1.实现思路
DataSource是和线程绑定的，动态数据源的配置主要是通过继承AbstractRoutingDataSource类实现的，实现在AbstractRoutingDataSource类中的 protected Object determineCurrentLookupKey()方法来获取数据源，所以我们需要先创建一个多线程线程数据隔离的类来存放DataSource，然后在determineCurrentLookupKey()方法中通过这个类获取当前线程的DataSource，在=AbstractRoutingDataSource类中，DataSource是通过Key-value的方式保存的，我们可以通过ThreadLocal来保存Key，从而实现数据源的动态切换。
2.修改配置文件
这里提一嘴，多数据源使用的是springboot默认的连接池Hikari，Hikari中没有url的属性，会报错。但是Hikari给提供了 jdbc-url
spring:
datasource:
# 可以自己定义
local:
username: root
password: 123456
driver-class-name: com.mysql.cj.jdbc.Driver
jdbc-url: jdbc:mysql://localhost:3306/demo?serverTimezone=UTC&useUnicode=true@characterEncoding=utf-8
remote:
username: root
password: 123456
driver-class-name: com.mysql.cj.jdbc.Driver
jdbc-url: jdbc:mysql://192.168.85.111:3306/demo?serverTimezone=UTC&useUnicode=true@characterEncoding=utf-8
3.创建数据源枚举类
package com.example.mult;
public enum DataSourceType {
// 我这里只配置了两个数据源
REMOTE,
LOCAL
}
4.数据源切换处理
package com.example.mult;
public class DynamicDataSourceContextHolder {
private static final ThreadLocal CONTEXT_HOLDER = new ThreadLocal<>();
public static void setDataSourceType(String dataSourceType){
System.out.printf("切换到{%s}数据源", dataSourceType);
CONTEXT_HOLDER.set(dataSourceType);
}
public static String getDataSourceType(){
return CONTEXT_HOLDER.get();
}
public static void clearDataSourceType(){
CONTEXT_HOLDER.remove();
}
}
5.继承AbstractRoutingDataSource
package com.example.mult;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import javax.sql.DataSource;
import java.util.Map;
public class DynamicDataSource extends AbstractRoutingDataSource {
public DynamicDataSource(DataSource defaultTargetDataSource, Map targetDataSources) {
super.setDefaultTargetDataSource(defaultTargetDataSource);
super.setTargetDataSources(targetDataSources);
// afterPropertiesSet()方法调用时用来将targetDataSources的属性写入resolvedDataSources中的
super.afterPropertiesSet();
}
@Override
protected Object determineCurrentLookupKey() {
return DynamicDataSourceContextHolder.getDataSourceType();
}
}
6.注入数据源
package com.example.mult;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;
@Configuration
public class DataSourceConfig {
@Bean
@ConfigurationProperties("spring.datasource.remote")
public DataSource remoteDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties("spring.datasource.local")
public DataSource localDataSource() {
return DataSourceBuilder.create().build();
}
@Bean(name = "dynamicDataSource")
@Primary
public DynamicDataSource dataSource(DataSource remoteDataSource, DataSource localDataSource) {
Map targetDataSources = new HashMap<>();
targetDataSources.put(DataSourceType.REMOTE.name(), remoteDataSource);
targetDataSources.put(DataSourceType.LOCAL.name(), localDataSource);
return new DynamicDataSource(remoteDataSource, targetDataSources);
}
}
7.自定义多数据源切换注解
package com.example.mult;
import java.lang.annotation.*;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface DataSource {
DataSourceType value() default DataSourceType.REMOTE;
}
8.AOP拦截类的实现
package com.example.mult;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
@Aspect
@Order(1)
@Component
public class DataSourceAspect {
@Pointcut("@annotation(com.example.mult.DataSource)")
public void dsPointCut() {
}
@Around("dsPointCut()")
public Object around(ProceedingJoinPoint point) throws Throwable {
MethodSignature signature = (MethodSignature) point.getSignature();
Method method = signature.getMethod();
DataSource dataSource = method.getAnnotation(DataSource.class);
if (dataSource != null) {
DynamicDataSourceContextHolder.setDataSourceType(dataSource.value().name());
}
try {
return point.proceed();
} finally {
// 销毁数据源 在执行方法之后
DynamicDataSourceContextHolder.clearDataSourceType();
}
}
}
9.使用切换数据源注解
package com.example.controller;
import com.example.mult.DataSource;
import com.example.mult.DataSourceType;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
import java.util.Map;
@RestController
public class EmpController {
@Autowired
JdbcTemplate jdbcTemplate;
@GetMapping("/local")
@DataSource(value = DataSourceType.LOCAL)
public List> local(){
List> maps = jdbcTemplate.queryForList("select * from sys_user");
return maps;
}
@GetMapping("/remote")
@DataSource(value = DataSourceType.REMOTE)
public List> remote(){
List> maps = jdbcTemplate.queryForList("select * from sys_user");
return maps;
}
}
10.在启动项目的过程中如果发生循环依赖的问题，直接修改启动类即可
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
public class SpringbootDataApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootDataApplication.class, args);
}
}
11.测试
分别访问不同的接口，请求的数据源也不同。
