Spring+Mybatis實現動態SQL查詢

 

在報表類應用中，通常需要根據不同的維度去組合復雜的查詢條件，然后構造SQL去執行查詢。如果只是通過在程序中簡單地拼接SQL語句，工作量會非常大，而且代碼可能也非常難以維護。Mybatis支持動態SQL查詢功能，可以通過配置動態的SQL來簡化程序代碼中復雜性，不過，這個頗有點XML編程的韻味，通過XML來處理復雜的數據判斷、循環的功能，其實也很好理解。

准備工作

下面，我們首先創建一個MySQL示例表，如下所示：

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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;

這個表用來存儲域名的流量信息，流量信息我們從互聯網上像Alexa、Compete、Quantcast等提供商獲取，通過Crawler抓取的方式實現。我們先從簡單的查詢做起，只是根據某個字段進行查詢，說明如何配置使用Mybatis，這里面也包含如何與Spring進行集成。

配置實踐

下面是用到的一些資源的定義：

• org.shirdrn.mybatis.TrafficInfo類

該類對應於traffic_info表中一條記錄的數據，我們簡單取幾個字段，如下所示：

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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接口類

該類定義了一個與SQL配置進行映射的基本操作，實際的SQL配置有專門的XML文件來進行配置。該接口定義了如下操作：

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package org.shirdrn.mybatis.mapper;   import java.util.List; import java.util.Map;   import org.shirdrn.mybatis.TrafficInfo;   public interface TrafficInfoMapper {         /**       * 根據指定id去查詢記錄，結果至多只有一條       * @param id       * @return       */       TrafficInfo getTrafficInfo( int id);             /**       * 根據指定的domain參數查詢記錄，返回一個記錄的列表       * @param domain       * @return       */       List<TrafficInfo> getTrafficInfoList(String domain);             /**       * 根據一個 字段domain進行查詢，但是存在多個domain的值，傳入一個數組       * @param domains       * @return       */       List<TrafficInfo> getMultiConditionsList(String[] domains);             /**       * 根據多個字段進行查詢，每個字段可能有多個值，所以參數是Map類型       * @param conditions       * @return       */       List<TrafficInfo> getMapConditionsList(Map<String, Object> conditions);   }

上面接口中定義的操作，一個比一個復雜，我們通過這一系列操作來說明在Mybatis中如果使用各種查詢功能。

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

這個文件TrafficInfoMapper.xml對應了上面的org.shirdrn.mybatis.mapper.TrafficInfoMapper中定義的操作，通過XML的方式將對應的SQL查詢構造出來，這個是Mybatis的核心功能。該文件的內容示例如下所示：

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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 = "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 >

如果你之前用過ibatis，應該很熟悉上面這個配置文件。上面：
namespace指定該SQL映射配置文件的Mapper接口類，其中定義了基本的SQL查詢操作（以我們給出的例子為例）；
resultMap中的type的值這里是一個別名，當然也可以使用對應的具體類全名（包名+類名），我們會在Mybatis的總的映射配置文件中進行配置，詳見后面說明；
select是查詢SQL的配置，可以通過不同的元素進行動態構造，如if、foreach等；

• Mybatis全局映射配置文件sqlMapConfig.xml

該文件可以指定數據庫連接池配置、別名配置、SQL映射配置文件組等內容，這里示例的配置內容如下所示：

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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 = "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

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<? 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/beans   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context-3.0.xsd     http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd     http://www.springframework.org/schema/tx     http://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 >

簡單說明一下：
dataSource使用的Proxool連接池組件；
sqlSessionFactory是Mybatis的SessionFactory，注入了前面獲取到的dataSource，同時指定了Mybatis的總的映射配置文件classpath:sqlMapConfig.xml，屬性名為configLocation；
trafficInfoMapper直接由Spring的org.mybatis.spring.mapper.MapperFactoryBean進行代理，需要注入屬性mapperInterface（即我們定義的SQL Mapper操作的接口類）和sqlSessionFactory（前面的SessionFactory實例）；
trafficInfoService是我們最終在其中進行調用的服務類，注入了我們定義的SQL Mapper接口類的實例trafficInfoMapper。

• org.shirdrn.mybatis.TrafficInfoService服務類

為簡單起見，我們就不定義服務接口了，直接在該類中實現，調用SQL Mapper中預定義的SQL查詢操作，實現代碼如下所示：

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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，我們就能夠實現從單個字段的查詢，到多個字段的組合復雜查詢。可以通過與實際編寫代碼來控制這些邏輯相比較，使用Mybatis可能配置上相對復雜一些，但是或得到的好處是非常多的，如代碼可維護性好，看起來配置比較直觀，出錯的幾率會大大減小。實際上，如果熟練的這種配置方式，就會在實際開發過程中，更好地去處理更加復雜的統計查詢條件的組合邏輯。

測試用例

測試用例可以檢測我們上面的配置是否生效，實現代碼：

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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);       }   }

查詢進階

這里，給出一個實際的例子，是對每日報表的一個統計實例，為簡單起見，只拿出2張表做LEFT JOIN連接。這個需求，要求查詢時可以對每個維度取過得查詢條件值，如對於維度osName，值可以使包含Android、IOS，對於另一個維度statDate，可以取最近2天（昨天和前天），等等，並且，這些組合條件可有可無。
對應的Mybatis映射配置文件，內容如下所示：

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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 = "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 >

上述映射配置對應的Mapper定義，接口如下所示：

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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); }

需要說明的是，如果多個表，一定要設置好Mapper映射配置中每個select元素的resultMap屬性，屬性值就是前部分的resultMap定義的id。如果只從單個表查詢數據，完全可以使用resultType，對應resultMap元素中配置的type屬性所指定的別名。
實際上，我們需要通過Map來傳遞參數，也就是把查詢的條件值都收集起來，然后放到Map中，示例如下：

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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); }

上面對應的DailyAppUserMapper中定義的一些Key常量名稱，要和Mapper配置文件中foreach元素的collection屬性值一致。