SSM动态配置多数据源

1. 数据源配置 spring.xml

<!-- 配置动态数据源开始 -->
    <!-- 配置连接池 druid 数据源，用于访问mysql数据库(${}这种写法称为占位符，具体值在运行时使用db.properties文件中配置的值) com.alibaba.druid.pool.DruidDataSource-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="url" value="${jdbc.url}${jdbc.dbname1}?${jdbc.params}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="initialSize" value="${initialSize}"/>
        <property name="maxActive" value="${maxActive}"/>
        <property name="minIdle" value="${minIdle}"/>
        <property name="maxIdle" value="${maxIdle}"/>
        <property name="maxWait" value="${maxWait}"/>
        <property name="validationQuery" value="${validationQuery}"/>
        <property name="poolPreparedStatements" value="${poolPreparedStatements}"/>
        <property name="maxPoolPreparedStatementPerConnectionSize" value="${maxPoolPreparedStatementPerConnectionSize}"/>
        <property name="timeBetweenEvictionRunsMillis" value="${timeBetweenEvictionRunsMillis}"/>
        <property name="minEvictableIdleTimeMillis" value="${minEvictableIdleTimeMillis}"/>
        <!-- 配置监控统计拦截的filters -->
        <property name="filters" value="stat"/>
    </bean>

    <bean id="dataSourceE" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="url" value="${jdbc.url}${jdbc.dbname2}?${jdbc.params}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="initialSize" value="${initialSize}"/>
        <property name="maxActive" value="${maxActive}"/>
        <property name="minIdle" value="${minIdle}"/>
        <property name="maxIdle" value="${maxIdle}"/>
        <property name="maxWait" value="${maxWait}"/>
        <property name="validationQuery" value="${validationQuery}"/>
        <property name="poolPreparedStatements" value="${poolPreparedStatements}"/>
        <property name="maxPoolPreparedStatementPerConnectionSize" value="${maxPoolPreparedStatementPerConnectionSize}"/>
        <property name="timeBetweenEvictionRunsMillis" value="${timeBetweenEvictionRunsMillis}"/>
        <property name="minEvictableIdleTimeMillis" value="${minEvictableIdleTimeMillis}"/>
        <!-- 配置监控统计拦截的filters -->
        <property name="filters" value="stat"/>
    </bean>

    <!-- 自定义数据源切换类 -->
    <bean id="myDataSource" class="com.zqu.DataSource.DynamicRoutingDataSource">
        <!-- 这里可以指定默认的数据源 -->
        <property name="defaultTargetDataSource" ref="dataSource" />
        <property name="targetDataSources">
            <map key-type="java.lang.String">
                <!-- 指定lookupKey和与之对应的数据源 -->
                <entry key="dataSource" value-ref="dataSource"></entry>
                <entry key="dataSourceE" value-ref="dataSourceE"></entry>
            </map>
        </property>
    </bean>
    <!-- 配置动态数据源结束 -->

2、配置数据源动态切面 spring.xml

<!-- 数据源动态切换切面配置 -->
    <aop:config>
        <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor" order="1">
            <!-- 拦截所有service实现类的方法 -->
            <aop:pointcut id="dataSourcePointcut"
                          expression="execution(* com.zqu.service..*Impl.*(..))"/>
            <aop:before pointcut-ref="dataSourcePointcut" method="intercept" />
        </aop:aspect>
    </aop:config>

    <!-- 数据源动态切换实体 -->
    <bean id="dataSourceInterceptor" class="com.zqu.DataSource.DynamicDataSourceInterceptor"/>
    <!-- 数据源动态切换切面配置结束 -->

3、配置数据库连接参数 jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/
jdbc.dbname1=family
jdbc.dbname2=employees
jdbc.params= useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=false&allowPublicKeyRetrieval=true
jdbc.username=root
jdbc.password=123
#配置初始化大小、最小、最大
initialSize=0
maxActive=8
minIdle=0
maxIdle=8

#配置获取连接等待超时的时间
maxWait=20000
validationQuery=select 1

#打开PSCache，并且指定每个连接上PSCache的大小
poolPreparedStatements=true
maxPoolPreparedStatementPerConnectionSize=10

#配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
timeBetweenEvictionRunsMillis=60000

#配置一个连接在池中最小生存的时间，单位是毫秒

minEvictableIdleTimeMillis=1800000

4、定义一个类继承DynamicRoutingDataSource实现determineCurrentLookupKey方法，来实现数据库的动态切换

import org.apache.log4j.Logger;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;


public class DynamicRoutingDataSource extends AbstractRoutingDataSource {
    private static final Logger LOG=Logger.getLogger(DynamicRoutingDataSource.class);
    @Override
    protected Object determineCurrentLookupKey() {
        LOG.info("当前数据源：{}"+DynamicDataSourceContextHolder.get());
        return  DynamicDataSourceContextHolder.get();
    }
}

5、定义工具类DynamicDataSourceContextHolder ，用于动态切换数据源

import org.apache.log4j.Logger;

/**
 * @ClassName DynamicDataSourceContextHolder
 * @Description: TODO
 * @Author Jason
 * @Date 2020/3/18  12:15
 * @Version V1.0
 **/
public class DynamicDataSourceContextHolder {
    private  static  final Logger LOG=Logger.getLogger(DynamicDataSourceContextHolder.class);
    private static final ThreadLocal<String> currenDataSource=new ThreadLocal<>();
    /**
     * @Author Jason
     * @Description //清除当前数据源
     * @Date 2020/3/18 12:19
     * @Param
     * @return
     **/
    public static  void clear(){
        currenDataSource.remove();
    }
   /**
    * @Author Jason
    * @Description //Description
    * @Date 2020/3/18 20:50
    * @Param []
    * @return java.lang.String
    **/
    public static String get(){
        return currenDataSource.get();
    }

    /**
     * @Author Jason
     * @Description 设置数据源
     * @Date 2020/3/18 15:49
     * @Param []
     * @return void
     **/
    public static void setDataSource(String datasource) {
        currenDataSource.set(datasource);
    }
}

6、自定义注解@TargetDataSource，通过注解的值来获取当前数据源，并进行切换

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * @ClassName TargetDataSource
 * @Description: 定义注解
 * @Author Jason
 * @Date 2020/3/18  17:07
 * @Version V1.0
 **/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public  @interface TargetDataSource {
   String value();
}

7、定义拦截器DynamicDataSourceInterceptor，解析注解切换数据源

import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;

import java.lang.reflect.Method;


/**
 * @ClassName DynamicDataSourceInterceptor
 * @Description: 数据源切换拦截器
 * @Author Jason
 * @Date 2020/3/18  17:32
 * @Version V1.0
 **/
public class DynamicDataSourceInterceptor {
    private static final Logger LOG = Logger.getLogger(DynamicDataSourceInterceptor.class);
    /**
     * @Author Jason
     * @Description 拦截目标方法，获取由@DataSource指定的数据源标识，设置到线程存储中以便切换数据源
     * @Date 2020/3/18 17:39
     * @Param [point]
     * @return void
     **/
    public void intercept(JoinPoint point) throws Exception {
        Class<?> target = point.getTarget().getClass();
        MethodSignature signature = (MethodSignature) point.getSignature();
        resolveDataSource(target, signature.getMethod());
    }

    /**
     * @Author Jason
     * @Description 提取目标对象方法注解和类型注解中的数据源标识
     * @Date 2020/3/18 17:40
     * @Param [clazz, method]
     * @return void
     **/
    private void resolveDataSource(Class<?> clazz, Method method) {
        try {
            Class<?>[] types = method.getParameterTypes();
            // 默认使用类型注解
            if (clazz.isAnnotationPresent(TargetDataSource.class)) {
                TargetDataSource source = clazz.getAnnotation(TargetDataSource.class);
                DynamicDataSourceContextHolder.setDataSource(source.value());
            }
            // 方法注解可以覆盖类型注解
            Method m = clazz.getMethod(method.getName(), types);
            if (m != null && m.isAnnotationPresent(TargetDataSource.class)) {
                TargetDataSource source = m.getAnnotation(TargetDataSource.class);
                DynamicDataSourceContextHolder.setDataSource(source.value());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * @Author Jason
     * @Description 执行方法后清除数据源设置
     * @Date 2020/3/18 21:26
     * @Param [joinPoint, targetDataSource]
     * @return void
     **/
    public void afterIntercept(JoinPoint point) {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Class<?>[] types = signature.getParameterTypes();
        Class<?> target = point.getTarget().getClass();
        try {
            Method m = target.getMethod(signature.getName(), types);
            if (m != null && m.isAnnotationPresent(TargetDataSource.class)) {
                TargetDataSource source = m.getAnnotation(TargetDataSource.class);
                LOG.info("当前数据源"+ source.value()+ "执行清理方法");
            }
            else{
                LOG.info("当前数据源"+ DynamicDataSourceContextHolder.get()+ "执行清理方法");
            }

        }catch (Exception e) {
            e.printStackTrace();
        }
        DynamicDataSourceContextHolder.clear();
    }
}

8、@TargetDataSource注解实现数据源切换实例

import com.zqu.DataSource.TargetDataSource;
import com.zqu.bean.Employees;
import com.zqu.dao.IEmployeesDao;
import com.zqu.service.IEmployeesService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

/**
 * @ClassName IEmployeesServiceImpl
 * @Description: TODO
 * @Author Jason
 * @Date 2020/3/18  18:02
 * @Version V1.0
 **/
@Service("employeesService")
public class IEmployeesServiceImpl implements IEmployeesService {
    @Resource(name="IEmployeesDao")
    private IEmployeesDao eDao;
    public List<Employees> findDemo(){
        return eDao.findDemo();
    }
    @TargetDataSource("dataSourceE")//切换数据源dataSourceE
    public List<Employees> find(){
        return  eDao.find();
    }
}

[参考文章](https://blog.csdn.net/johnf_nash/article/details/63260561

)