Spring4+dbcp+mysql6.06使用注解实现动态切库（不支持跨库事务）

maven依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mutil.transaction</groupId>
    <artifactId>transaction</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>transaction</name>
    <description>Demo project for Spring Boot</description>

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

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.6</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
            <version>1.4</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

db.properties

spring.datasource.sakila.url=jdbc:mysql://localhost:3306/sakila?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC&useSSL=true
spring.datasource.sakila.username=root
spring.datasource.sakila.password=root
spring.datasource.sakila.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.sakila.initialSize=1
spring.datasource.sakila.maxIdle=2
spring.datasource.sakila.minIdle=1


spring.datasource.library.url=jdbc:mysql://localhost:3306/library?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC&useSSL=true
spring.datasource.library.username=root
spring.datasource.library.password=root
spring.datasource.library.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.library.initialSize=1
spring.datasource.library.maxIdle=2
spring.datasource.library.minIdle=1

spring.datasource.defalut.defaultDataSourceName=libraryDataSource

DBConfig2 ：配置数据源、DataSourceTransactionManager、JdbcTemplate

package com.mutil.transaction.config;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.context.annotation.PropertySource;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

/**
 * Created by WuTing on 2017/12/5.
 */
@Configuration
@PropertySource("classpath:db.properties")
public class DBConfig2 {

    @Bean("libraryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.library")
    @Primary
    public DataSource libraryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean("sakilaDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.sakila")
    public DataSource sakilaDataSource() {

        return DataSourceBuilder.create().build();
    }

    @Bean("dataSource")
    public DynamicDataSource dataSource() {

        return new DynamicDataSource("libraryDataSource");
    }

    @Bean("jdbcTemplate")
    public JdbcTemplate jdbcTemplate(@Qualifier("dataSource") DynamicDataSource dataSource) {

        return new JdbcTemplate(dataSource);
    }

    @Bean("transactionManager")
    public DataSourceTransactionManager transactionManager(@Qualifier("dataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

DynamicDataSource：继承了AbstractRoutingDataSource，设置多个数据源，将数据源交给Spring控制

package com.mutil.transaction.config;

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import javax.sql.DataSource;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import com.atomikos.jdbc.AtomikosDataSourceBean;

/**
 * Created by WuTing on 2017/12/5.
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    public DynamicDataSource(String defaultDataSourceName) {
        Map<Object, Object> dataSourcs = SpringContextUtil.getBeans(DataSource.class, DynamicDataSource.class);
        List dataSourceIds = dataSourcs.keySet().stream().collect(Collectors.toList());
        DataSourceContextHolder.dataSourceIds.addAll(dataSourceIds);
        this.setTargetDataSources(dataSourcs);
        this.setDefaultTargetDataSource(dataSourcs.get(defaultDataSourceName));
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceType();
    }

}

为了使用注解方式进行动态切换数据源，需要定义一个DataSource注解，并且使用AOP方式进行数据源动态切换。DataSourceAspect 切面便是用于数据源切换。

DataSource注解：可作用于方法、class上， 用于class表明当前class的所有方法使用相同的数据源，用于方法上申明当前方法使用的数据源，当同时用于方法和class上时，用于方法上优先级较高。

package com.mutil.transaction.config;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Created by WuTing on 2017/12/5.
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface DataSource {
    String value();
}

DataSourceAspect：用于动态切换数据源.

package com.mutil.transaction.config;

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**
 * Created by WuTing on 2017/12/5.
 */
@Component
@Aspect
@Order(1)
public class DataSourceAspect {
    private static final Logger logger = LoggerFactory.getLogger(DataSourceAspect.class);

    @Before(value = "execution(* com.mutil.transaction.service.*.*(..))")
    public void before(JoinPoint point) {
        DataSource annotation = getDataSourceAnnotation(point);
        if (annotation != null) {
            DataSourceContextHolder.setDataSourceType(annotation.value());
            logger.debug("Set DataSource : {} > {}", annotation.value(), point.getSignature());
        }
    }

    @After(value = "execution(* com.mutil.transaction.service.*.*(..))")
    public void restoreDataSource(JoinPoint point) {

        DataSource annotation = getDataSourceAnnotation(point);
        if (annotation != null) {
            logger.debug("Revert DataSource : {} > {}", annotation.value(), point.getSignature());
        }
        DataSourceContextHolder.clearDataSourceType();
    }

    private DataSource getDataSourceAnnotation(JoinPoint point) {
        DataSource annotation = null;
        Class[] parameterTypes = ((MethodSignature)point.getSignature()).getMethod().getParameterTypes();
        String methodName = point.getSignature().getName();
        try {
            Method method = point.getTarget().getClass().getMethod(methodName, parameterTypes);
            if (method.isAnnotationPresent(DataSource.class)) {
                annotation = method.getAnnotation(DataSource.class);
            } else {
                annotation = point.getTarget().getClass().getAnnotation(DataSource.class);
            }
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }

        return annotation;
    }
}

DataSourceContextHolder：数据源切换实现类

package com.mutil.transaction.config;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by WuTing on 2017/12/5.
 */
public class DataSourceContextHolder {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    public static List<String> dataSourceIds = new ArrayList<>();

    public static void setDataSourceType(String dataSourceType) {
        contextHolder.set(dataSourceType);
    }

    public static String getDataSourceType() {
        return contextHolder.get();
    }

    public static void clearDataSourceType() {
        contextHolder.remove();
    }

    public static boolean containsDataSource(String dataSourceId) {
        return dataSourceIds.contains(dataSourceId);
    }
}

项目地址：https://github.com/wutingting1993/transaction/tree/Switch-DB-Automatic/