org.hsqldb.jdbc.JDBCRowId Maven / Gradle / Ivy
/* Copyright (c) 2001-2011, The HSQL Development Group
* All rights reserved.
*
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* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the HSQL Development Group nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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package org.hsqldb.jdbc;
import org.hsqldb.error.ErrorCode;
import org.hsqldb.lib.StringConverter;
import java.io.IOException;
import java.sql.RowId;
import java.sql.SQLException;
import java.util.Arrays;
/* $Id: JDBCRowId.java 5161 2013-02-03 01:45:10Z fredt $ */
//boucherb@users 20060522 - doc 1.8.1 full synch up to Mustang Build 84
/**
*
* The representation (mapping) in the Java programming language of an SQL ROWID
* value. An SQL ROWID is a built-in type, a value of which can be thought of as
* an address for its identified row in a database table. Whether that address
* is logical or, in any respects, physical is determined by its originating data
* source.
*
* Methods in the interfaces ResultSet, CallableStatement,
* and PreparedStatement, such as getRowId and setRowId
* allow a programmer to access a SQL ROWID value. The RowId
* interface provides a method
* for representing the value of the ROWID as a byte array or as a
* String.
*
* The method getRowIdLifetime in the interface DatabaseMetaData,
* can be used
* to determine if a RowId object remains valid for the duration of the transaction in
* which the RowId was created, the duration of the session in which
* the RowId was created,
* or, effectively, for as long as its identified row is not deleted. In addition
* to specifying the duration of its valid lifetime outside its originating data
* source, getRowIdLifetime specifies the duration of a ROWID
* value's valid lifetime
* within its originating data source. In this, it differs from a large object,
* because there is no limit on the valid lifetime of a large object within its
* originating data source.
*
* All methods on the RowId interface must be fully implemented if the
* JDBC driver supports the data type.
*
* @see java.sql.DatabaseMetaData
* @since JDK 1.6, HSQLDB 2.0
* @author boucherb@users
*/
public final class JDBCRowId implements RowId {
private int hash;
// ------------------------- Internal Implementation -----------------------
private final byte[] id;
/**
* Constructs a new JDBCRowId instance wrapping the given octet sequence.
*
* This constructor may be used internally to retrieve result set values as
* RowId objects, yet it also may need to be public to allow access from
* other packages. As such (in the interest of efficiency) this object
* maintains a reference to the given octet sequence rather than making a
* copy; special care should be taken by extenal clients never to use this
* constructor with a byte array object that may later be modified
* extenally.
*
* @param id the octet sequence representing the Rowid value
* @throws SQLException if the argument is null
*/
public JDBCRowId(final byte[] id) throws SQLException {
if (id == null) {
throw JDBCUtil.nullArgument("id");
}
this.id = id;
}
/**
* Constructs a new JDBCRowId instance whose internal octet sequence is
* is a copy of the octet sequence of the given RowId object.
*
* @param id the octet sequence representing the Rowid value
* @throws SQLException if the argument is null
*/
public JDBCRowId(RowId id) throws SQLException {
this(id.getBytes());
}
/**
* Constructs a new JDBCRowId instance whose internal octet sequence is
* is that represented by the given hexidecimal character sequence.
* @param hex the hexadecimal character sequence from which to derive
* the internal octet sequence
* @throws java.sql.SQLException if the argument is null or is not a valid
* hexadecimal character sequence
*/
public JDBCRowId(final String hex) throws SQLException {
if (hex == null) {
throw JDBCUtil.nullArgument("hex");
}
try {
this.id = StringConverter.hexStringToByteArray(hex);
} catch (IOException e) {
throw JDBCUtil.sqlException(ErrorCode.JDBC_INVALID_ARGUMENT,
"hex: " + e);
// .illegalHexadecimalCharacterSequenceArgumentException("hex", e);
}
}
/**
* Compares this RowId to the specified object. The result is
* true if and only if the argument is not null and is a RowId
* object that represents the same ROWID as this object.
*
* It is important
* to consider both the origin and the valid lifetime of a RowId
* when comparing it to another RowId. If both are valid, and
* both are from the same table on the same data source, then if they are equal
* they identify
* the same row; if one or more is no longer guaranteed to be valid, or if
* they originate from different data sources, or different tables on the
* same data source, they may be equal but still
* not identify the same row.
*
* @param obj the Object to compare this RowId object
* against.
* @return true if the RowIds are equal; false otherwise
* @since JDK 1.6, HSQLDB 2.0
*/
public boolean equals(Object obj) {
return (obj instanceof JDBCRowId)
&& Arrays.equals(this.id, ((JDBCRowId) obj).id);
}
/**
* Returns an array of bytes representing the value of the SQL ROWID
* designated by this java.sql.RowId object.
*
* @return an array of bytes, whose length is determined by the driver supplying
* the connection, representing the value of the ROWID designated by this
* java.sql.RowId object.
*/
public byte[] getBytes() {
return id.clone();
}
/**
* Returns a String representing the value of the SQL ROWID designated by this
* java.sql.RowId object.
*
* Like java.sql.Date.toString()
* returns the contents of its DATE as the String "2004-03-17"
* rather than as DATE literal in SQL (which would have been the String
* DATE "2004-03-17"), toString()
* returns the contents of its ROWID in a form specific to the driver supplying
* the connection, and possibly not as a ROWID literal.
*
* @return a String whose format is determined by the driver supplying the
* connection, representing the value of the ROWID designated
* by this java.sql.RowId object.
*/
public String toString() {
return StringConverter.byteArrayToHexString(id);
}
/**
* Returns a hash code value of this RowId object.
*
* @return a hash code for the RowId
*/
public int hashCode() {
if (hash == 0) {
hash = Arrays.hashCode(id);
}
return hash;
}
/**
* Direct access to id bytes for subclassing.
*
* @return direct reference to id bytes.
*/
Object id() {
return id;
}
}