完全实现 Springboot2.x + druid1.1.x配置多数据源并实现自动切换

迷南。 2021-11-15 13:42 275阅读 0赞

看到网上有不少实现，但是大多讲的不仔细，或实现的不优雅这里记录一下我的实现方式。

### 实现思路 ###

1.  利用springboot配置多个数据源
2.  配置默认数据源，编写数据源切换类
3.  创建切面实现自动切换

### UML类图 ###

如下是实现该功能的类图  
![multiDataSource][]

### 具体实现 ###

### 多数据源的实现 ###

1.  导入依赖

<dependencies>
        <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>2.1.0</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-configuration-processor</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.commons</groupId>
                <artifactId>commons-pool2</artifactId>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-aop</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.55</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.apache.commons</groupId>
                <artifactId>commons-lang3</artifactId>
                <version>3.8.1</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
            </dependency>
            
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid-spring-boot-starter</artifactId>
                <version>1.1.17</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter</artifactId>
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-logging</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-log4j2</artifactId>
            </dependency>
        </dependencies>

2.创建多数据源bean的配置类

/** * 多数据源bean的配置类 * @author hy */
    @Configuration
    public class MultipleDataSourceConfig { 
    
        @Bean("master")
        @ConfigurationProperties(prefix = "spring.datasource.master")
        public DataSource createMasterDataSource(){ 
            return new DruidDataSource();
        }
    
        @Bean("slave1")
        @ConfigurationProperties(prefix = "spring.datasource.slave1")
        public DataSource createSlave1DataSource(){ 
            return new DruidDataSource();
        }
    
        /** * 设置动态数据源，通过@Primary 来确定主DataSource * @return */
        @Bean
        @Primary
        public DataSource createDynamicDataSource(@Qualifier("master") DataSource master, @Qualifier("slave1") DataSource slave1){ 
            DynamicDataSource dynamicDataSource = new DynamicDataSource();
            //设置默认数据源
            dynamicDataSource.setDefaultTargetDataSource(master);
            //配置多数据源
            Map<Object, Object> map = new HashMap<>();
            map.put("master",master);
            map.put("slave1",slave1);
            dynamicDataSource.setTargetDataSources(map);
            return  dynamicDataSource;
        }
    }

这里是使用配置类注入bean  
使用注解@Configuration和ConfigurationProperties，bean的属性值由配置文件的 spring.datasource.master和spring.datasource.slave1决定  
bean的类型是Datasource，名字是由注解@Bean 指定  
随后在方法createDynamicDataSource中使用 @Qualifier 使用指定名字的

1.  重写determineCurrentLookupKey() 方法

public class DynamicDataSource extends AbstractRoutingDataSource { 
    
        Logger logger = LoggerFactory.getLogger(DynamicDataSource.class);
    
        @Override
        protected Object determineCurrentLookupKey() { 
            logger.info("------------------当前数据源 {}", DynamicDataSourceSwitcher.getDataSource());
            return DynamicDataSourceSwitcher.getDataSource();
        }
    }

AbstractRoutingDataSource 是spring jdbc提供的操作读数据源的抽象类，重写determineCurrentLookupKey() 指定获得当前数据源

查看父类AbstractRoutingDataSource 的源码

protected DataSource determineTargetDataSource() { 
    		Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
    		Object lookupKey = determineCurrentLookupKey();
    		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 + "]");
    		}
    		return dataSource;
    	}

上面是determineTargetDataSource方法，可以看到若determineCurrentLookupKey返回空则使用默认数据源

1.  实现操作数据源的类

/** * 操作数据源 * @author hy */
    public class DynamicDataSourceSwitcher { 
    
        static Logger logger = LoggerFactory.getLogger(DynamicDataSourceSwitcher.class);
    
        public static final String Mater = "master";
        public static final String Slave1 = "slave1";
    
        private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();
    
        public static void setDataSource(String name){ 
            logger.info("-------- 设置数据源数据源为 ：{} ", name);
            contextHolder.set(name);
        }
    
        public static String getDataSource(){ 
            return contextHolder.get();
        }
    
        public static void cleanDataSource(){ 
            contextHolder.remove();
        }
    
    }

利用ThreadLocal 将数据源与当前线程绑定，并提供get set方法

5.配置application.yml文件

spring:
      profiles: multi
      datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        master:
          url: jdbc:mysql://xxx:3306/xxx?useSSL=false&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&failOverReadOnly=false
          username: xxx
          password: xxx
          type: com.alibaba.druid.pool.DruidDataSource
          name: master
          initialize: true
          # 监控统计拦截的filters 有stat,wall,log4j
          filters: stat
        slave1:
          url: jdbc:mysql://xxx:3306/xxx?useSSL=false&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&failOverReadOnly=false
          username: xxx
          password: xxx
          type: com.alibaba.druid.pool.DruidDataSource
          name: slave1
          initialize: true
          filters: stat

以上就已经实现了多数据源的配置，要实现自动切换还需要加入aop切面

### 加入aop切面 ###

1.  自定义数据源的注解

/** * 自定义的数据源的注解 * @author hy */
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ 
            ElementType.METHOD
    })
    public @interface MyDataSource { 
        String value() default "master";
    }

1.  创建切面

/** * 创建aop切面 * @author hy */
    @Aspect
    @Component
    @Order(1) //需要加入切面排序
    public class DynamicDataSourceAspect { 
        private Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
    
        /** * 切入点只对@Service注解的类上的@DataSource方法生效 * @param myDataSource */
        @Pointcut(value="@within(org.springframework.stereotype.Service) && @annotation(myDataSource)" )
        public void dynamicDataSourcePointCut(MyDataSource myDataSource){ }
    
        @Before(value = "dynamicDataSourcePointCut(myDataSource)")
        public void switchDataSource(MyDataSource myDataSource) { 
            DynamicDataSourceSwitcher.setDataSource(myDataSource.value());
        }
    
        /** * 切点执行完后 切换成主数据库 * @param myDataSource */
        @After(value="dynamicDataSourcePointCut(myDataSource)")
        public void after(MyDataSource myDataSource){ 
            DynamicDataSourceSwitcher.cleanDataSource();
        }
    }

使用：

@Service
    public class WxUserService { 
    
        @Resource
        WxUserMapper wxUserMapper;
    
        public WxUser getUserById(Integer id){ 
            return wxUserMapper.selectByPrimaryKey(id);
        }
    
        @MyDataSource(value = DynamicDataSourceSwitcher.Slave1)
        public WxUser getUserByIdWithSlave(Integer id) { 
            return wxUserMapper.selectByPrimaryKey(id);
        }
    }

效果如图：  
![在这里插入图片描述][20190731173611575.png]

[multiDataSource]: /images/20211115/9e3c5406ecf8444fb5a715d25118f926.png
[20190731173611575.png]: /images/20211115/7bf089e1b1a542eab26e19af66f38ece.png