Mybatis+MySQL动态分页查询数据经典案例

最近在用Mybatis做项目的时候遇到了不少问题，今天我就在这和大家分享一下，稀稀拉拉的研究了两天，终于搞好了！

开发人员：1111

开发软件：Myeclipse

用到的框架技术：Mybatis

数据库：MySql

主要内容：动态分页查询数据

好了，现在开始演示，我先把代码贴上来以便大家的理解：

mybatis-config.xml的主要配置内容：

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <typeAliases>

        
        <typeAlias type="cn.bdqn.mhouse.entity.HouseCondition" alias="houseC"/>
        <typeAlias type="cn.bdqn.mhouse.util.Page" alias="page"/>
        
        <typeAlias type="cn.bdqn.mhouse.entity.District" alias="district"/>
        <typeAlias type="cn.bdqn.mhouse.dao.IDistrictDao" alias="districtDao"/>
        
        <typeAlias type="cn.bdqn.mhouse.entity.House" alias="house"/>
        <typeAlias type="cn.bdqn.mhouse.dao.IHouseDao" alias="houseDao"/>
        
        <typeAlias type="cn.bdqn.mhouse.entity.Street" alias="street"/>
        <typeAlias type="cn.bdqn.mhouse.dao.IStreetDao" alias="streetDao"/>
        
        <typeAlias type="cn.bdqn.mhouse.entity.Types" alias="types"/>
        <typeAlias type="cn.bdqn.mhouse.dao.ITypesDao" alias="typesDao"/>
        
        <typeAlias type="cn.bdqn.mhouse.entity.Users" alias="users"/>
        <typeAlias type="cn.bdqn.mhouse.dao.IUsersDao" alias="usersDao"/>
    </typeAliases>
    <environments default="Mysqldevelopment">
        
        <environment id="Oracledevelopment">
        <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
            <property name="driver" value="oracle.jdbc.OracleDriver"/>
            <property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:orcl"/>
            <property name="username" value="scott"/>
            <property name="password" value="123"/>
            </dataSource>
        </environment>
        
        <environment id="Mysqldevelopment">
        <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://192.168.1.128:3306/house"/>
            <property name="username" value="root"/>
            <property name="password" value="171268"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="cn/bdqn/mhouse/dao/DistrictDaoMapper.xml"/>
        <mapper resource="cn/bdqn/mhouse/dao/HouseDaoMapper.xml"/>
        <mapper resource="cn/bdqn/mhouse/dao/StreetDaoMapper.xml"/>
        <mapper resource="cn/bdqn/mhouse/dao/TypesDaoMapper.xml"/>
        <mapper resource="cn/bdqn/mhouse/dao/UsersDaoMapper.xml"/>
    </mappers>
</configuration>

由于分页查询得用到总记录数，所以我写了两个方法来实现的，第一个是动态查询数据总记录数，接下来大家看看impl类和相对应的Mapper.xml配置信息吧，由于dao接口是由impl实现类来实现的，所以在这我就不给大家放dao层接口的代码了：

动态查询数据的impl代码：

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/**
     * (非 Javadoc)
    * <p>Title: reCount</p>
    * <p>Description(描述):动态查询总计录数</p>
    * @param housec
    * @return
    * @see cn.bdqn.mhouse.dao.IHouseDao#reCount(cn.bdqn.mhouse.entity.HouseCondition)
     */
    @Override
    public int reCount(HouseCondition housec) {
        SqlSession session=MybatisUtil.getSession();
        Integer count=(Integer)session.selectOne("houseDao.reCount",housec);
        return count;
    }

代码中的MybatisUtils是mybatis的工具类，动态查询数据方法在Mapper.xml里面的配置详情代码：

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<select id="reCount" parameterType="houseC" resultType="Integer">
select count(0) from house h
<where>
    <if test="priceBegin!=null">
         and h.price > #{priceBegin}
    </if>
    <if test="priceEnd!=null">
        and h.price   <![CDATA[<]]>  #{priceEnd}
    </if>
    
    <if test="street!=null">
         and h.street_id = #{street.id}
     </if>
     
     <if test="types!=null">
         and h.type_id = #{types.id}
     </if>
    <if test="floorageBegin!=null">
         and h.floorage > #{floorageBegin}
    </if>
    <if test="floorageEnd!=null">
        and h.floorage <![CDATA[<]]>  #{floorageEnd}
    </if>
</where>
</select>

然后我把表与表之间的关联映射在放上来供大家看看：

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<resultMap id="BaseResultMap" type="house" >
  <id column="ID" property="id" jdbcType="INTEGER" />
  <result column="TITLE" property="title" jdbcType="VARCHAR" />
  <result column="DESCRIPTION" property="description" jdbcType="VARCHAR" />
  <result column="PRICE" property="price" jdbcType="REAL" />
  <result column="PUBDATE" property="pubdate" jdbcType="DATE" />
  <result column="FLOORAGE" property="floorage" jdbcType="INTEGER" />
  <result column="CONTACT" property="contact" jdbcType="VARCHAR" />
  
  
  <association property="users" column="user_id" select="selectUsers"/>
  
  <association property="types" column="type_id" select="selectTypes"/>
  
  <association property="street" column="street_id" select="selectStreet"/>
</resultMap>

<resultMap id="usersMapper" type="users" >
  <id column="ID" property="id" jdbcType="INTEGER" />
  <result column="NAME" property="name" jdbcType="VARCHAR" />
  <result column="PASSWORD" property="password" jdbcType="VARCHAR" />
  <result column="TELEPHONE" property="telephone" jdbcType="VARCHAR" />
  <result column="USERNAME" property="username" jdbcType="VARCHAR" />
  <result column="ISADMIN" property="isadmin" jdbcType="VARCHAR" />
</resultMap>

<resultMap id="streetMapper" type="street" >
  <id column="ID" property="id" />
  <result column="NAME" property="name" jdbcType="VARCHAR" />
<association property="district" column="district_id" select ="selectDirstrict"/>
</resultMap>

    <resultMap id="districtDaoMapper" type="district" >
   <id column="ID" property="id"/>
   <result column="NAME" property="name"/>
</resultMap>

    <select id="selectDirstrict" resultMap="districtDaoMapper">
        select * form district where id=#{district_id}
    </select>

<resultMap id="typeMapper" type="types" >
   <id column="ID" property="id"/>
   <result column="NAME" property="name" jdbcType="VARCHAR" />
</resultMap>


<select id="selectUsers" resultMap="usersMapper">
    select * from users where id=#{user_id}
</select>

<select id="selectStreet" resultMap="streetMapper">
    select * from street where id=#{street_id}
</select>

    <select id="selectTypes" resultMap="typeMapper">
    select * from types where id=#{type_id}
</select>
<sql id="Base_Column_List" >
  ID, USER_ID, TYPE_ID, TITLE, DESCRIPTION, PRICE, PUBDATE, FLOORAGE, CONTACT, STREET_ID
</sql>

           上面都有相对应的注释，在这就不多做解释了，

总记录数现在查询出来了，就开始动态分页查询数据了，首先得用到一个分页类Page，分页类的代码：

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package cn.bdqn.mhouse.util;

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

import cn.bdqn.mhouse.entity.House;

/**
*
*
* 项目名称：mhouse
* 类名称：Page
* 类描述：   分页的工具类
* 创建人：Mu Xiongxiong
* 创建时间：2017-3-17 下午1:04:02
* 修改人：Mu Xiongxiong
* 修改时间：2017-3-17 下午1:04:02
* 修改备注：
* @version
*
*/
public class Page {
    private int pageSize=3;            //页大小
    private int pageIndex=0;           //当前页号
    private int totalPageCount=0;      //总页数
    private int record=0;              //记录总数
    private Integer nextPage;          //下一页
    private Integer prePage;           //上一页
    private List<House> houseList=new ArrayList<House>();     //房屋信息的集合



    /**
     * @author Mu Xiongxiong
     * @created 2017-3-17 下午10:04:41
     * @return type
     */

    public List<House> getHouseList() {
        return houseList;
    }

    /**
     * @author Mu Xiongxiong
     * @created 2017-3-17 下午10:04:41
     * @param houseList
     */
    public void setHouseList(List<House> houseList) {
        this.houseList = houseList;
    }

    //得到开始记录数
    public int getSartRow(){
        return (pageIndex-1)*pageSize;
    }

    //得到结束记录数
    public int getEndRow(){
        return pageSize;
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getPageIndex() {
        return pageIndex;
    }

    //得到当前页
    public void setPageIndex(int pageIndex) {
        this.pageIndex = pageIndex;
        //下一页
        setNextPage();
        //上一页
        setPrePage();
    }

    public int getTotalPageCount() {
        return totalPageCount;
    }

    //总页数
    public void setTotalPageCount() {
        int totalP = record % getPageSize() == 0 ? record / getPageSize() :
            record/ getPageSize() + 1;
        this.totalPageCount = totalP;
    }

    public int getRecord() {
        return record;
    }

    //总记录数
    public void setRecord(int record) {
        this.record = record;
        //设置总页数
        setTotalPageCount();
    }

    public Integer getNextPage() {
        return nextPage;
    }

    //设置下一页
    public void setNextPage() {
        this.nextPage = this.pageIndex+1;

    }

    public Integer getPrePage() {
        return prePage;
    }

    //设置上一页
    public void setPrePage() {
        this.prePage =this.pageIndex-1;
        if(this.prePage<1){
            this.prePage=1;
        }
    }



}

现在分页的工具类也出来了，就差分页查询数据了，先看impl里面的方法：

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/**
* (非 Javadoc)
* <p>Title: getHouseInfoByDymanic</p>
* <p>Description:‘动态分页查询房屋信息</p>
* @param housec
* @param pageIndex
* @return
* @see cn.bdqn.mhouse.dao.IHouseDao#getHouseInfoByDymanic(cn.bdqn.mhouse.entity.HouseCondition, int)
*/
@Override
public Page getHouseInfoByDymanic(HouseCondition housec,int pageIndex) {
    Page page=new Page();
    page.setPageIndex(pageIndex);      //当前页
    int reCount=reCount(housec);
    page.setRecord(reCount);           //总记录数
    List<House> houseList=new ArrayList<House>();
    HashMap parMap=new HashMap();
    parMap.put("priceBegin",housec.getPriceBegin());
    parMap.put("priceEnd",housec.getPriceEnd());
    if(housec.getStreet()!=null){
    parMap.put("street",housec.getStreet());
    }
    if(housec.getTypes()!=null){
        parMap.put("types",housec.getTypes());
    }
    parMap.put("floorageBegin", housec.getFloorageBegin());
    parMap.put("floorageEnd",housec.getFloorageEnd());
    parMap.put("stratRow",page.getSartRow());
    parMap.put("endRow",page.getEndRow());
    SqlSession session=MybatisUtil.getSession();
    try {
        houseList=session.selectList("houseDao.getHouseInfoByDymanic",parMap);
        page.setHouseList(houseList);
    } catch (Exception e) {
        e.printStackTrace();
    }finally{
        MybatisUtil.closeSession();
    }
    return page;
}

        对应的Mapper.xml配置信息：

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<select id="getHouseInfoByDymanic" parameterType="hashmap" resultMap="BaseResultMap">
        select * from house h
<where>
    <if test="priceBegin!=null">
         and h.price > #{priceBegin}
    </if>
    <if test="priceEnd!=null">
        and h.price   <![CDATA[<]]>  #{priceEnd}
    </if>
    <if test="street!=null">
         and h.street_id = #{street.id}
     </if>
    <if test="types!=null||!types==null">
         and h.type_id = #{types.id}
     </if>
    <if test="floorageBegin!=null">
         and h.floorage > #{floorageBegin}
    </if>
    <if test="floorageEnd!=null">
        and h.floorage <![CDATA[<]]>  #{floorageEnd}
    </if>
</where>
        limit #{stratRow},#{endRow}
</select>

最后我写了test测试，看看能不能正常执行：test测试类的方法如下：

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    /**
     *
    * @Title: reCount
    * @Description: 该方法的主要作用：分页查询房屋信息
    * @param   设定文件
    * @return  返回类型：void
    * @throws
     */
    @Test
    public void getHouseInfoByDymanic(){
        Page page=new Page();
//      houseC.setPriceBegin(50);                      //起始价格
//      houseC.setPriceEnd(4000);                      //结束价格
//      houseC.setFloorageBegin(10);                   //起始面积
//      houseC.setFloorageEnd(6000);                   //最终面积
        types.setId(1003);                             //房屋类型
        houseC.setTypes(types);
        street.setId(1003);                            //所在的街道
//      //street.setDistrict(district);
        houseC.setStreet(street);
        int pageIndex=3;
        page=houseDao.getHouseInfoByDymanic(houseC, pageIndex);
        System.out.println("当前页是："+page.getPageIndex());
        System.out.println("下一页是："+page.getNextPage());
        System.out.println("上一页是："+page.getPrePage());
        System.out.println("总记录数："+page.getRecord());
        System.out.println("总页数是："+page.getTotalPageCount());
        System.out.println("页大小是："+page.getPageSize());
        List<House> houselist=page.getHouseList();
        for (House house : houselist) {
            System.out.println("房屋标题："+house.getTitle());
        }
    }

      执行完成之后，分页的信息，上一页，下一页，总页数等等都可以正常显示出来，但是，只有数据库里面的数据没有显示出来（调试如图所示）：

集合里面是空的！！！

出现错误之后我就开始解决，于是写了个测试查询全部的房屋信息的方法，测试了一遍之后,果然不出所料，查出来的都是null,更为奇怪的是：数据库中有34条记录，而程序运行后查询出来的是34个null，对没错，就是34个null,一个也不多，一个也不少！！！

但是还很纳闷，于是各种假设各种调试，还是不行，当我吧问题发在csdn上面问的时候，忽然想起来了，原来是映射的resultType错了，我查询的是house,应该映射的是house实体类的权限定名，我写的是Page的全限定名，我写成page也不足为奇，因为我的返回类型就是page，哎，就这个错，我弄了两小时才解决掉！！！实现是累的不行了！

这个问题解决了之后，我就继续测试其他的功能，现在是数据数来了,但是正儿八经最主要的测试还没进行呢，汗，于是我就开始测试动态查询数据，一步一步的测试的时候，错又来了，我把错误信息贴上来大家看看：

org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.apache.ibatis.reflection.ReflectionException:There is no getter for property named 'id' in 'class java.lang.Integer'
### Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'id' in 'class java.lang.Integer'