Springboot 主從庫切換配置

應用場景：

在主從庫讀寫分離時，讓程序自動根據業務來區分對主庫還是從庫進行讀寫操作，在所有的寫操作時，自動對主庫進行操作，所有的讀操作時，則訪問從庫。

應用前提：

在兩台機器上配置好兩個數據庫，建立主從關系，接下來在springboot的框架中配置

 

首先在.yml或者.porperties文件中配置主從數據庫

#自定義druid主從連接
druid:
 datasource:
 type: com.alibaba.druid.pool.DruidDataSource
 #主節點
 master:
 url: jdbc:mysql://192.168.1.1:3306/datebase1?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true&serverTimezone=GMT
 username: root
 password: root
 driverClassName: com.mysql.cj.jdbc.Driver
 #下面為連接池的補充設置，應用到上面所有數據源中
 filters: stat,wall,log4j
 initialSize: 5
 maxActive: 20
 maxPoolPreparedStatementPerConnectionSize: 20
 maxWait: 60000
 minEvictableIdleTimeMillis: 300000
 minIdle: 5
 poolPreparedStatements: true
 testOnBorrow: false
 testOnReturn: false
 testWhileIdle: true
 timeBetweenEvictionRunsMillis: 60000
 useGlobalDataSourceStat: true
 validationQuery: SELECT 1 FROM DUAL
 #從節點
 slave:
 url: jdbc:mysql://192.168.1.2:3306/datebase2?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true&serverTimezone=GMT
 username: root
 password: root
 driverClassName: com.mysql.cj.jdbc.Driver
 #下面為連接池的補充設置，應用到上面所有數據源中
 initialSize: 5
 minIdle: 5
 maxActive: 20
 # 配置獲取連接等待超時的時間
 maxWait: 60000
 # 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒
 timeBetweenEvictionRunsMillis: 60000
 # 配置一個連接在池中最小生存的時間，單位是毫秒
 minEvictableIdleTimeMillis: 300000
 validationQuery: SELECT 1
 testWhileIdle: true
 testOnBorrow: false
 testOnReturn: false
 # 打開PSCache，並且指定每個連接上PSCache的大小
 poolPreparedStatements: true
 # 配置監控統計攔截的filters，去掉后監控界面sql無法統計，'wall'用於防火牆
 filters: stat,wall,log4j
 logSlowSql: true
 maxPoolPreparedStatementPerConnectionSize: 20
 # 通過connectProperties屬性來打開mergeSql功能；慢SQL記錄
 connectionProperties:
 druid:
 stat:
 mergeSql: true
 slowSqlMillis: 5000
 # 合並多個DruidDataSource的監控數據
 useGlobalDataSourceStat: true


緊接着配置mybatis相關

#mybatis
mybatis:
 #掃描xml
 mapper-locations: classpath:com/email/support/mapping/*.xml
 #配置
# configuration:
 #控制台sql日志輸出
# log-impl: org.apache.ibatis.logging.log4j2.Log4j2Impl
 #mybatis返回類型省略全路徑包名
 type-aliases-package: com.email.support.mapper

然后添加datesource配置類

/**
 * 數據庫連接池配置
 */
@Configuration
@EnableTransactionManagement
public class DatasourceConfig {
 private static Logger LOG = LoggerFactory.getLogger(DatasourceConfig.class);

 /**
 * 引入druid數據庫連接池類型
 */
 @Value("${druid.datasource.type}")
 private Class<? extends DataSource> datasourceType;

 /**
 * 主數據源
 * @return DataSource
 */
 @Primary
 @Bean("masterDatasource")
 @ConfigurationProperties("druid.datasource.master")
 public DataSource masterDatasource() {
 LOG.info("=========== master run =========");
 return DataSourceBuilder.create().type(datasourceType).build();
 }

 /**
 * 從數據源
 * @return DataSource
 */
 @Bean("slaveDatasource")
 @ConfigurationProperties("druid.datasource.slave")
 public DataSource slaveDatasource() {
 LOG.info("============ slave run ==========");
 return DataSourceBuilder.create().type(datasourceType).build();
 }

 /**
 * druid的servlet
 * @return ServletRegistrationBean
 */
 @Bean
 public ServletRegistrationBean druidServlet() {
 ServletRegistrationBean<StatViewServlet> servletRegistrationBean = new ServletRegistrationBean<>();
 servletRegistrationBean.setServlet(new StatViewServlet());
 servletRegistrationBean.addUrlMappings("/druid/*");
 servletRegistrationBean.addInitParameter("allow", "127.0.0.1");
 servletRegistrationBean.addInitParameter("deny", "/deny");
 return servletRegistrationBean;
 }

 /**
 * druid的filter
 * @return FilterRegistrationBean
 */
 @Bean
 public FilterRegistrationBean druidFilter() {
 FilterRegistrationBean<WebStatFilter> webStatFilterRegistrationBean = new FilterRegistrationBean<>();
 webStatFilterRegistrationBean.setFilter(new WebStatFilter());
 webStatFilterRegistrationBean.addUrlPatterns("/*");
 webStatFilterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
 return webStatFilterRegistrationBean;
 }
}

然后配置數據庫的讀寫操作
新建contextholder類

**
 * 數據源本地線程操作
 */
public class DynamicDataSourceContextHolder {

 private static final ThreadLocal<DatasourseType> CONTEXT_HOLDER = new ThreadLocal<>();

 public enum DatasourseType{
 /**
 * 數據源類型
 */
 MASTER,
 SLAVE;

 }

 /**
 * 設置本地線程變量
 * @param datasourseType 數據類型
 */
 public static void setContextHolder(DatasourseType datasourseType){
 CONTEXT_HOLDER.set(datasourseType);
 }

 /**
 * 獲取本地線程變量的值 默認返回主數據源
 * @return DatasourseType
 */
 public static DatasourseType getContextHolder(){
 DatasourseType datasourseType = CONTEXT_HOLDER.get();
 return Objects.isNull(datasourseType) ? DatasourseType.MASTER :datasourseType;
 }

 /**
 * 清空本地線程變量
 */
 public static void removeDataSourceType(){
 CONTEXT_HOLDER.remove();
 }

}

添加mybatis配置類繼承MybatisAutoConfiguration接口  注意：mybatis和datesource有強依賴關系   所以必須先添加datesource的相關配置再進行mybatis的配置
然后將datesource通過@Resource注解 進行注入  放入mybatis的sqlsessionfactory進行管理

/**
 * mybatis配置
 */
@Configuration
public class MybatisConfig extends MybatisAutoConfiguration {
 /**
 * 主數據源 根據名稱注入
 */
 @Resource(name = "slaveDatasource")
 private DataSource slaveDatasource;

 @Resource(name = "masterDatasource")
 private DataSource masterDatasource;

 @Bean
 public SqlSessionFactory sqlSessionFactory() throws Exception {
 return super.sqlSessionFactory(datasourceStrategy());
 }

 /**
 * 數據源策略 ----此方法是在添加DynamicDataSource后 將數據源注入進sqlsessionfactroy進行數據源管理
 * @return 數據源
 */
 @SuppressWarnings("unchecked")
 private AbstractRoutingDataSource datasourceStrategy(){
 DynamicDataSource dynamicDataSource = new DynamicDataSource();
 //軟引用map
 ClassLoaderRepository.SoftHashMap softHashMap = new ClassLoaderRepository.SoftHashMap();
 //設置主從
 softHashMap.put(DynamicDataSourceContextHolder.DatasourseType.MASTER, masterDatasource);
 softHashMap.put(DynamicDataSourceContextHolder.DatasourseType.SLAVE, slaveDatasource);
 //默認使用主數據源
 dynamicDataSource.setTargetDataSources(softHashMap);
 //將兩個數據源放入map
 dynamicDataSource.setDefaultTargetDataSource(masterDatasource);
 return dynamicDataSource;
 }
}

接下來就是要把主從庫動態切換的配置
新建RoutingDataSource  繼承 AbstractRoutingDataSource

/**
 * 配置數據源容器對象
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

 @Override
 protected Object determineCurrentLookupKey() {
 return DynamicDataSourceContextHolder.getContextHolder();
 }

}

 

接下來使用自定義注解告訴方法訪問哪個數據庫
建立SlaveDatasource注解

/**
 * slave數據源標識
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface SlaveDatasource {

}


新建自定義注解的aop切面 

/**
 * slave數據源aop
 */
@Aspect
@Component
public class SlaveDatasourceAop implements Ordered {
 private static final Logger LOGGER = LoggerFactory.getLogger(SlaveDatasourceAop.class);

 @Pointcut("@annotation(com.email.support.annotation.SlaveDatasource)")
 public void slaveDatasource(){}

 @Around("slaveDatasource()")
 public Object doAround(ProceedingJoinPoint joinPoint) throws Throwable {
 try {
 DynamicDataSourceContextHolder.setContextHolder(DynamicDataSourceContextHolder.DatasourseType.SLAVE);
 LOGGER.info("========== change to slave ==========");
 return joinPoint.proceed();
 }finally {
 DynamicDataSourceContextHolder.removeDataSourceType();
 }
 }

 @Override
 public int getOrder() {
 return 0;
 }
}

至此配置完成 下面測試查看效果

添加測試方法

//測試主從庫切換
@Resource(name = "slaveDatasource")
private DataSource slaveDatasource;

@Resource(name = "masterDatasource")
private DataSource masterDatasource;

@Test
public void contextLoads() throws Exception{
 Connection c1=masterDatasource.getConnection("主數據庫賬號","主數據庫密碼");
 System.err.println("c1:" + c1.getMetaData().getURL());
 Connection c2=slaveDatasource.getConnection("從數據庫賬號","從數據庫密碼");
 System.err.println("c2:" + c2.getMetaData().getURL());
}


輸出結果

 

 

 

c1：為我的主庫地址

c2：為我的從庫地址