Interface Wrapper
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- All Known Subinterfaces:
- CachedRowSet, CallableStatement, Connection, DatabaseMetaData, DataSource, FilteredRowSet, JdbcRowSet, JoinRowSet, ParameterMetaData, PreparedStatement, ResultSet, ResultSetMetaData, RowSet, RowSetMetaData, Statement, SyncResolver, WebRowSet
- All Known Implementing Classes:
- RowSetMetaDataImpl
public interface WrapperInterface for JDBC classes which provide the ability to retrieve the delegate instance when the instance in question is in fact a proxy class.The wrapper pattern is employed by many JDBC driver implementations to provide extensions beyond the traditional JDBC API that are specific to a data source. Developers may wish to gain access to these resources that are wrapped (the delegates) as proxy class instances representing the the actual resources. This interface describes a standard mechanism to access these wrapped resources represented by their proxy, to permit direct access to the resource delegates.
- Since:
- 1.6
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method and Description booleanisWrapperFor(Class<?> iface)Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does.<T> Tunwrap(Class<T> iface)Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.
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Method Detail
unwrap
<T> T unwrap(Class<T> iface) throws SQLException
Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy. If the receiver implements the interface then the result is the receiver or a proxy for the receiver. If the receiver is a wrapper and the wrapped object implements the interface then the result is the wrapped object or a proxy for the wrapped object. Otherwise return the the result of callingunwraprecursively on the wrapped object or a proxy for that result. If the receiver is not a wrapper and does not implement the interface, then anSQLExceptionis thrown.- Type Parameters:
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T- the type of the class modeled by this Class object - Parameters:
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iface- A Class defining an interface that the result must implement. - Returns:
- an object that implements the interface. May be a proxy for the actual implementing object.
- Throws:
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SQLException- If no object found that implements the interface - Since:
- 1.6
isWrapperFor
boolean isWrapperFor(Class<?> iface) throws SQLException
Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does. Returns false otherwise. If this implements the interface then return true, else if this is a wrapper then return the result of recursively callingisWrapperForon the wrapped object. If this does not implement the interface and is not a wrapper, return false. This method should be implemented as a low-cost operation compared tounwrapso that callers can use this method to avoid expensiveunwrapcalls that may fail. If this method returns true then callingunwrapwith the same argument should succeed.- Parameters:
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iface- a Class defining an interface. - Returns:
- true if this implements the interface or directly or indirectly wraps an object that does.
- Throws:
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SQLException- if an error occurs while determining whether this is a wrapper for an object with the given interface. - Since:
- 1.6
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