Spring Boot + Mybatis 多資料來源配置實現讀寫分離
阿新 • • 發佈：2018-12-12
本文來自網易雲社群
作者：王超
應用場景：專案中有一些報表統計與查詢功能，對資料實時性要求不高，因此考慮對報表的統計與查詢去操作slave db，減少對master的壓力。
根據網上多份資料測試發現總是使用master資料來源，無法切換到slave，經過多次除錯修改現已完美通過，現整理下詳細步驟和完整程式碼如下：
實現方式：配置多個數據源，使用Spring AOP實現攔截註解實現資料來源的動態切換。
1. application.yml資料庫配置：druid:
type: com.alibaba.druid.pool.DruidDataSource master: url: jdbc:mysql://127.0.0.1:3306/test?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true driver-class-name: com.mysql.jdbc.Driver username: test password: 123 initial-size: 5 max-active: 10 min-idle: 5 max-wait: 60000 time-between-eviction-runs-millis: 3000 min-evictable-idle-time-millis: 300000 validation-query: SELECT 'x' FROM DUAL test-while-idle: true test-on-borrow: true test-on-return: false filters: stat,wall,log4j2 slave: url: jdbc:mysql://127.0.0.1:3307/test?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true driver-class-name: com.mysql.jdbc.Driver username: test password: 123 initial-size: 5 max-active: 10 min-idle: 5 max-wait: 60000 time-between-eviction-runs-millis: 3000 min-evictable-idle-time-millis: 300000 validation-query: SELECT 'x' FROM DUAL test-while-idle: true test-on-borrow: true test-on-return: false filters: stat,wall,log4j2
2. 通過MybatisAutoConfiguration實現多資料來源注入:
@Configuration
@EnableTransactionManagement
public class DataSourceConfiguration extends MybatisAutoConfiguration {
@Value("${druid.type}")
private Class<? extends DataSource> dataSourceType;
@Bean(name = "masterDataSource")
@Primary
@ConfigurationProperties(prefix = "druid.master")
public DataSource masterDataSource(){
return DataSourceBuilder.create().type(dataSourceType).build();
}
@Bean(name = "slaveDataSource")
@ConfigurationProperties(prefix = "druid.slave")
public DataSource slaveDataSource(){
return DataSourceBuilder.create().type(dataSourceType).build();
}
@Bean
@Override
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
return super.sqlSessionFactory(dataSource());
}
@Bean(name = "dataSource")
public AbstractRoutingDataSource dataSource() {
MasterSlaveRoutingDataSource proxy = new MasterSlaveRoutingDataSource();
Map<Object, Object> targetDataResources = new HashMap<>();
targetDataResources.put(DbContextHolder.DbType.MASTER, masterDataSource());
targetDataResources.put(DbContextHolder.DbType.SLAVE, slaveDataSource());
proxy.setDefaultTargetDataSource(masterDataSource());
proxy.setTargetDataSources(targetDataResources);
proxy.afterPropertiesSet();
return proxy;
}
}3. 基於 AbstractRoutingDataSource 和 AOP 的多資料來源的配置
我們自己定義一個DataSource類，來繼承 AbstractRoutingDataSource：
public class MasterSlaveRoutingDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DbContextHolder.getDbType();
}
}這裡通過determineCurrentLookupKey（）返回的不同key到sqlSessionFactory中獲取對應資料來源然後使用ThreadLocal來存放執行緒的變數，將不同的資料來源標識記錄在ThreadLocal中
public class DbContextHolder {
public enum DbType{
MASTER, SLAVE
}
private static final ThreadLocal<DbType> contextHolder = new ThreadLocal<>();
public static void setDbType(DbType dbType){
if (dbType==null) {
throw new NullPointerException();
}
contextHolder.set(dbType);
}
public static DbType getDbType(){
return contextHolder.get()==null?DbType.MASTER:contextHolder.get();
}
public static void clearDbType(){
contextHolder.remove();
}
}4. 註解實現
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ReadOnlyConnection {
}@Aspect
@Component
public class ReadOnlyConnectionInterceptor implements Ordered {
@Around("@annotation(readOnlyConnection)")
public Object proceed(ProceedingJoinPoint proceedingJoinPoint, ReadOnlyConnection readOnlyConnection) throws Throwable {
try {
DbContextHolder.setDbType(DbContextHolder.DbType.SLAVE);
Object result = proceedingJoinPoint.proceed();
return result;
}finally {
DbContextHolder.clearDbType();
}
}
@Override
public int getOrder() {
return 0;
}
}5. 應用方式：
service層介面增加ReadOnlyConnection註解即可：
@ReadOnlyConnectionpublic CommonPagingVO<GroupGoodsVO>
pagingByCondition(GroupGoodsCondition condition, int pageNum, int pageSize)
{
Page<GroupGoodsVO>
page = PageHelper.startPage(pageNum, pageSize).doSelectPage(()
-> groupGoodsMapper.listByCondition(condition));
return CommonPagingVO.get(page,page.getResult());
}
對於未加ReadOnlyConnection註解的預設使用masterDataSource。網易雲免費體驗館，0成本體驗20+款雲產品！
更多網易研發、產品、運營經驗分享請訪問網易雲社群。