PageHelper是目前最強大最好用的分頁外掛。

使用PageHelper外掛一定要注意jar包之間的依賴關係，否則就死活出不來結果呀！！

比方說作者這裡使用的是pagehelper-5.0.2.jar    jsqlparser-0.9.5.jar    mybatis-3.2.8。那麼我為啥知道版本之間的依賴關係是這樣的呢，請看下圖：

廢話不多說了，下面來看具體的例項。

要使用pagehelper，可以配置在mybatis的核心配置檔案中，也可以配置在spring中。這裡採取mybatis的配置方式，spring的配置方式以後再探討。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
    PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    "mybatis-3-config.dtd">
<configuration>
	<typeAliases>
		<typeAlias type="com.obtk.entitys.StudentEntity" alias="StudentEntity"/>
	</typeAliases>
	
	<plugins>
        <plugin interceptor="com.github.pagehelper.PageInterceptor">
           <!-- property屬性可以不用配置，新版本能自動識別底層資料庫 -->
           <property name="helperDialect" value="mysql"/>
        </plugin>
    </plugins>
    
	<environments default="mysql">
		<environment id="mysql">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver" />
				<property name="url" value="jdbc:mysql://localhost:3306/schooldb" />
				<property name="username" value="root" />
				<property name="password" value="123456" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="com/obtk/entitys/UserMapper.xml" />
		<mapper resource="com/obtk/entitys/StudentMapper.xml" />
	</mappers>
</configuration>
 

sql配置:

<select id="selectByPage"  resultType="StudentEntity">
		select * from student 
		order by age desc
	</select>

package com.obtk.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.obtk.entitys.StudentEntity;
import com.obtk.utils.MybatisUtil;

public class TestPageQuery {
	public static void main(String[] args) {
		SqlSession session=null;
		try {
			//4.得到session
			session=MybatisUtil.getSession();
			//分頁引數,第一個引數是當前頁碼(pageNo),第二個引數是每頁顯示多少條(pageSize)
			PageHelper.startPage(2, 3);
			//5.執行語句
			List<StudentEntity> stuList=session.selectList("stu.selectByPage");
			for(StudentEntity stu : stuList){
				System.out.println(stu.getStuName()+"\t"+stu.getGender()+"\t"+stu.getAge());
			}
			//分頁實體
			PageInfo<StudentEntity> thePage=new PageInfo<StudentEntity>(stuList);
			System.out.println("下一頁:"+thePage.getNextPage()+",上一頁:"+thePage.getPrePage()
					+",總條數:"+thePage.getTotal()+",總頁碼:"+thePage.getPages()); 
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			MybatisUtil.closeSession();
		}
	}
}
 

案例2   用業務實體類處理表的關聯及分頁

sql程式碼：

<select id="selectByJoinPage"  resultType="com.obtk.entitys.JoinEntity">
		SELECT  s.stuId,s.stuName,s.gender,s.age,d.departName 
		FROM student s INNER JOIN department d 
		ON s.deptIdd=d.deptId
		ORDER BY s.age DESC
	</select>
 

package com.obtk.entitys;

import java.io.Serializable;

public class JoinEntity implements Serializable{
	private static final long serialVersionUID = -935724073017787380L;
	private int stuId;
	private String stuName;
	private String gender;
	private int age;
	private String departName;
	
	public JoinEntity() {
	}

	public int getStuId() {
		return stuId;
	}

	public void setStuId(int stuId) {
		this.stuId = stuId;
	}

	public String getStuName() {
		return stuName;
	}

	public void setStuName(String stuName) {
		this.stuName = stuName;
	}

	public String getGender() {
		return gender;
	}

	public void setGender(String gender) {
		this.gender = gender;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getDepartName() {
		return departName;
	}

	public void setDepartName(String departName) {
		this.departName = departName;
	}
	
	
}

package com.obtk.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.obtk.entitys.JoinEntity;
import com.obtk.entitys.StudentEntity;
import com.obtk.utils.MybatisUtil;

public class TestPageJoinQuery {
	public static void main(String[] args) {
		SqlSession session=null;
		try {
			//4.得到session
			session=MybatisUtil.getSession();
			//分頁引數,第一個引數是當前頁碼(pageNo),第二個引數是每頁顯示多少條(pageSize)
			PageHelper.startPage(2, 3);
			//5.執行語句
			List<JoinEntity> stuList=session.selectList("stu.selectByJoinPage");
			for(JoinEntity stu : stuList){
				System.out.println(stu.getStuName()+"\t"+stu.getGender()+"\t"+stu.getAge()+"\t"+stu.getDepartName());
			}
			//分頁實體
			PageInfo<JoinEntity> thePage=new PageInfo<JoinEntity>(stuList);
			System.out.println("下一頁:"+thePage.getNextPage()+",上一頁:"+thePage.getPrePage()
					+",總條數:"+thePage.getTotal()+",總頁碼:"+thePage.getPages()); 
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			MybatisUtil.closeSession();
		}
	}
}

<select id="selectByMapPage"  resultType="hashmap">
		SELECT  s.stuId,s.stuName,s.gender,s.age,d.departName 
		FROM student s INNER JOIN department d 
		ON s.deptIdd=d.deptId
		ORDER BY s.age DESC
	</select>

package com.obtk.test;

import java.util.List;
import java.util.Map;

import org.apache.ibatis.session.SqlSession;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.obtk.entitys.StudentEntity;
import com.obtk.utils.MybatisUtil;

public class TestPageMapQuery {
	public static void main(String[] args) {
		SqlSession session=null;
		try {
			//4.得到session
			session=MybatisUtil.getSession();
			//分頁引數,第一個引數是當前頁碼(pageNo),第二個引數是每頁顯示多少條(pageSize)
			PageHelper.startPage(2, 3);
			//5.執行語句
			List<Map> stuList=session.selectList("stu.selectByMapPage");
			for(Map oneRow : stuList){
				System.out.println(oneRow.get("stuName")+"\t"+oneRow.get("gender")+"\t"
						+oneRow.get("age")+"\t"+oneRow.get("departName"));
			}
			//分頁實體
			PageInfo<Map> thePage=new PageInfo<Map>(stuList);
			System.out.println("下一頁:"+thePage.getNextPage()+",上一頁:"+thePage.getPrePage()
					+",總條數:"+thePage.getTotal()+",總頁碼:"+thePage.getPages()); 
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			MybatisUtil.closeSession();
		}
	}
}