java web实现分页查询实例方法

2019-11-26 09:37:23

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Javaweb分页技术实现

分页技术就是通过SQL语句(如下)来获取数据，具体实现看下面代码

//分页查询语句select * from 表名 where limit page , count;和//获取表中的总数据，确定页数select count(*) from 表名;

不说废话直接上代码

前端代码：

<!DOCTYPE html><html><head> <meta charset="UTF-8"> <title>Title</title> <script src="js/jquery-3.3.1.js"></script> <link rel="stylesheet" href="css/bootstrap.min.css" rel="external nofollow" ></head><body> <div> <div class="row clearfix">  <div class="col-md-12 column">   <table class="table table-bordered table-hover">    <thead>    <tr>     <th>City_ID</th>     <th>City_EN</th>     <th>City_CN</th>     <th>Country_code</th>     <th>Country_EN</th>     <th>Country_CN</th>     <th>Province_EN</th>     <th>Province_CN</th>    </tr>    </thead>    <tbody id="tbody">     </tbody>   </table>   <!--分页-->   第<span id="paging">1</span>页/   共<span id="countPage">1</span>页/   <a id="homePage">Home</a>/   <a id="prevPage">Prev</a>/   <a id="nextPage">Next</a>/   转到第：   <input type="text" style="width: 2em" id="pageNum">   页   <a id="goPage">Go</a>    </div> </div></div></body><script> $(function () {  //页面初始化 （显示第一页）  selectPage(1);  home();  prev();  next();  goPage(); }) function selectPage(pageCode) {  //分页查询 pageCode：页数  $.ajax("getCity",{   type:"get",   data:{"currenPage":pageCode},   success:function (data) {    $("#tbody").html("");    //总页数    $("#countPage").text(data.totalPage);     $.each(data.pageData,function (index,obj) {     var clazz="";     if(index%2==0){      clazz="success";     }     $("#tbody").append(      "<tr class='"+clazz+"'>/n" +      "<td>"+obj.cityId+"</td>/n" +      "<td>"+obj.cityEn+"</td>/n" +      "<td>"+obj.cityCn+"</td>/n" +      "<td>"+obj.countryCode+"</td>/n" +      "<td>"+obj.countryEn+"</td>/n" +      "<td>"+obj.countryCn+"</td>/n" +      "<td>"+obj.provinceEn+"</td>/n" +      "<td>"+obj.provinceCn+"</td>/n" +      "</tr>"     );    })    }  }); } //第一页 function home() {  $("#homePage").on("click",function () {   $("#paging").text(1);   selectPage(1);  }) }  //上一页 function prev() {  $("#prevPage").on("click",function () {   var prevText=$("#paging").text();   var prevNum=parseInt(prevText);   prevNum=prevNum-1;   if(prevNum<=1){    selectPage(1);    $("#paging").text(1);    return;   }   $("#paging").text(prevNum);   selectPage(prevNum);  }) } //下一页 function next() {  $("#nextPage").on("click",function () {   //获取文本的值 页数   var prevText=$("#paging").text();   //类型转换   var prevNum=parseInt(prevText);   //总页数   var countText=$("#countPage").text();   //类型转换   var countNum = parseInt(countText);   //页数加1   prevNum=prevNum+1;   //判断超出了总页码   if(prevNum>=countNum){    selectPage(countNum);    $("#paging").text(countNum);    return;   }   //设置网页增加的值   $("#paging").text(prevNum);   //调用分页查询   selectPage(prevNum);  }) } //去到几页 function goPage() {  $("#goPage").on("click",function () {   var pageNum=parseInt($("#pageNum").val());   var countPage=parseInt($("#countPage").text())   //判断超出了总页码   if(pageNum>=countPage){    selectPage(countPage);    $("#paging").text(countPage);    $("#pageNum").val(countPage);    return;   }   //判断低于了总页码   if(pageNum<=1){    selectPage(1);    $("#paging").text(1);    $("#pageNum").val(1);    return;   }   selectPage(pageNum);   $("#paging").text(pageNum);  }) } </script></html>

后台servlet代码：

/** * @author hh * @Date 2018/9/12 */@WebServlet("/getCity")public class PageServlet extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {  //获取当前页参数，第一次访问为空  String currPage = req.getParameter("currenPage");  // 判断，如果为空，则设置为1  if (currPage == null || "".equals(currPage.trim())) {   currPage = "1";  }  //调用service返回分页类实例  PageBean<City> pageBean=new PageService().getPage(currPage);  //设置相应文本类型  resp.setContentType("application/json;charset=utf-8");  //响应前端  resp.getWriter().print(new Gson().toJson(pageBean)); }}

City 实体类：

package edu.nf.demo.entity; /** * @author hh * @Date 2018/9/12 */public class City { private String cityId; private String cityEn; private String cityCn; private String countryCode; private String countryEn; private String countryCn; private String provinceEn; private String provinceCn; public String getCityId() {  return cityId; } public void setCityId(String cityId) {  this.cityId = cityId; } public String getCityEn() {  return cityEn; } public void setCityEn(String cityEn) {  this.cityEn = cityEn; }  public String getCityCn() {  return cityCn; } public void setCityCn(String cityCn) {  this.cityCn = cityCn; } public String getCountryCode() {  return countryCode; } public void setCountryCode(String countryCode) {  this.countryCode = countryCode; } public String getCountryEn() {  return countryEn; } public void setCountryEn(String countryEn) {  this.countryEn = countryEn; } public String getCountryCn() {  return countryCn; }  public void setCountryCn(String countryCn) {  this.countryCn = countryCn; }  public String getProvinceEn() {  return provinceEn; }  public void setProvinceEn(String provinceEn) {  this.provinceEn = provinceEn; }  public String getProvinceCn() {  return provinceCn; }  public void setProvinceCn(String provinceCn) {  this.provinceCn = provinceCn; }}

自己写的一个类，专门用于分页查询用的：

package edu.nf.demo.entity; import java.util.List; /** * @author hh * @Date 2018/9/12 */public class PageBean<T> { /**  * 当前页， 默认显示第一页  */ private Integer currntPage = 1; /**  * 查询返回的行数（每页显示的行数），默认每页显示10行  */ private int pageCount = 10; /**  * 总记录数  */ private int totalCount; /**  * 总页数 = 总记录数/每页显示的行数（+1）  */ private int totalPage; /**  * 分页查询的数据,运用泛型，可以重复利用  */ private List<T> pageData;  public int getTotalPage() {  if (totalCount % pageCount == 0) {   totalPage = totalCount / pageCount;  } else {   totalPage = totalCount / pageCount + 1;  }  return totalPage; }  public void setTotalPage(int totalPage) {  this.totalPage = totalPage; }  public int getCurrntPage() {  return currntPage; }  public void setCurrntPage(int currntPage) {  this.currntPage = currntPage; }  public int getPageCount() {  return pageCount; }  public void setPageCount(int pageCount) {  this.pageCount = pageCount; }  public int getTotalCount() {  return totalCount; }  public void setTotalCount(int totalCount) {  this.totalCount = totalCount; }   public List<T> getPageData() {  return pageData; }  public void setPageData(List<T> pageData) {  this.pageData = pageData; }}

后台service，逻辑业务层：

/** * @author hh * @Date 2018/9/12 */public class PageService {  public PageBean getPage(String currPage){  //类型转换 当前页数  Integer currenPage = Integer.valueOf(currPage);  //实例化分页类  PageBean<City> pageBean = new PageBean();  //实例化CityDaoImpl类  CityDaoImpl cityDao=new CityDaoImpl();   //数据库第几行开始查询  int startPage=(currenPage-1)*pageBean.getPageCount();  //查询多少行数据 分页类里默认30行  int selectCount=pageBean.getPageCount();  //查询数据库获取分页返回的数据 : select * from regional_info limit startPage,selectCount  List<City> list=cityDao.listCity(startPage,selectCount);  //获取总数  int cityCount=cityDao.getCityCount();  //设置查询的数据  pageBean.setPageData(list);  //共多少行  pageBean.setTotalCount(cityCount);  //设置总页数  pageBean.setTotalPage(cityCount/pageBean.getPageCount()+1);  return pageBean; }}

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