java web如何实现分页查询 java web实现分页查询实例方法

时间:2021-03-30 人气:0

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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