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利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解

程序员文章站 2024-02-22 10:34:46
前言 因为最近没什么事,所以想着写一个分页的例子出来给大家分享一下。这个案例分前端和后台两部分,前端使用面向对象的方式写的,里面用到了一些回调函数和事件代理,有兴趣的朋友...

前言

因为最近没什么事,所以想着写一个分页的例子出来给大家分享一下。这个案例分前端和后台两部分,前端使用面向对象的方式写的,里面用到了一些回调函数和事件代理,有兴趣的朋友可以研究一下。后台的实现技术是将分页pager作为一个实体对象放到domain层,当前页、单页数据量、当前页开始数、当前页结束数、总数据条数、总页数都作为成员属性放到实体类里面。

以前项目数据库用的是oracle,sql语句的写法会从当前页开始数到当前页结束数查询数据。刚刚在这纠结了很长时间,查询到的数据显示数量总是有偏差,后来发现mysql的语句limit用的是当前页开始数到查询的条数,the fuck,我还一直以为它也是到当前页结束数呢。下面话不多说了,来一起看看详细的实现过程吧:

第一步,搭建这个小案例,引入spring和mybtis的jar包,配置对应的配置文件:

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解  

第二步,前端页面和数据的处理:

页面布局很简单。我将table和pager单独作为对象来处理,各自处理各自该干的事情,做到了很好的封装处理。个人认为这两个js和java的类很相似。

其它的地方都是按照正常分页的流程走的,话不多说,看看代码吧。 

<%@ page language="java" import="java.util.*" pageencoding="utf-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
 <head>
 <style>
  .hide{display:none}
  .mypager{height:40px;border-bottom:1px solid #eee;}
 .mypager .pagerrow{width:100%;float:left;height:30px;margin-top:10px;}
 .mypager .showpage{width:100%;float:left;height:30px;margin-top:10px;text-align: left;}
 .mypager .showpage .numdiv{display:inline-block;}
 .mypager .showpage .tobtn{color:#fff;font-size:20px;}
 .mypager .showpage .disable{background-color: #c9c9c9;}
 .mypager .showpage .nable{background-color:rgb(10%,65%,85%);cursor:default;}
 .mypager .showpage .numdiv .disable{color:#777;}
 .mypager .showpage .numdiv .nable{color:#fff;}
 .mypager .showpage .cursor_default{cursor:default;}
 .mypager .showpage .cursor_pointer{cursor:pointer;}
 .showpage span{display: inline-block;padding: 0px 0px 1px 1px;margin-left:5px;
  width: 21px;height: 21px;border-radius: 12px;line-height: 22px;font-size: 12px;
  text-align: center;overflow: hidden;}
 </style>
 <script type="text/javascript" src="<c:url value='/res/jquery.js'/>"></script>
 <script type="text/javascript" src="<c:url value='/res/mypager.js'/>"></script>
 <script type="text/javascript" src="<c:url value='/res/mytable.js'/>"></script>
 <script>
 $(function(){
  var $btn = $(".sub_btn");
  $btn.click(function(){
  $(this).addclass("hide");
  new mytable("employeetab","<c:url value='/mam/querylistpage'/>");
  })
 })
 </script>
 </head>
 
 <body>
 <div class="wrap">
  <table class="employeetab">
  <tr>
   <th>id</th>
   <th>姓名</th>
   <th>年龄</th>
   <th>性别</th>
  </tr>
  </table>
  <button class="sub_btn">显示数据</button>
 </div>
 </body>
</html>

页面引入了mypager.js和mytable.js,mypager这套东西是封装的比较好的,有兴趣的朋友可以直接拿去用。现在插件满天飞,自己造的*肯定会逊色很多,但是这里涉及到js很多基础的知识点,初学的朋友可以当做学习参考使用;

pager.getspan = function(value,classname){
 return $("<span class='"+classname+"'>"+value+"</span>");
}
function pager($parent){
 this.$parent = $parent;
 this.pagecallback = $.noop;
 this.preval = "<";
 this.nextval = ">";
 this.splitchar = "…";
 this.init();
 this.spacestep = 2;
}
pager.prototype.setpagecallback = function(pagecallback){
 this.pagecallback = pagecallback;
 return this;
}
pager.prototype.init = function(){
 if(this.$parent.length == 0){
 alert("pagediv not exists ");
 }
 this.$divrow = $("<div class='pagerrow'></div>").appendto(this.$parent);
 this.$div = $("<div class='showpage'>").appendto(this.$parent);
}
pager.prototype.clear = function(){
 this.$div.empty();
 this.$divrow.empty();
}
pager.prototype.addspan = function(value,classname){
 var $span = pager.getspan(value,classname).appendto(this.$numdiv);
 $span.css("width",this.getspanwidth(value)+"px");
 return $span;
}
pager.prototype.getspanwidth = function(value){
 var width = 21;
 var curneed = 0;
 if(!isnan(value)){
 curneed = value.tostring().length * 8;
 }
 return curneed>width?curneed:width;
}
pager.prototype.disable = function($span,flag){
 var removeclass = flag?"nable cursor_pointer":"disable cursor_default";
 var addclass = flag?"disable cursor_default":"nable cursor_pointer";
 $span.removeclass(removeclass).addclass(addclass);
 return $span;
}
pager.prototype.show = function(pagecount,curpage,rowcount){
 alert(0)
 this.clear();
 this.$divrow.html("  共有"+pagecount+"页,"+rowcount+"条数据");
 pagecount = pagecount?pagecount-0:0;
 if(pagecount<=0){
 return;
 }
 var self = this;
 this.$prev = pager.getspan(this.preval,"tobtn").appendto(this.$div);
 this.$numdiv = $("<div class='numdiv'></div>").appendto(this.$div);
 this.$nextval = pager.getspan(this.nextval,"tobtn").appendto(this.$div);
 curpage = curpage?curpage-0:1;
 curpage = curpage<1?1:curpage;
 curpage = curpage>pagecount?pagecount:curpage;
 this.disable(this.$prev,curpage == 1);
 if(curpage>1){
 this.$prev.click(function(){
  self.pagecallback(curpage-1);
  });
 }
 this.disable(this.$nextval,curpage == pagecount);
 if(curpage<pagecount){
 this.$nextval.click(function(){
  self.pagecallback(curpage+1);
  });
 }
 var steps = this.getsteps(pagecount,curpage);
 for(var i in steps){
 if(i == curpage){
  this.addspan(steps[i],"nable");
  continue;
 }
 if(steps[i] == this.splitchar){
  this.addspan(steps[i]);
  continue;
 }
 
 this.addspan(steps[i],"disable").hover($.proxy(this.mouseover,this),$.proxy(this.mouseout,this))
  .click(function(){
  alert(0)
  self.pagecallback($(this).html());
  });
 }
}
pager.prototype.mouseout = function(e){
 var $span = $(e.target);
 this.disable($span,true);
}
pager.prototype.mouseover = function(e){
 var $span = $(e.target);
 this.disable($span,false);
}
pager.prototype.getsteps = function (pagecount,curpage){
 var steps = {};
 var curstar = curpage-3;
 var curend = curpage+3;
 for(var i=1;i<=pagecount;i++){
 if((i>this.spacestep && i<curstar)||(i>curend && i<pagecount-1)){
  continue;
 }
 if((i==curstar && i>this.spacestep) || (i==curend && i<pagecount-1)){
  steps[i]=this.splitchar;
  continue;
 }
 steps[i]=i;
 }
 return steps;
}

下面是mytable的实现代码:

function mytable(tabname,url){
 this.$tab = $("."+tabname);
 this.$wrap = this.$tab.parent();
 this.queryurl = url;
 this.querydata = null;
 this.pager = null;
 this.init();
}
mytable.prototype.init = function(){
 this.pager = new pager($("<div class='mypager'><div>").insertafter(this.$wrap))
  .setpagecallback($.proxy(this.gotopage,this));
 this.gotopage(1);
}

mytable.prototype.gotopage = function(curpage){
 if(curpage){
 this.querydata = {"curpage":curpage};
 }
 $.post(this.queryurl,this.querydata,$.proxy(this.show,this),"json");
}

mytable.prototype.show = function(data){
 this.clear();
 var list = data.list;
 var len = list.length;
 var df = document.createdocumentfragment();
 for(var i=0;i<len;i++){
 var $tr = $("<tr></tr>");
 var $id = $("<td>"+list[i].id+"</td>").appendto($tr);
 var $name = $("<td>"+list[i].name+"</td>").appendto($tr);
 var $age = $("<td>"+list[i].age+"</td>").appendto($tr);
 var $sex = $("<td>"+list[i].sex+"</td>").appendto($tr);
 df.appendchild($tr[0]);
 }
 this.$tab[0].appendchild(df);
 this.pager.show(data.pager.pagecount, data.pager.curpage, data.pager.rowcount);
}

mytable.prototype.clear = function(){
 this.$tab.empty();
}

前端页面的处理就是这些,展示效果如下:

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解  

第三步:后台的处理

后台的处理很简单,因为是自己写的数据,所以没有做太复杂的处理,首先我先把数据库的数据贴出来

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解  

一共18条数据,四个字段,id为主键。下面是controller处理前端请求的代码:

package cn.wangze.controller;


import javax.servlet.http.httpservletresponse;

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.requestmapping;

import cn.wangze.domain.employee;
import cn.wangze.domain.pager;
import cn.wangze.service.baseservice;

@controller
@requestmapping("/mam")
public class basecontroller extends supercontroller{
                                
 @autowired
 private baseservice<employee> baseservice;
 
 @requestmapping(value="/querylistpage")
 public void querylistpage(employee employee, pager pager, httpservletresponse response){
 if(employee == null || pager == null){
  senderror("参数错误",response);
 }
 sendjsonpager(pager, baseservice.querylistpage(employee,pager), response);
 }
}

这个页面涉及到了前端返回值得处理,senderror和sendjsonpager方法在它的父类中有声明,代码如下:

public void sendparam(boolean successflag,object key,object value,httpservletresponse response){
 stringbuffer sb = append(null,success,successflag?success:error);
 if(!isempty(key)){
  append(sb,key,value);
 }
 if(!message.equals(key)){
  append(sb,message,successflag?"操作已成功":"操作以失败");
 }
 writejsonbuffer(sb.append("}"),response);
}

public void sendmsg(boolean successflag,string errmsg,httpservletresponse response){
 sendparam(successflag,message,errmsg,response);
}

public void senderror(string msg,httpservletresponse response){
 sendmsg(false,msg,response);
}
public void sendjsonpager(pager pager, list<? extends jsonentity> list, int i, httpservletresponse response){
 stringbuffer sb = append(null, message, "success");
 if(list==null || list.size()==0){
  sendmsg(false, "查无数据", response);
 }else{
  sb.append(",").append(getjsonlist(list,i)).append(pager.tojsonstring());
 }
 sb.append("}");
 logger.debug(sb);
 htmlutil.writer(response, sb.tostring());
 }
 
 public void sendjsonpager(pager pager, list<? extends jsonentity> list, httpservletresponse response){
 sendjsonpager(pager, list, 0, response);
 }

通过上面basecontroller的处理,我们可以看到它调用了baseservice的querylistpager方法,

package cn.wangze.service;

import java.util.list;

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.stereotype.service;

import cn.wangze.domain.pager;
import cn.wangze.mapper.basemapper;

@service
public class baseservice<t> {
 
 @autowired
 private basemapper<t> basemapper;
 
 public pager queryrowcount(t t, pager pager){
 return pager.initrowcount(basemapper.queryrowcount(t));
 }
 
 public list<t> querylistpage(t t, pager pager){
 pager = this.queryrowcount(t,pager);
 if(pager == null) return null;
 return basemapper.querylistpage(t, pager.getpagesize(), pager.getstart());
 }
}

baseservie的queryrowcount方法先查询了一下数据的总条数,然后调用了basemapper的querylistpage方法,我们来看一下:

package cn.wangze.mapper;

import java.util.list;

import org.apache.ibatis.annotations.param;

public interface basemapper<t> {
 public int queryrowcount(t t);
 public list<t> querylistpage(@param("t") t t,@param("end") integer end,@param("start") integer start);
}

这个basemapper对应的是mybatis的xml文件,它负责编写sql语句:

<?xml version="1.0" encoding="utf-8"?>
<!doctype mapper public "-//mybatis.org//dtd mapper 3.0//en" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.wangze.mapper.basemapper">
 <sql id="columnlist">
 id,name,age,sex
 </sql>
 <sql id="columnlist_t" >
 t.id,t.name,t.age,t.sex
 </sql>
 <sql id="valuelist">
 #{id},#{name},#{age},#{sex}
 </sql>
 <sql id="whereclause">
 where 1=1 
 <if test="id!=null and id!=''">and id=#{id}</if>
 <if test="name!=null and name!=''">and name=#{name}</if>
 <if test="age!=null and age!=''">and age=#{age}</if>
 <if test="sex!=null and sex!=''">and sex=#{sex}</if>
 </sql>
 <sql id="whereclause_pager" >
 where 1=1 
 <if test="t.id!=null and t.id!=''">and t.id=#{t.id}</if>
 <if test="t.name!=null and t.name!=''">and t.name=#{t.name}</if>
 <if test="t.age!=null">and t.age=#{t.age}</if>
 <if test="t.sex!=null and t.sex!=''">and t.sex=#{t.sex}</if>
 </sql>
 <sql id="setclause" >
 set 
 <trim suffixoverrides="," >
  <if test="id!=null">id=#{id},</if>
  <if test="name!=null">name=#{name},</if>
  <if test="pid!=null">age=#{age},</if>
  <if test="url!=null">sex=#{sex},</if>
 </trim>
 </sql> 
 <select id="queryrowcount" resulttype="int" parametertype="employee">
 select count(1) from employee <!-- <include refid="whereclause"/>-->
 </select>
 <select id="querylistpage" resulttype="employee">
 <!-- 0-4 3-7 6-10 -->
 select <include refid="columnlist"/> from employee limit #{start},#{end};
 </select>
</mapper>

最后我们看下employee和pager的实体类把:

package cn.wangze.domain;

public class employee extends jsonentity{
 private int id;
 private string name;
 private string age;
 private string sex;
 public int getid() {
 return id;
 }
 public void setid(int id) {
 this.id = id;
 }
 public string getname() {
 return name;
 }
 public void setname(string name) {
 this.name = name;
 }
 public string getage() {
 return age;
 }
 public void setage(string age) {
 this.age = age;
 }
 public string getsalary() {
 return sex;
 }
 public void setsalary(string sex) {
 this.sex = sex;
 }
 @override
 protected void addjsonfields(int i) {
 addfield("id", id).addfield("name",name).addfield("age", age).addfield("sex", sex);
 }
 
 @override
 public string tostring() {
 return "id:"+id+",name:"+name+",age:"+age+",sex:"+sex;
 }
}
package cn.wangze.domain;

public class pager {
 private int curpage = 1;
 private int pagesize = 5;
 private int start = 0;
 private int end = 0;
 private int pagecount;
 private int rowcount;
 public int getcurpage() {
 return curpage;
 }
 public void setcurpage(int curpage) {
 this.curpage = curpage;
 }
 public int getpagesize() {
 return pagesize;
 }
 public void setpagesize(int pagesize) {
 this.pagesize = pagesize;
 }
 public int getstart() {
 return start;
 }
 public void setstart(int start) {
 this.start = start;
 }
 public int getend() {
 return end;
 }
 public void setend(int end) {
 this.end = end;
 }
 public int getpagecount() {
 return pagecount;
 }
 public void setpagecount(int pagecount) {
 this.pagecount = pagecount;
 }
 public int getrowcount() {
 return rowcount;
 }
 public void setrowcount(int rowcount) {
 this.rowcount = rowcount;
 }
 
 public pager initrowcount(int rowcount) {
 if (rowcount == 0) {
  return null;
 }
 int ps = getpagesize();
 if (ps == 0) {
  ps = 5;
 }
 int pc = (rowcount + ps - 1) / ps;//
 int cp = getcurpage();
 cp = cp > pc ? pc : cp;
 cp = cp < 1 ? 1 : cp;
 this.setpagecount(pc);
 this.setcurpage(cp);
 this.setend(cp * ps );
 this.setstart((cp - 1) * ps);
 this.rowcount = rowcount;
 return this;
 }
 
 public stringbuffer tojsonstring() {
 return new stringbuffer(","+"\"pager\":{\"curpage\":\"" + this.curpage
  + "\",\"pagecount\":\"" + this.pagecount + "\",\"rowcount\":\""
  + this.rowcount + "\"}");
 }

 @override
 public string tostring() {
 return "pager [curpage=" + curpage + ", pagesize=" + pagesize
  + ", start=" + start + ", end=" + end + ", pagecount="
  + pagecount + ", rowcount=" + rowcount + "]";
 }
}

不知道你还记不记得在baseservice的处理方法里面调用了pager的initrowcount方法没,这个方法就是判断当前执行到第几页,从哪个数字开始,到那个数字结束,是分页查询里面一个很关键的方法。

第四步:通过前后端的配合,看下实现后效果:

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解

利用Spring MVC+Mybatis实现Mysql分页数据查询的过程详解

很low,页面我没做太多处理,这其实是一个table哈哈。

总结

分页查询大概就是这些了,希望本文的内容对大家的学习或者工作能带来一定的帮助,如果有疑问大家可以留言交流,谢谢大家对的支持。