Java EE数据持久化框架mybatis练习——获取id值为1的角色信息。

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();
		}
	}
}