Mybatis引入PageHelper插件实现分页查询的效果-----Mybatis框架

蔚落 2024-03-02 03:45 52阅读 0赞

>     <?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>
>         <properties resource="jdbc.properties"/>
>         <settings>
>     
>             <setting name="lazyLoadingEnabled" value="true"/>
>             <setting name="mapUnderscoreToCamelCase" value="true"/>
>             <setting name="logImpl" value="SLF4J"/>
>             <setting name="cacheEnabled" value="true"/>
>         </settings>
>         <typeAliases>
>             <package name="com.powernode.mybatis.pojo"/>
>         </typeAliases>
>     
>         <plugins>
>             <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
>         </plugins>
>         <environments default="development">
>             <environment id="development">
>                 <transactionManager type="JDBC"/>
>                 <dataSource type="POOLED">
>                     <property name="driver" value="${jdbc.driver}"/>
>                     <property name="url" value="${jdbc.url}"/>
>                     <property name="username" value="${jdbc.username}"/>
>                     <property name="password" value="${jdbc.password}"/>
>                 </dataSource>
>             </environment>
>         </environments>
>         <mappers>
>             <package name="com.powernode.mybatis.mappers"/>
>         </mappers>
>     </configuration>
> 
>     <?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>
>         <properties resource="jdbc.properties"/>
>         <settings>
>     
>             <setting name="lazyLoadingEnabled" value="true"/>
>             <setting name="mapUnderscoreToCamelCase" value="true"/>
>             <setting name="logImpl" value="SLF4J"/>
>             <setting name="cacheEnabled" value="true"/>
>         </settings>
>         <typeAliases>
>             <package name="com.powernode.mybatis.pojo"/>
>         </typeAliases>
>     
>         <plugins>
>             <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
>         </plugins>
>         <environments default="development">
>             <environment id="development">
>                 <transactionManager type="JDBC"/>
>                 <dataSource type="POOLED">
>                     <property name="driver" value="${jdbc.driver}"/>
>                     <property name="url" value="${jdbc.url}"/>
>                     <property name="username" value="${jdbc.username}"/>
>                     <property name="password" value="${jdbc.password}"/>
>                 </dataSource>
>             </environment>
>         </environments>
>         <mappers>
>             <package name="com.powernode.mybatis.mappers"/>
>         </mappers>
>     </configuration>

>     <?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.powernode.mybatis.mappers.CarMapper">
>       <resultMap id="BaseResultMap" type="com.powernode.mybatis.pojo.Car">
>         <id column="id" jdbcType="BIGINT" property="id" />
>         <result column="car_num" jdbcType="VARCHAR" property="carNum" />
>         <result column="brand" jdbcType="VARCHAR" property="brand" />
>         <result column="guide_price" jdbcType="DECIMAL" property="guidePrice" />
>         <result column="produce_time" jdbcType="CHAR" property="produceTime" />
>         <result column="car_type" jdbcType="VARCHAR" property="carType" />
>       </resultMap>
>       <sql id="Example_Where_Clause">
>         <where>
>           <foreach collection="oredCriteria" item="criteria" separator="or">
>             <if test="criteria.valid">
>               <trim prefix="(" prefixOverrides="and" suffix=")">
>                 <foreach collection="criteria.criteria" item="criterion">
>                   <choose>
>                     <when test="criterion.noValue">
>                       and ${criterion.condition}
>                     </when>
>                     <when test="criterion.singleValue">
>                       and ${criterion.condition} #{criterion.value}
>                     </when>
>                     <when test="criterion.betweenValue">
>                       and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
>                     </when>
>                     <when test="criterion.listValue">
>                       and ${criterion.condition}
>                       <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
>                         #{listItem}
>                       </foreach>
>                     </when>
>                   </choose>
>                 </foreach>
>               </trim>
>             </if>
>           </foreach>
>         </where>
>       </sql>
>       <select id="selectByPage" resultType="car">
>         select * from t_car limit #{startIndex},#{pageSize}
>       </select>
>       <select id="selectAllByPageHelper" resultType="Car">
>         select * from t_car
>       </select>
>       <sql id="Update_By_Example_Where_Clause">
>         <where>
>           <foreach collection="example.oredCriteria" item="criteria" separator="or">
>             <if test="criteria.valid">
>               <trim prefix="(" prefixOverrides="and" suffix=")">
>                 <foreach collection="criteria.criteria" item="criterion">
>                   <choose>
>                     <when test="criterion.noValue">
>                       and ${criterion.condition}
>                     </when>
>                     <when test="criterion.singleValue">
>                       and ${criterion.condition} #{criterion.value}
>                     </when>
>                     <when test="criterion.betweenValue">
>                       and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
>                     </when>
>                     <when test="criterion.listValue">
>                       and ${criterion.condition}
>                       <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
>                         #{listItem}
>                       </foreach>
>                     </when>
>                   </choose>
>                 </foreach>
>               </trim>
>             </if>
>           </foreach>
>         </where>
>       </sql>
>       <sql id="Base_Column_List">
>         id, car_num, brand, guide_price, produce_time, car_type
>       </sql>
>       <select id="selectByExample" parameterType="com.powernode.mybatis.pojo.CarExample" resultMap="BaseResultMap">
>         select
>         <if test="distinct">
>           distinct
>         </if>
>         <include refid="Base_Column_List" />
>         from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>         <if test="orderByClause != null">
>           order by ${orderByClause}
>         </if>
>       </select>
>       <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
>         select 
>         <include refid="Base_Column_List" />
>         from t_car
>         where id = #{id,jdbcType=BIGINT}
>       </select>
>       <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
>         delete from t_car
>         where id = #{id,jdbcType=BIGINT}
>       </delete>
>       <delete id="deleteByExample" parameterType="com.powernode.mybatis.pojo.CarExample">
>         delete from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>       </delete>
>       <insert id="insert" parameterType="com.powernode.mybatis.pojo.Car">
>         insert into t_car (id, car_num, brand, 
>           guide_price, produce_time, car_type
>           )
>         values (#{id,jdbcType=BIGINT}, #{carNum,jdbcType=VARCHAR}, #{brand,jdbcType=VARCHAR}, 
>           #{guidePrice,jdbcType=DECIMAL}, #{produceTime,jdbcType=CHAR}, #{carType,jdbcType=VARCHAR}
>           )
>       </insert>
>       <insert id="insertSelective" parameterType="com.powernode.mybatis.pojo.Car">
>         insert into t_car
>         <trim prefix="(" suffix=")" suffixOverrides=",">
>           <if test="id != null">
>             id,
>           </if>
>           <if test="carNum != null">
>             car_num,
>           </if>
>           <if test="brand != null">
>             brand,
>           </if>
>           <if test="guidePrice != null">
>             guide_price,
>           </if>
>           <if test="produceTime != null">
>             produce_time,
>           </if>
>           <if test="carType != null">
>             car_type,
>           </if>
>         </trim>
>         <trim prefix="values (" suffix=")" suffixOverrides=",">
>           <if test="id != null">
>             #{id,jdbcType=BIGINT},
>           </if>
>           <if test="carNum != null">
>             #{carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="brand != null">
>             #{brand,jdbcType=VARCHAR},
>           </if>
>           <if test="guidePrice != null">
>             #{guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="produceTime != null">
>             #{produceTime,jdbcType=CHAR},
>           </if>
>           <if test="carType != null">
>             #{carType,jdbcType=VARCHAR},
>           </if>
>         </trim>
>       </insert>
>       <select id="countByExample" parameterType="com.powernode.mybatis.pojo.CarExample" resultType="java.lang.Long">
>         select count(*) from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>       </select>
>       <update id="updateByExampleSelective" parameterType="map">
>         update t_car
>         <set>
>           <if test="row.id != null">
>             id = #{row.id,jdbcType=BIGINT},
>           </if>
>           <if test="row.carNum != null">
>             car_num = #{row.carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="row.brand != null">
>             brand = #{row.brand,jdbcType=VARCHAR},
>           </if>
>           <if test="row.guidePrice != null">
>             guide_price = #{row.guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="row.produceTime != null">
>             produce_time = #{row.produceTime,jdbcType=CHAR},
>           </if>
>           <if test="row.carType != null">
>             car_type = #{row.carType,jdbcType=VARCHAR},
>           </if>
>         </set>
>         <if test="example != null">
>           <include refid="Update_By_Example_Where_Clause" />
>         </if>
>       </update>
>       <update id="updateByExample" parameterType="map">
>         update t_car
>         set id = #{row.id,jdbcType=BIGINT},
>           car_num = #{row.carNum,jdbcType=VARCHAR},
>           brand = #{row.brand,jdbcType=VARCHAR},
>           guide_price = #{row.guidePrice,jdbcType=DECIMAL},
>           produce_time = #{row.produceTime,jdbcType=CHAR},
>           car_type = #{row.carType,jdbcType=VARCHAR}
>         <if test="example != null">
>           <include refid="Update_By_Example_Where_Clause" />
>         </if>
>       </update>
>       <update id="updateByPrimaryKeySelective" parameterType="com.powernode.mybatis.pojo.Car">
>         update t_car
>         <set>
>           <if test="carNum != null">
>             car_num = #{carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="brand != null">
>             brand = #{brand,jdbcType=VARCHAR},
>           </if>
>           <if test="guidePrice != null">
>             guide_price = #{guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="produceTime != null">
>             produce_time = #{produceTime,jdbcType=CHAR},
>           </if>
>           <if test="carType != null">
>             car_type = #{carType,jdbcType=VARCHAR},
>           </if>
>         </set>
>         where id = #{id,jdbcType=BIGINT}
>       </update>
>       <update id="updateByPrimaryKey" parameterType="com.powernode.mybatis.pojo.Car">
>         update t_car
>         set car_num = #{carNum,jdbcType=VARCHAR},
>           brand = #{brand,jdbcType=VARCHAR},
>           guide_price = #{guidePrice,jdbcType=DECIMAL},
>           produce_time = #{produceTime,jdbcType=CHAR},
>           car_type = #{carType,jdbcType=VARCHAR}
>         where id = #{id,jdbcType=BIGINT}
>       </update>
>     </mapper>
> 
>     <?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.powernode.mybatis.mappers.CarMapper">
>       <resultMap id="BaseResultMap" type="com.powernode.mybatis.pojo.Car">
>         <id column="id" jdbcType="BIGINT" property="id" />
>         <result column="car_num" jdbcType="VARCHAR" property="carNum" />
>         <result column="brand" jdbcType="VARCHAR" property="brand" />
>         <result column="guide_price" jdbcType="DECIMAL" property="guidePrice" />
>         <result column="produce_time" jdbcType="CHAR" property="produceTime" />
>         <result column="car_type" jdbcType="VARCHAR" property="carType" />
>       </resultMap>
>       <sql id="Example_Where_Clause">
>         <where>
>           <foreach collection="oredCriteria" item="criteria" separator="or">
>             <if test="criteria.valid">
>               <trim prefix="(" prefixOverrides="and" suffix=")">
>                 <foreach collection="criteria.criteria" item="criterion">
>                   <choose>
>                     <when test="criterion.noValue">
>                       and ${criterion.condition}
>                     </when>
>                     <when test="criterion.singleValue">
>                       and ${criterion.condition} #{criterion.value}
>                     </when>
>                     <when test="criterion.betweenValue">
>                       and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
>                     </when>
>                     <when test="criterion.listValue">
>                       and ${criterion.condition}
>                       <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
>                         #{listItem}
>                       </foreach>
>                     </when>
>                   </choose>
>                 </foreach>
>               </trim>
>             </if>
>           </foreach>
>         </where>
>       </sql>
>       <select id="selectByPage" resultType="car">
>         select * from t_car limit #{startIndex},#{pageSize}
>       </select>
>       <select id="selectAllByPageHelper" resultType="Car">
>         select * from t_car
>       </select>
>       <sql id="Update_By_Example_Where_Clause">
>         <where>
>           <foreach collection="example.oredCriteria" item="criteria" separator="or">
>             <if test="criteria.valid">
>               <trim prefix="(" prefixOverrides="and" suffix=")">
>                 <foreach collection="criteria.criteria" item="criterion">
>                   <choose>
>                     <when test="criterion.noValue">
>                       and ${criterion.condition}
>                     </when>
>                     <when test="criterion.singleValue">
>                       and ${criterion.condition} #{criterion.value}
>                     </when>
>                     <when test="criterion.betweenValue">
>                       and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
>                     </when>
>                     <when test="criterion.listValue">
>                       and ${criterion.condition}
>                       <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
>                         #{listItem}
>                       </foreach>
>                     </when>
>                   </choose>
>                 </foreach>
>               </trim>
>             </if>
>           </foreach>
>         </where>
>       </sql>
>       <sql id="Base_Column_List">
>         id, car_num, brand, guide_price, produce_time, car_type
>       </sql>
>       <select id="selectByExample" parameterType="com.powernode.mybatis.pojo.CarExample" resultMap="BaseResultMap">
>         select
>         <if test="distinct">
>           distinct
>         </if>
>         <include refid="Base_Column_List" />
>         from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>         <if test="orderByClause != null">
>           order by ${orderByClause}
>         </if>
>       </select>
>       <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
>         select 
>         <include refid="Base_Column_List" />
>         from t_car
>         where id = #{id,jdbcType=BIGINT}
>       </select>
>       <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
>         delete from t_car
>         where id = #{id,jdbcType=BIGINT}
>       </delete>
>       <delete id="deleteByExample" parameterType="com.powernode.mybatis.pojo.CarExample">
>         delete from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>       </delete>
>       <insert id="insert" parameterType="com.powernode.mybatis.pojo.Car">
>         insert into t_car (id, car_num, brand, 
>           guide_price, produce_time, car_type
>           )
>         values (#{id,jdbcType=BIGINT}, #{carNum,jdbcType=VARCHAR}, #{brand,jdbcType=VARCHAR}, 
>           #{guidePrice,jdbcType=DECIMAL}, #{produceTime,jdbcType=CHAR}, #{carType,jdbcType=VARCHAR}
>           )
>       </insert>
>       <insert id="insertSelective" parameterType="com.powernode.mybatis.pojo.Car">
>         insert into t_car
>         <trim prefix="(" suffix=")" suffixOverrides=",">
>           <if test="id != null">
>             id,
>           </if>
>           <if test="carNum != null">
>             car_num,
>           </if>
>           <if test="brand != null">
>             brand,
>           </if>
>           <if test="guidePrice != null">
>             guide_price,
>           </if>
>           <if test="produceTime != null">
>             produce_time,
>           </if>
>           <if test="carType != null">
>             car_type,
>           </if>
>         </trim>
>         <trim prefix="values (" suffix=")" suffixOverrides=",">
>           <if test="id != null">
>             #{id,jdbcType=BIGINT},
>           </if>
>           <if test="carNum != null">
>             #{carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="brand != null">
>             #{brand,jdbcType=VARCHAR},
>           </if>
>           <if test="guidePrice != null">
>             #{guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="produceTime != null">
>             #{produceTime,jdbcType=CHAR},
>           </if>
>           <if test="carType != null">
>             #{carType,jdbcType=VARCHAR},
>           </if>
>         </trim>
>       </insert>
>       <select id="countByExample" parameterType="com.powernode.mybatis.pojo.CarExample" resultType="java.lang.Long">
>         select count(*) from t_car
>         <if test="_parameter != null">
>           <include refid="Example_Where_Clause" />
>         </if>
>       </select>
>       <update id="updateByExampleSelective" parameterType="map">
>         update t_car
>         <set>
>           <if test="row.id != null">
>             id = #{row.id,jdbcType=BIGINT},
>           </if>
>           <if test="row.carNum != null">
>             car_num = #{row.carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="row.brand != null">
>             brand = #{row.brand,jdbcType=VARCHAR},
>           </if>
>           <if test="row.guidePrice != null">
>             guide_price = #{row.guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="row.produceTime != null">
>             produce_time = #{row.produceTime,jdbcType=CHAR},
>           </if>
>           <if test="row.carType != null">
>             car_type = #{row.carType,jdbcType=VARCHAR},
>           </if>
>         </set>
>         <if test="example != null">
>           <include refid="Update_By_Example_Where_Clause" />
>         </if>
>       </update>
>       <update id="updateByExample" parameterType="map">
>         update t_car
>         set id = #{row.id,jdbcType=BIGINT},
>           car_num = #{row.carNum,jdbcType=VARCHAR},
>           brand = #{row.brand,jdbcType=VARCHAR},
>           guide_price = #{row.guidePrice,jdbcType=DECIMAL},
>           produce_time = #{row.produceTime,jdbcType=CHAR},
>           car_type = #{row.carType,jdbcType=VARCHAR}
>         <if test="example != null">
>           <include refid="Update_By_Example_Where_Clause" />
>         </if>
>       </update>
>       <update id="updateByPrimaryKeySelective" parameterType="com.powernode.mybatis.pojo.Car">
>         update t_car
>         <set>
>           <if test="carNum != null">
>             car_num = #{carNum,jdbcType=VARCHAR},
>           </if>
>           <if test="brand != null">
>             brand = #{brand,jdbcType=VARCHAR},
>           </if>
>           <if test="guidePrice != null">
>             guide_price = #{guidePrice,jdbcType=DECIMAL},
>           </if>
>           <if test="produceTime != null">
>             produce_time = #{produceTime,jdbcType=CHAR},
>           </if>
>           <if test="carType != null">
>             car_type = #{carType,jdbcType=VARCHAR},
>           </if>
>         </set>
>         where id = #{id,jdbcType=BIGINT}
>       </update>
>       <update id="updateByPrimaryKey" parameterType="com.powernode.mybatis.pojo.Car">
>         update t_car
>         set car_num = #{carNum,jdbcType=VARCHAR},
>           brand = #{brand,jdbcType=VARCHAR},
>           guide_price = #{guidePrice,jdbcType=DECIMAL},
>           produce_time = #{produceTime,jdbcType=CHAR},
>           car_type = #{carType,jdbcType=VARCHAR}
>         where id = #{id,jdbcType=BIGINT}
>       </update>
>     </mapper>

>     package com.powernode.mybatis.mappers;
>     
>     import com.powernode.mybatis.pojo.Car;
>     import com.powernode.mybatis.pojo.CarExample;
>     import java.util.List;
>     import org.apache.ibatis.annotations.Param;
>     
>     public interface CarMapper {
>         List<Car> selectAllByPageHelper();
>         long countByExample(CarExample example);
>     
>         int deleteByExample(CarExample example);
>     
>         int deleteByPrimaryKey(Long id);
>     
>         List<Car> selectByPage(@Param("startIndex") int startIndex,@Param("pageSize") int pageSize);
>     
>         int insert(Car row);
>     
>         int insertSelective(Car row);
>     
>         List<Car> selectByExample(CarExample example);
>     
>         Car selectByPrimaryKey(Long id);
>     
>         int updateByExampleSelective(@Param("row") Car row, @Param("example") CarExample example);
>     
>         int updateByExample(@Param("row") Car row, @Param("example") CarExample example);
>     
>         int updateByPrimaryKeySelective(Car row);
>     
>         int updateByPrimaryKey(Car row);
>     }
> 
>     package com.powernode.mybatis.mappers;
>     
>     import com.powernode.mybatis.pojo.Car;
>     import com.powernode.mybatis.pojo.CarExample;
>     import java.util.List;
>     import org.apache.ibatis.annotations.Param;
>     
>     public interface CarMapper {
>         List<Car> selectAllByPageHelper();
>         long countByExample(CarExample example);
>     
>         int deleteByExample(CarExample example);
>     
>         int deleteByPrimaryKey(Long id);
>     
>         List<Car> selectByPage(@Param("startIndex") int startIndex,@Param("pageSize") int pageSize);
>     
>         int insert(Car row);
>     
>         int insertSelective(Car row);
>     
>         List<Car> selectByExample(CarExample example);
>     
>         Car selectByPrimaryKey(Long id);
>     
>         int updateByExampleSelective(@Param("row") Car row, @Param("example") CarExample example);
>     
>         int updateByExample(@Param("row") Car row, @Param("example") CarExample example);
>     
>         int updateByPrimaryKeySelective(Car row);
>     
>         int updateByPrimaryKey(Car row);
>     }

>     package com.powernode.mybatis.Test;
>     
>     import com.github.pagehelper.PageHelper;
>     import com.powernode.mybatis.mappers.CarMapper;
>     import com.powernode.mybatis.pojo.Car;
>     import com.powernode.mybatis.utils.SqlSessionUtils;
>     import org.apache.ibatis.session.SqlSession;
>     import org.slf4j.Logger;
>     import org.slf4j.LoggerFactory;
>     
>     import java.util.List;
>     
>     public class Test
>     {
>         private static final Logger logger = LoggerFactory.getLogger(Test.class);
>         @org.junit.Test
>         public void selectByPage()
>         {
>             SqlSession sqlSession = SqlSessionUtils.openSession();
>             CarMapper mapper = sqlSession.getMapper(CarMapper.class);
>             int pageNum = 1;
>             int pageSize = 3;
>             int startIndex = (pageNum - 1) * pageSize;
>             List<Car> cars =  mapper.selectByPage(startIndex,pageSize);
>             cars.forEach(car -> logger.info(car.toString()));
>         }
>         @org.junit.Test
>         public void selectAllByPageHelper()
>         {
>             SqlSession sqlSession = SqlSessionUtils.openSession();
>             CarMapper mapper = sqlSession.getMapper(CarMapper.class);
>             //执行DQL语句之前一定要开启pageHelper
>             int pageNum = 1;
>             int pageSize = 2;
>             PageHelper.startPage(pageNum,pageSize);
>             List<Car> cars = mapper.selectAllByPageHelper();
>             cars.forEach(car -> logger.info(car.toString()));
>             SqlSessionUtils.close(sqlSession);
>         }
>     }
> 
>     package com.powernode.mybatis.Test;
>     
>     import com.github.pagehelper.PageHelper;
>     import com.powernode.mybatis.mappers.CarMapper;
>     import com.powernode.mybatis.pojo.Car;
>     import com.powernode.mybatis.utils.SqlSessionUtils;
>     import org.apache.ibatis.session.SqlSession;
>     import org.slf4j.Logger;
>     import org.slf4j.LoggerFactory;
>     
>     import java.util.List;
>     
>     public class Test
>     {
>         private static final Logger logger = LoggerFactory.getLogger(Test.class);
>         @org.junit.Test
>         public void selectByPage()
>         {
>             SqlSession sqlSession = SqlSessionUtils.openSession();
>             CarMapper mapper = sqlSession.getMapper(CarMapper.class);
>             int pageNum = 1;
>             int pageSize = 3;
>             int startIndex = (pageNum - 1) * pageSize;
>             List<Car> cars =  mapper.selectByPage(startIndex,pageSize);
>             cars.forEach(car -> logger.info(car.toString()));
>         }
>         @org.junit.Test
>         public void selectAllByPageHelper()
>         {
>             SqlSession sqlSession = SqlSessionUtils.openSession();
>             CarMapper mapper = sqlSession.getMapper(CarMapper.class);
>             //执行DQL语句之前一定要开启pageHelper
>             int pageNum = 1;
>             int pageSize = 2;
>             PageHelper.startPage(pageNum,pageSize);
>             List<Car> cars = mapper.selectAllByPageHelper();
>             cars.forEach(car -> logger.info(car.toString()));
>             SqlSessionUtils.close(sqlSession);
>         }
>     }