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SpringBoot + Mybatis + Druid多数据源集成的心得

最近在做一个项目，需要使用SpringBoot+Mybatis+Druid使用多数据源，前提条件是数据源的个数和名称不确定，是在application.properties文件中设定，在使用时根据条件动态切换。

这样就不能像Druid官网提到的，通过ConfigurationProperties注解创建多个DruidDataSource，因为这样属于硬编码，添加一个数据源就要再添加代码，我考虑的是只使用一套构建DataSource的代码，添加或删除数据源只需要修改配置文件。

Spring提供的AbstractRoutingDataSource提供了运行时动态切换DataSource的功能，但是AbstractRoutingDataSource对象中包含的DataSourceBuilder构建的仅仅是Spring JDBC的DataSource，并不是我们使用的DruidDataSource,需要自行构建。

这篇文章介绍了如何使用AbstractRoutingDataSource构建多数据源，但是它有几点不足：

1)构建的TargetDataSources中的DataSource仅包含driverClassName,username,password,url等基本属性，对于DruidDataSource这种复杂的DataSource，仅赋这些属性是不够的。

2)构建AbstractingRoutingDataSource使用ImportBeanDefinitionRegistrar进行注册，不够直观。

我的方案对这个解决方案做了一定的修改。

我在本地MySQL新建三个数据库testdb_1,testdb_2,testdb_3,每个数据库新建一张student表

建表语句如下

CREATE TABLE student (

ID int(11) NOT NULL AUTO_INCREMENT,

NAME varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,

CLASS_NAME varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,

CREATE_DATE timestamp(0) NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP(0),

UPDATE_DATE timestamp(0) NOT NULL ON UPDATE CURRENT_TIMESTAMP(0),

PRIMARY KEY ( ID ) USING BTREE

) ENGINE = InnoDB AUTO_INCREMENT = 0 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

分别创建三个用户appuser_1,appuser_2,appuser_3，用于连接三个数据库(需要赋予它们访问数据库的相应权限)

我们构建一个名为SpringBootDruidMultiDB的SpringBoot项目，导入mybatis-spring-boot-starter和

spring-boot-starter-web以及spring-boot-starter-test，为了使用Druid方便，项目还导入druid-spring-boot-starter。由于使用Log4j2记录日志，在每个导入的starter中都要exclude掉spring-boot-starter-logging(去掉自带的slf4j)，添加log4j2所需要的库，pom文件的配置如下

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
    <relativePath/> 
</parent>

<dependencies>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>1.1.6</version>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.3.1</version>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.10.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.10.0</version>
    </dependency>
    <dependency>
        <groupId>com.lmax</groupId>
        <artifactId>disruptor</artifactId>
        <version>3.3.7</version>
    </dependency>       

    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.2</version>
    </dependency>
 </dependencies>

修改src/main/resources文件，添加多个数据源信息

spring.custom.datasource.name=db1,db2,db3

spring.custom.datasource.db1.name=db1

spring.custom.datasource.db1.driver-class-name=com.mysql.jdbc.Driver

spring.custom.datasource.db1.url=jdbc:mysql://localhost:3306/testdb_1?characterEncoding=utf8&autoReconnect=true&useSSL=false&useAffectedRows=true

spring.custom.datasource.db1.username=appuser1

spring.custom.datasource.db1.password=admin

spring.custom.datasource.db2.name=db2

spring.custom.datasource.db2.driver-class-name=com.mysql.jdbc.Driver

spring.custom.datasource.db2.url=jdbc:mysql://localhost:3306/testdb_2?characterEncoding=utf8&autoReconnect=true&useSSL=false&useAffectedRows=true

spring.custom.datasource.db2.username=appuser2

spring.custom.datasource.db2.password=admin

spring.custom.datasource.db3.name=db3

spring.custom.datasource.db3.driver-class-name=com.mysql.jdbc.Driver

spring.custom.datasource.db3.url=jdbc:mysql://localhost:3306/testdb_3?characterEncoding=utf8&autoReconnect=true&useSSL=false&useAffectedRows=true

spring.custom.datasource.db3.username=appuser3

spring.custom.datasource.db3.password=admin

再添加DruidDataSource的属性

spring.datasource.druid.initial-size=5

spring.datasource.druid.min-idle=5

spring.datasource.druid.async-init=true

spring.datasource.druid.async-close-connection-enable=true

spring.datasource.druid.max-active=20

spring.datasource.druid.max-wait=60000

spring.datasource.druid.time-between-eviction-runs-millis=60000

spring.datasource.druid.min-evictable-idle-time-millis=30000

spring.datasource.druid.validation-query=SELECT 1 FROM DUAL

spring.datasource.druid.test-while-idle=true

spring.datasource.druid.test-on-borrow=false

spring.datasource.druid.test-on-return=false

spring.datasource.druid.pool-prepared-statements=true

spring.datasource.druid.max-pool-prepared-statement-per-connection-size=20

spring.datasource.druid.filters=stat,wall,log4j2

spring.datasource.druid.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000

spring.datasource.druid.web-stat-filter.enabled=true

spring.datasource.druid.web-stat-filter.url-pattern=/*

spring.datasource.druid.web-stat-filter.exclusions= .js, .gif, .jpg, .png, .css, .ico,/druid/*

spring.datasource.druid.web-stat-filter.session-stat-enable=true

spring.datasource.druid.web-stat-filter.profile-enable=true

spring.datasource.druid.stat-view-servlet.enabled=true

spring.datasource.druid.stat-view-servlet.url-pattern=/druid/*

spring.datasource.druid.stat-view-servlet.login-username=admin

spring.datasource.druid.stat-view-servlet.login-password=admin

spring.datasource.druid.stat-view-servlet.reset-enable=false

spring.datasource.druid.stat-view-servlet.allow=127.0.0.1

spring.datasource.druid.filter.wall.enabled=true

spring.datasource.druid.filter.wall.db-type=mysql

spring.datasource.druid.filter.wall.config.alter-table-allow=false

spring.datasource.druid.filter.wall.config.truncate-allow=false

spring.datasource.druid.filter.wall.config.drop-table-allow=false

spring.datasource.druid.filter.wall.config.none-base-statement-allow=false

spring.datasource.druid.filter.wall.config.update-where-none-check=true

spring.datasource.druid.filter.wall.config.select-into-outfile-allow=false

spring.datasource.druid.filter.wall.config.metadata-allow=true

spring.datasource.druid.filter.wall.log-violation=true

spring.datasource.druid.filter.wall.throw-exception=true

spring.datasource.druid.filter.stat.log-slow-sql= true

spring.datasource.druid.filter.stat.slow-sql-millis=1000

spring.datasource.druid.filter.stat.merge-sql=true

spring.datasource.druid.filter.stat.db-type=mysql

spring.datasource.druid.filter.stat.enabled=true

spring.datasource.druid.filter.log4j2.enabled=true

spring.datasource.druid.filter.log4j2.connection-log-enabled=true

spring.datasource.druid.filter.log4j2.connection-close-after-log-enabled=true

spring.datasource.druid.filter.log4j2.connection-commit-after-log-enabled=true

spring.datasource.druid.filter.log4j2.connection-connect-after-log-enabled=true

spring.datasource.druid.filter.log4j2.connection-connect-before-log-enabled=true

spring.datasource.druid.filter.log4j2.connection-log-error-enabled=true

spring.datasource.druid.filter.log4j2.data-source-log-enabled=true

spring.datasource.druid.filter.log4j2.result-set-log-enabled=true

spring.datasource.druid.filter.log4j2.statement-log-enabled=true

在src/main/resources目录下添加log4j2.xml文件

<?xml version="1.0" encoding="UTF-8"?>

<properties>
    <property name="logPath">./logs/</property>
</properties>

<Appenders>
    <Console name="Console" target="SYSTEM_OUT" ignoreExceptions="false">
        <PatternLayout pattern="%d [%t] %-5p %c - %m%n"/>
        <ThresholdFilter level="trace" onMatch="ACCEPT" onMismatch="DENY"/>
    </Console>
    <RollingFile name="infoLog" fileName="${logPath}/multidb_info.log"
                 filePattern="${logPath}/multidb_info-%d{yyyy-MM-dd}.log" append="true" immediateFlush="true">
        <PatternLayout pattern="%d [%t] %-5p %c - %m%n" />
        <TimeBasedTriggeringPolicy />
        <Policies>
            <SizeBasedTriggeringPolicy size="10 MB"/>
        </Policies>
        <DefaultRolloverStrategy max="30"/>
        <Filters>
            <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
            <ThresholdFilter level="trace" onMatch="ACCEPT" onMismatch="DENY"/>
        </Filters>
    </RollingFile>

    <RollingFile name="errorLog" fileName="${logPath}/multidb_error.log"
                 filePattern="${logPath}/multidb_error-%d{yyyy-MM-dd}.log" append="true" immediateFlush="true">
        <PatternLayout pattern="%d [%t] %-5p %c - %m%n" />
        <TimeBasedTriggeringPolicy />
        <Policies>
            <SizeBasedTriggeringPolicy size="10 MB"/>
        </Policies>
        <DefaultRolloverStrategy max="30"/>
        <Filters>
            <ThresholdFilter level="error" onMatch="ACCEPT" onMismatch="DENY"/>
        </Filters>
    </RollingFile>
</Appenders>
<Loggers>
    <AsyncLogger name="org.springframework.*" level="INFO"/>
    <AsyncLogger name="com.rick" level="INFO" additivity="false">
        <AppenderRef ref="infoLog" />
        <AppenderRef ref="errorLog" />
        <AppenderRef ref="Console" />
    </AsyncLogger>
    <Root level="INFO">
        <AppenderRef ref="Console"/>
    </Root>
</Loggers>

</Configuration>

一开始我参照单数据源的构建方式，想像下面的方式构建DruidDataSource数据源

public DataSource createDataSource(Environment environment,

String prefix)

{

return DruidDataSourceBuilder.create().build(environment,prefix);

}

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原文 https://segmentfault.com/a/1190000012735921

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