在SpringMVC中使用Mybatis怎么实现对Mysql数据库进行分页查询
在SpringMVC中使用Mybatis怎么实现对MySQL数据库进行分页查询?相信很多没有经验的人对此束手无策,为此本文总结了问题出现的原因和解决方法,通过这篇文章希望你能解决这个问题。
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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:
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" %>
ID 姓名 年龄 性别
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;
Pager.getSpan = function(value,className){ return $(""+value+""); } function Pager($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 = $("").appendTo(this.$parent); this.$div = $("").appendTo(this.$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 = $("").appendTo(this.$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.$nextVal,curPage == pageCount); if(curPagethis.spaceStep && i curEnd && i this.spaceStep) || (i==curEnd && i 下面是Mytable的实现代码:
function MyTable(tabName,url){ this.$tab = $("."+tabName); this.$wrap = this.$tab.parent(); this.queryURL = url; this.queryData = null; this.pager = null; this.init(); } MyTable.prototype.init = function(){ this.pager = new Pager($("").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"); var $id = $(" "+list[i].id+" ").appendTo($tr); var $name = $(""+list[i].name+" ").appendTo($tr); var $age = $(""+list[i].age+" ").appendTo($tr); var $sex = $(""+list[i].sex+" ").appendTo($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:
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
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 BaseServicebaseService; @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{ @Autowired private BaseMapper baseMapper; public Pager queryRowCount(T t, Pager pager){ return pager.initRowCount(baseMapper.queryRowCount(t)); } public List 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{ public int queryRowCount(T t); public List 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"?>id,name,age,sex t.id,t.name,t.age,t.sex #{id},#{name},#{age},#{sex} where 1=1 and id=#{id} and name=#{name} and age=#{age} and sex=#{sex} where 1=1 and t.id=#{t.id} and t.name=#{t.name} and t.age=#{t.age} and t.sex=#{t.sex} set id=#{id}, name=#{name}, age=#{age}, sex=#{sex}, 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:
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