jsp 实现分页操作

1. 分页依据：
   select 字段列表 from 表名 limit m,n;
   m: 表示起始记录，并且从0开始
   n: 查询记录的个数，每页记录数
2. 分页信息
   共多少页
   有没有上一页
   有没有下一页
   当前页
   注：分页信息类Page
   注2：创建分页信息辅助类PageUtil
   public static Page createPage(int everyPage,int totalCount,int currentPage)
   everyPage: 程序员定
   totalCount: 总记录数，查询数据库表记录 select count(*) from 表名
   currentPage: 从默认第一页开始，下一页= 当前页+1 上一页 = 当前页-1
3. 分页数据集合List
   依据查询语句获得集合： select 字段列表 from 表名 limit m,n;
   m: beginIndex
   n: everyPage

具体实现：：：

UserBiz:
//分页

public int getCont();
public List findByPage(Page page);

UserBizImpl：

@Overridepublic int getCont() {String sql = "select count(*) as count from user";CountUtil count = (CountUtil) udao.get(sql, CountUtil.class);return count.getCount();}@Overridepublic List findByPage(Page page) {String sql = "select * from user limit "+page.getBeginIndex()+", "+page.getEveryPage();return udao.query(sql, User.class);}

servlet：：UserServlet

int everyPage = 5;//每页记录数int totalCount = ubiz.getCont();//获取总记录数//点击链接重新获取当前页
String scurrentPage = request.getParameter("currentPage");int currentPage = 1; //当前页，默认1if(scurrentPage == null){currentPage = 1;//从第一页开始访问}else{currentPage = Integer.parseInt(scurrentPage);}//分页信息Page page = PageUtil.createPage(everyPage, totalCount, currentPage);//分页数据信息List<User> list = ubiz.findByPage(page);request.setAttribute("page", page);request.setAttribute("list", list);//转发到userlist.jsprequest.getRequestDispatcher("/back/manager/userlist.jsp").forward(request, response);

userlist.jsp中的分页表现

<table width="461" height="24" border="1" cellpadding="0" cellspacing="0"><tr><td width="199">当前为第${page.currentPage}页,共${page.totalPage}页td><td width="256"><c:choose><c:when test="${page.hasPrePage}"><a href="<%=path %>/user.do?method=list¤tPage=1">首页a> | <a href="<%=path %>/user.do?method=list¤tPage=${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="${page.hasNextPage}"><a href="<%=path %>/user.do?method=list¤tPage=${page.currentPage + 1 }">下一页a> | <a href="<%=path %>/user.do?method=list¤tPage=${page.totalPage }">尾页a>c:when><c:otherwise>下一页 | 尾页c:otherwise>c:choose>td>tr>
table>

附：：：：page类（分页信息实体类）

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) {  //自定义构造方法this.everyPage = everyPage;this.totalCount = totalCount;this.totalPage = totalPage;this.currentPage = currentPage;this.beginIndex = beginIndex;this.hasPrePage = hasPrePage;this.hasNextPage = hasNextPage;}///get，set方法略
}

附：pageutil 分页信息辅助类

public class PageUtil {//创建Page对象public static Page createPage(int everyPage,int totalCount,int currentPage) {//创建分页信息对象everyPage = getEveryPage(everyPage);currentPage = getCurrentPage(currentPage);int totalPage = getTotalPage(everyPage, totalCount);int beginIndex = getBeginIndex(everyPage, currentPage);boolean hasPrePage = getHasPrePage(currentPage);boolean hasNextPage = getHasNextPage(totalPage, currentPage);return new Page(everyPage, totalCount, totalPage, currentPage,beginIndex, hasPrePage,  hasNextPage);}// 以下方法辅助创建Page对象public static int getEveryPage(int everyPage) {     //获得每页显示记录数return everyPage == 0 ? 10 : everyPage;}public static int getCurrentPage(int currentPage) { //获得当前页return currentPage == 0 ? 1 : currentPage;}public static int getTotalPage(int everyPage,int totalCount) {//获得总页数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) {//获得起始位置return (currentPage - 1) * everyPage;}public static boolean getHasPrePage(int currentPage) {//获得是否有上一页return currentPage == 1 ? false : true;}public static boolean getHasNextPage(int totalPage, int currentPage) {  //获得是否有上一页return currentPage == totalPage || totalPage == 0 ? false : true;}
}

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