Java分页技术的实现(一)
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(一)创建一个web项目
(二)编写Java类
1.建立一个com.imooc.page包
package com.imooc.page;public class Constant { /** * 男性 */ public static final int GENDER_MALE = 1; /** * 女性 */ public static final int GENDER_FEMALE = 2; /** * 默认每页显示多少条记录 */ public static final int DEFAULT_PAGE_SIZE = 5; /** * 默认显示第几页记录 */ public static final int DEFAULT_PAGE_NUM = 1; /** * 默认学生性别 */ public static final int DEFAULT_GENDER = 0;}///////////////////////////////////////////////////////////package com.imooc.page;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class EncodingFilter implements Filter { @Override public void destroy() { // TODO Auto-generated method stub } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); chain.doFilter(request,response); } @Override public void init(FilterConfig arg0) throws ServletException { // TODO Auto-generated method stub }}2.创建一个com.imooc.page,model
package com.imooc.page.model;import java.io.Serializable;import java.util.List;public class Pager<T> implements Serializable { private static final long serialVersionUID = -8741766802354222579L; private int pageSize; // 每页显示多少条记录 private int currentPage; //当前第几页数据 private int totalRecord; // 一共多少条记录 private int totalPage; // 一共多少页记录 private List<T> dataList; //要显示的数据 public Pager(int pageNum, int pageSize, List<T> sourceList){ if(sourceList == null || sourceList.isEmpty()){ return; } // 总记录条数 this.totalRecord = sourceList.size(); // 每页显示多少条记录 this.pageSize = pageSize; //获取总页数 this.totalPage = this.totalRecord / this.pageSize; if(this.totalRecord % this.pageSize !=0){ this.totalPage = this.totalPage + 1; } // 当前第几页数据 this.currentPage = this.totalPage < pageNum ? this.totalPage : pageNum; // 起始索引 int fromIndex = this.pageSize * (this.currentPage -1); // 结束索引 int toIndex = this.pageSize * this.currentPage > this.totalRecord ? this.totalRecord : this.pageSize * this.currentPage; this.dataList = sourceList.subList(fromIndex, toIndex); } public Pager(){ } public Pager(int pageSize, int currentPage, int totalRecord, int totalPage, List<T> dataList) { super(); this.pageSize = pageSize; this.currentPage = currentPage; this.totalRecord = totalRecord; this.totalPage = totalPage; this.dataList = dataList; } public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public int getCurrentPage() { return currentPage; } public void setCurrentPage(int currentPage) { this.currentPage = currentPage; } public int getTotalRecord() { return totalRecord; } public void setTotalRecord(int totalRecord) { this.totalRecord = totalRecord; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public List<T> getDataList() { return dataList; } public void setDataList(List<T> dataList) { this.dataList = dataList; }}//////////////////////////////////////////////////////////package com.imooc.page.model;import java.io.Serializable;import java.util.Map;public class Student implements Serializable { private static final long serialVersionUID = -7476381137287496245L; private int id; //学生记录id private String stuName;//学生姓名 private int age; //学生年龄 private int gender; //学生性别 private String address;//学生住址 public Student() { super(); } public Student(int id, String stuName, int age, int gender, String address) { super(); this.id = id; this.stuName = stuName; this.age = age; this.gender = gender; this.address = address; } public Student(Map<String, Object> map){ this.id = (int)map.get("id"); this.stuName = (String)map.get("stu_name"); this.age = (int)map.get("age"); this.gender = (int)map.get("gender"); this.address = (String)map.get("address"); } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getStuName() { return stuName; } public void setStuName(String stuName) { this.stuName = stuName; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getGender() { return gender; } public void setGender(int gender) { this.gender = gender; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { return "Student [id=" + id + ", stuName=" + stuName + ", age=" + age + ", gender=" + gender + ", address=" + address + "]"; }}3.创建一个com.imooc.page.dao包
package com.imooc.page.dao;import com.imooc.page.model.Pager;import com.imooc.page.model.Student;public interface StudentDao { /** * 根据查询条件，查询学生分页信息 * * @param searchModel * 封装查询条件 * @param pageNum * 查询第几页数据 * @param pageSize * 每页显示多少条记录 * @return 查询结果 */ public Pager<Student> findStudent(Student searchModel, int pageNum, int pageSize);}//////////////////////////////////////////////////////////////////package com.imooc.page.dao;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import java.util.Map;import com.imooc.page.Constant;import com.imooc.page.model.Pager;import com.imooc.page.model.Student;import com.imooc.page.util.JdbcUtil;public class SublistStudentDaoImpl implements StudentDao { @Override public Pager<Student> findStudent(Student searchModel, int pageNum, int pageSize) { List<Student> allStudenList = getAllStudent(searchModel); Pager<Student> pager = new Pager<Student>(pageNum, pageSize, allStudenList); return pager; } /** * 模仿获取所有数据 * * @param searchModel * 查询参数 * @return 查询结果 */ private static List<Student> getAllStudent(Student searchModel) { List<Student> result = new ArrayList<Student>(); List<Object> paramList = new ArrayList<Object>(); String stuName = searchModel.getStuName(); int gender = searchModel.getGender(); StringBuilder sql = new StringBuilder( "select * from t_student where 1=1"); if (stuName != null && !stuName.equals("")) { sql.append(" and stu_name like ?"); paramList.add("%" + stuName + "%"); } if (gender == Constant.GENDER_FEMALE || gender == Constant.GENDER_MALE) { sql.append(" and gender = ?"); paramList.add(gender); } JdbcUtil jdbcUtil = null; try { jdbcUtil = new JdbcUtil(); jdbcUtil.getConnection(); // 获取数据库链接 List<Map<String, Object>> mapList = jdbcUtil.findResult( sql.toString(), paramList); if (mapList != null) { for (Map<String, Object> map : mapList) { Student s = new Student(map); result.add(s); } } } catch (SQLException e) { throw new RuntimeException("查询所有数据异常！", e); } finally { if (jdbcUtil != null) { jdbcUtil.releaseConn(); // 一定要释放资源 } } return result; } public static void main(String[] args) { List<Student> lst = getAllStudent(new Student()); for (Student s : lst) { System.out.println(s); } }}4.创建一个com.imooc.page.service包
package com.imooc.page.service;import com.imooc.page.model.Pager;import com.imooc.page.model.Student;public interface StudentService { /** * 根据查询条件，查询学生分页信息 * * @param searchModel * 封装查询条件 * @param pageNum * 查询第几页数据 * @param pageSize * 每页显示多少条记录 * @return 查询结果 */ public Pager<Student> findStudent(Student searchModel, int pageNum, int pageSize);}////////////////////////////////////////////////////////////////package com.imooc.page.service;import com.imooc.page.dao.StudentDao;import com.imooc.page.dao.SublistStudentDaoImpl;import com.imooc.page.model.Pager;import com.imooc.page.model.Student;public class SublistStudentServiceImpl implements StudentService { private StudentDao studentDao; public SublistStudentServiceImpl() { // 创建servivce实现类时，初始化dao对象。 studentDao = new SublistStudentDaoImpl(); } @Override public Pager<Student> findStudent(Student searchModel, int pageNum, int pageSize) { Pager<Student> result = studentDao.findStudent(searchModel, pageNum, pageSize); return result; } public StudentDao getStudentDao() { return studentDao; } public void setStudentDao(StudentDao studentDao) { this.studentDao = studentDao; }}5.创建一个com.imooc.page.servlet包
package com.imooc.page.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.imooc.page.Constant;import com.imooc.page.model.Pager;import com.imooc.page.model.Student;import com.imooc.page.service.StudentService;import com.imooc.page.service.SublistStudentServiceImpl;import com.imooc.page.util.StringUtil;public class SublistServlet extends HttpServlet { private static final long serialVersionUID = -3658128508633145268L; private StudentService studentService = new SublistStudentServiceImpl(); public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 接收request里的参数 String stuName = request.getParameter("stuName"); //学生姓名 // 获取学生性别 int gender = Constant.DEFAULT_GENDER; String genderStr = request.getParameter("gender"); if(genderStr!=null && !"".equals(genderStr.trim())){ gender = Integer.parseInt(genderStr); } // 校验pageNum参数输入合法性 String pageNumStr = request.getParameter("pageNum"); if(pageNumStr !=null && !StringUtil.isNum(pageNumStr)){ request.setAttribute("errorMsg", "参数传输错误"); request.getRequestDispatcher("sublistStudent.jsp").forward(request, response); return; } int pageNum = Constant.DEFAULT_PAGE_NUM; //显示第几页数据 if(pageNumStr!=null && !"".equals(pageNumStr.trim())){ pageNum = Integer.parseInt(pageNumStr); } int pageSize = Constant.DEFAULT_PAGE_SIZE; // 每页显示多少条记录 String pageSizeStr = request.getParameter("pageSize"); if(pageSizeStr!=null && !"".equals(pageSizeStr.trim())){ pageSize = Integer.parseInt(pageSizeStr); } // 组装查询条件 Student searchModel = new Student(); searchModel.setStuName(stuName); searchModel.setGender(gender); //调用service 获取查询结果 Pager<Student> result = studentService.findStudent(searchModel, pageNum, pageSize); // 返回结果到页面 request.setAttribute("result", result); request.setAttribute("stuName", stuName); request.setAttribute("gender", gender); request.getRequestDispatcher("sublistStudent.jsp").forward(request, response); }}6.创建一个com.imooc.page.Util包
package com.imooc.page.util;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Properties;public class JdbcUtil { // 表示定义数据库的用户名 private static String USERNAME ; // 定义数据库的密码 private static String PASSWORD; // 定义数据库的驱动信息 private static String DRIVER; // 定义访问数据库的地址 private static String URL; // 定义数据库的链接 private Connection connection; // 定义sql语句的执行对象 private PreparedStatement pstmt; // 定义查询返回的结果集合 private ResultSet resultSet; static{ //加载数据库配置信息，并给相关的属性赋值 loadConfig(); } /** * 加载数据库配置信息，并给相关的属性赋值 */ public static void loadConfig() { try { InputStream inStream = JdbcUtil.class .getResourceAsStream("/jdbc.properties"); Properties prop = new Properties(); prop.load(inStream); USERNAME = prop.getProperty("jdbc.username"); PASSWORD = prop.getProperty("jdbc.password"); DRIVER= prop.getProperty("jdbc.driver"); URL = prop.getProperty("jdbc.url"); } catch (Exception e) { throw new RuntimeException("读取数据库配置文件异常！", e); } } public JdbcUtil() { } /** * 获取数据库连接 * * @return 数据库连接 */ public Connection getConnection() { try { Class.forName(DRIVER); // 注册驱动 connection = DriverManager.getConnection(URL, USERNAME, PASSWORD); // 获取连接 } catch (Exception e) { throw new RuntimeException("get connection error!", e); } return connection; } /** * 执行更新操作 * * @param sql * sql语句 * @param params * 执行参数 * @return 执行结果 * @throws SQLException */ public boolean updateByPreparedStatement(String sql, List<?> params) throws SQLException { boolean flag = false; int result = -1;// 表示当用户执行添加删除和修改的时候所影响数据库的行数 pstmt = connection.prepareStatement(sql); int index = 1; // 填充sql语句中的占位符 if (params != null && !params.isEmpty()) { for (int i = 0; i < params.size(); i++) { pstmt.setObject(index++, params.get(i)); } } result = pstmt.executeUpdate(); flag = result > 0 ? true : false; return flag; } /** * 执行查询操作 * * @param sql * sql语句 * @param params * 执行参数 * @return * @throws SQLException */ public List<Map<String, Object>> findResult(String sql, List<?> params) throws SQLException { List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); int index = 1; pstmt = connection.prepareStatement(sql); if (params != null && !params.isEmpty()) { for (int i = 0; i < params.size(); i++) { pstmt.setObject(index++, params.get(i)); } } resultSet = pstmt.executeQuery(); ResultSetMetaData metaData = resultSet.getMetaData(); int cols_len = metaData.getColumnCount(); while (resultSet.next()) { Map<String, Object> map = new HashMap<String, Object>(); for (int i = 0; i < cols_len; i++) { String cols_name = metaData.getColumnName(i + 1); Object cols_value = resultSet.getObject(cols_name); if (cols_value == null) { cols_value = ""; } map.put(cols_name, cols_value); } list.add(map); } return list; } /** * 释放资源 */ public void releaseConn() { if (resultSet != null) { try { resultSet.close(); } catch (SQLException e) { e.printStackTrace(); } } if (pstmt != null) { try { pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if (connection != null) { try { connection.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void main(String[] args) { JdbcUtil jdbcUtil = new JdbcUtil(); jdbcUtil.getConnection(); try { List<Map<String, Object>> result = jdbcUtil.findResult( "select * from t_student", null); for (Map<String, Object> m : result) { System.out.println(m); } } catch (SQLException e) { e.printStackTrace(); } finally { jdbcUtil.releaseConn(); } }}//////////////////////////////////////////////////////////////package com.imooc.page.util;import java.util.regex.Matcher;import java.util.regex.Pattern;public class StringUtil { /** * 校验字符串是否是大于0的数字 * @param string * @return */ public static boolean isNum(String string){ Pattern pattern = Pattern.compile("[1-9]{1}\\d*"); Matcher matcher = pattern.matcher(string); return matcher.matches(); }}(三)在page项目文件夹下创建一个config文件夹，在config文件夹下创建jdbc.properties文件。
jdbc.username=rootjdbc.password=rootjdbc.driver=com.mysql.jdbc.Driverjdbc.url=jdbc:mysql://127.0.0.1:3306/imooc(四)在WebContext文件夹下创建sublist文件夹，在sublist文件夹下创建jsp页面。
<%@ 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"><%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>学生信息</title></head><% // 获取请求的上下文 String context = request.getContextPath();%><script type="text/javascript">// 当前第几页数据var currentPage = ${result.currentPage};// 总页数var totalPage = ${result.totalPage};function submitForm(actionUrl){ var formElement = document.getElementById("stuForm"); formElement.action = actionUrl; formElement.submit();}// 第一页function firstPage(){ if(currentPage == 1){ alert("已经是第一页数据"); return false; }else{ submitForm("<%=context %>/sublist/SublistServlet?pageNum=1"); return true; }}// 下一页function nextPage(){ if(currentPage == totalPage){ alert("已经是最后一页数据"); return false; }else{ submitForm("<%=context %>/sublist/SublistServlet?pageNum=" + (currentPage+1)); return true; }}// 上一页function previousPage(){ if(currentPage == 1){ alert("已经是第一页数据"); return false; }else{ submitForm("<%=context %>/sublist/SublistServlet?pageNum=" + (currentPage-1)); return true; }}// 尾页function lastPage(){ if(currentPage == totalPage){ alert("已经是最后一页数据"); return false; }else{ submitForm("<%=context %>/sublist/SublistServlet?pageNum=${result.totalPage}"); return true; }}function initPage(){ var genderRequest = "${gender}" ; var genderVal = 0; var genderElement = document.getElementById("gender"); if(genderRequest != ""){ genderVal = parseInt(genderRequest); } var options = genderElement.options; var i = 0; for(i = 0; i < options.length; i++){ if(options[i].value == genderVal){ options[i].selected=true; break; } }}</script><body onload="initPage();"> <div style="margin-left: 100px; margin-top: 100px;"> <div> <font color="red">${errorMsg }</font> </div> <div> <form action="<%=context %>/sublist/SublistServlet" id="stuForm" method="post"> 姓名 <input type="text" name="stuName" id="stu_name" style="width:120px" value="${stuName }"> 性别 <select name="gender" id="gender" style="width:80px"> <option value="0">全部</option> <option value="1">男</option> <option value="2">女</option> </select> <input type="submit" value="查询"> </form> </div> <br> 学生信息列表：<br> <br> <!-- 后台返回结果为空 --> <c:if test="${fn:length(result.dataList) eq 0 }"> <span>查询的结果不存在</span> </c:if> <!-- 后台返回结果不为空 --> <c:if test="${fn:length(result.dataList) gt 0 }"> <table border="1px" cellspacing="0px" style="border-collapse: collapse"> <thead> <tr height="30"> <th width="130">姓名</th> <th width="130">性别</th> <th width="130">年龄</th> <th width="190">家庭地址</th> </tr> </thead> <c:forEach items="${result.dataList }" var="student"> <tr> <td><c:out value="${student.stuName }"></c:out></td> <td> <c:if test="${ student.gender eq 1}">男</c:if> <c:if test="${ student.gender eq 2}">女</c:if> </td> <td><c:out value="${student.age }"></c:out></td> <td><c:out value="${student.address }"></c:out></td> </tr> </c:forEach> </table> <br> 共${result.totalRecord }条记录共${result.totalPage }页 当前第${result.currentPage }页 <a href="#" onclick="firstPage();">首页</a> <a href="#" onclick="nextPage();">下一页</a> <a href="#" onclick="previousPage();">上一页</a> <a href="#" onblur="lastPage();">尾页</a> </c:if> </div></body></html>(五)在WEB-INF文件夹下创建一个lib文件夹导入相关jar包。
(六)在WEB-INF文件夹下创建一个web.xml配置文件
<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>pager</display-name> <filter> <filter-name>EncodingFilter</filter-name> <filter-class>com.imooc.page.EncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>*</url-pattern> </filter-mapping> <servlet> <servlet-name>SublistServlet</servlet-name> <servlet-class>com.imooc.page.servlet.SublistServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>SublistServlet</servlet-name> <url-pattern>/sublist/SublistServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>(七)创建数据库
CREATE TABLE `t_student` ( `id` int(11) NOT NULL AUTO_INCREMENT, `stu_name` varchar(16) NOT NULL, `gender` int(11) DEFAULT NULL, `age` int(11) DEFAULT NULL, `address` varchar(128) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8;-- Records of t_student-- ----------------------------INSERT INTO `t_student` VALUES ('1', '王小军', '1', '17', '北京市东城区');INSERT INTO `t_student` VALUES ('2', '李雷雷', '1', '16', '北京市朝阳区');INSERT INTO `t_student` VALUES ('3', '张静', '2', '16', '北京市昌平区');INSERT INTO `t_student` VALUES ('4', '王晓萌', '2', '17', '北京市顺义区');INSERT INTO `t_student` VALUES ('5', '韩梅梅', '2', '16', '北京市朝阳区');INSERT INTO `t_student` VALUES ('6', '李小军', '1', '17', '北京市海淀区');INSERT INTO `t_student` VALUES ('7', '成龙', '1', '16', '北京市石景山区');INSERT INTO `t_student` VALUES ('8', '李海飞', '2', '16', '北京市海淀区');INSERT INTO `t_student` VALUES ('9', '罗红', '2', '16', '北京市朝阳区');INSERT INTO `t_student` VALUES ('10', '孙海杰', '1', '16', '北京市石景山区');INSERT INTO `t_student` VALUES ('11', '王海龙', '1', '16', '北京市东城区');(八)演示结果
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