spring boot下的list查询分页

实际项目里遇到的问题

如何实现spring下的list查询分页

此文并非教程, 而是个人学习

在common目录下utils 新建一个xxxUtils.class

输入一下的代码（百度来的）
传值传 “page” 到你需要实现的地方 如impl代码里
返回值是一个list集合 主要目的是实现与前端交互时回传的数据有多少

/**
 *
 * @param page
 * @return list集合
 */
public static List<ExcelDataEntity> page(List<ExcelDataEntity> datalist, Integer page, Integer size) {
    List<ExcelDataEntity> list = new ArrayList<>();
    if (datalist != null && datalist.size() > 0) {
        int cuurIdx = (page > 1 ? (page - 1) * size : 0);
        for (int i = 0; i < size && i < datalist.size() - cuurIdx; i++) {
            ExcelDataEntity user = datalist.get(cuurIdx + i);
            list.add(user);
        }
    }
    return list;//2020.11.11 集合分类
}

在你需要实现的impl里加上这样的初始定义

先接收传过来的数据 serviceimpl中用string给其定义

params.get("page");

params.get("limit");

String pages = (String) params.get("page");//从utils传过来page的参数
long page = Long.parseLong(pages);
String limits = (String) params.get("limit");
long limit1 = Long.parseLong(limits);

具体实现方法 在impl中

List<ExcelDataEntity> data = DateUtils.page(dataList, (int) page, (int) limit1);

该impl中 具体代码用到的位置
添加位置 “！”标识出了

@Override
public HashMap<String, Object> alarmFunction(Map<String, Object> params) throws ParseException {
    List categorys = null;
    List departments = null;
    HashMap<String, Object> dataMap = new HashMap<>();
    String likeKey = StringUtils.defaultIfEmpty((String) params.get("likeKey"), "name");
    ！！！String pages = (String) params.get("page");//从utils传过来page的参数
    ！！！long page = Long.parseLong(pages);
    ！！！String limits = (String) params.get("limit");
    ！！！long limit1 = Long.parseLong(limits);
    String likeValue = (String) params.get("likeValue");
    likeValue = "%" + likeValue + "%";
    //分页参数
    Long curPage = 0L;
    Long limit = 10L;
    if (params.get(Constant.PAGE) != null) {
        curPage = Long.parseLong((String) params.get(Constant.PAGE)) - 1L;
    }
    if (params.get(Constant.LIMIT) != null) {
        limit = Long.parseLong((String) params.get(Constant.LIMIT));
    }
    Long start = curPage * limit;
    String json = (String) params.get("preciseValue");
    if (!StringUtils.isEmpty(json)) {
        HashMap<String, String> map = JSON.parseObject(json, HashMap.class);
        Set<String> keys = map.keySet();
        for (String key : keys) {
            switch (key) {
                case "category":
                    String categorysString = map.get(key);
                    if (StringUtils.isEmpty(categorysString)) {
                        break;
                    }
                    categorys = Arrays.asList(categorysString.split(","));
                    break;
                case "department":
                    String departmentsString = map.get(key);
                    if (StringUtils.isEmpty(departmentsString)) {
                        break;
                    }
                    departments = Arrays.asList(departmentsString.split(","));
                    break;
            }
        }
    }
    List<String> unit = UserUtils.getUserDepartment();
    List<ApparatusInfoEntity> entitiesInfo = apparatusInfoDao.getAllByKeys(likeKey, likeValue, start, limit, categorys, departments, unit);
    List<ExcelDataEntity> dataList = new ArrayList<>();
    for (int i = 0; i < entitiesInfo.size(); i++) {
        ApparatusInfoEntity entity = entitiesInfo.get(i);
        for (int j = 1; j < 8; j++) {
            ExcelDataEntity data = new ExcelDataEntity();
            String s = DateUtils.getPastDate(j);
            Date date = DateUtils.stringToDate(s, "yyyy-MM-dd");
            ExcelDataEntity type = apparatusProcessDao.selectProcessByDate(date, entity.getId());
            if (type == null) {
                ExcelDataEntity app = apparatusProcessDao.getTimeByProcess(entity.getId());
                if (app != null) {
                    data.setId(entity.getId());
                    data.setName(entity.getName());
                    data.setCategory(entity.getCategory());
                    data.setModel(entity.getModel());
                    data.setPosition(entity.getPosition());
                    data.setPlannedMaintenance(s);
                    data.setDepartment(entity.getDepartment());
                    data.setCommissioningtime(entity.getCommissioningtime());
                    data.setSn(entity.getSn());
                    data.setExecutor(app.getExecutor());
                    data.setResponsible(app.getResponsible());
                    int time = DateUtils.daysBetween(app.getOperationTime(), new Date());
                    data.setLastSaved(time + "天");
                    data.setDescription("运转记录");
                    data.setType(-1L);
                    dataList.add(data);
                } else {
                    data.setId(entity.getId());
                    data.setName(entity.getName());
                    data.setCategory(entity.getCategory());
                    data.setModel(entity.getModel());
                    data.setPosition(entity.getPosition());
                    data.setPlannedMaintenance(s);
                    data.setDepartment(entity.getDepartment());
                    data.setCommissioningtime(entity.getCommissioningtime());
                    data.setSn(entity.getSn());
                    data.setDescription("运转记录");
                    data.setType(-1L);
                    dataList.add(data);
                }
            }
        }
    }


    ！！！List<ExcelDataEntity> data = DateUtils.page(dataList, (int) page, (int) limit1);
	//这里调用与回传的的数值就是在！until！包中给出的
    dataMap.put("dataList", data);
    dataMap.put("num", dataList.size() - 1);
    return dataMap;
}
}