MyBatis入门实例-包括实体类与数据库字段对应&CLOB字段处理

1、我的开发环境是 jdk1.7+ecplise+oracle 11g

     用到的jar包：mybatis-3.1.1.jar 

ojdbc6.jar            

2、项目整体结构 

 

 

3、首先配置conf.xml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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="oracle.jdbc.driver.OracleDriver" />
                <property name="url" value="jdbc:oracle:thin:@xxx.xxx.xxx.xxx:1521:orcl" />
                <property name="username" value="xxx" />
                <property name="password" value="xxx" />
            </dataSource>
        </environment>
    </environments>

</configuration>

4、数据库表创建

-- Create table
create table DIM_LANE_AREA
(
  lane_id       NUMBER(4) not null,
  lane_name     VARCHAR2(100) not null,
  direction     CHAR(2) not null,
  facility_list CLOB not null,
  account_list  CLOB not null,
  description   VARCHAR2(100)
)
tablespace USERS
  pctfree 10
  initrans 1
  maxtrans 255
  storage
  (
    initial 64K
    next 1M
    minextents 1
    maxextents unlimited
  );
-- Add comments to the columns
comment on column DIM_LANE_AREA.lane_id
  is '单行道编号';
comment on column DIM_LANE_AREA.lane_name
  is '单行道名称';
comment on column DIM_LANE_AREA.direction
  is '单行道方向';
comment on column DIM_LANE_AREA.facility_list
  is '设备列表';
comment on column DIM_LANE_AREA.account_list
  is '账户列表';
comment on column DIM_LANE_AREA.description
  is '描述';
-- Create/Recreate indexes
create unique index DIM_LANE_AREA_1 on DIM_LANE_AREA (LANE_ID)
  tablespace USERS
  pctfree 10
  initrans 2
  maxtrans 255
  storage
  (
    initial 64K
    next 8K
    minextents 1
    maxextents unlimited
  );
create index DIM_LANE_AREA_2 on DIM_LANE_AREA (DIRECTION)
  tablespace USERS
  pctfree 10
  initrans 2
  maxtrans 255
  storage
  (
    initial 64K
    next 8K
    minextents 1
    maxextents unlimited
  );
-- Create/Recreate primary, unique and foreign key constraints
alter table DIM_LANE_AREA
  add constraint DIM_LANE_AREA primary key (LANE_ID);

5、编写实体类LaneArea.java

package me.gacl.po;

/**
 * 单行道配置信息PO
 * @author wqq
 * @time 2016-09-21
 */
public class LaneArea
{
    /**
     * 单行道编号
     */
    private Integer laneId;

    /**
     * 单行道名称
     */
    private String laneName;

    /**
     * 单行道方向
     */
    private String direction;

    /**
     * 设备列表<span style="font-family: Arial, Helvetica, sans-serif;">（该字段为CLOB类型，以逗号分隔）</span>
     */
    private String facilityList;

    /**
     * 账户列表（该字段为CLOB类型，以逗号分隔）
     */
    private String accountList;

    /**
     * 描述
     */
    private String description;

    public Integer getLaneId() {
        return laneId;
    }

    public void setLaneId(Integer laneId) {
        this.laneId = laneId;
    }

    public String getLaneName() {
        return laneName;
    }

    public void setLaneName(String laneName) {
        this.laneName = laneName;
    }

    public String getDirection() {
        return direction;
    }

    public void setDirection(String direction) {
        this.direction = direction;
    }

    public String getFacilityList() {
        return facilityList;
    }

    public void setFacilityList(String facilityList) {
        this.facilityList = facilityList;
    }

    public String getAccountList() {
        return accountList;
    }

    public void setAccountList(String accountList) {
        this.accountList = accountList;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString()
    {
        return "LaneArea [lane_id=" + laneId + ", lane_name=" + laneName + ", facility_list=" + facilityList + "]";
    }
}

 

注意：1、我之前没有在这个实体类里加入toString()，返回了一个对象，虽然也对，但是没有直观效果，这个toString()可以直观的看到你返回的结果。

 

6、配置LaneAreaMapper.xml文件

<?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="me.gacl.mapping.laneAreaMapper">
    <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，
    不能够重复 使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型
        resultType="me.gacl.po.LaneArea"就表示将查询结果封装成一个LaneArea类的对象返回 LaneArea类
        就是dim_lane_area表所对应的实体类 -->
    <!-- 根据id查询得到一个LaneArea对象 -->
    <select id="getLaneAreaResultMap" parameterType="int" resultMap="LaneAreaResultMap">
        select * from dim_lane_area where lane_id = #{lane_id}
    </select>
    <!--这里因为实体类的属性与数据库字段不对应，所以要加上resultMap-->
    <resultMap type="me.gacl.po.LaneArea" id="LaneAreaResultMap">
         <id property="laneId" column="lane_id"/>
         <result property="laneName" column="lane_name"/>
         <result property="facilityList" column="facility_list" javaType="String" jdbcType="VARBINARY"/>
    </resultMap>
</mapper>

7、在conf.xml中注册LaneAreaMapper.xml

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="oracle.jdbc.driver.OracleDriver" />
                <property name="url" value="jdbc:oracle:thin:@192.168.1.40:1521:ETL" />
                <property name="username" value="lane" />
                <property name="password" value="123" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
         <!-- 注册LaneAreaMapper.xml文件，
         LaneAreaMapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/LaneAreaMapper.xml-->
         <mapper resource="me/gacl/mapping/laneAreaMapper.xml"/>
    </mappers>

</configuration>

8、编写测试类

package me.gacl.test;

import java.io.IOException;
import java.io.InputStream;
import me.gacl.po.LaneArea;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Test1 {

    public static void main(String[] args) throws IOException {
        //mybatis的配置文件
        String resource = "conf.xml";
        //使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
        InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource);
        //构建sqlSession的工厂
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        //使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）
        //Reader reader = Resources.getResourceAsReader(resource);
        //构建sqlSession的工厂
        //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //创建能执行映射文件中sql的sqlSession
        SqlSession session = sessionFactory.openSession();
        /**
         * 映射sql的标识字符串，
         * me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
         */
        String statement = "me.gacl.mapping.laneAreaMapper.getLaneAreaResultMap";//映射sql的标识字符串

        LaneArea laneArea = session.selectOne(statement, 8);
        System.out.println(laneArea);
    }
}

启动Tomact，运行Test1，返回结果如下：

 

至此大工告成。

 

9、最后推荐一个自动生成实体类，Mapper.xml，DAO的工具：Mybatis-Generator

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