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();
    }
  }
}