源码 点击打开链接
其他web项目传送门 http://blog.csdn.net/u011299745/article/details/53547279
有一个学生表，可以通过姓名进行模糊查找，或者性别查找。
使用subList()实现,步骤（MVC）：
- （M）根据查询条件生成有一定信息的Student对象，查询出所有符合条件的学生，所有信息存储在List<Map<k,v>>中。
- 遍历结果，用Map<k,v>来实例化Student，所有符合条件的学生，存入List<Student>。（这个List就是通过输入条件查找到的所有结果，结果可能太多所以需要分页显示）
- 用上一步的List，和每页大小（pageSize）、当前页（pageNum）实例化一个Pager对象。Pager对象包含总页数，总条数，当前页，每页大小，当前页显示的对象（使用List.subList()来截取）。用传入的参数可以计算出来。
- (C)在servlet中初始化参数，实现上面的步骤，将结果Pager对象存成一个属性，jsp中可以使用。同时存入查询条件，方便下页等标签使用。
- （V）Jsp界面中可以通过EL表达式，取得上一步存入的结果，显示。下一页等标签可以使用js或者url传值，主要是pageNum+1，还有上次查询的条件。点击跳转到servlet，根据同样的查询条件和pageNum，计算新的Pager对象，在jsp显示。
核心代码：
//JdbcUtil.java jdbc工具包，有查询、更新、释放
package com.xf.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;
/**
* @author XF
* JDBC工具类
*/
public class JdbcUtil {
private static String USERNAME;
private static String PASSWORD;
private static String DRIVER;
private static String URL;
private Connection connection;
private PreparedStatement pstmt;
private ResultSet resultSet;
static{
loadConfig();
}
/**
* 加载数据库配置信息,并给相关的属性赋值
*/
public static void loadConfig(){
USERNAME = "root";
PASSWORD = "root";
DRIVER = "com.mysql.jdbc.Driver";
URL = "jdbc:mysql://localhost:3306/page"; //根据项目选择dataBase
}
public JdbcUtil() {
}
public Connection getConnection() {
try {
Class.forName(DRIVER);
connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
} catch (Exception e) {
throw new RuntimeException("get connection error!");
}
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();
}
}
}
}
//SublistStudentDaoImpl.java 查询满足条件的对象，并传入参数，生成Pager对象，即结果
package com.xf.page.dao;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.xf.page.model.Pager;
import com.xf.page.model.Student;
import com.xf.page.util.JdbcUtil;
public class SublistStudentDaoImpl implements StudentDao {
//调用方法getAllStudent，然后根据传入的参数，生成Pager对象，即结果。
@Override
public Pager<Student> findStudent(Student searchModel, int pageNum,
int pageSize) {
// TODO Auto-generated method stub
List<Student> allStudents = getAllStudent(searchModel);
Pager<Student > pager = new Pager<Student>(pageNum, pageSize, allStudents);
System.out.println("DaoImpl: pageNum= "+pageNum);
return pager;
}
//查找所有满足条件的对象
private List<Student> getAllStudent(Student searchModel){
List<Student> result = new ArrayList<Student>();
List<Object> paramList = new ArrayList<Object>();
String stuName = searchModel.getName();
// System.out.println("impl : name: "+stuName);
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();
List<Map<String, Object>> mapList = jdbcUtil.findResult(sql.toString(), paramList);
if(mapList != null){
for(Map<String, Object> map:mapList){
Student s = new Student(map);
// System.out.println("name: "+s.getName());
result.add(s);
}
}
} catch (SQLException e) {
// TODO Auto-generated catch block
throw new RuntimeException("查询所有数据异常!",e);
}finally{
if(jdbcUtil != null){
jdbcUtil.releaseConn();
}
}
return result;
}
}
</pre><pre name="code" class="java">//Pager.java <span style="font-family: Arial, Helvetica, sans-serif;">根据传入参数实例化Pager对象，计算相应的信息</span>
package com.xf.page.model;
import java.io.Serializable;
import java.util.List;
public class Pager<T> implements Serializable {
/**
*
*/
private static final long serialVersionUID = -1380898667849848066L;
private int pageSize;
private int currentPage;
private int totalRecord;//一共多少条记录
private int totalPage;
private List<T> dataList;
//根据传入参数实例化Pager对象，计算相应的信息以及结果dataList
public Pager(int pageNum, int pageSize, List<T> sourceList){
if(sourceList == null) return;
this.totalRecord = sourceList.size();
this.pageSize = pageSize;
this.totalPage = this.totalRecord / this.pageSize;
//非整除+1
if(this.totalRecord % this.pageSize != 0) this.totalPage +=1;
//当前第几页,大于总页数则赋值为总页数，小于1则赋值为1
if(this.totalPage < pageNum){
this.currentPage = this.totalPage;
}else{
this.currentPage = pageNum;
}
if(this.currentPage < 1) this.currentPage =1;
int fromIndex = this.pageSize * (this.currentPage -1);
int toIndex = this.pageSize * this.currentPage > this.totalRecord? this.totalRecord: this.pageSize * this.currentPage;
this.dataList = sourceList.subList(fromIndex, toIndex);
}
public Pager() {
super();
}
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;
}
public static long getSerialversionuid() {
return serialVersionUID;
}
}
//SublistServlet.java
package com.xf.page.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.xf.page.dao.Constant;
import com.xf.page.model.Pager;
import com.xf.page.model.Student;
import com.xf.page.service.StudentService;
import com.xf.page.service.SublistStudentServiceImpl;
public class SublistServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = -5459092412782251847L;
private StudentService studentService = new SublistStudentServiceImpl();
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
//请求中含有中文，讲req编码设置为utf-8
req.setCharacterEncoding("utf-8");
//接受request参数,先赋值为默认值，避免为null，发生error
String name = req.getParameter("name");
System.out.println("servlet : name: "+name);
//
int gender = Constant.DEFAULT_GENDER;
String genderStr = req.getParameter("gender");
if(genderStr != null && !("".equals(genderStr.trim()))){
gender = Integer.parseInt(genderStr);
}
//
int pageNum = Constant.DEFAULT_PAGE_NUM;
String pageNumStr = req.getParameter("pageNum");
if(pageNumStr != null && !("".equals(pageNumStr.trim()))){
pageNum = Integer.parseInt(pageNumStr);
}
//
int pageSize = Constant.DEFAULT_PAGE_SIZE;
String pageSizeStr = req.getParameter("pageSize");
if(pageSizeStr != null && !("".equals(pageSizeStr.trim()))){
pageSize = Integer.parseInt(pageSizeStr);
}
//组装查询条件
Student searchModel = new Student();
searchModel.setName(name);
searchModel.setGender(gender);
//查询结果
Pager<Student> result = studentService.findStudent(searchModel, pageNum, pageSize);
//存储返回的结果
req.setAttribute("result", result);
//存储查询信息，为下页，上页等标签保留查询信息
req.setAttribute("name", name);
req.setAttribute("gender", gender);
req.getRequestDispatcher("/sublistStudent.jsp").forward(req, res);
}
}
//sublistStudent.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>学生信息</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<style type="text/css">
</style>
<%
String context = request.getContextPath();
%>
</head>
<body>
<h2>学生信息</h2>
<div>
<form action="<%=context%>/servlet/sublistServlet" id= "stuForm" method="post">
姓名
<input type='text' name="name" id="name" >
性别
<select name="gender" id="gender">
<option value="-1">全部</option>
<option value="1">男</option>
<option value="2">女</option>
</select>
<input type="submit" value="查询">
</form>
</div>
<div>
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;>
<tr height="30" >
<th width="130">姓名</th>
<th width="130">性别</th>
<th width="130">年龄</th>
<th width="230">家庭住址</th>
</tr>
<c:forEach items="${result.dataList }" var="student">
<tr>
<td><c:out value="${student.name }"></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${result.currentPage}页
<a href="servlet/sublistServlet?pageNum=1&name=${name}&gender=${gender}" >首页</a>
<!-- 这类标签必须带有查询信息 -->
<a href="servlet/sublistServlet?pageNum=${result.currentPage+1 }&name=${name}&gender=${gender}" >下一页</a>
<a href="servlet/sublistServlet?pageNum=${result.currentPage-1 }&name=${name}&gender=${gender}" >上一页</a>
<a href="servlet/sublistServlet?pageNum=${result.totalPage }&name=${name}&gender=${gender}" >尾页</a>
</c:if>
</div>
</body>
</html>