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基于spring boot 2.0 实现动态数据源切换


1. maven 文件的引用。

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mayikt</groupId>
<artifactId>springboot-mybatis-02</artifactId>
<version>0.0.1-SNAPSHOT</version>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.2.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>

<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.23</version>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>2.2.2.RELEASE</version>
</plugin>
</plugins>
</build>

</project>

2. 配置文件定义

spring:
datasource:
###可读数据源
select:
jdbc-url: jdbc:mysql://192.168.212.206:8066/mycat_testdb
driver-class-name: com.mysql.jdbc.Driver
username: user
password: user
####可写数据源
update:
jdbc-url: jdbc:mysql://192.168.212.206:8066/mycat_testdb
driver-class-name: com.mysql.jdbc.Driver
username: root
password: 123456
type: com.alibaba.druid.pool.DruidDataSource

3. 数据源配置文件

import javax.sql.DataSource;

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;

@Configuration
public class DataSourceConfig {

// 创建可读数据源
@Bean(name = "selectDataSource")
@ConfigurationProperties(prefix = "spring.datasource.select") // application.properteis中对应属性的前缀
public DataSource dataSource1() {
return DataSourceBuilder.create().build();
}

// 创建可写数据源
@Bean(name = "updateDataSource")
@ConfigurationProperties(prefix = "spring.datasource.update") // application.properteis中对应属性的前缀
public DataSource dataSource2() {
return DataSourceBuilder.create().build();
}

}

4. 动态数据源管理类

//在Spring 2.0.1中引入了AbstractRoutingDataSource, 该类充当了DataSource的路由中介, 能有在运行时, 根据某种key值来动态切换到真正的DataSource上。

import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.stereotype.Component;

@Component
@Primary
public class DynamicDataSource extends AbstractRoutingDataSource {
@Autowired
@Qualifier("selectDataSource")
private DataSource selectDataSource;

@Autowired
@Qualifier("updateDataSource")
private DataSource updateDataSource;

/**
* 这个是主要的方法,返回的是生效的数据源名称
*/
@Override
protected Object determineCurrentLookupKey() {
System.out.println("DataSourceContextHolder:::" + DataSourceContextHolder.getDbType());
return DataSourceContextHolder.getDbType();
}

/**
* 配置数据源信息
*/
@Override
public void afterPropertiesSet() {
Map<Object, Object> map = new HashMap<>();
map.put("selectDataSource", selectDataSource);
map.put("updateDataSource", updateDataSource);
setTargetDataSources(map);
setDefaultTargetDataSource(updateDataSource);
super.afterPropertiesSet();
}
}

import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;

@Component
@Lazy(false)
public class DataSourceContextHolder {
// 采用ThreadLocal 保存本地多数据源
private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

// 设置数据源类型
public static void setDbType(String dbType) {
contextHolder.set(dbType);
}

public static String getDbType() {
return contextHolder.get();
}

public static void clearDbType() {
contextHolder.remove();
}

}

5. 动态数据源使用

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.context.annotation.Lazy;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import com.hou.config.DataSourceContextHolder;

@Aspect
@Component
@Lazy(false)
@Order(0) // Order设定AOP执行顺序 使之在数据库事务上先执行
public class SwitchDataSourceAOP {
// 这里切到你的方法目录
@Before("execution(* com.hou.service.*.*(..))")
public void process(JoinPoint joinPoint) {
String methodName = joinPoint.getSignature().getName();
if (methodName.startsWith("get") || methodName.startsWith("count") || methodName.startsWith("find")
|| methodName.startsWith("list") || methodName.startsWith("select") || methodName.startsWith("check")) {
// 读
DataSourceContextHolder.setDbType("selectDataSource");
} else {
// 切换dataSource
DataSourceContextHolder.setDbType("updateDataSource");
}
}
}

总结:

  上面的案例是实现,读写分离的一种数据源动态切换的方案。

   后面会补充一下,通过注解实现数据源动态切换的。

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