org.apache.commons.pool2.proxy

## Class ProxiedObjectPool<T>

- java.lang.Object
- - org.apache.commons.pool2.proxy.ProxiedObjectPool<T>

- Type Parameters:
    `T` - type of the pooled object
  All Implemented Interfaces:
    Closeable, AutoCloseable, ObjectPool<T>

      public class ProxiedObjectPool<T>
      extends Object
      implements ObjectPool<T>

  Create a new object pool where the pooled objects are wrapped in proxies allowing better control of pooled objects and in particular the prevention of the continued use of an object by a client after that client returns the object to the pool.
  Since:
    2.0

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `ProxiedObjectPool(ObjectPool<T> pool, org.apache.commons.pool2.proxy.ProxySource<T> proxySource)` Create a new proxied object pool.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addObject()` Create an object using the `factory` or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
    `T` | `borrowObject()` Obtains an instance from this pool.
    `void` | `clear()` Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).
    `void` | `close()` Close this pool, and free any resources associated with it.
    `int` | `getNumActive()` Return the number of instances currently borrowed from this pool.
    `int` | `getNumIdle()` Return the number of instances currently idle in this pool.
    `void` | `invalidateObject(T proxy)` Invalidates an object from the pool.
    `void` | `returnObject(T proxy)` Return an instance to the pool.
    `String` | `toString()`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### ProxiedObjectPool

          public ProxiedObjectPool(ObjectPool<T> pool,
                           org.apache.commons.pool2.proxy.ProxySource<T> proxySource)

      Create a new proxied object pool.
      Parameters:
        `pool` - The object pool to wrap
        `proxySource` - The source of the proxy objects

  - ### Method Detail

    - #### borrowObject

          public T borrowObject()
                         throws Exception,
                                NoSuchElementException,
                                IllegalStateException

      Description copied from interface: `ObjectPool`
      Obtains an instance from this pool.

      Instances returned from this method will have been either newly created with `PooledObjectFactory.makeObject()` or will be a previously idle object and have been activated with `PooledObjectFactory.activateObject(org.apache.commons.pool2.PooledObject<T>)` and then validated with `PooledObjectFactory.validateObject(org.apache.commons.pool2.PooledObject<T>)`.

      By contract, clients must return the borrowed instance using `ObjectPool.returnObject(T)`, `ObjectPool.invalidateObject(T)`, or a related method as defined in an implementation or sub-interface.

      The behaviour of this method when the pool has been exhausted is not strictly specified (although it may be specified by implementations).

      Specified by:
        `borrowObject` in interface `ObjectPool<T>`
      Returns:
        an instance from this pool.
      Throws:
        `IllegalStateException` - after `close` has been called on this pool.
        `Exception` - when `PooledObjectFactory.makeObject()` throws an exception.
        `NoSuchElementException` - when the pool is exhausted and cannot or will not return another instance.

    - #### returnObject

          public void returnObject(T proxy)
                            throws Exception

      Description copied from interface: `ObjectPool`
      Return an instance to the pool. By contract, `obj` must have been obtained using `ObjectPool.borrowObject()` or a related method as defined in an implementation or sub-interface.
      Specified by:
        `returnObject` in interface `ObjectPool<T>`
      Parameters:
        `proxy` - a `borrowed` instance to be returned.
      Throws:
        `IllegalStateException` - if an attempt is made to return an object to the pool that is in any state other than allocated (i.e. borrowed). Attempting to return an object more than once or attempting to return an object that was never borrowed from the pool will trigger this exception.
        `Exception` - if an instance cannot be returned to the pool

    - #### invalidateObject

          public void invalidateObject(T proxy)
                                throws Exception

      Description copied from interface: `ObjectPool`
      Invalidates an object from the pool.

      By contract, `obj` must have been obtained using `ObjectPool.borrowObject()` or a related method as defined in an implementation or sub-interface.

      This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.

      Specified by:
        `invalidateObject` in interface `ObjectPool<T>`
      Parameters:
        `proxy` - a `borrowed` instance to be disposed.
      Throws:
        `Exception` - if the instance cannot be invalidated

    - #### addObject

          public void addObject()
                         throws Exception,
                                IllegalStateException,
                                UnsupportedOperationException

      Description copied from interface: `ObjectPool`
      Create an object using the `factory` or other implementation dependent mechanism, passivate it, and then place it in the idle object pool. `addObject` is useful for "pre-loading" a pool with idle objects. (Optional operation).
      Specified by:
        `addObject` in interface `ObjectPool<T>`
      Throws:
        `Exception` - when `PooledObjectFactory.makeObject()` fails.
        `IllegalStateException` - after `ObjectPool.close()` has been called on this pool.
        `UnsupportedOperationException` - when this pool cannot add new idle objects.

    - #### getNumIdle

          public int getNumIdle()

      Description copied from interface: `ObjectPool`
      Return the number of instances currently idle in this pool. This may be considered an approximation of the number of objects that can be `borrowed` without creating any new instances. Returns a negative value if this information is not available.
      Specified by:
        `getNumIdle` in interface `ObjectPool<T>`
      Returns:
        the number of instances currently idle in this pool.

    - #### getNumActive

          public int getNumActive()

      Description copied from interface: `ObjectPool`
      Return the number of instances currently borrowed from this pool. Returns a negative value if this information is not available.
      Specified by:
        `getNumActive` in interface `ObjectPool<T>`
      Returns:
        the number of instances currently borrowed from this pool.

    - #### clear

          public void clear()
                     throws Exception,
                            UnsupportedOperationException

      Description copied from interface: `ObjectPool`
      Clears any objects sitting idle in the pool, releasing any associated resources (optional operation). Idle objects cleared must be `PooledObjectFactory.destroyObject(PooledObject)`.
      Specified by:
        `clear` in interface `ObjectPool<T>`
      Throws:
        `UnsupportedOperationException` - if this implementation does not support the operation
        `Exception` - if the pool cannot be cleared

    - #### close

          public void close()

      Description copied from interface: `ObjectPool`
      Close this pool, and free any resources associated with it.

      Calling `ObjectPool.addObject()` or `ObjectPool.borrowObject()` after invoking this method on a pool will cause them to throw an `IllegalStateException`.

      Implementations should silently fail if not all resources can be freed.

      Specified by:
        `close` in interface `Closeable`
      Specified by:
        `close` in interface `AutoCloseable`
      Specified by:
        `close` in interface `ObjectPool<T>`

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`
      Since:
        2.4.3

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