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
 
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<?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);
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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
 
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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();
    }
}

posted on 2018-12-29 13:51  我是司  阅读(634)  评论(0)    收藏  举报

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