分页技术总结

分页在Web开发中是很常用的技术，下面介绍下最简单的分页实现：
首先介绍一下实现分页需要的类：
Page：分页信息类，封装了分页所需的所有信息，如每页显示记录数、总记录数、总页数、当前页、查询起始点、是否有上一页、是否有下一页。
PageUtil：分页辅助类，进行分页的时候，必须知道3个信息，分别是当前页、每页显示记录数、总记录数，其他信息都可以通过这三个信息计算得到。
Page类：

public class Page {

    private int everyPage;      //每页显示记录数

    private int totalCount;     //总记录数

    private int totalPage;      //总页数

    private int currentPage;    //当前页

    private int beginIndex;     //查询起始点

    private boolean hasPrePage;    //是否有上一页

    private boolean hasNextPage;   //是否有下一页

    public Page(int everyPage, int totalCount, int totalPage, int currentPage,
            int beginIndex, boolean hasPrePage, boolean hasNextPage) {
        super();
        this.everyPage = everyPage;
        this.totalCount = totalCount;
        this.totalPage = totalPage;
        this.currentPage = currentPage;
        this.beginIndex = beginIndex;
        this.hasPrePage = hasPrePage;
        this.hasNextPage = hasNextPage;
    }

    public int getEveryPage() {
        return everyPage;
    }

    public void setEveryPage(int everyPage) {
        this.everyPage = everyPage;
    }

    public int getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(int totalCount) {
        this.totalCount = totalCount;
    }

    public int getTotalPage() {
        return totalPage;
    }

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

    public int getCurrentPage() {
        return currentPage;
    }

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

    public int getBeginIndex() {
        return beginIndex;
    }

    public void setBeginIndex(int beginIndex) {
        this.beginIndex = beginIndex;
    }

    public boolean isHasPrePage() {
        return hasPrePage;
    }

    public void setHasPrePage(boolean hasPrePage) {
        this.hasPrePage = hasPrePage;
    }

    public boolean isHasNextPage() {
        return hasNextPage;
    }

    public void setHasNextPage(boolean hasNextPage) {
        this.hasNextPage = hasNextPage;
    }

}

PageUtil类：

public class PageUtil {

    public static Page createPage (int everyPage, int totalCount, int currentPage) {
        everyPage = getEveryPage(everyPage);
        currentPage = getCurrentPage(currentPage);
        int totalPage = getTotalPage(everyPage, totalCount);
        int beginIndex = getBeginIndex(everyPage, currentPage);
        boolean hasPrePage = getHasPrePage(currentPage);
        boolean hasNextPage = getNextPage(totalPage, currentPage);
        return new Page(everyPage, totalCount, totalPage, currentPage, 
                beginIndex, hasPrePage, hasNextPage);
    }

    public static int getEveryPage(int everyPage) {
        return everyPage == 0 ? 10 : everyPage;
    }

    public static int getCurrentPage(int currentPage) {
        return currentPage == 0 ? 1 : currentPage;
    }

    public static int getTotalPage(int everyPage, int totalCount) {
        int totalPage = 0;
        if (totalCount != 0 && totalCount%everyPage == 0) {
            totalPage = totalCount/everyPage;
        } else {
            totalPage = totalCount/everyPage + 1;
        }
        return totalPage;
    }

    public static int getBeginIndex (int everyPage, int currentPage) {
        return (currentPage - 1)*everyPage;
    }

    public static boolean getHasPrePage(int currentPage) {
        return currentPage != 1 ? true : false;
    }

    public static boolean getNextPage(int totalPage, int currentPage) {
        return totalPage == currentPage || totalPage == 0 ? false : true;
    }

}

在Controller中封装好Page，传入Service获取相应的数据，然后将数据列表和Page对象返回前台，
页面写法：

<div>
        <c:choose>
            <c:when test="${page.hasPrePage}">
                <a href="xxx?currentPage=1">首页</a>
                <a href="xxx?currentPage=${page.currentPage-1}">上一页</a>
            </c:when>
            <c:otherwise>首页|上一页</c:otherwise>
        </c:choose>
        <c:choose>
            <c:when test="${page.hasNextPage}">
                <a href="xxx?currentPage=${page.currentPage+1}">下一页</a>
                <a href="xxx?currentPage=${page.totalPage}">尾页</a>
            </c:when>
            <c:otherwise>下一页|尾页</c:otherwise>
        </c:choose>
        当前为第${page.currentPage}页，共${page.totalPage}页
    </div>

到此一个简单的分页实现完毕。