分页设计(平时在表下面的栏框，有首页 | 上一页 | 下一页

分页设计(平时在表下面的栏框，有首页 | 上一页 | 下一页 | 尾页)，下面代码带你实现

分页设计的本质就是，分页查询，就是SQL语句当中的(select * from ? limit ? , ？）,这里第一个？是所分页的那张表，第二个？从哪条开始，第三个？是在页面上想让这张表出现几条数据。

下面先看一下分页所需要的两个函数。1.查询所有表的数据 2.获取当前页数据

   /*** 查询表中所有数据，返回进行渲染*/public List<emp> selectAll(String sql) {ArrayList<emp> emps = new ArrayList<>();Connection conn = DbLink.getConn();try {PreparedStatement statement = conn.prepareStatement(sql);ResultSet resultSet = statement.executeQuery();while (resultSet.next()) {Integer id = resultSet.getInt("id");String name = resultSet.getString("name");String city = resultSet.getString("city");String country = resultSet.getString("country");emps.add(new emp(id, name, city, country));}} catch (SQLException e) {e.printStackTrace();}return emps;}/*** 获取当前页数据* @param start         偏移量* @param pageSize      规定每页的记录数* @return list         存放所有查询表当中的所有数据*/public List<emp> QueryRecords(int start,int pageSize){Connection conn = DbLink.getConn();ArrayList<emp> list = new ArrayList<>();String sql = "select * from emp limit ?,?";try {PreparedStatement statement = conn.prepareStatement(sql);statement.setInt(1,start);statement.setInt(2,pageSize);ResultSet resultSet = statement.executeQuery();while (resultSet.next()){emp emp = new emp();int id = resultSet.getInt("id");String name = resultSet.getString("name");String city = resultSet.getString("city");String country = resultSet.getString("country");emp.setId(id);emp.setName(name);emp.setCity(city);emp.setCountry(country);list.add(emp);}} catch (SQLException e) {e.printStackTrace();}return list;}

下面我们看jsp代码，如何去实现

<%@ page import="Dao.handleDb" %>
<%@ page import="Pojo.emp" %>
<%@ page import="java.util.List" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>分页设计</title>
</head>
<body>
<%handleDb handleDb = new handleDb();//1.规定每页的记录数int pageSize = 3;//2.总的sql记录条数 countList<emp> emps = handleDb.selectAll("select * from emp");int count = emps.size();//页的数量//3.计算总页数int pageCount = count % pageSize == 0 ? count / pageSize : count / pageSize + 1;//4.当前页Integer page1;if (request.getParameter("page1") == null) {page1 = 1;} else {page1 = Integer.valueOf(request.getParameter("page1"));}//sql=select * from emp limit start,pageSize;//5.计算偏移值int start = (page1 - 1) * pageSize;//6.获取当前页的数据List<emp> list = handleDb.QueryRecords(start, pageSize);
%>
<table cellspacing="0" border="1"><tr><th>id</th><th>姓名</th><th>城市</th><th>国家</th></tr><%for (int i = 0; i < list.size(); i++) {%><tr><td><%=list.get(i).getId()%></td><td><%=list.get(i).getName()%></td><td><%=list.get(i).getCity()%></td><td><%=list.get(i).getCountry()%></td></tr><%}%></table><%if (page1==1){%><a>首页</a><a>上一页</a><a href=showList1.jsp?page1=<%=page1 + 1%>>下一页</a><a href=showList1.jsp?page1=<%=pageCount%>>尾页</a><%}else if (page1 == pageCount){%><a href=showList1.jsp?page1=1>首页</a><a href=showList1.jsp?page1=<%=page1 - 1%>>上一页</a><a>下一页</a><a>尾页</a><%}else {%><a href=showList1.jsp?page1=1>首页</a><a href=showList1.jsp?page1=<%=page1 - 1%>>上一页</a><a href=showList1.jsp?page1=<%=page1 + 1%>>下一页</a><a href=showList1.jsp?page1=<%=pageCount%>>尾页</a><%}
%>
</body>
</html>

下面我面看下运行效果：