最简洁的分页插件PageHelper

大部分后台管理项目，用的最多的展现方式是列表显示，所以我把列表查询中的分页插件拿出来写一下,方便以后写代码的时候直接复制粘贴。在我们最熟悉的springboot微服务开发中，持久型框架mybatis使用PageHelper还是比较方便的。下面我们来看一下分页插件PageHelper的简单使用方法。

1.首先在pom.xml中pageHelper引入

<dependencies>  
  <!-- 分页 -->
    <dependency>
        <groupId>com.github.pagehelper</groupId>
        <artifactId>pagehelper</artifactId>
        <version>4.1.6</version>
    </dependency>
  <!-- 引入mybatis --> 
  <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.6</version>
    </dependency>
  <!-- 引入mysql --> 
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
</dependencies>

2.配置application.yml文件

#数据库链接
datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver  #com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/hzc_db?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
    username: root
    password: root
    tomcat:
      initial-size: 5
      max-active: 30
#配置mybatis
mybatis:
    mapperLocations: classpath:mybatis/mapper*.xml
    typeAliasesPackage: com.ten.cn.*.model
#配置pageHelper
pageHelper:
  reasonable: "true"
  supportMethodsArguments: "true"
  returnPageInfo: check
  params: count=countSql

3.建立一个分页传输数据的实体，用来传输当前页和分页条数

package com.ten.ms.cn.sys.bean;

import com.ten.ms.cn.sys.model.User;

/***
 * 用户分页实体
 * @author:lcj
 */
public class UserPageInvo extends User {
    /**
     * 页数
     */
    private Integer page;

    /**
     * 条数
     */
    private Integer rows;

    public Integer getPage() {
        return page;
    }

    public void setPage(Integer page) {
        this.page = page;
    }

    public Integer getRows() {
        return rows;
    }

    public void setRows(Integer rows) {
        this.rows = rows;
    }
}

5.创建一个分页配置方法

package com.ten.ms.cn.common.config;

import com.github.pagehelper.PageHelper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Properties;

/***
 * 分页配置
 * @author:lcj
 */
@Configuration
public class PageHelperConfig {

    /**
     * 配置mybatis的分页插件pageHelper
     *
     * @return
     */
    @Bean
    public PageHelper pageHelper() {
        PageHelper pageHelper = new PageHelper();
        Properties properties = new Properties();
        properties.setProperty("offsetAsPageNum", "true");
        properties.setProperty("rowBoundsWithCount", "true");
        properties.setProperty("reasonable", "true");
        properties.setProperty("dialect", "postgresql");//配置postgresql数据库的方言支持Oracle,Mysql,MariaDB,SQLite,Hsqldb,PostgreSQL六种数据库
        pageHelper.setProperties(properties);
        return pageHelper;
    }
}

6.创建一个返回实体

package com.ten.ms.cn.common.bean;

/**
 * 全局统一json返回值接口
 *
 * @author user
 */
public class ResultInfo {

    /**
     * 错误编号
     */
    private String errorCode = "0";
    private String code = "200";
    /**
     * 错误信息
     */
    private String errorMessage;
    /**
     * 包装实体
     */
    private Object data;
    /**
     * 返回dataGrid的总页数
     */
    private long total;
    public ResultInfo() {
    }
    /**
     * 返回分页数据数据
     */
    private Object rows;
    public ResultInfo(String errorCode, String errorMessage, Object data, long total, Object rows) {
        this.errorCode = errorCode;
        this.errorMessage = errorMessage;
        this.data = data;
        this.total = total;
        this.rows = rows;
    }
    public ResultInfo(String errorCode, String errorMessage, Object data) {
        this.errorCode = errorCode;
        this.errorMessage = errorMessage;
        this.data = data;
    }
    public String getErrorCode() {
        return errorCode;
    }
    public void setErrorCode(String errorCode) {
        this.errorCode = errorCode;
    }

    public String getErrorMessage() {
        return errorMessage;
    }

    public void setErrorMessage(String errorMessage) {
        this.errorMessage = errorMessage;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public long getTotal() {
        return total;
    }

    public void setTotal(long total) {
        if ((int) total == 0) {
            total = 1;
        }
        this.total = total;
    }

    public Object getRows() {
        return rows;
    }

    public void setRows(Object rows) {
        this.rows = rows;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }
}

7.简单的分页实例

@RequestMapping(value = "/getUserList", method = {RequestMethod.GET, RequestMethod.POST})
@ResponseBody
public ResultInfo getUserList(@RequestBody SysUserPageInvo sysUserPageInvo) {
    // 定义传参
    int page = sysUserPageInvo != null && sysUserPageInvo.getPage() != null ? sysUserPageInvo.getPage() : 0;// 当前页数
    int rows = sysUserPageInvo != null && sysUserPageInvo.getRows() != null ? sysUserPageInvo.getRows() : 10;//一页多少条数据

    ResultInfo result = new ResultInfo();
    PageHelper.startPage(page, rows);
  // 获取数据
    List<SysUserOut> list = this.sysUserService.getUserList(sysUserPageInvo);
    PageInfo pageInfo = new PageInfo(list);
  // 当前分页数据
    Page pages = (Page) list;
  // 总共多少条数据
    result.setTotal(pageInfo.getTotal());
    result.setRows(pages);
    
    return result;
}

总结

        PageHelper的使用大概就是这样返回给前台的数据是当前分页的list列表和数据的总数。同样如果后台返回固定的json格式数据，前台自动加载到列表控件中。后续我会分享更多的技术相关的内容，请大家多多关注。