SpringBoot2.X实现动态数据源
一、核心原理
动态数据源实现的核心类就是：AbstractRoutingDataSource，在这个类中有五个方法需要特别注意，分别如下：
//设置目标数据源
public void setTargetDataSources(Map targetDataSources) {
this.targetDataSources = targetDataSources;
}
//设置默认数据源
public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
this.defaultTargetDataSource = defaultTargetDataSource;
}
//选择当前所需数据源
protected DataSource determineTargetDataSource() {
Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
Object lookupKey = this.determineCurrentLookupKey();
DataSource dataSource = (DataSource)this.resolvedDataSources.get(lookupKey);
if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
dataSource = this.resolvedDefaultDataSource;
}
if (dataSource == null) {
throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
} else {
return dataSource;
}
}
@Nullable
//选择当前数据源所需K
protected abstract Object determineCurrentLookupKey();
//初始化resolveDataSources和defaultDataSources
public void afterPropertiesSet() {
if (this.targetDataSources == null) {
throw new IllegalArgumentException("Property 'targetDataSources' is required");
} else {
this.resolvedDataSources = new HashMap(this.targetDataSources.size());
this.targetDataSources.forEach((key, value) -> {
Object lookupKey = this.resolveSpecifiedLookupKey(key);
DataSource dataSource = this.resolveSpecifiedDataSource(value);
this.resolvedDataSources.put(lookupKey, dataSource);
});
if (this.defaultTargetDataSource != null) {
this.resolvedDefaultDataSource = this.resolveSpecifiedDataSource(this.defaultTargetDataSource);
}
}
} 从这五个方法可以看出，决定用什么数据源主要由三个条件决定：一、setTargetDataSources方法设置的目标数据源；二、setDefaultTargetDataSource方法设置的默认数据源；三、determineCurrentLookupKey方法返回的key。
二、代码实现
2.1 数据源配置常量
import com.google.common.collect.Lists;
import java.util.List;
/**
* @author sunyiran
* @createTime 2019-09-04 15:37
*/
public class DataSourceTypeConstant {
public static final String USERNAME = "username";
public static final String URL = "url";
public static final String PASSWORD = "password";
public static final String CONFIG = "config";
public static final String ENV_NAME = "spring.datasource.%s.%s";
public static final String DEFAULT_ENV_NAME = "spring.datasource.%s";
public static final String TEST = "test";
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static List ALL_DATASOURCE = Lists.newArrayList();
static {
ALL_DATASOURCE.add(TEST);
ALL_DATASOURCE.add(CONFIG);
}
}
2.2 数据源上下文
/**
* 动态数据源上下文
* @author sunyiran
* @createTime 2019-09-04 15:43
*/
public class DynamicDataSourceHolder {
public static final ThreadLocal DATA_SOURCE_NAME = new ThreadLocal<>();
public static void set(String name){
DATA_SOURCE_NAME.set(name);
}
public static void clear(){
DATA_SOURCE_NAME.remove();
}
public static String get(){
return DATA_SOURCE_NAME.get();
}
} 2.3 重写AbstractRoutingDataSource
/**
* @author sunyiran
* @createTime 2019-09-04 15:42
*/
public class DynamicDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DynamicDataSourceHolder.get();
}
}
2.4 将重写的数据源放入容器
/**
* @author sunyiran
* @createTime 2019-09-04 16:44
*/
@Configuration
@Log
public class DataSourceConfig {
@Resource
Environment environment;
@Bean
public DataSource dataSource() {
DynamicDataSource dynamicDataSource = new DynamicDataSource();
dynamicDataSource.setDefaultTargetDataSource(getDefaultDataSource());
dynamicDataSource.setTargetDataSources(getDataSourceMap());
return dynamicDataSource;
}
private Object getDefaultDataSource() {
return DataSourceBuilder.create().driverClassName(DataSourceTypeConstant.DRIVER)
.password(environment.getProperty(String.format(DataSourceTypeConstant.DEFAULT_ENV_NAME, DataSourceTypeConstant.PASSWORD)))
.url(environment.getProperty(String.format(DataSourceTypeConstant.DEFAULT_ENV_NAME, DataSourceTypeConstant.URL)))
.username(environment.getProperty(String.format(DataSourceTypeConstant.DEFAULT_ENV_NAME, DataSourceTypeConstant.USERNAME))).build();
}
private Map getDataSourceMap() {
Map dataSourceMap = Maps.newHashMap();
List allDatasource = DataSourceTypeConstant.ALL_DATASOURCE;
DataSourceBuilder sourceBuilder = DataSourceBuilder.create().driverClassName(DataSourceTypeConstant.DRIVER);
for (String name : allDatasource) {
DataSource dataSource = sourceBuilder.password(environment.getProperty(String.format(DataSourceTypeConstant.ENV_NAME, name, DataSourceTypeConstant.PASSWORD)))
.url(environment.getProperty(String.format(DataSourceTypeConstant.ENV_NAME, name, DataSourceTypeConstant.URL)))
.username(environment.getProperty(String.format(DataSourceTypeConstant.ENV_NAME, name, DataSourceTypeConstant.USERNAME))).build();
dataSourceMap.put(name, dataSource);
}
return dataSourceMap;
}
}
2.5 自定义注解
/**
* @author sunyiran
* @dateTime 2019-09-04 16:53
*/
@Documented
@Inherited
@Target({ElementType.METHOD,ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSourceType {
String name() ;
}
2.6 注解切面环绕处理
/**
* @author sunyiran
* @createTime 2019-09-04 16:58
*/
@Aspect
@Component
@Order(-1)
@Log4j2
public class DataSourceTypeHandle {
@Around("execution(* com.litb.business.base.service.impl.*.*(..))")
@Order(1)
public Object handleType(ProceedingJoinPoint jp) {
//同时支持类和方法上的注解，以方法上为主
DataSourceType typeInClass = jp.getTarget().getClass().getAnnotation(DataSourceType.class);
MethodSignature methodSignature = (MethodSignature) jp.getSignature();
DataSourceType typeInMethod = methodSignature.getMethod().getDeclaredAnnotation(DataSourceType.class);
String name;
if (typeInMethod != null) {
name = typeInMethod.name();
}else {
name = typeInClass.name();
}
return dealWithTargetDS(jp,name);
}
private Object dealWithTargetDS(ProceedingJoinPoint jp,String name) {
if (DataSourceTypeConstant.ALL_DATASOURCE.contains(name)) {
log.info("开始切换数据源，方法{}，数据源{}",jp.getSignature().getName(),name);
DynamicDataSourceHolder.set(name);
} else {
log.error("方法{}，切换非法数据源{}",jp.getSignature().getName(),name);
}
Object proceed ;
try {
proceed = jp.proceed();
} catch (Throwable throwable) {
throw new ApiException(BasicResult.ERROR);
}
DynamicDataSourceHolder.clear();
return proceed;
}
}
2.7 测试用例
/**
* @author sunyiran
* @createTime 2019-09-04 17:27
*/
@RestController
@Log4j2
public class Test {
@Resource
CityService cityService;
@RequestMapping("/t1")
@DataSourceType(name = "test")
public Object test1() {
log.info("t1----执行------需要test数据源");
City byId = cityService.findById(1L);
System.out.println(byId);
return byId;
}
@RequestMapping("/t2")
@DataSourceType(name = "config")
public Object test2() {
log.info("t2----执行------需要config数据源");
City byId = cityService.findById(1L);
System.out.println(byId);
return byId;
}
@RequestMapping("/t3")
public Object test3() {
log.info("t3----执行------需要默认数据源");
City byId = cityService.findById(1L);
System.out.println(byId);
return byId;
}
}结果打印：
c.l.b.base.anotation.handle.DataSourceTypeHandle[30] 开始切换数据源，方法test1，数据源test
com.litb.business.base.controller.test.Test[26] t1----执行------需要test数据源
City(cityId=1, stateId=0, countryId=0, cityNameEn=resr, cityNameZh=test, cityIsoCode2=1, cityIsoCode3=1, defaultLanguagesId=1, objectsStatusId=1, dateAdded=Thu Sep 09 15:00:00
c.l.b.base.anotation.handle.DataSourceTypeHandle[30] 开始切换数据源，方法test2，数据源config
com.litb.business.base.controller.test.Test[35] t2----执行------需要config数据源
City(cityId=1, stateId=1, countryId=223, cityNameEn=ADDISON, cityNameZh=, cityIsoCode2=, cityIsoCode3=, defaultLanguagesId=1, objectsStatusId=1, dateAdded=Thu Sep 09 15:00:00 CST
com.litb.business.base.controller.test.Test[43] t3----执行------需要默认数据源
City(cityId=1, stateId=1, countryId=223, cityNameEn=ADDISON, cityNameZh=, cityIsoCode2=, cityIsoCode3=, defaultLanguagesId=1, objectsStatusId=1, dateAdded=Thu Sep 09 15:00:00 CST 1999, lastUpdate=Wed Dec 13 15:50:59 CST 2017)