SqlSessionUtils {

    private static SqlSession sqlSession;
    public static SqlSession getSqlsession(){

        try {
            InputStream resource = Resources.getResourceAsStream("mysql_config.xml");
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(resource);
            sqlSession = sessionFactory.openSession(true);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return sqlSession;
    }

    public static void closeSession(){
        if (sqlSession != null){
            sqlSession.close();
        }
    }
}

测试类

点击查看代码

public class mysqlTest {
    @Test
    public void test01(){
        SqlSession sqlsession = SqlSessionUtils.getSqlsession();
        UserMapper mapper = sqlsession.getMapper(UserMapper.class);
        List<User> users = mapper.queryList();

        for (User user : users) {
            System.out.println(user);
        }
    }
}