MyBaits入门

下载与配置：
下载地址：https://github.com/mybaits/mybaits-3/releases
配置和导入普通的jar包一样，直接将解压后的jar包导入项目就行了，注意解压后lib文件夹中的jar包也要导入。
mybaits核心组件：
SqlSessionFactoryBuilder：它根据你写的配置文件或者代码来生成SqlSessionFactory
SqlSessionFactory：它生成SqlSession
SqlSession：发送SQL语句进行对数据库的增删查改
SQL Mapper：由一个java接口和XML（或者注解）构成，同样可以对数据库进行操作
示例：
首先创建一个类：

public class Role {

    private Long id;
    private String roleName;
    private String note;

    /** setter and getter **/
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getRoleName() {
        return roleName;
    }

    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }

    public String getNote() {
        return note;
    }

    public void setNote(String note) {
        this.note = note;
    }

}

然后采用XML方式构建映射，包括一个java接口和XML

public interface RoleMapper {
    public int insertRole(Role role);
    public int deleteRole(Long id);
    public int updateRole(Role role);
    public Role getRole(Long id);
    public List<Role> findRoles(String roleName);
}

XML如下：

<?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.learn.ssm.chapter3.mapper.RoleMapper">

    <insert id="insertRole" parameterType="role">
        insert into t_role(role_name, note) values(#{roleName}, #{note})
    </insert>

    <delete id="deleteRole" parameterType="long">
        delete from t_role where id= #{id}
    </delete>

    <update id="updateRole" parameterType="role">
        update t_role set role_name = #{roleName}, note = #{note} where id= #{id}
    </update>

    <select id="getRole" parameterType="long" resultType="role">
        select id,
        role_name as roleName, note from t_role where id = #{id}
    </select>

    <select id="findRoles" parameterType="string" resultType="role">
        select id, role_name as roleName, note from t_role
        where role_name like concat('%', #{roleName}, '%')
    </select>
</mapper>

之后配置mybaits的基础配置文件：

<?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>
  <typeAliases><!-- 别名 -->
      <typeAlias alias="role" type="com.learn.ssm.chapter3.pojo.Role"/>
  </typeAliases>
  <!-- 数据库环境 -->
  <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/chapter3"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
      </dataSource>
    </environment>
  </environments>
  <!-- 映射文件 -->
  <mappers>
    <mapper resource="com/learn/ssm/chapter3/mapper/RoleMapper.xml"/>
  </mappers>
</configuration>

然后构建SqlSessionFactory

public class SqlSessionFactoryUtils {

    private final static Class<SqlSessionFactoryUtils> LOCK = SqlSessionFactoryUtils.class;

    private static SqlSessionFactory sqlSessionFactory = null;

    private SqlSessionFactoryUtils() {
    }

    public static SqlSessionFactory getSqlSessionFactory() {
        synchronized (LOCK) {
            if (sqlSessionFactory != null) {
                return sqlSessionFactory;
            }
            String resource = "mybatis-config.xml";
            InputStream inputStream;
            try {
                inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                e.printStackTrace();
                return null;
            }
            return sqlSessionFactory;
        }
    }
}

最后编写运行代码：

public class Test {

    public static void main(String[] args) {
        testRoleMapper();
    }


    private static void testRoleMapper() {

        SqlSession sqlSession = null;
        try {
            sqlSession = SqlSessionFactoryUtils.openSqlSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            Role role = roleMapper.getRole(1L);
            Sysem.out.println(role.getRoleName());
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
}

基本上就这些步骤。
注意数据库要自己构建，注意改用户名密码啥的。

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