JavaWeb分頁查詢功能怎么實現

本篇內容主要講解“JavaWeb分頁查詢功能怎么實現”，感興趣的朋友不妨來看看。本文介紹的方法操作簡單快捷，實用性強。下面就讓小編來帶大家學習“JavaWeb分頁查詢功能怎么實現”吧!

效果：

實現：

分頁查詢有幾個比較重要的參數，pageNum當前的頁數，pageSize每頁所展示的數據，totalRecord總共有多少數據，其他的數據可以根據這三個數據得出，有了這幾個數據就可以分頁查詢了

public class Page {    //當前的頁數
    private int pageNum;    //每頁所展示的數據
    private int pageSize;    //總共有多少數據
    private int totalRecord;    //總頁數
    private int totalPage;    //查詢數據的起始位置
    private int startIndex;    //存放查詢到的數據
    private List<Book> booklist;    //相對的頭頁
    private int start;    //相對的尾頁
    private int end; 
    public Page(int pageNum, int pageSize, int totalRecord) {        this.pageNum = pageNum;        this.pageSize = pageSize;        this.totalRecord = totalRecord; 
        if(totalRecord%pageSize == 0){            //如果剛好能夠整除，則totalPage = totalRecord/pageSize
            this.totalPage = totalRecord/pageSize;
        }else{            //如歌不能整除，則需要多加一頁顯示余下的數據
            this.totalPage = (totalRecord/pageSize)+1;
        }        this.startIndex = (pageNum-1)*pageSize;        //初始頭頁
        this.start = 1;        //初始尾頁
        this.end = 5;        if(totalPage<5){            //如果總頁數小于5頁，則尾頁為總頁數
            this.end = this.totalPage;
        }else{            this.start = this.pageNum-2;            this.end = this.pageNum+2;            if(this.start<0){                this.start = 1;                this.end = 5;
            }            if(this.end>totalPage){                this.end = totalPage;                this.start = this.end-5;
            }
        }
    } 
    //下面的為get/set方法
    public int getPageNum() {        return pageNum;
    } 
    public void setPageNum(int pageNum) {        this.pageNum = pageNum;
    } 
    public int getPageSize() {        return pageSize;
    } 
    public void setPageSize(int pageSize) {        this.pageSize = pageSize;
    } 
    public int getTotalRecord() {        return totalRecord;
    } 
    public void setTotalRecord(int totalRecord) {        this.totalRecord = totalRecord;
    } 
    public int getTotalPage() {        return totalPage;
    } 
    public void setTotalPage(int totalPage) {        this.totalPage = totalPage;
    } 
    public int getStartIndex() {        return startIndex;
    }    public void setStartIndex(int startIndex) {        this.startIndex = startIndex;
    } 
    public List<Book> getBooklist() {        return booklist;
    } 
    public void setBooklist(List<Book> booklist) {        this.booklist = booklist;
    } 
    public int getStart() {        return start;
    } 
    public void setStart(int start) {        this.start = start;
    } 
    public int getEnd() {        return end;
    } 
    public void setEnd(int end) {        this.end = end;
    }
}

pageNum從請求中獲得，pageSize自己設置，totalRecord通過mybatis查詢獲得，一開始登錄的時候請求中沒有pageNum，所以進行一個判斷，如果沒有pageNum則賦值為1

 //pageNum 
 String pageNum = request.getParameter("pageNum") == null?"1":request.getParameter("pageNum");//pageSize 
   int pageSize = 7;//totalRecordint totalRecord = bookMapper.BookSize();//mybatis<select id="BookSize" resultType="int">        select count(*) from book
 </select>

有了pageNum和startIndex就可以查詢到特定范圍的數據，通過使用mysql中的limit函數，limit有兩個參數，第一個參數為起始位置，即從那開始查，第二個參數為查詢范圍，即查多少個，如 limit 14,7 為從第14個數據開始往后查七個。

<select id="Books" parameterType="java.util.Map" resultType="book">        select *from book  limit #{startIndex},#{pageSize}
    </select>

public static Page getPageUser(int pageNum,int pageSize){
        SqlSession sqlSession = GetSqlSession.getSqlSession();
        BookMapper bookMapper = sqlSession.getMapper(BookMapper.class);        int totalRecord = bookMapper.BookSize(); 
        Page page = new Page(pageNum,pageSize ,totalRecord );        int startIndex = page.getStartIndex();
        Map<String,Integer> map = new HashMap<>();        map.put("startIndex",startIndex );        map.put("pageSize",pageSize );
        page.setBooklist(bookMapper.Books(map));        return page;
    }

jsp頁面：

<a href="index?pageNum=1">首頁</a>
            <%--當前頁數為第一頁--%>
        <c:if test="${sessionScope.page.pageNum == 1}">
            <c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
                <c:if test="${sessionScope.page.pageNum == i}">
                    <span  style="color: deeppink">${i}</span>
                </c:if>
                <c:if test="${sessionScope.page.pageNum != i}">
                    <a href="index?pageNum=${i}">${i}</a>
                </c:if>
            </c:forEach>
            <a href="index?pageNum=${sessionScope.page.pageNum+1}">下一頁</a>
        </c:if>
        <%--當前頁數為中間頁數--%>
        <c:if test="${sessionScope.page.pageNum >1 && sessionScope.page.pageNum<sessionScope.page.totalPage}">
            <a href="index?pageNum=${sessionScope.page.pageNum-1}">上一頁</a>
            <c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
                <c:if test="${sessionScope.page.pageNum == i}">
                    <span  style="color: deeppink">${i}</span>
                </c:if>
                <c:if test="${sessionScope.page.pageNum != i}">
                    <a href="index?pageNum=${i}">${i}</a>
                </c:if>
            </c:forEach>
            <a href="index?pageNum=${sessionScope.page.pageNum+1}">下一頁</a>
        </c:if>
        <%--當前頁數為最后一頁--%>
        <c:if test="${sessionScope.page.pageNum == sessionScope.page.totalPage}">
            <a href="index?pageNum=${sessionScope.page.pageNum-1}">上一頁</a>
            <c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
                <c:if test="${sessionScope.page.pageNum == i}">
                    <span  style="color: deeppink">${i}</span>
                </c:if>
                <c:if test="${sessionScope.page.pageNum != i}">
                    <a href="index?pageNum=${i}">${i}</a>
                </c:if>
            </c:forEach>
        </c:if>
        <a href="index?pageNum=${sessionScope.page.totalPage}">尾頁</a>

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