pagehelper插件进行分页-蒲公英云

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第一步（完成以下操作进行下一步）：

" class="reference-link">第二步：

一、原理概述

PageHelper是MyBatis的一个插件，内部实现了一个PageInterceptor拦截器。Mybatis会加载这个拦截器到拦截器链中。在我们使用过程中先使用PageHelper.startPage这样的语句在当前线程上下文中设置一个ThreadLocal变量，再利用PageInterceptor这个分页拦截器拦截，从ThreadLocal中拿到分页的信息，如果有分页信息拼装分页SQL（limit语句等）进行分页查询，最后再把ThreadLocal中的东西清除掉。

二、 springboot+pageHelper带条件分页

2.1 添加依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.1</version>
</dependency>

2.2 pageHelper分页插件的yml配置

#pageHelper 分页插件的配置 
pagehelper: 
  auto-dialect: true 
  reasonable: true 
  support-methods-arguments: true 
  params: count=countSql

2.3 建立实体类

package com.boot.springboot1223.pojo;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
import java.io.Serializable;
import java.util.Date;
/**
* 
* @TableName action
*/
@Data
@TableName("action")
public class Action{
    /**
    * 操作ID
    */
    @TableId(type = IdType.AUTO)
    private Integer actionId;
    /**
    * 订单编号
    */
    private String orderSn;
    /**
    * 操作人
    */
    private Integer actionUser;
    /**
    * 订单状态
    */
    private Integer orderStatus;
    /**
    * 支付状态
    */
    private Integer payStatus;
    /**
    * 配送状态
    */
    private Integer shippingStatus;
    /**
    * 操作记录
    */
    private String actionNote;
    /**
    * 操作时间
    */
    private String actionTime;
    /**
    * 状态描述
    */
    private String statusDesc;
    /**
     * 下单时间
     */
    @TableField(exist = false)
    private String orderTime;
}

2.4 mapper层 (数据持久层)

package com.boot.springboot1223.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.boot.springboot1223.pojo.Action;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper
public interface ActionMapper extends BaseMapper<Action> {
    /**
     * 分页加模糊查询
     * @param action
     * @return
     */
    List<Action> findPage(Action action);
}

2.5 service层 (业务逻辑层)

package com.boot.springboot1223.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.boot.springboot1223.pojo.Action;
import com.github.pagehelper.PageInfo;
import java.util.List;
public interface ActionService extends IService<Action> {
    PageInfo<Action> findPage(Action action,Integer pageIndex,Integer pageSize);
}
package com.boot.springboot1223.service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.boot.springboot1223.mapper.ActionMapper;
import com.boot.springboot1223.pojo.Action;
import com.boot.springboot1223.service.ActionService;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
/**
 * @Author 
 * @Date 2022/12/23
 * @Description 类功能描述
 */
@Service
public class ActionServiceImpl extends ServiceImpl<ActionMapper, Action> implements ActionService {
    @Autowired
    private ActionMapper actionMapper;
    @Override
    public PageInfo<Action> findPage(Action action, Integer pageIndex, Integer pageSize) {
        //调用分页插件的工具类  计算总页数
        PageHelper.startPage(pageIndex,pageSize);
        //获取所有数据
        List<Action> page = actionMapper.findPage(action);
        //获取所有的数据直接给pageInfo
        PageInfo pageInfo=new PageInfo(page);
        return pageInfo;
    }
}

2.6 controller层

package com.boot.springboot1223.controller;
import com.boot.springboot1223.pojo.Action;
import com.boot.springboot1223.pojo.Order;
import com.boot.springboot1223.service.ActionService;
import com.boot.springboot1223.service.OrderService;
import com.github.pagehelper.PageInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
/**
 * @Author 
 * @Date 2022/12/23
 * @Description 类功能描述
 */
@Controller
public class ActionController {
    @Autowired
    private ActionService actionService;
    @RequestMapping("/findPage")
    public String findPage(
            Action action,
            @RequestParam(value = "pageIndex",defaultValue = "1") Integer pageIndex,
            @RequestParam(value = "pageSize",defaultValue = "1",required = false) Integer pageSize,
            Model model
    ){
        PageInfo<Action> page = actionService.findPage(action,pageIndex, pageSize);
        model.addAttribute("path","findPage?pageIndex=");
        model.addAttribute("page",page);
        model.addAttribute("action",action);
        return "list";
    }
}