# dbRouter

**Repository Path**: guo_zi_feng/db-router

## Basic Information

- **Project Name**: dbRouter
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2023-11-16
- **Last Updated**: 2023-11-24

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# dbRouter

#### 测试
先install本工程，然后拉取
https://gitee.com/guo_zi_feng/dbRouter-test


#### 分库原理
spring-jdbc的包中，提供了AbstractRoutingDataSource用于数据源路由操作

该类实现了InitializingBean接口，说明初始化时会调用afterPropertiesSet方法

```java
@Override
public void afterPropertiesSet() {
    //targetDataSources是一个Map<Object, Object>,实际上是<String,DataSource>
   if (this.targetDataSources == null) {
      throw new IllegalArgumentException("Property 'targetDataSources' is required");
   }
   this.resolvedDataSources = CollectionUtils.newHashMap(this.targetDataSources.size());
   this.targetDataSources.forEach((key, value) -> {
      Object lookupKey = resolveSpecifiedLookupKey(key);
      //可以看到这里把他转回了DataSource类型
      DataSource dataSource = resolveSpecifiedDataSource(value);
      this.resolvedDataSources.put(lookupKey, dataSource);
   });
   if (this.defaultTargetDataSource != null) {
      this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
   }
}
```
该抽象类拥有一个唯一的抽象方法

```java
/**
 * Determine the current lookup key. This will typically be
 * implemented to check a thread-bound transaction context.
 * <p>Allows for arbitrary keys. The returned key needs
 * to match the stored lookup key type, as resolved by the
 * {@link #resolveSpecifiedLookupKey} method.
 */
@Nullable
protected abstract Object determineCurrentLookupKey();

```
在determineTargetDataSource方法中调用了该抽象方法
```java
protected DataSource determineTargetDataSource() {
   Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
   //由我们实现，其实就是把要切换的key给他，他会去map里获取相应的数据源
   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;
}

```

主要逻辑在com.pj.DBRouterJoinPoint