项目中有些查询情况 数据并不在一个数据库中,有可能在两个数据库甚至更多的数据库中,这种情况就得用到动态切换数据源了
首先配置数据源的四大类
新建DataSource包,新建四个类
1.
package com.zxht.smart.environment.datasource;
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;
import com.zxht.smart.environment.annotation.DataSource;
@Aspect
@Order(-1)// 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, DataSource ds) throws Throwable {
String dsId = ds.value();
if (DynamicDataSourceContextHolder.dataSourceIds.contains(dsId)) {
logger.debug("Use DataSource :{} >", dsId, point.getSignature());
DynamicDataSourceContextHolder.setDataSourceRouterKey(dsId);
} else {
logger.info("数据源[{}]不存在,使用默认数据源 >{}", dsId, point.getSignature());
}
}
@After("@annotation(ds)")
public void restoreDataSource(JoinPoint point, DataSource ds) {
logger.debug("Revert DataSource : " + ds.value() + " > " + point.getSignature());
DynamicDataSourceContextHolder.removeDataSourceRouterKey();
}
}
2.
package com.zxht.smart.environment.datasource;
import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class DynamicDataSourceContextHolder {
private static Logger logger = LoggerFactory.getLogger(DynamicDataSourceContextHolder.class);
/**
* 存储已经注册的数据源的key
*/
public static List<String> dataSourceIds = new ArrayList<>();
/**
* 线程级别的私有变量
*/
private static final ThreadLocal<String> HOLDER = new ThreadLocal<>();
public static String getDataSourceRouterKey () {
return HOLDER.get();
}
public static void setDataSourceRouterKey (String dataSourceRouterKey) {
logger.info("切换至{}数据源", dataSourceRouterKey);
HOLDER.set(dataSourceRouterKey);
}
/**
* 设置数据源之前一定要先移除
*/
public static void removeDataSourceRouterKey () {
HOLDER.remove();
}
/**
* 判断指定DataSrouce当前是否存在
*
* @param dataSourceId
* @return
*/
public static boolean containsDataSource(String dataSourceId){
return dataSourceIds.contains(dataSourceId);
}
}
3.
package com.zxht.smart.environment.datasource;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.sql.DataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.context.properties.bind.Bindable;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
import org.springframework.boot.context.properties.source.ConfigurationPropertyNameAliases;
import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
import org.springframework.boot.context.properties.source.MapConfigurationPropertySource;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.StringUtils;
import com.zaxxer.hikari.HikariDataSource;
public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware{
private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceRegister.class);
/**
* 配置上下文(也可以理解为配置文件的获取工具)
*/
private Environment evn;
/**
* 别名
*/
private final static ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
/**
* 由于部分数据源配置不同,所以在此处添加别名,避免切换数据源出现某些参数无法注入的情况
*/
static {
aliases.addAliases("url", new String[]{"jdbc-url"});
aliases.addAliases("username", new String[]{"user"});
}
/**
* 存储我们注册的数据源
*/
private Map<String, DataSource> customDataSources = new HashMap<String, DataSource>();
/**
* 参数绑定工具 springboot2.0新推出
*/
private Binder binder;
/**
* ImportBeanDefinitionRegistrar接口的实现方法,通过该方法可以按照自己的方式注册bean
*
* @param annotationMetadata
* @param beanDefinitionRegistry
*/
@Override
public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) {
// 获取所有数据源配置
Map config, defauleDataSourceProperties;
defauleDataSourceProperties = binder.bind("spring.datasource.master", Map.class).get();
// 获取数据源类型
String typeStr = evn.getProperty("spring.datasource.master.type");
// 获取数据源类型
Class<? extends DataSource> clazz = getDataSourceType(typeStr);
// 绑定默认数据源参数 也就是主数据源
DataSource consumerDatasource, defaultDatasource = bind(clazz, defauleDataSourceProperties);
DynamicDataSourceContextHolder.dataSourceIds.add("master");
logger.info("注册默认数据源成功");
// 获取其他数据源配置
List<Map> configs = binder.bind("spring.datasource.cluster", Bindable.listOf(Map.class)).get();
// 遍历从数据源
for (int i = 0; i < configs.size(); i++) {
config = configs.get(i);
clazz = getDataSourceType((String) config.get("type"));
defauleDataSourceProperties = config;
// 绑定参数
consumerDatasource = bind(clazz, defauleDataSourceProperties);
// 获取数据源的key,以便通过该key可以定位到数据源
String key = config.get("key").toString();
customDataSources.put(key, consumerDatasource);
// 数据源上下文,用于管理数据源与记录已经注册的数据源key
DynamicDataSourceContextHolder.dataSourceIds.add(key);
logger.info("注册数据源{}成功", key);
}
// bean定义类
GenericBeanDefinition define = new GenericBeanDefinition();
// 设置bean的类型,此处DynamicRoutingDataSource是继承AbstractRoutingDataSource的实现类
define.setBeanClass(DynamicRoutingDataSource.class);
// 需要注入的参数
MutablePropertyValues mpv = define.getPropertyValues();
// 添加默认数据源,避免key不存在的情况没有数据源可用
mpv.add("defaultTargetDataSource", defaultDatasource);
// 添加其他数据源
mpv.add("targetDataSources", customDataSources);
// 将该bean注册为datasource,不使用springboot自动生成的datasource
beanDefinitionRegistry.registerBeanDefinition("datasource", define);
logger.info("注册数据源成功,一共注册{}个数据源", customDataSources.keySet().size() + 1);
}
/**
* 通过字符串获取数据源class对象
*
* @param typeStr
* @return
*/
private Class<? extends DataSource> getDataSourceType(String typeStr) {
Class<? extends DataSource> type;
try {
if (StringUtils.hasLength(typeStr)) {
// 字符串不为空则通过反射获取class对象
type = (Class<? extends DataSource>) Class.forName(typeStr);
} else {
// 默认为hikariCP数据源,与springboot默认数据源保持一致
type = HikariDataSource.class;
}
return type;
} catch (Exception e) {
throw new IllegalArgumentException("can not resolve class with type: " + typeStr); //无法通过反射获取class对象的情况则抛出异常,该情况一般是写错了,所以此次抛出一个runtimeexception
}
}
/**
* 绑定参数,以下三个方法都是参考DataSourceBuilder的bind方法实现的,目的是尽量保证我们自己添加的数据源构造过程与springboot保持一致
*
* @param result
* @param properties
*/
private void bind(DataSource result, Map properties) {
ConfigurationPropertySource source = new MapConfigurationPropertySource(properties);
Binder binder = new Binder(new ConfigurationPropertySource[]{source.withAliases(aliases)});
// 将参数绑定到对象
binder.bind(ConfigurationPropertyName.EMPTY, Bindable.ofInstance(result));
}
private <T extends DataSource> T bind(Class<T> clazz, Map properties) {
ConfigurationPropertySource source = new MapConfigurationPropertySource(properties);
Binder binder = new Binder(new ConfigurationPropertySource[]{source.withAliases(aliases)});
// 通过类型绑定参数并获得实例对象
return binder.bind(ConfigurationPropertyName.EMPTY, Bindable.of(clazz)).get();
}
/**
* @param clazz
* @param sourcePath 参数路径,对应配置文件中的值,如: spring.datasource
* @param <T>
* @return
*/
private <T extends DataSource> T bind(Class<T> clazz, String sourcePath) {
Map properties = binder.bind(sourcePath, Map.class).get();
return bind(clazz, properties);
}
/**
* EnvironmentAware接口的实现方法,通过aware的方式注入,此处是environment对象
*
* @param environment
*/
@Override
public void setEnvironment(Environment environment) {
logger.info("开始注册数据源");
this.evn = environment;
// 绑定配置器
binder = Binder.get(evn);
}
}
4.
package com.zxht.smart.environment.datasource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicRoutingDataSource extends AbstractRoutingDataSource {
private static Logger logger = LoggerFactory.getLogger(DynamicRoutingDataSource.class);
@Override
protected Object determineCurrentLookupKey() {
String dataSourceName = DynamicDataSourceContextHolder.getDataSourceRouterKey();
logger.info("当前数据源是:{}", dataSourceName);
return DynamicDataSourceContextHolder.getDataSourceRouterKey();
}
}
然后配置文件添加双数据源
#配置数据源
spring:
datasource:
master:
url: xxxx1
username: xxxx1
password: xxxx1
driver-class-name: oracle.jdbc.OracleDriver
type: com.zaxxer.hikari.HikariDataSource
cluster:
- key: economy
url: xxxx2
username: xxxx2
password: xxxx2
driver-class-name: oracle.jdbc.OracleDriver
type: com.zaxxer.hikari.HikariDataSource
master是主数据源 也是默认的,cluster为第二个数据源,key的值就是下面要用到的值
然后写个注解类:
package com.zxht.smart.environment.annotation;
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;
/**
* 切换数据注解 可以用于类或者方法级别 方法级别优先级 > 类级别
*/
@Target({ElementType.METHOD, ElementType.TYPE, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DataSource {
String value() default "master"; //该值即key值
}
注解默认值是master ,也就是主数据源
记录一下踩过的坑,第一个类DynamicDataSourceAspect,因为是在网上找的素材,
改动之前是这样的:
public class DynamicDataSourceAspect {
private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
@Before("@annotation(ds)")
public void changeDataSource(JoinPoint point, DataSource ds) throws Throwable {
String dsId = ds.value();
if (DynamicDataSourceContextHolder.dataSourceIds.contains(dsId)) {
logger.debug("Use DataSource :{} >", dsId, point.getSignature());
} else {
logger.info("数据源[{}]不存在,使用默认数据源 >{}", dsId, point.getSignature());
//这行代码一开始是放在这里的,所以导致注册不上数据源
DynamicDataSourceContextHolder.setDataSourceRouterKey(dsId);
}
}
所以启动的时候数据源注册不上,经过几次debug之后, DynamicDataSourceContextHolder.setDataSourceRouterKey(dsId);这行代码应该放在if 里面,而不是else里面 ,根据自己需求吧 else里面也可以放这行代码,只不过是找不到数据源的时候你可以使用默认的或者是其他的数据源
最后动态切换数据源
只需要在dao层上加上注解即可
package com.zxht.smart.environment.dao;
import java.util.List;
import org.apache.ibatis.annotations.Mapper;
import com.zxht.smart.environment.annotation.DataSource;
import com.zxht.smart.environment.entity.YkljSanitationResult;
@Mapper
public interface YkljSanitationResultDao {
@DataSource("economy")
List<xxxxxxResult> xxxxxxResult();
}
使用默认的数据源括号里面不用给值
最后启动类上别忘了加import注解
package com.zxht.smart.environment;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Import;
import org.springframework.scheduling.annotation.EnableScheduling;
import com.zxht.smart.environment.datasource.DynamicDataSourceRegister;
@SpringBootApplication
@EnableScheduling
@Import({DynamicDataSourceRegister.class}) // 注册动态多数据源
public class SmartEnvironmentSystemApplication {
public static void main(String[] args) {
SpringApplication.run(SmartEnvironmentSystemApplication.class, args);
}
}
至此完成数据源的动态切换。