SSM框架整合后使用pagehelper实现分页功能

一、导入pagehelper-5.1.10.jar和jsqlparser-3.1.jar两个jar包

二、配置pagehelper

2.1 在mybatis配置文件中配置

<plugins>
    <plugin interceptor="com.github.pagehelper.PageInterceptor">
    </plugin>
</plugins>

2.2 在spring配置文件中配置

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"></property>
    <property name="plugins">
           <array>
               <bean class="com.github.pagehelper.PageInterceptor">
               </bean>
           </array>
       </property>
</bean>

三、在已经实现mybatis连接数据库进行查询的前提下，修改service实现类的代码，修改如下：

package com.yh.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.github.pagehelper.PageHelper;
import com.yh.entity.Comment;
import com.yh.mybatis.mapper.CommentMapper;
import com.yh.service.CommentService;

@Service("commentService")
public class CommentServiceImpl implements CommentService {

    @Autowired
    private CommentMapper commentMapper;

    @Override
    public List<Comment> findCommentByBookId(int bookId) {
        // TODO Auto-generated method stub
        PageHelper.startPage(1, 3);
        List<Comment> comments = commentMapper.findCommentByBookId(bookId);
//        Page<Comment> page = (Page<Comment>) comments;
        return comments;
    }

}

黄色背景为添加代码，这是最简单的实现方式这是最简单的，两个参数分别是查找页数和每页长度。

四、其他方式（待补充）

package com.cjs.example.service.impl;

import com.cjs.example.dao.CouponMapper;
import com.cjs.example.model.Coupon;
import com.cjs.example.model.CouponExample;
import com.cjs.example.service.CouponService;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.github.pagehelper.PageRowBounds;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CouponServiceImpl implements CouponService {

    @Autowired
    private CouponMapper couponMapper;

    /**
     * 静态方法startPage
     */
    @Override
    public List<Coupon> getCouponListByPage(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        //  在你需要进行分页的 MyBatis 查询方法前调用 PageHelper.startPage 静态方法即可，紧跟在这个方法后的第一个MyBatis 查询方法会被进行分页。
        //  只要你可以保证在 PageHelper 方法调用后紧跟 MyBatis 查询方法，这就是安全的
        PageHelper.startPage(pageNum, pageSize);
        return couponMapper.selectByExample(couponExample);
    }

    /**
     * 分页时，实际返回的结果list类型是Page<E>，如果想取出分页信息，需要强制转换为Page<E>
     * 因为  public class Page<E> extends ArrayList<E> implements Closeable
     */
    @Override
    public Page<Coupon> getCouponListByPage1(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        PageHelper.startPage(pageNum, pageSize);
        List<Coupon> list = couponMapper.selectByExample(couponExample);
        if (null != list) {
            Page<Coupon> page = (Page<Coupon>) list;
            System.out.println(page);
            return page;
        }
        return null;
    }

    /**
     * 用PageRowBounds
     */
    @Override
    public List<Coupon> getCouponListByPage2(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        PageRowBounds pageRowBounds = new PageRowBounds(pageNum, pageSize);
        List<Coupon> couponList = couponMapper.selectByExample(couponExample, pageRowBounds);

        System.out.println(pageRowBounds.getTotal());

        Page<Coupon> page = (Page<Coupon>) couponList;
        System.out.println(page);

        return couponList;
    }

    @Override
    public Page<Coupon> getCouponListByPage3(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        Page<Coupon> page = PageHelper.startPage(pageNum, pageSize).doSelectPage(()->couponMapper.selectByExample(couponExample));
        System.out.println(page);
        return page;
    }

    /**
     * 方法参数
     */
    @Override
    public PageInfo<Coupon> getCouponListByPage4(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        PageInfo<Coupon> pageInfo = PageHelper.startPage(pageNum, pageSize).doSelectPageInfo(()->couponMapper.selectByExample(couponExample));
        System.out.println(pageInfo);
        return pageInfo;
    }

    /**
     * PageInfo
     */
    @Override
    public PageInfo<Coupon> getCouponListByPage5(CouponExample couponExample, Integer pageNum, Integer pageSize) {
        List<Coupon> list = couponMapper.selectByExample(couponExample);
        if (null == list) {
            return null;
        }
        PageInfo<Coupon> pageInfo = new PageInfo<>(list);
        System.out.println(pageInfo);
        return pageInfo;
    }

    @Override
    public Page<Coupon> getCouponListByPage6(CouponExample couponExample, Integer offset, Integer limit) {
        return (Page<Coupon>) couponMapper.selectByExample(couponExample, new PageRowBounds(offset, limit));
    }
}