mybatis（1）：入坑篇

---

依赖

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.0</version>
        </dependency>
        <!-- 测试数据库 -->
        <dependency>
            <groupId>org.hsqldb</groupId>
            <artifactId>hsqldb</artifactId>
            <version>2.3.4</version>
        </dependency>

myBatis 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">
<configuration>
    <!-- 引入properties配置文件 -->
    <properties resource="jdbc.properties"/>
    <environments default="test">
        <environment id="test">
            <transactionManager type="JDBC" />
            <dataSource type="UNPOOLED">
                <property name="driver" value="${hsqldb.driver}" />
                <property name="url" value="${hsqldb.url}" />
                <property name="username" value="${hsqldb.username}" />
                <property name="password" value="${hsqldb.password}" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- mapping 配置： 加载 Mapper.xml 和 Mapper.class -->
        <mapper class="com.github.xsj.model.Mapper"/>
    </mappers>
</configuration>

映射配置

使用 Mapper wrapper

package com.github.xsj.model;

public class User {

    private Long id;   // id 使用 Long 类型而非 long
    private String name;
    ...
}

Wrapper：

package com.github.xsj.model;

public interface Mapper {

    User getUser(long id);

    void insertUser(User user);

    @Update("update users set name = #{name}")
    void updateUser(User user);

    @Delete("delete from users where id = #{id}")
    void deleteUser(long id);

}

映射文件: src\main\resources\com\github\xsj\model\Mapper.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.github.xsj.model.Mapper">
    <select id="getUser" resultType="com.github.xsj.model.User">
        select * from users where id = #{id}
    </select>
    <!-- get generated key! Note: keyColumn 之所以使用 ID 而非 id 是 hsqldb 将列名强行转换为大写所导致 -->
    <insert id="insertUser" useGeneratedKeys="true" keyProperty="id" keyColumn="ID">
          insert into users values(#{id}, #{name})
    </insert>
</mapper>

单元测试

sql 脚本

drop table users if exists;
create table users (
  id INTEGER GENERATED BY DEFAULT AS IDENTITY(START WITH 1, INCREMENT BY 1) primary key,
  name varchar(126) not null
);
insert into users(name) values('User1');

样例

public class BaseTest {

    private final static Logger log =  LoggerFactory.getLogger(BaseTest.class);

    private static SqlSessionFactory sqlSessionFactory;

    @BeforeClass
    public static void setUp() throws Exception{
        Reader reader = Resources.getResourceAsReader("mybatis-test-config.xml");
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        reader.close();
        // 数据初始化
        SqlSession session = sqlSessionFactory.openSession();
        Connection conn = session.getConnection();
        reader = Resources.getResourceAsReader("com/github/xsj/model/CreateDB.sql");
        ScriptRunner runner = new ScriptRunner(conn);
        runner.setLogWriter(new PrintWriter(System.out));
        runner.runScript(reader);
        reader.close();
        conn.close();
        session.close();
    }

    @Test
    public void selectTest() {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            Mapper mapper = session.getMapper(Mapper.class);
            assertThat(mapper.getUser(1), is(notNullValue()));
        } finally {
            session.close();
        }
    }
    ...
}

源码： https://github.com/xsj24/mybaits-getStarted/tree/v1.0.0