pagehelper插件进行分页

待我称王封你为后i 2023-09-27 13:32 156阅读 0赞

## 创建项目 ##

#### 第一步（完成以下操作进行下一步）： ####

![6e03539dfd7a45239493436b48cd60dc.png][]

#### 第二步： ![1d44e6cc8dbc4f92b6551a746f811ae7.png][] ####

## 一、 原理概述 ##

PageHelper是MyBatis的一个插件，内部实现了一个PageInterceptor[拦截器][Link 1]。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";
        }
    }

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[6e03539dfd7a45239493436b48cd60dc.png]: https://img-blog.csdnimg.cn/6e03539dfd7a45239493436b48cd60dc.png
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[Link 1]: https://so.csdn.net/so/search?q=%E6%8B%A6%E6%88%AA%E5%99%A8&spm=1001.2101.3001.7020
[90b88e21475b41e3b35448b451e5c88e.png]: https://img-blog.csdnimg.cn/90b88e21475b41e3b35448b451e5c88e.png