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SpringMVC+Mybatis实现的Mysql分页数据查询

时间:2017-10-10 23:19:15      阅读:322      评论:0      收藏:0      [点我收藏+]

标签:jsonp   count   处理   body   .post   getname   实体类   protect   class   

  周末这天手痒,正好没事干,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。

  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:

  技术分享

  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。 

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<%@ 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>
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  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,自己造的轮子肯定会逊色很多,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;

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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;
}
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  下面是Mytable的实现代码:

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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();
}
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  前端页面的处理就是这些,展示效果如下:

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  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

  技术分享

  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:

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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);
    }
}
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  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:

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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);
}
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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);
    }    
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  通过上面BaseController的处理,我们可以看到它调用了BaseService的queryListPager方法,

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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());
    }
}
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  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:

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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);
}
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  这个BaseMapper对应的是mybatis的xml文件,它负责编写sql语句:

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<?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>
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   最后我们看下employee和pager的实体类把:

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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;
    }
}
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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 + "]";
    }
}
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  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:

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  很low,页面我没做太多处理,这其实是一个table哈哈。

 分页查询大概就是这些了,肚子很饿,还没有吃饭,先写到这里把。

 

SpringMVC+Mybatis实现的Mysql分页数据查询

标签:jsonp   count   处理   body   .post   getname   实体类   protect   class   

原文地址:http://www.cnblogs.com/shitaotao/p/7648241.html

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