Java 为什么GenericObjectPool.addObject引发选中异常

Apache的（有用的）org.Apache.commons.pool.impl.commmons.pool.GenericObjectPool.addObject（）被声明为抛出异常有什么好的理由吗

/**
 * 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;
    }
}

实际上，org.apache.commons.pool.BaseObjectPool在org.apache.commons.pool接口中声明了它：

/**
 * 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;

为什么不使用RuntimeException的派生

/**
 * 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;
    }
}

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好的，直接的答案就在Javadoc中：

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

（旁白：工厂接口实际上似乎是

PooledObjectFactory

，而不是

pooleable

）

---

那么，为什么makeObject抛出异常呢？对象池的一个常见用例是池数据库连接，创建和销毁数据库连接的成本很高，并且（曾经？）有时受到软件许可（N-connection许可）的限制。创建新的数据库连接可能引发SQLException，如果数据库服务器位于远程计算机上，则可能引发IOException。makeObject被声明为引发异常，因此在尝试将连接放入池或从池中检索连接时，可以传递并捕获这些已检查的异常。

您至少需要跟踪诸如addObjectToPool和destroyObject之类的调用，以查看其中一个或多个是否引发异常。为什么呢？谁知道。。。但是抛出RuntimeException也不是一个好主意。