spring boot 多数据源加载原理
git代码：https://gitee.com/wwj912790488/multiple-data-sources
DynamicDataSourceAspect切面 必须定义@Order(-10)，保证该aop在@Transaction之前执行
配置如下，分别加载三个数据库配置
1.利用ImportBeanDefinitionRegistrar和EnvironmentAware 加载注册多个数据源bean
package org.spring.boot.multiple.ds;
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.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;
/**
* @author donghongchen
* @create 2017-09-04 15:34
* <p>
* 动态数据源注册
**/
public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware {
private Logger logger = LoggerFactory.getLogger(this.getClass());
//如果配置文件中未指定数据源类型，使用默认值
private static final Object DATASOURCE_TYPE_DEFAULT = "org.apache.tomcat.jdbc.pool.DataSource";
private ConversionService conversionService = new DefaultConversionService();
private PropertyValues dataSourcePropertyValues;
//默认数据源
private DataSource defaultDataSource;
private Map<String, DataSource> customDataSources = new HashMap<>();
/**
* 加载多数据源配置
*
* @param environment
*/
@Override
public void setEnvironment(Environment environment) {
initDefaultDataSource(environment);
initCustomDataSources(environment);
}
private void initDefaultDataSource(Environment environment) {
//读取主数据源
RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(environment, "spring.datasource.");
Map<String, Object> dsMap = new HashMap<>();
dsMap.put("type", propertyResolver.getProperty("type"));
dsMap.put("driverClassName", propertyResolver.getProperty("driverClassName"));
dsMap.put("url", propertyResolver.getProperty("url"));
dsMap.put("username", propertyResolver.getProperty("username"));
dsMap.put("password", propertyResolver.getProperty("password"));
//创建数据源
defaultDataSource = buildDataSource(dsMap);
dataBinder(defaultDataSource, environment);
}
private void initCustomDataSources(Environment environment) {
//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(environment, "custom.datasource.");
String dsPrefixs = propertyResolver.getProperty("names");
if (null == dsPrefixs || "".equals(dsPrefixs)) {
return;
}
String[] dsPrefixsArr = dsPrefixs.split(",");
for (String dsPrefix : dsPrefixsArr) {
Map<String, Object> dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
DataSource ds = buildDataSource(dsMap);
customDataSources.put(dsPrefix, ds);
dataBinder(ds, environment);
}
}
private DataSource buildDataSource(Map<String, Object> dsMap) {
Object type = dsMap.get("type");
if (type == null) {
type = DATASOURCE_TYPE_DEFAULT;
}
Class<? extends DataSource> dataSourceType;
try {
dataSourceType = (Class<? extends DataSource>) Class.forName((String) type);
String driverClassName = dsMap.get("driverClassName").toString();
String url = dsMap.get("url").toString();
String username = dsMap.get("username").toString();
String password = dsMap.get("password").toString();
DruidDataSource dataSource = new DruidDataSource();
dataSource.setUrl(url);
dataSource.setUsername(username);
dataSource.setPassword(password);
dataSource.setDriverClassName(driverClassName);
return dataSource;
// DataSourceBuilder factory = DataSourceBuilder.create().
// driverClassName(driverClassName).type(dataSourceType).url(url).username(username).password(password);
// return factory.build();
} catch (ClassNotFoundException ex) {
logger.error(ex.getMessage(), ex);
}
return null;
}
private void dataBinder(DataSource dataSource, Environment environment) {
RelaxedDataBinder dataBinder = new RelaxedDataBinder(dataSource);
dataBinder.setConversionService(conversionService);
dataBinder.setIgnoreNestedProperties(false);
dataBinder.setIgnoreInvalidFields(false);
dataBinder.setIgnoreUnknownFields(true);
if (dataSourcePropertyValues == null) {
Map<String, Object> rpr = new RelaxedPropertyResolver(environment, "spring.datasource").
getSubProperties(".");
Map<String, Object> values = new HashMap<>(rpr);
//排除已经设置的属性
values.remove("type");
values.remove("driverClassName");
values.remove("url");
values.remove("username");
values.remove("password");
dataSourcePropertyValues = new MutablePropertyValues(values);
}
dataBinder.bind(dataSourcePropertyValues);
}
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
Map<String, Object> targetDataSource = new HashMap<>();
//将主数据源添加到更多数据源中
targetDataSource.put("dataSource", defaultDataSource);
DynamicDataSourceContextHolder.dataSourceIDS.add("dataSource");
//添加更多数据源
targetDataSource.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();
//添加属性
mpv.addPropertyValue("defaultTargetDataSource", defaultDataSource);
mpv.addPropertyValue("targetDataSources", targetDataSource);
registry.registerBeanDefinition("dataSource", beanDefinition);
}
}
根据@annotation 去动态切换数据源
package org.spring.boot.multiple.ds;
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 donghongchen
* @create 2017-09-04 14:44
* <p>
* 切换数据源Advice
**/
@Aspect
@Order(-10) //保证该aop在@Transaction之前执行
@Component
public class DynamicDataSourceAspect {
private Logger logger = LoggerFactory.getLogger(this.getClass());
/**
* * @Before("@annotation(ds)")
* 的意思是：@Before：在方法执行之前进行执行; @annotation(targetDataSource)：会拦截注解targetDataSource的方法，否则不拦截;
* @param point
* @param targetDataSource
*/
@Before("@annotation(targetDataSource)")
public void changeDataSource(JoinPoint point, TargetDataSource targetDataSource){
//获取当前的指定数据源
String dsID = targetDataSource.value();
//如果不在我们注入的所有的数据源范围内，输出警告信息，系统自动使用默认的数据源
if (!DynamicDataSourceContextHolder.containsDataSource(dsID)){
logger.error("数据源["+dsID+"]不存在，使用默认的数据源 > { " + dsID+", 方法签名："+point.getSignature()+"}");
}else {
logger.info("Use DataSource: {" +dsID+", 方法签名："+point.getSignature() +"}");
//找到的话，那么设置动态数据源上下文
DynamicDataSourceContextHolder.setDataSourceType(dsID);
}
}
@After("@annotation(targetDataSource)")
public void restoreDataSource(JoinPoint point, TargetDataSource targetDataSource){
//方法执行完毕后，销毁当前数据源信息，进行垃圾回收
DynamicDataSourceContextHolder.clearDataSourceType();
}
}
最后对应到对应的DAO层调用 。
