You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
170 lines
5.0 KiB
170 lines
5.0 KiB
--- |
|
title: 基于Springboot实现动态数据源 |
|
id: 1939 |
|
category: 后端 |
|
tags: springboot |
|
toc: true |
|
--- |
|
|
|
### 实现原理 |
|
|
|
>Spring内置了一个AbstractRoutingDataSource类,它可以把多个数据源配置成一个Map,然后根据不同的key返回不同的数据源(通过实现抽象方法determineCurrentLookupKey)。 |
|
|
|
>我们在使用AbstractRoutingDataSource时,主要涉及两个操作: |
|
>1. 生成数据源相关map,并赋值给AbstractRoutingDataSource的targetDataSources |
|
>2. 实现determineCurrentLookupKey方法(方法的用途为:获取要使用数据源的key) |
|
|
|
|
|
### 配置多数据源 |
|
首先,我们在SpringBoot中配置两个数据源,其中第二个数据源是slave-datasource: |
|
|
|
```yaml |
|
spring: |
|
datasource: |
|
jdbc-url: jdbc:mysql://localhost/master?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true&allowPublicKeyRetrieval=true |
|
username: root #master |
|
password: dreamlyn #master_password |
|
driver-class-name: com.mysql.cj.jdbc.Driver |
|
hikari: |
|
pool-name: HikariCP |
|
auto-commit: false |
|
|
|
slave-datasource: |
|
jdbc-url: jdbc:mysql://localhost/slave?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true&allowPublicKeyRetrieval=true |
|
username: root #slave |
|
password: dreamlyn #slave_password |
|
driver-class-name: com.mysql.cj.jdbc.Driver |
|
hikari: |
|
pool-name: HikariCP |
|
auto-commit: false |
|
``` |
|
|
|
|
|
在SpringBoot的配置代码中,初始化两个数据源: |
|
|
|
|
|
```java |
|
/** |
|
* Master data source. |
|
*/ |
|
@Bean("masterDataSource") |
|
@ConfigurationProperties(prefix = "spring.datasource") |
|
DataSource masterDataSource() { |
|
return DataSourceBuilder.create().build(); |
|
} |
|
|
|
/** |
|
* Slave data source. |
|
*/ |
|
@Bean("slaveDataSource") |
|
@ConfigurationProperties(prefix = "spring.slave-datasource") |
|
DataSource slaveDataSource() { |
|
return DataSourceBuilder.create().build(); |
|
} |
|
``` |
|
|
|
### 生成数据源相关map |
|
|
|
将两个数据源生成相关map,并赋值给AbstractRoutingDataSource的targetDataSources |
|
|
|
```java |
|
@Bean |
|
@Primary |
|
DataSource primaryDataSource( |
|
@Autowired @Qualifier("masterDataSource") DataSource masterDataSource, |
|
@Autowired @Qualifier("slaveDataSource") DataSource slaveDataSource |
|
) { |
|
Map<Object, Object> map = new HashMap<>(); |
|
map.put("master", masterDataSource); |
|
map.put("slave", slaveDataSource); |
|
DynamicDataSource routing = new DynamicDataSource(); |
|
routing.setTargetDataSources(map); |
|
routing.setDefaultTargetDataSource(masterDataSource); |
|
return routing; |
|
} |
|
``` |
|
|
|
### 实现determineCurrentLookupKey方法 |
|
```java |
|
/** |
|
* 动态数据源 |
|
*/ |
|
public class DynamicDataSource extends AbstractRoutingDataSource { |
|
/** |
|
* 指定路由Key |
|
*/ |
|
@Override |
|
protected Object determineCurrentLookupKey() { |
|
return DynamicDataSourceContextHolder.getDataSource(); |
|
} |
|
} |
|
``` |
|
大家可能会好奇DynamicDataSourceContextHolder是个什么鬼: |
|
|
|
在Servlet的线程模型中,使用ThreadLocal存储key最合适,因此,我们编写一个DynamicDataSourceContextHolder来设置并动态存储key: |
|
|
|
```java |
|
/** |
|
* 根据当前线程来选择具体的数据源 |
|
*/ |
|
@UtilityClass |
|
public class DynamicDataSourceContextHolder { |
|
private final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>(); |
|
|
|
/** |
|
* 提供给AOP去设置当前的线程的数据源的信息 |
|
*/ |
|
public void setDataSource(String dataSourceType) { |
|
CONTEXT_HOLDER.set(dataSourceType); |
|
} |
|
|
|
/** |
|
* 提供给AbstractRoutingDataSource的实现类,通过key选择数据源 |
|
*/ |
|
public String getDataSource() { |
|
return CONTEXT_HOLDER.get(); |
|
} |
|
|
|
/** |
|
* 清除数据源 |
|
*/ |
|
public void clearDataSource() { |
|
CONTEXT_HOLDER.remove(); |
|
} |
|
} |
|
``` |
|
|
|
这样,在某个地方,就可以动态设置DataSource的Key: |
|
|
|
|
|
```java |
|
@RunWith(SpringRunner.class) |
|
@SpringBootTest |
|
@Slf4j |
|
@MapperScan("com.dreamlyn.dynamic.mapper") |
|
class DynamicApplicationTests { |
|
@Autowired |
|
private MenuMapper menuMapper; |
|
@Autowired |
|
private UserMapper userMapper; |
|
|
|
@Test |
|
void dynamic() { |
|
//设置数据源 |
|
DynamicDataSourceContextHolder.setDataSource("master"); |
|
List<User> users = userMapper.selectList(null); |
|
log.info("user count:{}", users.size()); |
|
|
|
DynamicDataSourceContextHolder.setDataSource("slave"); |
|
List<Menu> menus = menuMapper.selectList(null); |
|
log.info("menu count:{}", menus.size()); |
|
} |
|
} |
|
``` |
|
|
|
到此为止,我们已经成功实现了数据库的动态路由访问。 |
|
|
|
### 拓展 |
|
如果需要更方便一些,可以自己手动编写aop,通过注解来区分使用哪个数据源将更加方便,这种方法留给读者自己思考。 |
|
|
|
思考不出来可以参考代码:[https://gitee.com/dreamlyn/dynamic](https://gitee.com/dreamlyn/dynamic) |