后端内存分页PageHelper使用（代码实现）

╰+哭是因爲堅強的太久メ 2022-10-31 10:52 63阅读 0赞

## 核心API说明： ##

**PageInfo**：

//当前页
        private int pageNum;
        //每页的数量
        private int pageSize;
        //当前页的数量
        private int size;
    
        //由于startRow和endRow不常用，这里说个具体的用法
        //可以在页面中"显示startRow到endRow 共size条数据"
    
        //当前页面第一个元素在数据库中的行号
        private int startRow;
        //当前页面最后一个元素在数据库中的行号
        private int endRow;
        //总记录数
        private long total;
        //总页数
        private int pages;
        //结果集
        private List<T> list;
    
        //前一页
        private int prePage;
        //下一页
        private int nextPage;
    
        //是否为第一页
        private boolean isFirstPage = false;
        //是否为最后一页
        private boolean isLastPage = false;
        //是否有前一页
        private boolean hasPreviousPage = false;
        //是否有下一页
        private boolean hasNextPage = false;
        //导航页码数
        private int navigatePages;
        //所有导航页号
        private int[] navigatepageNums;
        //导航条上的第一页
        private int navigateFirstPage;
        //导航条上的最后一页
        private int navigateLastPage;

**首先在pom.xml文件中导入依赖（导入插件的jar包（pagehelper，jsqlparser））**

<dependency>
          <groupId>com.github.pagehelper</groupId>
          <artifactId>pagehelper</artifactId>
          <version>5.2.0</version>
        </dependency>
        
        <dependency>
          <groupId>com.github.jsqlparser</groupId>
          <artifactId>jsqlparser</artifactId>
          <version>3.2</version>
        </dependency>

**1、实体类**

package com.hdit.pageHelperDemo.domain;
    
    import lombok.AllArgsConstructor;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    import lombok.extern.log4j.Log4j;
    
    //使用了lambok插件
    @Data
    public class Goods { 
        private int good_id;
        private String good_name;
        private String good_brand;
        private int category_id;
        private String picture_one;
        private String picture_two;
        private String picture_three;
        private String picture_four;
        private String picture_five;
        private double sale_price;
        private int remaining_count;
        private int good_sales;
        private String good_des;
        private int good_state;
    
    }

**2、spring.xml配置文件（配置mybatis 插件）**

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource"></property>
            <property name="typeAliasesPackage" value="com.hdit.guimeimall.domain"></property>
            
            
            <property name="plugins">
                <set>
                    
                    <bean class="com.github.pagehelper.PageInterceptor">
                        <property name="properties">
                            <props>
                                
                                <prop key="helperDialect">mysql</prop>
                            </props>
                        </property>
                    </bean>
                </set>
            </property>
        </bean>

**3、mapper接口类**

package com.hdit.pageHelperDemo.mapper;
    
    import com.hdit.pageHelperDemo.domain.Goods;
    import org.apache.ibatis.annotations.Select;
    
    import java.util.List;
    
    public interface GoodsMapper { 
        @Select("select * from goods")
        List<Goods> findAllGoods();
    }

**4、service接口类**

package com.hdit.pageHelperDemo.service;
    
    import com.github.pagehelper.PageInfo;
    import com.hdit.pageHelperDemo.domain.Goods;
    
    public interface GoodsService { 
        PageInfo<Goods> findGoodsPage(int pageNum,int pageSize);
    }

**5、service实现类**

package com.hdit.pageHelperDemo.service.impl;
    
    import com.github.pagehelper.PageHelper;
    import com.github.pagehelper.PageInfo;
    import com.hdit.pageHelperDemo.domain.Goods;
    import com.hdit.pageHelperDemo.mapper.GoodsMapper;
    import com.hdit.pageHelperDemo.service.GoodsService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import java.util.List;
    
    @Service
    public class GoodsServiceImpl implements GoodsService { 
        @Autowired
        private GoodsMapper goodsMapper;
        @Override
        public PageInfo<Goods> findGoodsPage(int pageNum, int pageSize) { 
            PageHelper.startPage(pageNum,pageSize);
            List<Goods> goodsList= goodsMapper.findAllGoods();
            PageInfo<Goods> pageInfo = new PageInfo<>(goodsList);
            return pageInfo;
        }
    }

**6、controller类**

package com.hdit.pageHelperDemo.controller;
    
    import com.github.pagehelper.PageInfo;
    import com.hdit.pageHelperDemo.domain.Goods;
    import com.hdit.pageHelperDemo.service.GoodsService;
    import com.hdit.pageHelperDemo.util.ResponeseData;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class GoodsController { 
        @Autowired
        private GoodsService goodsService;
        @GetMapping("/findGoodsByPage")
        public ResponeseData<PageInfo> findGoodsByPage(Integer pageNum,Integer pageSize){ 
            PageInfo<Goods> pageInfo = goodsService.findGoodsPage(pageNum,pageSize);
            //ResponeseData自定义响应数据工具类
            ResponeseData<PageInfo> responeseData = new ResponeseData<>();
            responeseData.setCode(200);
            responeseData.setMess("OK");
            responeseData.setData(pageInfo);
            return responeseData;
        }
    
    }

**7、工具类**

package com.hdit.pageHelperDemo.util;
    
    import lombok.Data;
    import lombok.ToString;
    
    @Data
    @ToString
    public class ResponseData<T> { 
        private int code;
        private String mess;
        private T data;
    }