javaweb分页原理详解

本文实例为大家分享了javaweb分页原理的具体实现代码，供大家参考，具体内容如下

public class page {
  private int currentpage;
  private int totalpage;
  private int count;
  private int pagesize;
  private list<product> list;
  private string category;
  
 } 

servlet：

package com.learning.web.servlet;

import java.io.ioexception;
import java.util.list;

import javax.enterprise.inject.new;
import javax.servlet.servletexception;
import javax.servlet.annotation.webservlet;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

import com.learning.domain.page;
import com.learning.domain.product;
import com.learning.service.productservice;


@webservlet("/showproductbypage")
public class showproductbypage extends httpservlet {
 private static final long serialversionuid = 1l;
  
 
 protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
   int currentpage=1;
   int pagesize=4;
   //第一次取为空
   string currentpagestring=request.getparameter("currentpage");
   if (currentpagestring!=null) {
    currentpage=integer.parseint(currentpagestring);
   }
   string category = request.getparameter("category");
   if ("".equals(category)) {
    category=null;
   } 
   productservice productservice=new productservice();
   page page=productservice.showproductbypage(currentpage,pagesize,category);
   request.setattribute("page", page);
   request.getrequestdispatcher("/product_list.jsp").forward(request, response);
 }
 protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
  doget(request, response);
 }

}

service：

public page showproductbypage(int currentpage, int pagesize, string category) {
  try {
   page page=new page();
   int count=productdao.count(category);
   page.setcount(count);
   page.setlist(productdao.findproductsbypage(currentpage,pagesize,category));
   int totalpage=(int) math.ceil(1.0*count/pagesize);
   page.setpagesize(pagesize);
   page.setcurrentpage(currentpage);
   page.settotalpage(totalpage);
   page.setcategory(category);
   return page;
  } catch (sqlexception e) {
   e.printstacktrace();
  }
  return null;
 }

dao：

 public int count(string category) throws sqlexception {
  queryrunner queryrunner=new queryrunner(c3p0util.getdatasource());
  string sql=" select count(*) from products ";
  if (category!=null) {
   sql+=" where category='"+category+"'";
  }
  long l= (long)queryrunner.query(sql, new scalarhandler(1));
  return (int) l;
 }



 public list<product> findproductsbypage(int currentpage, int pagesize, string category) throws sqlexception {
  queryrunner queryrunner=new queryrunner(c3p0util.getdatasource());
  string sql=" select * from products ";
  if (category!=null) {
   sql+=" where category='"+category+"'";
  }
  sql+=" limit ?,?";
  return queryrunner.query(sql, new beanlisthandler<product>(product.class),(currentpage-1)*pagesize,pagesize);
 }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。