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Java實(shí)現(xiàn)List集合手動分頁的方法

更新時(shí)間：2024年03月06日 10:47:57 作者：師小師

在工作中難免會遇到,將組裝的集合數(shù)據(jù)進(jìn)行分頁處理,本文主要介紹了Java實(shí)現(xiàn)List集合手動分頁的方法,具有一定的參考價(jià)值,感興趣的可以了解一下

List 手動分頁

@GetMapping("/getUserInfo")
    public Map<String,Object> getUserInfo(@RequestParam("pageNo") Integer pageNo,@RequestParam("pageSize") Integer pageSize){
        if(null == pageNo){
            pageNo = 1;
        }
        if(null == pageSize){
            pageSize = 10;
        }
        List<User> userList = new ArrayList<>();
        userList.add(new User(1,"奧迪1",23,"123@qq.com","地址1"));
        userList.add(new User(2,"奧迪2",23,"124@qq.com","地址2"));
        userList.add(new User(3,"奧迪3",23,"124@qq.com","地址3"));
        userList.add(new User(4,"奧迪4",23,"125@qq.com","地址4"));
        userList.add(new User(5,"奧迪4",23,"126@qq.com","地址5"));
        userList.add(new User(6,"奧迪5",23,"127@qq.com","地址6"));
        userList.add(new User(7,"奧迪6",23,"128@qq.com","地址7"));
        userList.add(new User(8,"奧迪7",23,"129@qq.com","地址8"));
        userList.add(new User(9,"奧迪7",23,"1219@qq.com","地址9"));
        userList.add(new User(10,"奧迪10",23,"1231@qq.com","地址10"));
        userList.add(new User(11,"奧迪11",23,"1232@qq.com","地址11"));

        Integer limit = (pageNo-1)*pageSize;
        Integer totalSize = userList.size();
        // 方法一
        Integer totalPage = totalSize % pageSize == 0 ? totalSize / pageSize : totalSize / pageSize + 1;
        // 方法二（推薦）其中 pageSize-1 就是 totalSize/pageSize 的最大的余數(shù)
        // Integer totalPage = (totalSize + pageSize -1) / pageSize;
        // 方法三
        // Integer totalPage = (int) Math.ceil(totalSize / pageSize);

        if(pageNo > totalPage){
            throw new RuntimeException("頁數(shù)超出了");
        }
        List<User> subList = null;
        if(pageNo == totalPage){
            // 最后一頁
            subList = userList.subList(limit, totalSize);
        }else{
            Integer end= limit + pageSize;
            // 截取的最后的下標(biāo)
            subList = userList.subList(limit, end);
            // 出現(xiàn)空值處理
            // subList = CollectionUtils.isEmpty(userList) ? new ArrayList<>() : userList.subList(limit, Math.min(userList.size(), end));
        }
        Map<String,Object> map = new HashMap<>();
        map.put("data",subList);
        map.put("total",userList.size());
        subList.forEach(System.out::println);
        return map;
    }
    static class User{
        private Integer id;
        private String name;
        private Integer age;
        private String email;
        private String address;

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public Integer getAge() {
            return age;
        }

        public void setAge(Integer age) {
            this.age = age;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }

        public String getAddress() {
            return address;
        }

        public void setAddress(String address) {
            this.address = address;
        }

        public User(Integer id, String name, Integer age, String email, String address) {
            this.id = id;
            this.name = name;
            this.age = age;
            this.email = email;
            this.address = address;
        }

        @Override
        public String toString() {
            return "User{" +
                    "id='" + id + '\'' +
                    ", name='" + name + '\'' +
                    ", age=" + age +
                    ", email='" + email + '\'' +
                    ", address='" + address + '\'' +
                    '}';
        }
    }

計(jì)算總頁數(shù)方法

// totalPage 總頁數(shù)，pageSize 每頁顯示多少條，totalSize 總條數(shù)
// 方法一
Integer totalPage = totalSize % pageSize == 0 ? totalSize / pageSize : totalSize / pageSize + 1;
// 方法二（推薦）其中 pageSize-1 就是 totalSize/pageSize 的最大的余數(shù)
// Integer totalPage = (totalSize + pageSize -1) / pageSize;
// 方法三
// Integer totalPage = (int) Math.ceil(totalSize / pageSize);

補(bǔ)：

利用 Lists.partition() 方法進(jìn)行數(shù)據(jù)將數(shù)據(jù)切割分頁

List<UserEntity> resultList = new ArrayList<>();　　　　　// 將數(shù)據(jù)按照傳過來頁長進(jìn)行切割
        List<List<UserEntity>> partition = Lists.partition(userList,pageSize);
        for (int i = 0; i < partition.size(); i++) {
            if (i == pageIndex){
                resultList  = partition.get(pageIndex);
            }
      }

利用封裝的分頁工具進(jìn)行分頁

（1）分頁工具

/**
 * @project 
 * @Description 對List集合進(jìn)行份分頁
 * @Author songwp
 * @Date 2023/5/12 13:55
 **/
public class ListPagingUtil {
        private Integer currentPage;//當(dāng)前頁
        private Integer pageSize;//每頁顯示記錄條數(shù)
        private Integer totalPage;//總頁數(shù)
        private Integer star;//開始數(shù)據(jù)
        private Integer total;//總條數(shù)
        private List<?> dataList;//每頁顯示的數(shù)據(jù)

        public Integer getCurrentPage() {
            return currentPage;
        }

        public void setCurrentPage(Integer currentPage) {
            this.currentPage = currentPage;
        }

        public Integer getPageSize() {
            return pageSize;
        }

        public void setPageSize(Integer pageSize) {
            this.pageSize = pageSize;
        }

        public Integer getTotalPage() {
            return totalPage;
        }

        public void setTotalPage(Integer totalPage) {
            this.totalPage = totalPage;
        }

        public List<?> getDataList() {
            return dataList;
        }

        public void setDataList(List<?> dataList) {
            this.dataList = dataList;
        }

        public Integer getStar() {
            return star;
        }

        public void setStar(Integer star) {
            this.star = star;
        }

        public Integer getTotal() {
            return total;
        }

        public void setTotal(Integer total) {
            this.total = total;
        }

        @Override
        public String toString() {
            return "ListPagingUtil{" +
                    "currentPage=" + currentPage +
                    ", pageSize=" + pageSize +
                    ", totalPage=" + totalPage +
                    ", dataList=" + dataList +
                    ", star=" + star +
                    ", total=" + total +
                    '}';
        }

        public void pageStartInfo(Integer currentPage, Integer pageSize){
            //如果傳入的pageNumber為null給pageNumber賦為1
            currentPage = currentPage == null ? 1 : currentPage;
            //如果傳入的pageSize為null給pageSize賦為10
            pageSize = pageSize == null ? 10 : pageSize;
            this.setCurrentPage(currentPage);
            this.setPageSize(pageSize);
        }

        public static ListPagingUtil paging(Integer currentPage, Integer pageSize, List<?> list) {
            ListPagingUtil pagingUtil = new ListPagingUtil();
            //初始化
            pagingUtil.pageStartInfo(currentPage, pageSize);
            //設(shè)置起始數(shù)據(jù)
            pagingUtil.setStar((pagingUtil.getCurrentPage()-1)*pagingUtil.getPageSize());
            //設(shè)置總數(shù)
            pagingUtil.setTotal(list.size());
            //設(shè)置總頁數(shù)
            pagingUtil.setTotalPage(pagingUtil.getTotal() % pagingUtil.getPageSize() == 0 ? pagingUtil.getTotal()/pagingUtil.getPageSize() :pagingUtil.getTotal()/pagingUtil.getPageSize()+1);
            //截取list
            pagingUtil.setDataList(list.subList(pagingUtil.getStar(), pagingUtil.getTotal()-pagingUtil.getStar()>pagingUtil.getPageSize()?pagingUtil.getStar()+pagingUtil.getPageSize():pagingUtil.getTotal()));
            return pagingUtil;
        }
}

（2）方法調(diào)用

ListPagingUtil.paging(pageIndex,pageSize, userList)

利用 stream進(jìn)行分頁處理

方法一：

List<List<CompanyStaffEquipStatisticVO>> partition = ListUtils.partition(result, param.getPageSize());
        List<CompanyStaffEquipStatisticVO> companyStaffEquipStatisticVOS = param.getPageIndex() > partition.size() ? new ArrayList<>() : partition.get(param.getPageIndex() - 1);
        SafePageParam safePageParam = new SafePageParam();
        safePageParam.setPage(true);
        safePageParam.setPageSize(param.getPageSize());
        PageVO<CompanyStaffEquipStatisticVO> voResult = new PageVO<>(safePageParam, companyStaffEquipStatisticVOS, result.size());
        if (param.getPageIndex()*param.getPageSize()<result.size()) {
            voResult.setHasNext(true);
        }
        return voResult;

方法二：

List<VendorExcelVO> resultVO = getVendorProjectListInfo(param);
PageVO<VendorExcelVO> voPageVO = new PageVO<>();
List<VendorExcelVO> collectList = resultVO.stream().skip((param.getPageIndex() - 1) * param.getPageSize()).limit(param.getPageSize()).collect(Collectors.toList());
voPageVO.setPage(true);
voPageVO.setPageSize(param.getPageSize());
voPageVO.setCount(resultVO.size());
voPageVO.setList(collectList);
if (param.getPageIndex() * param.getPageSize() < resultVO.size()){
    voPageVO.setHasNext(true);
}
return voPageVO;

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