实现要求：

获取id值为1的角色信息。

实现思路：

创建角色表sys_role所对应的实体类sysRole。

package entity;

public class SysRole {

	private long id;

	private String roleName;

	private int enabled;

	private String createBy;

	private String createTime;

	public SysRole() {

		super();

	}

	public SysRole(long id, String roleName, int enabled, String createBy, String createTime) {

		super();

		this.id = id;

		this.roleName = roleName;

		this.enabled = enabled;

		this.createBy = createBy;

		this.createTime = createTime;

	}

	@Override

	public String toString() {

		return "SysRole [id=" + id + ", roleName=" + roleName + ", enabled=" + enabled + ", createBy=" + createBy

				+ ", createTime=" + createTime + "]";

	}

	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 int getEnabled() {

		return enabled;

	}

	public void setEnabled(int enabled) {

		this.enabled = enabled;

	}

	public String getCreateBy() {

		return createBy;

	}

	public void setCreateBy(String createBy) {

		this.createBy = createBy;

	}

	public String getCreateTime() {

		return createTime;

	}

	public void setCreateTime(String createTime) {

		this.createTime = createTime;

	}

}

创建操作sysRole的映射器接口RoleMapper，并在其中定义SysRole selectById(Long id)方法。

package mapper;

import entity.SysRole;

public interface RoleMapper {

	SysRole selectById(long id);

}

定义RoleMapper.xml，在其中定义<select>标签，注意返回结果的resultMap映射说明。

<?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">

<!-- SysRole类的映射 -->

<mapper namespace="mapper.RoleMapper">

	<resultMap type="SysRole" id="RoleMap">

		<id property="id" column="id"/>

		<result property="roleName" column="role_name"/>

		<result property="enabled" column="enabled"/>

		<result property="cretaBy" column="creta_by"/>

		<result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>

	</resultMap>

	<select id="selectById" resultMap="RoleMap">

		select * from sys_role where id=#{id}

	</select>

</mapper>

编写测试类测试方法调用。

package test;

import java.io.IOException;

import java.io.Reader;

import java.util.List;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import org.junit.BeforeClass;

import org.junit.Test;

import mapper.RoleMapper;

public class RoleMapperTest {

	private static SqlSessionFactory sqlSessionFactory;

	/* 完成mybatis配置的加载，创建得到SqlSessionFactory */

	@BeforeClass

	public static void init() {

		try {

			Reader reader = Resources.getResourceAsReader("mybatis-config.xml");

			sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

			reader.close();

		} catch (IOException e) {

			e.printStackTrace();

		}

	}

	/* 获取SqlSession对象，用于调用方法得到数据 */

	@Test

	public void testSelectAll() {

		SqlSession sqlSession = sqlSessionFactory.openSession();

		try {

			RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);

			roleMapper.selectById(1L);

		} finally {

			// 不要忘记关闭sqlSession

			sqlSession.close();

		}

	}

}