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分页的实现
想要实现例如以下分页效果：
分页实现逻辑：
关键代码例如以下：
page.jsp
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding= "UTF-8"%>
<%@taglib uri= "http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<base href= "http://${pageContext.request.serverName
}:${pageContext.request.serverPort }${pageContext.request.contextPath }/" />
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<title> Insert
title here</title >
<style type= "text/css">
#pageCode{
width: 30px;
border: 1px
solid black;
}
#current{
border: 1px
solid black;
background-color: #bbffaa ;
}
</style>
<script type= "text/javascript" src="script/jquery-1.7.2.js" ></script>
<script type= "text/javascript">
$(function(){
//onchange在文本框内容发生改变时触发事件
$( "#pageCode").change(function (){
var pageCode=$.trim(this.value);
//假设输入为空
if(pageCode=="" ){
this.value=http://www.mamicode.com/this .defaultValue;//恢复为默认值
return false ;
}
//假设输入值不是一个数字
if(isNaN(pageCode)){
this.value=http://www.mamicode.com/this .defaultValue;//恢复为默认值
return false ;
}
//通过window.location对象实现页面的跳转
window.location.href=http://www.mamicode.com/ "DataServlet?method=getPage&pageNo=" +pageCode;
});
});
</script>
</head>
<body>
<!--显示页面上的数据 -->
<c:forEach items="${page.list
} " var ="data">
${data }<br >
</c:forEach >
<!-- 假设有上一页的话就显示下面的超链接 -->
<c:if test="${page.hasPrev
} ">
<a href="/Page/DataServlet?method=getPage&pageNo=1" >首页 </a>
<a href="/Page/DataServlet?method=getPage&pageNo= ${page.prevNo
}"> 上一页</a >
</c:if >
<!--当前页码大于3时显示第一页的超链接 -->
<c:if test="${page.pageNo>3
} ">
<a href="/Page/DataServlet?method=getPage&pageNo=1" >1 </a>
</c:if >
<!--当前页码＞4 显示三个点“...” -->
<c:if test="${page.pageNo>4
} ">...</c:if >
<!-- 从1開始 到总页数结束 -->
<c:forEach begin="1" end= "${page.totalPageNum
}" var="num" >
<c:choose>
<c:when test= "${num==page.pageNo
}"><span id="current" >${num
}</ span></c:when >
<c:when test= "${num>=page.pageNo-2
&& num<=page.pageNo+2 }" >${num
} </c:when>
</c:choose>
</c:forEach >
<!--当前页码+3小于总页数时 显示三个点“...” -->
<c:if test="${page.pageNo+3<page.totalPageNum
}">...</c:if >
<c:if test="${page.pageNo+3<page.totalPageNum} ">
<a href="/Page/DataServlet?method=getPage&pageNo= ${page.totalPageNum}"> ${page.totalPageNum}</a >
</c:if >
<!--假设还有当前页还有下一页则显示下一页和末页-->
<c:if test="${page.hasNext
} ">
<a href="/Page/DataServlet?method=getPage&pageNo= ${page.nextNo
}"> 下一页</a >
<a href="/Page/DataServlet?method=getPage&pageNo= ${page.totalPageNum}"> 末页</a >
</c:if >
共同拥有 ${page.totalItemNum }条记录
前往第 <input id= "pageCode" type ="text" name="pageCode" value="${page.pageNo
} "/>页
</body>
</html>
DataServlet.java
public class DataServlet extends BaseServlet {
private static final long serialVersionUID = 1L ;
private DataService dataService = new DataServiceImpl();
protected void getDataList( HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
List <Data> dataList = dataService .getDataList() ;
WebUtils .forward( request, response , "dataList" , dataList, "/data.jsp" );
}
protected void getPage( HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//获取页码
String pageNoStr = request.getParameter( "pageNo");
//获取Page对象
Page <Data> page = dataService.getPage (pageNoStr );
//传到前台去
//WebUtils.forward(request, response, attrName,
attrVal, targetPath);
WebUtils .forward( request, response , "page" , page, "/page.jsp" );
}
}
BaseServlet .java
public abstract class BaseServlet extends HttpServlet {
private static final long serialVersionUID = 1L ;
@Override
protected void doGet( HttpServletRequest request, HttpServletResponse response )
throws ServletException, IOException {
doPost( request, response );
}
@Override
protected void doPost( HttpServletRequest request, HttpServletResponse response )
throws ServletException, IOException {
request .setCharacterEncoding( "UTF-8");
String methodName = request.getParameter( "method");
try {
Method method =
this. getClass() .getDeclaredMethod(
methodName ,
HttpServletRequest .class ,
HttpServletResponse .class
);
method .setAccessible( true);
method .invoke(this, request, response);
} catch (Exception e ) {
e .printStackTrace() ;
}
}
}
DataServiceImpl.java
public class DataServiceImpl implements DataService {
private DataDao dataDao = new DataDaoImpl ();
@Override
public List< Data> getDataList() {
return dataDao .getDataList() ;
}
@Override
public Page< Data> getPage(String pageNoStr) {
//1.取得总记录数
int totalItemNum = dataDao.getTotalItemNum ();
//2.通过參数pageNoStr和參数totalItemNum来创建page对象
//内部纠正了pageNo值
Page <Data> page= new Page<>(pageNoStr, totalItemNum);
//3.获取list数据。调用page.getPageNo()得到有效值
List <Data> list = dataDao.getPageList (page .getPageNo(), Page .pageSize) ;
page .setList(list);
//4.组装完page对象后将其返回
return page;
}
}
DataDaoImpl .java
public class DataDaoImpl extends DaoImpl <Data> implements DataDao {
@Override
public List< Data> getDataList() {
Connection connection = getConnection() ;
String sql = "select
data_id dataId,data_name dataName from datatable";
List <Data> dataList = this .getBeanList (sql , connection);
releaseConn(connection );
return dataList;
}
@Override
public List< Data> getPageList(int pageNo, int pageSize) {
Connection connection = JDBCUtils.getConnection() ;
String sql = "SELECT
data_id dataId,data_name dataName FROM datatable LIMIT ?
,?";
List <Data> list = this .getBeanList (sql , connection, (pageNo - 1) *pageSize, pageSize);
JDBCUtils .releaseConn( connection);
return list;
}
@Override
public int getTotalItemNum() {
Connection connection = JDBCUtils.getConnection() ;
String sql = "SELECT
COUNT(*) FROM datatable";
//运行count函数的SQL语句的Java函数返回的Java类型是Long
//将Long包装类型转换为long基本数据类型
long itemNum = this. getSigleValue(sql , connection);
JDBCUtils .releaseConn( connection);
//在返回时。将long基本数据类型强转为 int基本数据类型
return (int) itemNum;
}
}
DataDaoImpl.java
public class DataDaoImpl extends DaoImpl <Data> implements DataDao {
@Override
public List< Data> getDataList() {
Connection connection = JDBCUtils.getConnection() ;
String sql = "select
data_id dataId,data_name dataName from datatable";
List <Data> dataList = this .getBeanList (sql , connection);
JDBCUtils .releaseConn( connection);
return dataList;
}
@Override
public List< Data> getPageList(int pageNo, int pageSize) {
Connection connection = JDBCUtils.getConnection() ;
String sql = "SELECT
data_id dataId,data_name dataName FROM datatable LIMIT ?,?";
List <Data> list = this .getBeanList (sql , connection, (pageNo - 1) *pageSize, pageSize);
JDBCUtils .releaseConn( connection);
return list;
}
@Override
public int getTotalItemNum() {
Connection connection = JDBCUtils.getConnection() ;
String sql = "SELECT
COUNT(*) FROM datatable";
//运行count函数的SQL语句的Java函数返回的Java类型是Long
//将Long包装类型转换为long基本数据类型
long itemNum = this. getSigleValue(sql , connection);
JDBCUtils .releaseConn( connection);
//在返回时，将long基本数据类型强转为 int基本数据类型
return (int) itemNum;
}
}
分页的实现
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