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82 lines
3.2 KiB
82 lines
3.2 KiB
/*
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* Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.sql;
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/**
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* Interface for JDBC classes which provide the ability to retrieve the delegate instance when the instance
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* in question is in fact a proxy class.
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* <p>
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* The wrapper pattern is employed by many JDBC driver implementations to provide extensions beyond
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* the traditional JDBC API that are specific to a data source. Developers may wish to gain access to
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* these resources that are wrapped (the delegates) as proxy class instances representing the
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* the actual resources. This interface describes a standard mechanism to access
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* these wrapped resources
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* represented by their proxy, to permit direct access to the resource delegates.
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*
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* @since 1.6
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*/
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public interface Wrapper {
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/**
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* Returns an object that implements the given interface to allow access to
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* non-standard methods, or standard methods not exposed by the proxy.
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*
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* If the receiver implements the interface then the result is the receiver
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* or a proxy for the receiver. If the receiver is a wrapper
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* and the wrapped object implements the interface then the result is the
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* wrapped object or a proxy for the wrapped object. Otherwise return the
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* the result of calling <code>unwrap</code> recursively on the wrapped object
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* or a proxy for that result. If the receiver is not a
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* wrapper and does not implement the interface, then an <code>SQLException</code> is thrown.
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*
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* @param <T> the type of the class modeled by this Class object
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* @param iface A Class defining an interface that the result must implement.
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* @return an object that implements the interface. May be a proxy for the actual implementing object.
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* @throws java.sql.SQLException If no object found that implements the interface
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* @since 1.6
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*/
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<T> T unwrap(java.lang.Class<T> iface) throws java.sql.SQLException;
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/**
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* Returns true if this either implements the interface argument or is directly or indirectly a wrapper
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* for an object that does. Returns false otherwise. If this implements the interface then return true,
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* else if this is a wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped
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* object. If this does not implement the interface and is not a wrapper, return false.
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* This method should be implemented as a low-cost operation compared to <code>unwrap</code> so that
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* callers can use this method to avoid expensive <code>unwrap</code> calls that may fail. If this method
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* returns true then calling <code>unwrap</code> with the same argument should succeed.
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*
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* @param iface a Class defining an interface.
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* @return true if this implements the interface or directly or indirectly wraps an object that does.
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* @throws java.sql.SQLException if an error occurs while determining whether this is a wrapper
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* for an object with the given interface.
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* @since 1.6
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*/
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boolean isWrapperFor(java.lang.Class<?> iface) throws java.sql.SQLException;
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}
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