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>
- <!-- 动态查询房屋信息的条件类 -->
- <typeAlias type="cn.bdqn.mhouse.entity.HouseCondition" alias="houseC"/>
- <typeAlias type="cn.bdqn.mhouse.util.Page" alias="page"/>
- <!-- 区县别名 -->
- <typeAlias type="cn.bdqn.mhouse.entity.District" alias="district"/>
- <typeAlias type="cn.bdqn.mhouse.dao.IDistrictDao" alias="districtDao"/>
- <!-- 房屋信息的别名 -->
- <typeAlias type="cn.bdqn.mhouse.entity.House" alias="house"/>
- <typeAlias type="cn.bdqn.mhouse.dao.IHouseDao" alias="houseDao"/>
- <!-- 街道信息的别名 -->
- <typeAlias type="cn.bdqn.mhouse.entity.Street" alias="street"/>
- <typeAlias type="cn.bdqn.mhouse.dao.IStreetDao" alias="streetDao"/>
- <!-- 房屋类型的别名 -->
- <typeAlias type="cn.bdqn.mhouse.entity.Types" alias="types"/>
- <typeAlias type="cn.bdqn.mhouse.dao.ITypesDao" alias="typesDao"/>
- <!-- 用户信息的别名 -->
- <typeAlias type="cn.bdqn.mhouse.entity.Users" alias="users"/>
- <typeAlias type="cn.bdqn.mhouse.dao.IUsersDao" alias="usersDao"/>
- </typeAliases>
- <environments default="Mysqldevelopment">
- <!-- oracle的数据库配置 -->
- <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>
- <!-- mysql的数据库配置 -->
- <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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- <!-- 动态查询房屋信息的总记录数 -->
- <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>
- <!-- h.street_id是数据库的字段名 -->
- <if test="street!=null">
- and h.street_id = #{street.id}
- </if>
- <!-- h.type_id是数据库的字段名 -->
- <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" />
- <!-- 开始映射外键 -->
- <!-- 映射用户表 -->
- <association property="users" column="user_id" select="selectUsers"/>
- <!-- 映射类型表 -->
- <association property="types" column="type_id" select="selectTypes"/>
- <!-- 映射街道表 -->
- <association property="street" column="street_id" select="selectStreet"/>
- </resultMap>
- <!-- 关联用户表 -->
- <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>
- <!-- 关联街道表 -->
- <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>
- <!-- 关联区县表 -->
- <resultMap id="districtDaoMapper" type="district" >
- <id column="ID" property="id"/>
- <result column="NAME" property="name"/>
- </resultMap>
- <!-- 在根据区县id查询一遍区县表 -->
- <select id="selectDirstrict" resultMap="districtDaoMapper">
- select * form district where id=#{district_id}
- </select>
- <!--关联类型表 -->
- <resultMap id="typeMapper" type="types" >
- <id column="ID" property="id"/>
- <result column="NAME" property="name" jdbcType="VARCHAR" />
- </resultMap>
- <!-- 用户表 -->
- <select id="selectUsers" resultMap="usersMapper">
- select * from users where id=#{user_id}
- </select>
- <!-- 街道表 -->
- <select id="selectStreet" resultMap="streetMapper">
- select * from street where id=#{street_id}
- </select>
- <!-- 类型表 -->
- <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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- <!-- 分页动态查询房屋信息 -->
- <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'
,嘴里骂了一句之后,拿起水杯干了一杯普利斯,挽起袖子就开始调试!我就不信还解决不了你了,
慢慢的。。。慢慢的,时间过来20分钟之后终于找出来了,原来是类型错了!我给大家看看错误代码和正确代码:
错误代码:
大家注意红色框中的代码,我取的是对象,而后面赋值的却是id,怪不得报错!!!
正确的代码如下:
还是老规矩,看红框中的代码,去掉getId()就可以正常运行了!!!
还有其他的好多细节错误来着,这里就不具体详细说了,要想查看完整的分页动态查询代码,请移步到 1111的博客 这里去看,希望对大家有帮助!