PageHelp实现分页

一、Spring Boot 使用PageHelper 实现分页

1.引入依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.12</version>
</dependency>

2.在application.yml中做如下配置

# 分页配置
pagehelper:
  helper-dialect: mysql
  reasonable: true
  support-methods-arguments: true
  params: count=countSql

3.代码中使用

• 准备工作

3.1 在Vo包下新建一个PageVo类，用于封装分页返回的数据

/**
 *  PageVO<T> 分页返回的VO
 **/
@Data
public class PageVO<T> {
    
    
    private long total;//条数

    private List<T> rows = new ArrayList<>();//数据集合

    public PageVO(long total, List<T> data) {
    
    
        this.total = total;
        this.rows = data;
    }
}

3.2 在response包新建一个ResponseBean 类，用于返回给前端数据

@Data
public class ResponseBean<T> {
    
    

    /** 200:操作成功  -1：操作失败**/

    // http 状态码
    private boolean success;

    // 返回的数据
    private T data;

    public static <T> ResponseBean<T> success(T data) {
    
    
        ResponseBean<T> responseBean = new ResponseBean<>();
        responseBean.setSuccess(true);
        responseBean.setData(data);
        return responseBean;
    }


    public static <T> ResponseBean<T> error(T errorData) {
    
    
        ResponseBean<T> responseBean = new ResponseBean<>();
        responseBean.setSuccess(false);
        responseBean.setData(errorData);
        return responseBean;
    }

    public static <T> ResponseBean<T> success() {
    
    
        ResponseBean<T> responseBean = new ResponseBean<>();
        responseBean.setSuccess(true);
        return responseBean;
    }
}

3.3 编写Controller 类

@GetMapping("/findLoginLogList")
public ResponseBean findLoginLogList(
    @RequestParam(value = "pageNum", defaultValue = "1") Integer pageNum,
    @RequestParam(value = "pageSize") Integer pageSize,
    LoginLogVO loginLogVO) {
    
    
    PageVO<LoginLogVO> loginLogList = loginLogService.findLoginLogList(pageNum, pageSize, loginLogVO);
     return ResponseBean.success(loginLogList);
}

3.4 Service 接口

  /**
     * 登入日志列表
     * @param pageNum
     * @param pageSize
     * @param loginLogVO
     * @return
     */
PageVO<LoginLogVO> findLoginLogList(Integer pageNum, Integer pageSize, LoginLogVO loginLogVO);

3.5 ServiceImpl 类

	@Autowired
    private LoginLogMapper loginLogMapper; //mapper层
/**
     * 登入日志列表
     *
     * @param pageNum
     * @param pageSize
     * @param loginLogVO
     * @return
     */
    @Override
    public PageVO<LoginLogVO> findLoginLogList(Integer pageNum, Integer pageSize, LoginLogVO loginLogVO) {
    
    
	   //这行是重点，表示从pageNum页开始，每页pageSize条数据
        PageHelper.startPage(pageNum, pageSize);
        //这里可以发现查询出来的数据已经实现了分页
        List<LoginLog> loginLogs = loginLogMapper.selectByExample(o);
        List<LoginLogVO> loginLogVOS = new ArrayList<>();
        if (!CollectionUtils.isEmpty(loginLogs)) {
    
    
            for (LoginLog loginLog : loginLogs) {
    
    
                LoginLogVO logVO = new LoginLogVO();
                BeanUtils.copyProperties(loginLog, logVO);
                loginLogVOS.add(logVO);
            }
        }
        PageInfo<LoginLog> info = new PageInfo<>(loginLogs);
        return new PageVO<>(info.getTotal(), loginLogVOS);
    }

3.6mapper 接口

public interface LoginLogMapper extends Mapper<LoginLog> {
    
     }

二、使用 Postman 测试

{
    
    
    "success": true,
    "data": {
    
    
        "total": 62,
        "rows": [
            {
    
    
                "id": 162,
                "username": "admin",
                "loginTime": "2021-03-25 10:34:40",
                "location": "内网IP|0|0|内网IP|内网IP",
                "ip": "127.0.0.1",
                "userSystem": "Windows 10",
                "userBrowser": "Chrome 8"
            },
            {
    
    
                "id": 161,
                "username": "admin",
                "loginTime": "2021-03-24 21:12:07",
                "location": "内网IP|0|0|内网IP|内网IP",
                "ip": "127.0.0.1",
                "userSystem": "Windows 10",
                "userBrowser": "Chrome 8"
            }
        ]
    }
}