SSM 最简单的实现操作多数据源&动态切换

Bertha 。 2021-10-18 15:48 566阅读 0赞

在项目开发里面，多数据源是最普遍不过的，一个项目使用多个数据库是非常正常的，那么这篇就是基于SSM框架去轻松实现使用多数据源的实战场景。  
  
基于SSM框架（还不了解SSM的的可以参考：[https://blog.csdn.net/qq\_35387940/article/details/97911104][https_blog.csdn.net_qq_35387940_article_details_97911104]）

开始，

首先准备2个不同的数据源（多个也行），在jdbc.properties：

#数据源 1
    first_driverClass =com.mysql.jdbc.Driver
    first_jdbcUrl=jdbc:mysql://localhost:3306/game_message?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
    first_username=root
    first_password=root
    
    #数据源 2
    second_driverClass=com.mysql.jdbc.Driver
    second_jdbcUrl=jdbc:mysql://localhost:3306/web_slave?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
    second_username=root
    second_password=root
    
    
    #定义初始连接数
    initialSize=0
    #定义最大连接数
    maxActive=20
    #定义最大空闲
    maxIdle=20
    #定义最小空闲
    minIdle=1
    #定义最长等待时间
    maxWait=60000

然后在applicationContext.xml上面做修改，将原来只有一个数据源的配置改成多个（请看配置里的注释）：

<?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:beans="http://www.springframework.org/schema/beans"
           xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:aop="http://www.springframework.org/schema/aop"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
             http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
             http://www.springframework.org/schema/context
             http://www.springframework.org/schema/context/spring-context-4.2.xsd
             http://www.springframework.org/schema/mvc
             http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd ">
    
        
        <context:component-scan base-package="com.springmvc"/>
    
        <mvc:annotation-driven />
        
        
        <mvc:resources location="/images/" mapping="/images/**"/>
        <mvc:resources location="/css/" mapping="/css/**"/>
        <mvc:resources location="/styles/" mapping="/styles/**"/>
        <mvc:resources location="/js/" mapping="/js/**"/>
    
        
        <mvc:annotation-driven >
            
            <mvc:message-converters>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                    <property name="objectMapper">
                        <bean class="com.fasterxml.jackson.databind.ObjectMapper">
                            <property name="dateFormat">
                                <bean class="java.text.SimpleDateFormat">
                                    <constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />
                                </bean>
                            </property>
                        </bean>
                    </property>
                </bean>
            </mvc:message-converters>
        </mvc:annotation-driven>
    
    
    
        
        
        <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
            <property name="messageConverters">
                <list>
                    <ref bean="mappingJacksonHttpMessageConverter"/>
                </list>
            </property>
        </bean>
        <bean id="mappingJacksonHttpMessageConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="supportedMediaTypes">
                <list>
                    <value>application/json;charset=UTF-8</value>
                </list>
            </property>
        </bean>
    
    
        
        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
            <property name="prefix" value="/WEB-INF/views/" />
            <property name="suffix" value=".jsp" />
        </bean>
    
    
        
        
        
        
        <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
            <property name="locations">
                <list>
                    <value>classpath*:jdbc.properties</value>
                </list>
            </property>
            <property name="ignoreUnresolvablePlaceholders" value="true" />
        </bean>
        
        
        <bean id="firstSource" class="org.apache.commons.dbcp.BasicDataSource"
              destroy-method="close">
            <property name="driverClassName" value="${first_driverClass}"/>
            <property name="url" value="${first_jdbcUrl}"/>
            <property name="username" value="${first_username}"/>
            <property name="password" value="${first_password}"/>
            
            <property name="initialSize" value="${initialSize}"></property>
            
            <property name="maxActive" value="${maxActive}"></property>
            
            <property name="maxIdle" value="${maxIdle}"></property>
            
            <property name="minIdle" value="${minIdle}"></property>
            
            <property name="maxWait" value="${maxWait}"></property>
        </bean>
    
        
        <bean id="secondSource" class="org.apache.commons.dbcp.BasicDataSource"
              destroy-method="close">
            <property name="driverClassName" value="${second_driverClass}"/>
            <property name="url" value="${second_jdbcUrl}"/>
            <property name="username" value="${second_username}"/>
            <property name="password" value="${second_password}"/>
            
            <property name="initialSize" value="${initialSize}"></property>
            
            <property name="maxActive" value="${maxActive}"></property>
            
            <property name="maxIdle" value="${maxIdle}"></property>
            
            <property name="minIdle" value="${minIdle}"></property>
            
            <property name="maxWait" value="${maxWait}"></property>
        </bean>
    
        
        <bean id="dataSource" class="com.springmvc.dynamicsource.DynamicDataSource">
            <property name="targetDataSources">
                <map key-type="java.lang.String">
                    
                    <entry key="firstSource" value-ref="firstSource"></entry>
                    <entry key="secondSource" value-ref="secondSource"></entry>
                </map>
            </property>
            
            <property name="defaultTargetDataSource" ref="firstSource" />
        </bean>
    
    
        
        <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
            <property name="dataSource" ref="dataSource" />
        </bean>
    
        
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            
            <property name="dataSource" ref="dataSource"/>
            <property name="configLocation" value="classpath:mybatis.xml" />
            <property name="mapperLocations" value="classpath:sqlmap/*Mapper.xml"/>
            <property name="typeAliasesPackage" value="com.springmvc.entity" />
        </bean>
        
        <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
            
            <property name="basePackage" value="com.springmvc.dao"/>
            
            <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        </bean>
    
    
        
        <mvc:interceptors>
            
            <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" />
        </mvc:interceptors>
        
        
    
    
    
    </beans>

然后是定义动态数据源，DynamicDataSource.java：

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
    
    
    /**
     * @Author : JCccc
     * @CreateTime : 2019/8/15
     * @Description :
     **/
    public class DynamicDataSource extends AbstractRoutingDataSource{
    
    //定义动态数据源，集成spring提供的AbstractRoutingDataSource，实现determineCurrentLookupKey
    
        @Override
        protected Object determineCurrentLookupKey() {
            return DynamicDataSourceHolder.getDataSource();
        }
    
    
    
    }

接着是动态切换数据源方法类，DynamicDataSourceHolder.java：

/**
     * @Author : JCccc
     * @CreateTime : 2019/8/15
     * @Description :
     **/
    public class DynamicDataSourceHolder
    {
        private static final ThreadLocal<String> THREAD_DATA_SOURCE = new ThreadLocal();
    
        public static String getDataSource()
        {
            return (String)THREAD_DATA_SOURCE.get();
        }
    
        public static void setDataSource(String dataSource)
        {
            THREAD_DATA_SOURCE.set(dataSource);
        }
    
        public static void clearDataSource()
        {
            THREAD_DATA_SOURCE.remove();
        }
    }

到这，多数据源已经实现了，我们在切换数据源，使用的时候只需要用以下这行代码进行切换：

DynamicDataSourceHolder.setDataSource("XXXX"); //值为配置文件里面数据源设置的加载key

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1Mzg3OTQw_size_16_color_FFFFFF_t_70][]

最后测试下，写一个接口简单测试下：

@Autowired
        MessageboardService messageboardServiceImpl;
        @Autowired
        JdbcConfigService jdbcConfigServiceImpl;
    
        @RequestMapping(value = "/testDbSource", produces = "application/json; charset=utf-8")
        public void testDbSource() {
    
            DynamicDataSourceHolder.setDataSource("firstSource"); //切换到数据源1
            Messageboard  message = messageboardServiceImpl.selectByPrimaryKey(5);
            System.out.println(message.toString());
            DynamicDataSourceHolder.setDataSource("secondSource"); //切换到数据源2
            JdbcConfig jdbcConfig = jdbcConfigServiceImpl.selectByGameId("1234");
            System.out.println(jdbcConfig.toString());
            DynamicDataSourceHolder.setDataSource("firstSource"); //切换到数据源1
            Messageboard  messageExtra = messageboardServiceImpl.selectByPrimaryKey(4);
            System.out.println(messageExtra.toString());
        }

运行这个接口，我们会切换到第一个数据源进行操作，然后切换到第二个数据源进行操作，再切换到第一个数据源进行操作：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1Mzg3OTQw_size_16_color_FFFFFF_t_70 1][]

看下控制台输出（可以看到，切换自如）：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1Mzg3OTQw_size_16_color_FFFFFF_t_70 2][]

好，多数据源的简单使用就到此吧。

[https_blog.csdn.net_qq_35387940_article_details_97911104]: https://blog.csdn.net/qq_35387940/article/details/97911104
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