springboot动态多数据源

 参考文章：https://www.cnblogs.com/hehehaha/p/6147096.html

前言

目标是springboot工程支持多个MySQL数据源，在代码层面上，同一个SQL(Mapper)可以在多个数据源灵活使用，也就是所说的动态。

这种动态是通过LocalThread实现的，即一个web请求对应一个线程，在线程中指定一个数据源。

1、maven pom

pom.xml里有springboot的starter和数据库驱动，我这里用的是druid

<?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.ivan.studio</groupId>
    <artifactId>fantacy</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <!-- 文件拷贝时的编码 -->
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <!-- 编译时的编码 -->
        <maven.compiler.encoding>UTF-8</maven.compiler.encoding>
        <jdk.version>1.7</jdk.version>
        <hive.version>1.2.1</hive.version>
        <hadoop.version>2.7.2</hadoop.version>
        <shiro.version>1.4.0</shiro.version>
    </properties>
    <!-- 继承父包 -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.3.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <version>1.4.3.RELEASE</version>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <!--<dependency>-->
            <!--<groupId>org.apache.tomcat</groupId>-->
            <!--<artifactId>tomcat-jdbc</artifactId>-->
        <!--</dependency>-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.20</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>4.3.8.RELEASE</version>
        </dependency>
    
        </dependency>
        <!-- druid阿里巴巴数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.15</version>
        </dependency>
    </dependencies>
    

</project>

2、配置文件

application.properties配置文件里要有主数据源，多数据源，线程池等配置

# 主数据源
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/ivan?useUnicode=true&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=123456


# 更多数据源
custom.datasource.names=ds1,ds2

custom.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
custom.datasource.ds1.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds1.url=jdbc:mysql://127.0.0.1:3306/vicky?useUnicode=true&characterEncoding=utf-8
custom.datasource.ds1.username=root
custom.datasource.ds1.password=123456

custom.datasource.ds2.type=com.alibaba.druid.pool.DruidDataSource
custom.datasource.ds2.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds2.url=jdbc:mysql://127.0.0.1:3306/ivan?useUnicode=true&characterEncoding=utf-8
custom.datasource.ds2.username=root
custom.datasource.ds2.password=123456

#连接池的配置信息
spring.datasource.initialSize=10
spring.datasource.minIdle=10
spring.datasource.maxActive=100
spring.datasource.maxWait=60000
spring.datasource.timeBetweenEvictionRunsMillis=60000
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20
spring.datasource.filters=stat,wall,log4j
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000

3、动态数据源路由类

       动态数据源能进行自动切换的核心就是spring底层提供了AbstractRoutingDataSource类进行数据源的路由的，我们主要继承这个类，实现里面的方法即可实现我们想要的，这里主要是实现方法：determineCurrentLookupKey（），而此方法只需要返回一个数据库的名称即可，所以我们核心的是有一个类来管理数据源的线程池，这个类才是动态数据源的核心处理类。还有另外就是我们使用aop技术在执行事务方法前进行数据源的切换。所以这里有几个需要编码的类，具体如下：

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

/**
 * @Author: ivan
 * @Description:
 * @Date: Created in 15:23 18/5/24
 * @Modified By:
 */

public class DynamicDataSourceContextHolder {

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();

    public static List<String> dataSourceIds = new ArrayList<String>();

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

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

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

    /**
     * 判断指定DataSrouce当前是否存在
     *
     * @param dataSourceId
     * @return
     * @author ivan
     * @create  2016年1月24日
     */
    public static boolean containsDataSource(String dataSourceId){
        return dataSourceIds.contains(dataSourceId);
    }
}

数据源路由类：

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

/**
 * 动态多数据源
 * @Author: ivan
 * @Description:
 * @Date: Created in 15:22 18/5/24
 * @Modified By:
 */

public class DynamicDataSource extends AbstractRoutingDataSource {

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

}

指定数据源注解类>com.kfit.config.datasource.dynamic.TargetDataSource：

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

/**
 * @Author: ivan
 * @Description:
 * @Date: Created in 15:29 18/5/24
 * @Modified By:
 */


@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}

切换数据源Advice： 

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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**
 * @Author: ivan
 * @Description:
 * @Date: Created in 15:25 18/5/24
 * @Modified By:
 */


/**
 * 切换数据源Advice
 *
 * @author ivan
 */
@Aspect
@Order(-10)// 保证该AOP在@Transactional之前执行
@Component
public class DynamicDataSourceAspect {

    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);

    @Before("@annotation(ds)")
    public void changeDataSource(JoinPoint point, TargetDataSource ds) throws Throwable {
        String dsId = ds.name();
        if (!DynamicDataSourceContextHolder.containsDataSource(dsId)) {
            logger.error("ds=[{}]not exist，use main DataSource > {}", ds.name(), point.getSignature());
        } else {
            logger.debug("Use DataSource : {} > {}", ds.name(), point.getSignature());
            DynamicDataSourceContextHolder.setDataSourceType(ds.name());
        }
    }

    @After("@annotation(ds)")
    public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
        logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
        DynamicDataSourceContextHolder.clearDataSourceType();
    }

}

4、注册多数据源

以上都是动态数据源在注入的时候使用的代码，其实很重要的一部分代码就是注册我们在application.properties配置的多数据源，这才是重点，这里我们使用

ImportBeanDefinitionRegistrar进行注册，具体的代码如下：

package com.ivan.studio.fantacy.common;

/**
 * @Author: ivan
 * @Description:
 * @Date: Created in 15:27 18/5/24
 * @Modified By:
 */
import com.alibaba.druid.pool.DruidDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.bind.RelaxedDataBinder;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

/**
 * 动态数据源注册<br/>
 * 启动动态数据源请在启动类中（如SpringBootSampleApplication）
 * 添加 @Import(DynamicDataSourceRegister.class)
 *
 * @author ivan
 */
public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware {

    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceRegister.class);

    private ConversionService conversionService = new DefaultConversionService();
    private PropertyValues dataSourcePropertyValues;

    // 如配置文件中未指定数据源类型，使用该默认值
    private static final Object DATASOURCE_TYPE_DEFAULT = "org.apache.tomcat.jdbc.pool.DataSource";
    // private static final Object DATASOURCE_TYPE_DEFAULT =
    // "com.zaxxer.hikari.HikariDataSource";

    // 数据源
    private DataSource defaultDataSource;
    private Map<String, DataSource> customDataSources = new HashMap<String, DataSource>();

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
        // 将主数据源添加到更多数据源中
        targetDataSources.put("dataSource", defaultDataSource);
        DynamicDataSourceContextHolder.dataSourceIds.add("dataSource");
        // 添加更多数据源
        targetDataSources.putAll(customDataSources);
        for (String key : customDataSources.keySet()) {
            DynamicDataSourceContextHolder.dataSourceIds.add(key);
        }

        // 创建DynamicDataSource
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(DynamicDataSource.class);
        beanDefinition.setSynthetic(true);
        MutablePropertyValues mpv = beanDefinition.getPropertyValues();
        mpv.addPropertyValue("defaultTargetDataSource", defaultDataSource);
        mpv.addPropertyValue("targetDataSources", targetDataSources);
        registry.registerBeanDefinition("dataSource", beanDefinition);

        logger.info("Dynamic DataSource Registry");
    }

    /**
     * 创建DataSource
     * @return
     * @author ivan
     * @create 2016年1月24日
     */
    @SuppressWarnings("unchecked")
    public DataSource buildDataSource(Map<String, Object> dsMap) {
        try {
            Object type = dsMap.get("type");
            if (type == null) {
                type = DATASOURCE_TYPE_DEFAULT;// 默认DataSource
            }

            Class<? extends DataSource> dataSourceType;
            dataSourceType = (Class<? extends DataSource>) Class.forName((String) type);

            String driverClassName = dsMap.get("driver-class-name").toString();
            String url = dsMap.get("url").toString();
            String username = dsMap.get("username").toString();
            String password = dsMap.get("password").toString();

            DataSourceBuilder factory = DataSourceBuilder.create().driverClassName(driverClassName).url(url)
                    .username(username).password(password).type(dataSourceType);
            return factory.build();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    public DataSource getDataSource(Map<String, Object> dsMap) {

        DruidDataSource datasource = new DruidDataSource();
        datasource.setUrl(dsMap.get("url").toString());
        datasource.setUsername(dsMap.get("username").toString());
        datasource.setPassword(dsMap.get("password").toString());
        datasource.setDriverClassName(dsMap.get("driver-class-name").toString());

        return datasource;

    }

    /**
     * 加载多数据源配置
     */
    @Override
    public void setEnvironment(Environment env) {
        initDefaultDataSource(env);
        initCustomDataSources(env);
    }

    /**
     * 初始化主数据源
     *
     * @author ivan
     */
    private void initDefaultDataSource(Environment env) {
        // 读取主数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "spring.datasource.");
        Map<String, Object> dsMap = new HashMap<String, Object>();
        dsMap.put("type", propertyResolver.getProperty("type"));
        dsMap.put("driver-class-name", propertyResolver.getProperty("driver-class-name"));
        dsMap.put("url", propertyResolver.getProperty("url"));
        dsMap.put("username", propertyResolver.getProperty("username"));
        dsMap.put("password", propertyResolver.getProperty("password"));

        defaultDataSource = getDataSource(dsMap);

        dataBinder(defaultDataSource, env);
    }

    /**
     * 为DataSource绑定更多数据
     *
     * @param dataSource
     * @param env
     * @author ivan
     */
    private void dataBinder(DataSource dataSource, Environment env){
        RelaxedDataBinder dataBinder = new RelaxedDataBinder(dataSource);
        //dataBinder.setValidator(new LocalValidatorFactory().run(this.applicationContext));
        dataBinder.setConversionService(conversionService);
        dataBinder.setIgnoreNestedProperties(false);//false
        dataBinder.setIgnoreInvalidFields(false);//false
        dataBinder.setIgnoreUnknownFields(true);//true
        if(dataSourcePropertyValues == null){
            Map<String, Object> rpr = new RelaxedPropertyResolver(env, "spring.datasource").getSubProperties(".");
            Map<String, Object> values = new HashMap<String, Object>(rpr);
            // 排除已经设置的属性
            values.remove("type");
            values.remove("driver-class-name");
            values.remove("url");
            values.remove("username");
            values.remove("password");
            dataSourcePropertyValues = new MutablePropertyValues(values);
        }
        dataBinder.bind(dataSourcePropertyValues);
    }

    /**
     * 初始化更多数据源
     *
     * @author ivan
     * @create 2016年1月24日
     */
    private void initCustomDataSources(Environment env) {
        // 读取配置文件获取更多数据源，也可以通过defaultDataSource读取数据库获取更多数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "custom.datasource.");
        String dsPrefixs = propertyResolver.getProperty("names");
        for (String dsPrefix : dsPrefixs.split(",")) {
            Map<String, Object> dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
            DataSource ds = getDataSource(dsMap);
            customDataSources.put(dsPrefix, ds);
            dataBinder(ds, env);
        }
    }

}

这里还有一个步骤很重要，由于我们是使用的ImportBeanDefinitionRegistrar的方式进行注册的，所以我们需要在App.java类中使用@Import进行注册，具体改造之后的App.java代码如下：

import com.ivan.studio.fantacy.common.DynamicDataSourceRegister;
import com.ivan.studio.fantacy.service.AutowiredService;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Import;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import static org.springframework.boot.SpringApplication.run;

/**
 * @author ivan
 */
@SpringBootApplication
@Import({DynamicDataSourceRegister.class})
public class WebApplication {

    private static volatile boolean IS_REGISTRY = false;

    public static void main(String[] args) {
       SpringApplication.run(App.class, args);
    }
}