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分页原理：
从jsp页面传到servlet请求中,可以获得当前点击的页数,第一次进入为首页,通过在servlet中获得的当前页数,并且设计一次性显示的内容数,就是几条信息,
并且从dao层查询到数据库中总记录数,就可以得到总的多少页,把这些信息封装到PageBean对象中即可。
// 将分页组件保存到session中,到页面上遍历显示
// 将当前页要显示的数据集合保存到session中,到页面上遍历显示
// 将分页类对象保存到session中,到页面使用来做分页显示
// 重定向到显示页面
返回jsp页面遍历显示
操作步骤：
1.点击查询所有用户信息。
2.页面显示第一页的查询信息,以百度搜索的分页,当点击第六页是,显示的页面顺序变化,当为第一页时,第一页超链接隐藏,当点击最后一页时,下一页超链接隐藏。
设计Oracle数据库：表名test2,只有两个字段,name和password,插入数据
select.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <style> p { height: 100px; width: 400px; margin: 140px auto; } p a { font-size: 30px; text-decoration: none; } </style> </head> <body bgcolor="#abcdef"> <p> <a href="userlist">点击查询所有用户信息</a> </p> </body> </html>
UserListServlet.java
package com.auuzee.servlet; import java.io.IOException; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.auuzee.common.PageBean; import com.auuzee.dao.UserDao; import com.auuzee.entity.User; @WebServlet("/userlist") public class UserListServlet extends HttpServlet { private static final long serialVersionUID = 1L; UserDao oDao = new UserDao(); public UserListServlet() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("进入servlet"); // 创建PageBean分页类的对象 PageBean pg = new PageBean(); // 从页面请求中获得当前页 String str = request.getParameter("currentPage"); // 判断当前页是否存在，区分是第一次访问还是通过分页超链接访问 // 第一次访问时设定当前页为第一页 int currentPage = 0; if (str == null || "".equals(str)) { currentPage = 1; } else { currentPage = Integer.parseInt(str); } // 设定分页类的每页显示记录数 pg.setPageSize(10); // 获取总记录数 int size = oDao.selectUsersSize(); System.out.println("总记录数是：" + size + " 当前页是：" + currentPage); // 设定分页类的总记录数 pg.setTotalCount(size); // 设定分页类的当前页 pg.setCurrentPage(currentPage); // 通过数据库分页的方式取得当前页要显示的数据 // 参数为当前页开始记录索引和每页显示记录数 List<User> userList = oDao.selectAllUsers(currentPage, pg.getPageSize()); // 设定分页组件（1,2,3,4,5,6等） List<Integer> indexList = new ArrayList<Integer>(); for (int i = 0; i < pg.getTotalPages(); i++) { indexList.add(i + 1); } // 将分页组件保存到session中，到页面上遍历显示 request.getSession().setAttribute("il", indexList); // 将当前页要显示的数据集合保存到session中，到页面上遍历显示 request.getSession().setAttribute("ol", userList); // 将分页类对象保存到session中，到页面使用来做分页显示 request.getSession().setAttribute("pb", pg); // 重定向到显示页面 response.sendRedirect("jsp/userlist.jsp"); } }
User.java
package com.auuzee.entity; public class User { private String name; private String password; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
Config.java
package com.auuzee.dbutil; import java.io.IOException; import java.util.Properties; public class Config { private static Properties pro = new Properties(); static { try { // 通过反射的方式加载资源文件 // 只要资源文件和Config类在同一个路径下就能找到并加载到Properties对象中，以map的形式存放 pro.load(Config.class.getResourceAsStream("db.properties")); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static final String DBURL = pro.getProperty("DBURL"); public static final String DBIP = pro.getProperty("DBIP"); public static final String DBPORT = pro.getProperty("DBPORT"); public static final String DATABASE = pro.getProperty("DATABASE"); public static final String DBUSER = pro.getProperty("DBUSER"); public static final String DBPASS = pro.getProperty("DBPASS"); public static final String DBDRIVER = pro.getProperty("DBDRIVER"); }
DBUtil.java
package com.auuzee.dbutil; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DBUtil { // 数据库连接字符串 private String url = Config.DBURL + Config.DBIP + Config.DBPORT + Config.DATABASE; // 数据库连接用户名 private String user = Config.DBUSER; // 数据库连接密码 private String password = Config.DBPASS; private Connection con = null; private PreparedStatement pst = null; private Statement st = null; private ResultSet rs = null; // 获取连接 private void getConn() { try { // 加载驱动 Class.forName(Config.DBDRIVER); // 建立连接 con = DriverManager.getConnection(url, user, password); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } /* * 共通查询方法 params：Strng sql：需要执行的SQL语句 Object[] param：需要替换占位符的参数数组 * return：rs：执行查询得到的结果集 */ public ResultSet select(String sql, Object[] param) { // 调用共通方法获取连接 getConn(); try { // 创建Statement对象 pst = con.prepareStatement(sql); // SQL占位符替换 if (param != null) { for (int i = 0; i < param.length; i++) { pst.setObject(i + 1, param[i]); } } // 执行SQL rs = pst.executeQuery(); return rs; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); return null; } } /* * 共通更新方法 params：Strng sql：需要执行的SQL语句 Object[] param：需要替换占位符的参数数组 * return：count：执行更新得到的影响行数 */ public int update(String sql, Object[] param) { // 调用共通方法获取连接 getConn(); try { // 创建Statement对象 pst = con.prepareStatement(sql); // SQL占位符替换 if (param != null) { for (int i = 0; i < param.length; i++) { pst.setObject(i + 1, param[i]); } } // 执行SQL int count = pst.executeUpdate(); return count; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); return -1; } } /* * 共通批处理方法 params：String[] sql：需要执行的SQL语句数组 return：counts：执行批处理得到的影响行数数组 */ public int[] batch(String[] sql) { // 调用共通方法获取连接 getConn(); try { // 创建Statement对象 st = con.createStatement(); // 添加批处理SQL for (String s : sql) { st.addBatch(s); } // 执行批处理 int[] counts = st.executeBatch(); return counts; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); return null; } } // 关闭资源 public void close() { try { if (rs != null) { rs.close(); } if (st != null) { st.close(); } if (pst != null) { pst.close(); } if (con != null) { con.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
db.properties
DBURL=jdbc:oracle:thin:@ DBIP=localhost DBPORT=:1521 DATABASE=:BANK DBUSER=system DBPASS=123456 DBDRIVER=oracle.jdbc.driver.OracleDriver
UserDao.java
package com.auuzee.dao; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.auuzee.dbutil.DBUtil; import com.auuzee.entity.User; public class UserDao { DBUtil dbu = new DBUtil(); // 查询订单总记录数 public int selectUsersSize() { String sql = "select count(*) from test2"; ResultSet rs = dbu.select(sql, null); int size = 0; try { while (rs.next()) { size = rs.getInt(1); } return size; } catch (SQLException e) { e.printStackTrace(); return 0; } finally { dbu.close(); } } // 查询所有订单方法 public List<User> selectAllUsers(int currentPage, int pageSize) { String sql = "select * from (select a1.*,rownum rn from" + "(select * from test2) a1 where rownum <=?) where rn>=?"; Object[] param1; if (currentPage == 1) { Object[] param = { pageSize, 1 }; param1 = param; } else { Object[] param = { currentPage * pageSize, (currentPage - 1) * pageSize + 1 }; param1 = param; } ResultSet rs = dbu.select(sql, param1); List<User> userList = new ArrayList<User>(); try { while (rs.next()) { User user = new User(); user.setPassword(rs.getString("password")); user.setName(rs.getString("name")); userList.add(user); } return userList; } catch (SQLException e) { e.printStackTrace(); return null; } finally { dbu.close(); } } }
PageBean.java
package com.auuzee.common; public class PageBean { // 总记录数 private int totalCount; // 每页显示记录数 private int pageSize = 5; // 总页数 private int totalPages; // 当前页 private int currentPage; // 当前页开始记录索引 private int startIndex; // 当前页结束记录索引 private int endIndex; public int getTotalCount() { return totalCount; } // 设定总记录数并计算总页数 public void setTotalCount(int totalCount) { if (totalCount != 0) { this.totalCount = totalCount; if (this.totalCount % pageSize == 0) { totalPages = this.totalCount / pageSize; } else { totalPages = this.totalCount / pageSize + 1; } } else { totalPages = 1; } } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public int getPageSize() { return this.pageSize; } // 计算总页数 public int getTotalPages() { return totalPages; } // 设置当前页，计算开始和结束记录索引 public void setCurrentPage(int currentPage) { this.currentPage = currentPage; if (this.currentPage < 1) { this.currentPage = 1; } if (this.currentPage > totalPages) { this.currentPage = totalPages; } startIndex = (this.currentPage - 1) * pageSize; endIndex = this.currentPage * pageSize; } public int getCurrentPage() { return currentPage; } public int getStartIndex() { return startIndex; } public int getEndIndex() { return endIndex; } }
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原文地址：http://www.cnblogs.com/greatfish/p/5982999.html
