【11】Spring Boot系列之多数据源配置（方法1）_servertimezone=gmt%2b8&characterencoding=utf-8&all-优快云博客

本文介绍在SpringBoot中实现动态多数据源配置的方法，包括应用配置、自定义注解、切面处理、数据源类及上下文管理，适用于需要在运行时动态切换数据源的场景。

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本篇在【10】Spring Boot系列之通用 mapper 改进AOP 基础上修改。

（1）application.properties 添加配置

#数据源配置（默认）
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/db_master?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

#多数据源配置
#ds1,ds2 其他两个数据源
slave.datasource.names=ds1,ds2
#ds1
slave.datasource.ds1.driver-class-name=com.mysql.cj.jdbc.Driver
slave.datasource.ds1.url=jdbc:mysql://localhost:3306/db_2?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
slave.datasource.ds1.username=root
slave.datasource.ds1.password=123456
slave.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
#ds2
slave.datasource.ds2.driver-class-name=com.mysql.cj.jdbc.Driver
slave.datasource.ds2.url=jdbc:mysql://localhost:3306/db_3?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
slave.datasource.ds2.username=root
slave.datasource.ds2.password=123456
slave.datasource.ds2.type=com.alibaba.druid.pool.DruidDataSource

（2）定义注解：

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

（3）定义切面

/**
 * 切换数据源Advice
 * @author user
 */
@Aspect
@Order(-1)//保证在@Transactional之前执行
@Component
public class DynamicDataSourceAspect {

	private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
	
    //改变数据源
    @Before("@annotation(targetDataSource)")
    public void changeDataSource(JoinPoint joinPoint, TargetDataSource targetDataSource) {
        String dbid = targetDataSource.name();

        if (!DynamicDataSourceContextHolder.isContainsDataSource(dbid)) {
        	logger.error("数据源[{}]不存在，使用默认数据源 > {}", targetDataSource.name(), joinPoint.getSignature());
        } else {
        	 logger.debug("使用数据源：" + dbid);
            DynamicDataSourceContextHolder.setDataSourceType(dbid);
        }
    }

    @After("@annotation(targetDataSource)")
    public void clearDataSource(JoinPoint joinPoint, TargetDataSource targetDataSource) {
    	logger.debug("清除数据源 " + targetDataSource.name() + " !");
        DynamicDataSourceContextHolder.clearDataSourceType();
    }
}

（4）添加
DynamicDataSource.java
DynamicDataSourceContextHolder.java
DynamicDataSourceRegister.java

/**
 * AbstractRoutingDataSource(每执行一次数据库，动态获取DataSource)
 * @author user
 */
public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSourceType();
    }
}

/**
 * 动态数据源上下文管理
 * @author user
 */
public class DynamicDataSourceContextHolder {

    //存放当前线程使用的数据源类型信息
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    
    //存放数据源id
    public static List<String> dataSourceIds = new ArrayList<String>();

    //设置数据源
    public static void setDataSourceType(String dataSourceType) {
        contextHolder.set(dataSourceType);
    }

    //获取数据源
    public static String getDataSourceType() {
        return contextHolder.get();
    }

    //清除数据源
    public static void clearDataSourceType() {
        contextHolder.remove();
    }

    //判断当前数据源是否存在
    public static boolean isContainsDataSource(String dataSourceId) {
        return dataSourceIds.contains(dataSourceId);
    }
}

/**
 *  动态数据源注册
 *  @author user
 *  启动动态数据源请在启动类中添加 @Import(DynamicDataSourceRegister.class)
 */
public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware {

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

    //指定默认数据源(springboot2.0默认数据源是hikari如何想使用其他数据源可以自己配置)
    private static final String DATASOURCE_TYPE_DEFAULT = "com.zaxxer.hikari.HikariDataSource";
    //默认数据源
    private DataSource defaultDataSource;
    //用户自定义数据源
    private Map<String, DataSource> slaveDataSources = new HashMap<>();

    @Override
    public void setEnvironment(Environment environment) {
        initDefaultDataSource(environment);
        initslaveDataSources(environment);
    }

    private void initDefaultDataSource(Environment env) {
        // 读取主数据源
        Map<String, Object> dsMap = new HashMap<>();
        dsMap.put("driver-class-name", env.getProperty("spring.datasource.driver-class-name"));
        dsMap.put("url", env.getProperty("spring.datasource.url"));
        dsMap.put("username", env.getProperty("spring.datasource.username"));
        dsMap.put("password", env.getProperty("spring.datasource.password"));
        dsMap.put("type", env.getProperty("spring.datasource.type"));
        defaultDataSource = buildDataSource(dsMap);
    }


    private void initslaveDataSources(Environment env) {
        // 读取配置文件获取更多数据源
        String dsPrefixs = env.getProperty("slave.datasource.names");
        for (String dsPrefix : dsPrefixs.split(",")) {
            // 多个数据源
            Map<String, Object> dsMap = new HashMap<>();
            dsMap.put("driver-class-name", env.getProperty("slave.datasource." + dsPrefix + ".driver-class-name"));
            dsMap.put("url", env.getProperty("slave.datasource." + dsPrefix + ".url"));
            dsMap.put("username", env.getProperty("slave.datasource." + dsPrefix + ".username"));
            dsMap.put("password", env.getProperty("slave.datasource." + dsPrefix + ".password"));
            dsMap.put("type", env.getProperty("slave.datasource." + dsPrefix + ".type"));
            DataSource ds = buildDataSource(dsMap);
            slaveDataSources.put(dsPrefix, ds);
        }
    }

    @Override
    public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) {
        Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
        //添加默认数据源
        targetDataSources.put("dataSource", this.defaultDataSource);
        DynamicDataSourceContextHolder.dataSourceIds.add("dataSource");
        //添加其他数据源
        targetDataSources.putAll(slaveDataSources);
        for (String key : slaveDataSources.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);
        //注册 - BeanDefinitionRegistry
        beanDefinitionRegistry.registerBeanDefinition("dataSource", beanDefinition);
        logger.info("Dynamic DataSource Registry");
    }

    public DataSource buildDataSource(Map<String, Object> dataSourceMap) {
        try {
            Object type = dataSourceMap.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 = dataSourceMap.get("driver-class-name").toString();
            String url = dataSourceMap.get("url").toString();
            String username = dataSourceMap.get("username").toString();
            String password = dataSourceMap.get("password").toString();
            // 自定义DataSource配置
            DataSourceBuilder<?> factory = DataSourceBuilder.create().driverClassName(driverClassName).url(url)
                    .username(username).password(password).type(dataSourceType);
            return factory.build();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }
}

（5）启动类注册动态数据源

@SpringBootApplication
@MapperScan("com.example.demo.dao")
@Import(DynamicDataSourceRegister.class) // 注册动态多数据源
public class DemoApplication {

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