Spring+Mybatis实现动态SQL查询



在报表类应用中，通常需要根据不同的维度去组合复杂的查询条件，然后构造SQL去执行查询。如果只是通过在程序中简单地拼接SQL语句，工作量会非常大，而且代码可能也非常难以维护。Mybatis支持动态SQL查询功能，可以通过配置动态的SQL来简化程序代码中复杂性，不过，这个颇有点XML编程的韵味，通过XML来处理复杂的数据判断、循环的功能，其实也很好理解。

准备工作

下面，我们首先创建一个MySQL示例表，如下所示：

CREATE TABLE `traffic_info` (  `id` int(11) NOT NULL AUTO_INCREMENT,  `domain` varchar(64) NOT NULL,  `traffic_host` varchar(64) NOT NULL,  `month` varchar(8) NOT NULL,  `monthly_traffic` int(11) DEFAULT '0',  `global_traffic_rank` int(11) DEFAULT '0',  `native_traffic_rank` int(11) DEFAULT '0',  `rank_in_country` varchar(64) DEFAULT NULL,  `address` varchar(200) DEFAULT NULL,  `email` varchar(50) DEFAULT NULL,  `traffic_type` int(2) DEFAULT '-1',  `status` int(2) DEFAULT '0',  `created_at` date DEFAULT NULL,  `updated_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,  `f1` varchar(255) DEFAULT NULL,  `f2` varchar(255) DEFAULT NULL,  `f3` varchar(255) DEFAULT NULL,  PRIMARY KEY (`id`),  UNIQUE KEY `idx_traffic` (`domain`,`month`,`traffic_type`)) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

这个表用来存储域名的流量信息，流量信息我们从互联网上像Alexa、Compete、Quantcast等提供商获取，通过Crawler抓取的方式实现。我们先从简单的查询做起，只是根据某个字段进行查询，说明如何配置使用Mybatis，这里面也包含如何与Spring进行集成。

配置实践

下面是用到的一些资源的定义：

• org.shirdrn.mybatis.TrafficInfo类

该类对应于traffic_info表中一条记录的数据，我们简单取几个字段，如下所示：

package org.shirdrn.mybatis;import java.io.Serializable;public class TrafficInfo implements Serializable {         private static final long serialVersionUID = -8696613205078899594L;     int id;     String domain;     String month;     int monthlyTraffic;         public int getId() {          return id;     }     public void setId(int id) {          this.id = id;     }     public String getDomain() {          return domain;     }     public void setDomain(String domain) {          this.domain = domain;     }     public String getMonth() {          return month;     }     public void setMonth(String month) {          this.month = month;     }     public int getMonthlyTraffic() {          return monthlyTraffic;     }     public void setMonthlyTraffic(int monthlyTraffic) {          this.monthlyTraffic = monthlyTraffic;     }         @Override     public String toString() {          return "[id=" + id + ", domain=" + domain + ", month=" +                    month + ", monthlyTraffic=" + monthlyTraffic + "]";     }    }

org.shirdrn.mybatis.mapper.TrafficInfoMapper接口类

该类定义了一个与SQL配置进行映射的基本操作，实际的SQL配置有专门的XML文件来进行配置。该接口定义了如下操作：

package org.shirdrn.mybatis.mapper;import java.util.List;import java.util.Map;import org.shirdrn.mybatis.TrafficInfo;public interface TrafficInfoMapper {     /**     * 根据指定id去查询记录，结果至多只有一条     * @param id     * @return     */     TrafficInfo getTrafficInfo(int id);         /**     * 根据指定的domain参数查询记录，返回一个记录的列表     * @param domain     * @return     */     List<TrafficInfo> getTrafficInfoList(String domain);         /**     * 根据一个 字段domain进行查询，但是存在多个domain的值，传入一个数组     * @param domains     * @return     */     List<TrafficInfo> getMultiConditionsList(String[] domains);         /**     * 根据多个字段进行查询，每个字段可能有多个值，所以参数是Map类型     * @param conditions     * @return     */     List<TrafficInfo> getMapConditionsList(Map<String, Object> conditions);}

上面接口中定义的操作，一个比一个复杂，我们通过这一系列操作来说明在Mybatis中如果使用各种查询功能。

• org/shirdrn/mybatis/mapper/TrafficInfoMapper.xml映射配置文件

这个文件TrafficInfoMapper.xml对应了上面的org.shirdrn.mybatis.mapper.TrafficInfoMapper中定义的操作，通过XML的方式将对应的SQL查询构造出来，这个是Mybatis的核心功能。该文件的内容示例如下所示：

<?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="org.shirdrn.mybatis.mapper.TrafficInfoMapper">     <resultMap type="TrafficInfo" id="tfMap">          <id property="id" column="id" />          <result property="domain" column="domain" />          <result property="month" column="month" />          <result property="monthlyTraffic" column="monthlyTraffic" />     </resultMap>         <select id="getTrafficInfo" resultType="TrafficInfo" parameterType="int">          SELECT * FROM domain_db.traffic_info WHERE id = #{id}     </select>         <select id="getTrafficInfoList" resultType="TrafficInfo" parameterType="string">          SELECT * FROM domain_db.traffic_info WHERE domain = #{domain}     </select>         <select id="getMultiConditionsList" resultMap="tfMap">          SELECT * FROM domain_db.traffic_info WHERE domain IN          <foreach collection="array" index="index" item="domain" open=" (" separator="," close=")">              #{domain}          </foreach>     </select>         <select id="getMapConditionsList" resultMap="tfMap">          SELECT * FROM domain_db.traffic_info WHERE domain IN          <foreach collection="domains" index="index" item="domain" open=" (" separator="," close=")">              #{domain}          </foreach>         AND status = 0 AND month IN         <foreach collection="months" index="index" item="month" open=" (" separator="," close=")">              #{month}          </foreach>     </select></mapper> 

如果你之前用过ibatis，应该很熟悉上面这个配置文件。上面：
namespace指定该SQL映射配置文件的Mapper接口类，其中定义了基本的SQL查询操作（以我们给出的例子为例）；
resultMap中的type的值这里是一个别名，当然也可以使用对应的具体类全名（包名+类名），我们会在Mybatis的总的映射配置文件中进行配置，详见后面说明；
select是查询SQL的配置，可以通过不同的元素进行动态构造，如if、foreach等；

• Mybatis全局映射配置文件sqlMapConfig.xml

该文件可以指定数据库连接池配置、别名配置、SQL映射配置文件组等内容，这里示例的配置内容如下所示：

<?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="org.shirdrn.mybatis.TrafficInfo" alias="TrafficInfo" />     </typeAliases>     <mappers>          <mapper resource="org/shirdrn/mybatis/mapper/TrafficInfoMapper.xml" />     </mappers></configuration>

Spring配置文件applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"     xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"     xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.0.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-3.0.xsdhttp://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop-3.0.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-3.0.xsd">     <bean          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">          <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />          <property name="ignoreResourceNotFound" value="true" />          <property name="locations">               <list>                    <value>classpath*:/proxool.properties</value>               </list>          </property>     </bean>     <context:component-scan base-package="org.shirdrn.mybatis" />     <aop:aspectj-autoproxy proxy-target-class="true" />     <aop:config proxy-target-class="true" />     <bean id="dataSource" class="org.shirdrn.mybatis.utils.ProxoolDataSource">          <property name="driver" value="${jdbc-0.proxool.driver-class}" />          <property name="driverUrl" value="${jdbc-0.proxool.driver-url}" />          <property name="user" value="${jdbc-0.user}" />          <property name="password" value="${jdbc-0.password}" />          <property name="alias" value="${jdbc-0.proxool.alias}" />          <property name="prototypeCount" value="${jdbc-0.proxool.prototype-count}" />          <property name="maximumActiveTime" value="${jdbc-0.proxool.maximum-active-time}" />          <property name="maximumConnectionCount" value="${jdbc-0.proxool.maximum-connection-count}" />          <property name="minimumConnectionCount" value="${jdbc-0.proxool.minimum-connection-count}" />          <property name="simultaneousBuildThrottle"               value="${jdbc-0.proxool.simultaneous-build-throttle}" />          <property name="verbose" value="${jdbc-0.proxool.verbose}" />          <property name="trace" value="${jdbc-0.proxool.trace}" />          <property name="houseKeepingTestSql" value="${jdbc-0.proxool.house-keeping-test-sql}" />          <property name="houseKeepingSleepTime" value="${jdbc-0.proxool.house-keeping-sleep-time}" />          <property name="maximumConnectionLifetime"               value="${jdbc-0.proxool.maximum-connection-lifetime}" />     </bean>     <bean id="dataSource0" class="org.jdbcdslog.ConnectionPoolDataSourceProxy">          <property name="targetDSDirect" ref="dataSource" />     </bean>     <!-- http://mybatis.github.io/spring/getting-started.html -->     <!-- http://mybatis.github.io/spring/zh/ -->     <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">          <property name="dataSource" ref="dataSource0" />          <property name="configLocation" value="classpath:sqlMapConfig.xml"/>     </bean>     <bean id="trafficInfoMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">          <property name="mapperInterface" value="org.shirdrn.mybatis.mapper.TrafficInfoMapper" />          <property name="sqlSessionFactory" ref="sqlSessionFactory" />     </bean>     <bean id="trafficInfoService" class="org.shirdrn.mybatis.TrafficInfoService">          <property name="trafficInfoMapper" ref="trafficInfoMapper" />     </bean></beans>

简单说明一下：
dataSource使用的Proxool连接池组件；
sqlSessionFactory是Mybatis的SessionFactory，注入了前面获取到的dataSource，同时指定了Mybatis的总的映射配置文件classpath:sqlMapConfig.xml，属性名为configLocation；
trafficInfoMapper直接由Spring的org.mybatis.spring.mapper.MapperFactoryBean进行代理，需要注入属性mapperInterface（即我们定义的SQL Mapper操作的接口类）和sqlSessionFactory（前面的SessionFactory实例）；
trafficInfoService是我们最终在其中进行调用的服务类，注入了我们定义的SQL Mapper接口类的实例trafficInfoMapper。

• org.shirdrn.mybatis.TrafficInfoService服务类

为简单起见，我们就不定义服务接口了，直接在该类中实现，调用SQL Mapper中预定义的SQL查询操作，实现代码如下所示：

package org.shirdrn.mybatis;import java.util.List;import java.util.Map;import org.shirdrn.mybatis.mapper.TrafficInfoMapper;public class TrafficInfoService {     private TrafficInfoMapper trafficInfoMapper;         public void setTrafficInfoMapper(TrafficInfoMapper trafficInfoMapper) {          this.trafficInfoMapper = trafficInfoMapper;     }     public TrafficInfo getTrafficInfo(int id) {          return trafficInfoMapper.getTrafficInfo(id);     }         public List<TrafficInfo> getTrafficInfoList(String domain) {          return trafficInfoMapper.getTrafficInfoList(domain);     }         public List<TrafficInfo> getMultiConditionsList(String[] domains) {          return trafficInfoMapper.getMultiConditionsList(domains);     }         List<TrafficInfo> getMapConditionsList(Map<String, Object> conditions) {          return trafficInfoMapper.getMapConditionsList(conditions);     }}

按照上面的配置，我们就能够实现从单个字段的查询，到多个字段的组合复杂查询。可以通过与实际编写代码来控制这些逻辑相比较，使用Mybatis可能配置上相对复杂一些，但是或得到的好处是非常多的，如代码可维护性好，看起来配置比较直观，出错的几率会大大减小。实际上，如果熟练的这种配置方式，就会在实际开发过程中，更好地去处理更加复杂的统计查询条件的组合逻辑。

测试用例

测试用例可以检测我们上面的配置是否生效，实现代码：

package org.shirdrn.mybatis;import java.util.Arrays;import java.util.HashMap;import java.util.List;import java.util.Map;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = { "classpath:/applicationContext*.xml" })public class TestTrafficInfoService {     @Autowired     private TrafficInfoService trafficInfoService;     @Test     public void getTraffic() {          int id = 1196;          TrafficInfo result = trafficInfoService.getTrafficInfo(id);          System.out.println(result);     }         @Test     public void getTrafficList() {          String domain = "make-the-cut.com";          List<TrafficInfo> results = trafficInfoService.getTrafficInfoList(domain);          System.out.println(results);     }         @Test     public void getMultiConditionsList() {          String[] domains = new String[] {                    "make.tv", " make-the-cut.com", "makgrills.com", "makino.com"          };          List<TrafficInfo> results = trafficInfoService.getMultiConditionsList(domains);          System.out.println(results);     }         @Test     public void getMapConditionsList() {          String[] domains = new String[] {                    "make.tv", " make-the-cut.com", "makgrills.com", "makino.com"          };          List<String> months = Arrays.asList(new String[] {                    "201203", "201204", "201205"          });          Map<String, Object> conditions = new HashMap<String, Object>(2);          conditions.put("domains", domains);          conditions.put("months", months);          List<TrafficInfo> results = trafficInfoService.getMapConditionsList(conditions);          System.out.println(results);     }}

查询进阶

这里，给出一个实际的例子，是对每日报表的一个统计实例，为简单起见，只拿出2张表做LEFT JOIN连接。这个需求，要求查询时可以对每个维度取过得查询条件值，如对于维度osName，值可以使包含Android、IOS，对于另一个维度statDate，可以取最近2天（昨天和前天），等等，并且，这些组合条件可有可无。
对应的Mybatis映射配置文件，内容如下所示：

<?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="org.shirdrn.data.mappers.DailyAppUserMapper">     <resultMap id="dailyAppUserMap" type="DailyAppUser">          <id property="id" column="id" />          <result property="primaryCategoryId" column="primary_category_id" />          <result property="primaryCategoryName" column="primary_category_name" />          <result property="secondaryCategoryId" column="secondary_category_id" />          <result property="secondaryCategoryName" column="secondary_category_name" />          <result property="cooperationMode" column="cooperation_mode" />          <result property="merchantId" column="merchant_id" />          <result property="merchantName" column="merchant_name" />          <result property="osName" column="osName" />          <result property="channelId" column="channel_id" />          <result property="channelName" column="channel_name" />          <result property="version" column="version" />          <result property="statDate" column="stat_date" />          <result property="newUserOpen" column="new_user_open" />          <result property="activeUserOpen" column="active_user_open" />          <result property="activeUserPlay" column="active_user_play" />          <result property="oldUserOpen" column="old_user_open" />          <result property="oldUserPlay" column="old_user_play" />          <result property="averageTime" column="average_time" />          <result property="newUserAverageTime" column="new_user_average_time" />          <result property="oldUserAverageTime" column="old_user_average_time" />          <result property="newUserOpen2Retention" column="new_user_open_2retention" />          <result property="newUserOpen3Retention" column="new_user_open_3retention" />          <result property="newUserOpen7Retention" column="new_user_open_7retention" />          <result property="newUserOpen15Retention" column="new_user_open_15retention" />          <result property="newUserOpen30Retention" column="new_user_open_30retention" />     </resultMap>     <select id="getDailyAppUserListByPage" resultMap="dailyAppUserMap">          <include refid="getDailyAppUserList"/>          LIMIT #{offset}, #{limit}     </select>          <select id="getDailyAppUserListForReport" resultMap="dailyAppUserMap">          <include refid="getDailyAppUserList"/>     </select>          <sql id="getDailyAppUserList" >          SELECT                d.id AS id,               d.primary_category_id AS primary_category_id,               d.primary_category_name AS primary_category_name,               d.secondary_category_id AS secondary_category_id,               d.secondary_category_name AS secondary_category_name,               d.cooperation_mode AS cooperation_mode,               d.merchant_id AS merchant_id,               d.osName AS osName,               d.channel_id AS channel_id,               (CASE WHEN d.channel_name IS NOT NULL THEN d.channel_name ELSE d.channel_id END) AS channel_name,               d.version AS version,               d.stat_date AS stat_date,               d.new_user_open AS new_user_open,               d.new_user_play AS new_user_play,               d.active_user_open AS active_user_open,               d.active_user_play AS active_user_play,               d.old_user_open AS old_user_open,               d.old_user_play AS old_user_play,               d.average_time AS average_time,               d.new_user_average_time AS new_user_average_time,               d.old_user_average_time AS old_user_average_time,               d.new_user_open_2retention AS new_user_open_2retention,               d.new_user_open_3retention AS new_user_open_3retention,               d.new_user_open_7retention AS new_user_open_7retention,               d.new_user_open_15retention AS new_user_open_15retention,               d.new_user_open_30retention AS new_user_open_30retention,               d.uninstall_cnt AS uninstall_cnt,               m.merchant_name AS merchant_name          FROM daily_app_user d           LEFT JOIN merchant m ON d.merchant_id=m.id           WHERE d.stat_date = #{statDate}          <if test="osNames!=null">               AND d.osName IN               <foreach collection="osNames" index="index" item="osName" open=" (" separator="," close=")">                    #{osName}               </foreach>          </if>          <if test="channelNames!=null">               AND               <foreach collection="channelNames" index="index" item="channelName" open=" (" separator=" OR " close=")">                    (d.channel_name LIKE CONCAT('%', CONCAT(#{channelName}, '%')))               </foreach>          </if>          <if test="versions!=null">               AND d.version IN               <foreach collection="versions" index="index" item="version" open=" (" separator="," close=")">                    #{version}               </foreach>          </if>          <if test="merchantNames!=null">               AND               <foreach collection="merchantNames" index="index" item="merchantName" open=" (" separator=" OR " close=")">                    (m.merchant_name LIKE CONCAT('%', CONCAT(#{%merchantName%}, '%')))               </foreach>          </if>          <if test="primaryCategories!=null">               AND d.primary_category_id IN               <foreach collection="primaryCategories" index="index" item="primaryCategory" open=" (" separator="," close=")">                    #{primaryCategory}               </foreach>          </if>          <if test="secondaryCategories!=null">               AND d.secondary_category_id IN               <foreach collection="secondaryCategories" index="index" item="secondaryCategory" open=" (" separator="," close=")">                    #{secondaryCategory}               </foreach>          </if>          <if test="cooperationModes!=null">               AND d.cooperation_model IN               <foreach collection="cooperationModes" index="index" item="cooperationMode" open=" (" separator="," close=")">                    #{cooperationMode}               </foreach>          </if>     </sql>     </mapper> 

上述映射配置对应的Mapper定义，接口如下所示：

package org.shirdrn.data.mappers;import java.util.List;import java.util.Map;import org.shirdrn.data.beans.DailyAppUser;public class DailyAppUserMapper {     List<DailyAppUser> getDailyAppUserListByPage(Map<String, Object> conditions);     List<DailyAppUser> getDailyAppUserListForReport(Map<String, Object> conditions);}

需要说明的是，如果多个表，一定要设置好Mapper映射配置中每个select元素的resultMap属性，属性值就是前部分的resultMap定义的id。如果只从单个表查询数据，完全可以使用resultType，对应resultMap元素中配置的type属性所指定的别名。
实际上，我们需要通过Map来传递参数，也就是把查询的条件值都收集起来，然后放到Map中，示例如下：

Map<String, Object> conditions = new HashMap<String, Object>();if(osNames != null) {     conditions.put(DailyAppUserMapper.KEY_OS_NAMES, osNames);}if(channelNames != null) {     conditions.put(DailyAppUserMapper.KEY_CHANNEL_NAMES, channelNames);}if(versions != null) {     conditions.put(DailyAppUserMapper.KEY_VERSIONS, versions);}if(merchantNames != null) {     conditions.put(DailyAppUserMapper.KEY_MERCHANT_NAMES, merchantNames);}if(primaryCategories != null) {     conditions.put(DailyAppUserMapper.KEY_PRIMARY_CATEGORIES, primaryCategories);}if(secondaryCategories != null) {     conditions.put(DailyAppUserMapper.KEY_SECONDARY_CATEGORIES, secondaryCategories);}if(cooperationModes != null) {     conditions.put(ChannelDayMapper.KEY_COOPERATION_MODES, cooperationModes);}

上面对应的DailyAppUserMapper中定义的一些Key常量名称，要和Mapper配置文件中foreach元素的collection属性值一致。