运用EasyUI中datagrid读取数据库数据实现分页

Posted 2020-08-21 丶疏影横斜

1dao层

package com.hanqi.dao;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import com.han.entity.Student;

public class StudentDAO {

    //定义变量
    Configuration cfg = null ;
    ServiceRegistry sr = null ;
    SessionFactory sf = null ; 
    Session se = null ;
    Transaction ts = null ;
    
    //构造方法    
    public StudentDAO()
    {
        //1获取配置文件 
        cfg = new Configuration().configure() ;
        
        //2注册配置  
        sr = new StandardServiceRegistryBuilder().
                                            applySettings(cfg.getProperties()).build();
        
    }
    
    //初始化方法
    private void init()
    {
        //3获取SessionFactory
        sf = cfg.buildSessionFactory(sr) ;
        
        //4产生Session
        se =sf.openSession() ;
        
        //5启动事务
        ts = se.beginTransaction() ;
    }
    
    //关闭释放资源
    private void destroy()
    {
        ts.commit();  //提交事务
        
        se.close() ;//关闭释放资源
        
        sf.close();//关闭释放资源
    }
    
    //获取分页数据集合
    public List<Student> getPageList(int page, int rows)
    {
        List<Student> list = new ArrayList<>() ;//定义list变量并实例化
        
        init() ;//初始化方法
        
        list = se.createQuery("from Student")
                     .setMaxResults(rows)//每页行数
                     .setFirstResult((page-1)*rows)//起始页码
                     .list() ;
        
        destroy() ;//关闭释放资源
        
        return list ;//返回该集合
    }
    
    
    //获取数据条数
    public int getTotal()
    {
        int rtn = 0 ;//定义变量并赋值
        
        init() ;//初始化方法
        
        Query qu = se.createQuery("select count(1) from Student ") ;//获取Query对象
        
        List<Object> list = qu.list() ;//定义list变量并实例化
        
        if(list != null && list.size() > 0 )//判断获取的集合非空及长度
        {
            rtn = Integer.parseInt(list.get(0).toString()) ;//给变量rtn赋值
        }
        
        destroy();//关闭并释放资源
         
        return rtn ;//返回变量值
    }
}

2service层

package com.hanqi.service;

import java.util.List;

import com.alibaba.fastjson.JSONArray;
import com.han.entity.Student;
import com.hanqi.dao.StudentDAO;

public class StudentService {
    
    //查询分页数据，并返回JSON
    public String getPageJSON(int page, int rows)
    {
        String rtn = "{\'total\':0,\'rows\':[ ]}" ;
        
        int total =  new StudentDAO().getTotal() ;
        
        if(total > 0)
        {
            List<Student> list =  new StudentDAO().getPageList(page, rows) ;
            
            //将List集合转为JSON集合
            String json_list = JSONArray.toJSONString(list) ;
            
            //转义字符返回复合类型的JSON字符串
            rtn =  "{\\"total\\":"+total+",\\"rows\\":"+json_list+"}" ;
        }
        
        return rtn ;
    }
}

3servlet

package com.hanqi.web;

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.hanqi.service.StudentService;

/**
 * Servlet implementation class StudentServlet
 */
public class StudentServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public StudentServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html");
        
        //接收请求
            //1每页行数
        String rows = request.getParameter("rows") ;
        
            //2页码
        String page = request.getParameter("page") ;
        
        //System.out.println("rows = "+ rows );
        //System.out.println("page = " + page );
        if(page != null && rows != null)
        {
            int rowss = Integer.parseInt(rows) ;
            
            int pagess = Integer.parseInt(page) ;
             
            String json_list = new StudentService().getPageJSON(pagess, rowss) ;
            //返回数据
            System.out.println(json_list);
            response.getWriter().write(json_list) ;
        }
        else
        {
            response.getWriter().write("{total:0,rows:[]}") ;
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

4html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<!-- 1    jQuery的js包 -->
<script type="text/javascript" src="jquery-easyui-1.4.4/jquery.min.js"></script>

<!-- 2    css资源 -->
<link rel="stylesheet" type="text/css" href="jquery-easyui-1.4.4/themes/default/easyui.css">

<!-- 3    图标资源 -->
<link rel="stylesheet" type="text/css" href="jquery-easyui-1.4.4/themes/icon.css"> 

<!-- 4    EasyUI的js包 -->
<script type="text/javascript" src="jquery-easyui-1.4.4/jquery.easyui.min.js"></script>
 
<!-- 5    本地语言 -->
<script type="text/javascript" src="jquery-easyui-1.4.4/locale/easyui-lang-zh_CN.js"></script>

</head>
<body>
<script type="text/javascript">
$(function(){
$(\'#dg\').datagrid({    
    url:\'StudentServlet\',    
    columns:[[    
        {field:\'sno\',title:\'课程号\',width:100},    
        {field:\'sname\',title:\'姓名\',width:100},    
        {field:\'ssex\',title:\'性别\',width:100,align:\'right\'},
        {field:\'sbirthday\',title:\'生日\',width:100,align:\'right\'},
        {field:\'sclass\',title:\'班级\',width:100,align:\'right\'} 
    ]],
    pagination:true,//分页
    fitColumns:true,//列自适应宽度
});  
})
</script>
<table id="dg"></table>  
</body>
</html>