PageHelper分页

至少使用JDK8版本，请下载JDK8或者更高版本： 下载以及配置JDK环境

因为是第三方插件，所以需要额外的jar包，都在右上角提供了下载：pagehelper-5.1.0-beta2.jar，jsqlparser-1.0.jar

配置插件

在mybatis-config.xml中，添加15-19行的代码，表示开启PageHelper插件

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

<?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>     <settings>              <!-- 打开延迟加载的开关 -->              <setting name="lazyLoadingEnabled" value="true" />              <!-- 将积极加载改为消息加载即按需加载 -->              <setting name="aggressiveLazyLoading" value="false"/>          </settings>        <typeAliases>       <package name="com.how2java.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="com.mysql.jdbc.Driver"/>             <property name="url" value="jdbc:mysql://localhost:3306/how2java?characterEncoding=UTF-8"/>             <property name="username" value="root"/>             <property name="password" value="admin"/>             </dataSource>         </environment>     </environments>     <mappers>         <mapper resource="com/how2java/pojo/Category.xml"/>         <mapper class="com.how2java.mapper.CategoryMapper"/>          <mapper class="com.how2java.mapper.ProductMapper"/>      </mappers>     </configuration>

分页查询

查询很有意思，只需要在执行查询所有的调用之前，执行一条语句即可：

 

PageHelper.offsetPage(0, 5);

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

package com.how2java;     import java.io.IOException; import java.io.InputStream; 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 com.github.pagehelper.PageHelper; import com.how2java.pojo.Category;     public class TestMybatis {     public static void main(String[] args) throws IOException, InterruptedException {         String resource = "mybatis-config.xml";         InputStream inputStream = Resources.getResourceAsStream(resource);         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);         SqlSession session = sqlSessionFactory.openSession();                PageHelper.offsetPage(0, 5);           List<Category> cs = session.selectList("listCategory");         for (Category c : cs) {             System.out.println(c.getName());         }           session.commit();         session.close();     } }

 

获取总数

通过第31行的代码

 

PageInfo page= new PageInfo<>(cs);

 

就可以获取分页信息，包括总数以及其他的

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

package com.how2java;     import java.io.IOException; import java.io.InputStream; 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 com.github.pagehelper.PageHelper; import com.github.pagehelper.PageInfo; import com.how2java.pojo.Category;     public class TestMybatis {     public static void main(String[] args) throws IOException, InterruptedException {         String resource = "mybatis-config.xml";         InputStream inputStream = Resources.getResourceAsStream(resource);         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);         SqlSession session = sqlSessionFactory.openSession();                PageHelper.offsetPage(0, 5);           List<Category> cs = session.selectList("listCategory");         for (Category c : cs) {             System.out.println(c.getName());         }                   PageInfo pageInfo = new PageInfo<>(cs);         System.out.println("总数："+pageInfo.getTotal());         System.out.println(pageInfo);           session.commit();         session.close();     } }