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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
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
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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.- Parameters:
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:
SQLException- If no object found that implements the interface- Since:
- 1.6
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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:
iface- a Class defining an interface.- Returns:
- true if this implements the interface or directly or indirectly wraps an object that does.
- Throws:
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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Document created the 11/06/2005, last modified the 04/03/2020
Source of the printed document:https://www.gaudry.be/en/java-api-rf-java/sql/wrapper.html
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References
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