mybats 分页插件 pageHelper 入门使用示例

1、介绍

mybytis 的分页插件pageHelper是一个非常容易使用的后端分页插件，它的原理是用拦截器对sql语句进行拦截，然后修改从而实现分页的功能。下面通过i哟个简单的例子来看看pageHelper如何上手。

项目开源地址及官方文档 pageHelper官网

2、入门示例

配置：

添加maven依赖，在pom.xml中加入以下语句

<!--mybatis的分页插件，pageHelper-->
    <dependency>
      <groupId>com.github.pagehelper</groupId>
      <artifactId>pagehelper</artifactId>
      <version>5.0.0</version>
    </dependency>

在spring配置文件中，配置sqlSessionFactory的时候，添加pageHelper插件

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource"/>
            <property name="configLocation" value="classpath:com/xiao/springMVC/xml/mybatis/mybatis-config.xml"/>
            <property name="plugins">
                <array>
                    <bean class="com.github.pagehelper.PageInterceptor">
                        <property name="properties">
                            <!--什么都不配，使用默认的配置-->
                            <value></value>
                        </property>
                    </bean>
                </array>
            </property>
        </bean>

使用：

编写实体类

package com.xiao.springMVC.bean;
import java.io.Serializable;
public class Car implements Serializable {
    private int carid;
    private String brand;
    private String model;
    private String number;
    private String owner;
    private String phone;
    public int getCarid() {
        return carid;
    }
    public void setCarid(int carid) {
        this.carid = carid;
    }
    public String getBrand() {
        return brand;
    }
    public void setBrand(String brand) {
        this.brand = brand;
    }
    public String getModel() {
        return model;
    }
    public void setModel(String model) {
        this.model = model;
    }
    public String getNumber() {
        return number;
    }
    public void setNumber(String number) {
        this.number = number;
    }
    public String getOwner() {
        return owner;
    }
    public void setOwner(String owner) {
        this.owner = owner;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    @Override
    public String toString() {
        return "Car{" +
                "carid=" + carid +
                ", brand='" + brand + '\'' +
                ", model='" + model + '\'' +
                ", number='" + number + '\'' +
                ", owner='" + owner + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}

映射接口CarDao

package com.xiao.springMVC.dao;
import com.xiao.springMVC.bean.Car;
import java.util.List;
public interface carDao {
    List<Car> getCarList();
}

Mapper文件Car.xml(mybatis配置，数据库建表等过程省略)

    <?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.xiao.springMVC.dao.carDao">
        <select id="getCarList" resultType="com.xiao.springMVC.bean.Car">
            SELECT * FROM car
        </select>
    </mapper>
（可以发现，使用pageHelper插件，以上的文件与不是用时没有任何区别）

测试类，使用基本的pageHelper功能需要两个参数当前页和每页的记录数量。

package com.xiao.springMVC.bean;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.xiao.dubbo.demo.GetUserInfoByIDService;
import com.xiao.springMVC.dao.IUser;
import com.xiao.springMVC.dao.carDao;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.ArrayList;
import java.util.List;
public class Main {
    public static void main(String[] args) {
        List<Car> cars = new ArrayList<Car>();
        PageInfo pageInfo = ListCar(3,10);
        cars =  pageInfo.getList();
        for(Car car:cars){
            System.out.println(car.toString());
        }
        long total = pageInfo.getTotal();
        System.out.println("Total:"+total);

        }
        public static PageInfo<Car> ListCar(int pageNo,int pageSize){
            //Mapper接口方式的调用
            PageHelper.startPage(pageNo,pageSize);
            ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
            carDao carMapper = (carDao) context.getBean("carMapper");
            List<Car> carList = carMapper.getCarList();
            PageInfo<Car> pageInfo = new PageInfo<Car>(carList);
            return pageInfo;
        }
    }