爲什麼GenericObjectPool.addObject拋出檢查異常

是否有任何理由爲什麼Apache的（有用的）org.apache.commons.pool.impl.commmons.pool.GenericObjectPool.addObject（）被聲明爲拋出異常？爲什麼GenericObjectPool.addObject拋出檢查異常

其實，org.apache.commons.pool.BaseObjectPool宣稱它是這樣，從org.apache.commons.pool接口：

/** 
* Create an object using the {@link PoolableObjectFactory factory} or other 
* implementation dependent mechanism, passivate it, and then place it in the idle object pool. 
* <code>addObject</code> is useful for "pre-loading" a pool with idle objects. 
* (Optional operation). 
* 
* @throws Exception when {@link PoolableObjectFactory#makeObject} fails. 
* @throws IllegalStateException after {@link #close} has been called on this pool. 
* @throws UnsupportedOperationException when this pool cannot add new idle objects. 
*/ 
void addObject() throws Exception, IllegalStateException, UnsupportedOperationException;

爲什麼不RuntimeException的一些衍生品？

/** 
* Create an object, and place it into the pool. 
* addObject() is useful for "pre-loading" a pool with idle objects. 
*/ 
@Override 
public void addObject() throws Exception { 
    assertOpen(); 
    if (_factory == null) { 
     throw new IllegalStateException("Cannot add objects without a factory."); 
    } 
    T obj = _factory.makeObject(); 
    try { 
     assertOpen(); 
     addObjectToPool(obj, false); 
    } catch (IllegalStateException ex) { // Pool closed 
     try { 
      _factory.destroyObject(obj); 
     } catch (Exception ex2) { 
      // swallow 
     } 
     throw ex; 
    } 
}

來源

2013-10-14 justingordon

您至少需要跟蹤諸如addObjectToPool和destroyObject之類的調用，以查看是否有一個或多個調用了Exception。至於爲什麼？誰知道......但拋出一個RuntimeException也不是一個好主意。 – TofuBeer

那麼，直接的答案是正確的，在的Javadoc：

@throws Exception when {@link PoolableObjectFactory#makeObject} fails.

（旁白：工廠接口似乎實際上是PooledObjectFactory，不Poolable）

那麼，爲什麼makeObject拋出異常？對象池的一個常見用例是對數據庫連接進行池化，這些連接的創建和銷燬成本很高，並且有時受到軟件許可（N連接許可證）的限制。創建新的數據庫連接可能會引發SQLException，或者如果數據庫服務器位於遠程計算機上，可能會引發IOException。 makeObject被聲明爲拋出異常，因此這些被檢查的異常可以通過並在嘗試向/從池中取回/取回連接時被捕獲。

來源

2014-06-19 18:36:54

爲什麼GenericObjectPool.addObject拋出檢查異常

回答

相關問題