/* Copyright (c) 2001-2009, The HSQL Development Group
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* 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
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.hsqldb.jdbc;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
// boucherb@users 2004-04-xx - patch 1.7.2 - position and truncate methods
// implemented; minor changes for moderate thread
// safety and optimal performance
// boucherb@users 2004-04-xx - doc 1.7.2 - javadocs updated; methods put in
// correct (historical, interface declared) order
// boucherb@users 2005-12-07 - patch 1.8.0.x - initial JDBC 4.0 support work
// boucherb@users 2006-05-22 - doc 1.9.0 - full synch up to Mustang Build 84
// - patch 1.9.0 - setBinaryStream improvement
// patch 1.9.0
// - fixed invalid reference to new BinaryStream(...) in getBinaryStream
//
// patch 1.9.0 - full synch up to Mustang b90
// - better bounds checking
// - added support for clients to decide whether getBinaryStream
// uses copy of internal byte buffer
/**
* The representation (mapping) in
* the Java<sup><font size=-2>TM</font></sup> programming
* language of an SQL
* <code>BLOB</code> value. An SQL <code>BLOB</code> is a built-in type
* that stores a Binary Large Object as a column value in a row of
* a database table. By default drivers implement <code>Blob</code> using
* an SQL <code>locator(BLOB)</code>, which means that a
* <code>Blob</code> object contains a logical pointer to the
* SQL <code>BLOB</code> data rather than the data itself.
* A <code>Blob</code> object is valid for the duration of the
* transaction in which is was created.
*
* <P>Methods in the interfaces {@link java.sql.ResultSet},
* {@link java.sql.CallableStatement}, and {@link java.sql.PreparedStatement}, such as
* <code>getBlob</code> and <code>setBlob</code> allow a programmer to
* access an SQL <code>BLOB</code> value.
* The <code>Blob</code> interface provides methods for getting the
* length of an SQL <code>BLOB</code> (Binary Large Object) value,
* for materializing a <code>BLOB</code> value on the client, and for
* determining the position of a pattern of bytes within a
* <code>BLOB</code> value. In addition, this interface has methods for updating
* a <code>BLOB</code> value.
* <p>
* All methods on the <code>Blob</code> interface must be fully implemented if the
* JDBC driver supports the data type.
*
* <!-- start Release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* Previous to 1.9.0, the HSQLDB driver did not implement Blob using an SQL
* locator(BLOB). That is, an HSQLDB Blob object did not contain a logical
* pointer to SQL BLOB data; rather it directly contained a representation of
* the data (a byte array). As a result, an HSQLDB Blob object was itself
* valid beyond the duration of the transaction in which is was created,
* although it did not necessarily represent a corresponding value
* on the database. Also, the interface methods for updating a BLOB value
* were unsupported, with the exception of the truncate method,
* in that it could be used to truncate the local value. <p>
*
* Starting with 1.9.0, the HSQLDB driver fully supports both local and remote
* SQL BLOB data implementations, meaning that an HSQLDB Blob object <em>may</em>
* contain a logical pointer to remote SQL BLOB data (see {@link JDBCBlobClient
* JDBCBlobClient}) or it may directly contain a local representation of the
* data (as implemented in this class). In particular, when the product is built
* under JDK 1.6+ and the Blob instance is constructed as a result of calling
* JDBCConnection.createBlob(), then the resulting Blob instance is initially
* disconnected (is not bound to the tranaction scope of the vending Connection
* object), the data is contained directly and all interface methods for
* updating the BLOB value are supported for local use until the first
* invocation of free(); otherwise, an HSQLDB Blob's implementation is
* determined at runtime by the driver, it is typically not valid beyond the
* duration of the transaction in which is was created, and there no
* standard way to query whether it represents a local or remote
* value.<p>
*
* </div>
* <!-- end Release-specific documentation -->
*
* @author james house jhouse@part.net
* @author boucherb@users
* @version 1.9.0
* @since JDK 1.2, HSQLDB 1.7.2
* @revised JDK 1.6, HSQLDB 1.9.0
*/
public class JDBCBlob implements Blob {
/**
* Returns the number of bytes in the <code>BLOB</code> value
* designated by this <code>Blob</code> object.
* @return length of the <code>BLOB</code> in bytes
* @exception SQLException if there is an error accessing the
* length of the <code>BLOB</code>
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.2, HSQLDB 1.7.2
*/
public long length() throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
return ldata.length;
}
/**
* Retrieves all or part of the <code>BLOB</code>
* value that this <code>Blob</code> object represents, as an array of
* bytes. This <code>byte</code> array contains up to <code>length</code>
* consecutive bytes starting at position <code>pos</code>.
*
* <!-- start release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* The official specification above is ambiguous in that it does not
* precisely indicate the policy to be observed when
* pos > this.length() - length. One policy would be to retrieve the
* octets from pos to this.length(). Another would be to throw an
* exception. HSQLDB observes the second policy.
* </div> <!-- end release-specific documentation -->
*
* @param pos the ordinal position of the first byte in the
* <code>BLOB</code> value to be extracted; the first byte is at
* position 1
* @param length the number of consecutive bytes to be copied
* @return a byte array containing up to <code>length</code>
* consecutive bytes from the <code>BLOB</code> value designated
* by this <code>Blob</code> object, starting with the
* byte at position <code>pos</code>
* @exception SQLException if there is an error accessing the BLOB value;
* if <code>pos</code> is less than 1 or <code>length</code> is
* less than 0.
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @see #setBytes
* @since JDK 1.2, HSQLDB 1.7.2
*/
public byte[] getBytes(long pos, final int length) throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
final int dlen = ldata.length;
if (pos < MIN_POS || pos > MIN_POS + dlen) {
throw Util.outOfRangeArgument("pos: " + pos);
}
pos--;
if (length < 0 || length > dlen - pos) {
throw Util.outOfRangeArgument("length: " + length);
}
final byte[] out = new byte[length];
System.arraycopy(ldata, (int) pos, out, 0, length);
return out;
}
/**
* Retrieves the <code>BLOB</code> value designated by this
* <code>Blob</code> instance as a stream.
*
* @return a stream containing the <code>BLOB</code> data
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @see #setBinaryStream
* @since JDK 1.2, HSQLDB 1.7.2
*/
public InputStream getBinaryStream() throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
return new ByteArrayInputStream(ldata);
}
/**
* Retrieves the byte position at which the specified byte array
* <code>pattern</code> begins within the <code>BLOB</code>
* value that this <code>Blob</code> object represents. The
* search for <code>pattern</code> begins at position
* <code>start</code>.
*
* @param pattern the byte array for which to search
* @param start the position at which to begin searching; the
* first position is 1
* @return the position at which the pattern appears, else -1
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> or if start is less than 1
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.2, HSQLDB 1.7.2
*/
public long position(final byte[] pattern,
long start) throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
final int dlen = ldata.length;
if (start < MIN_POS) {
throw Util.outOfRangeArgument("start: " + start);
} else if (start > dlen || pattern == null) {
return -1L;
} else {
start--;
}
final int plen = pattern.length;
if (plen == 0 || start > dlen - plen) {
return -1L;
}
final int stop = dlen - plen;
final byte b0 = pattern[0];
outer_loop:
for (int i = (int) start; i <= stop; i++) {
if (ldata[i] != b0) {
continue;
}
int len = plen;
int doffset = i;
int poffset = 0;
boolean match = true;
while (len-- > 0) {
if (ldata[doffset++] != pattern[poffset++]) {
continue outer_loop;
}
}
return (i + 1);
}
return -1L;
}
/**
* Retrieves the byte position in the <code>BLOB</code> value
* designated by this <code>Blob</code> object at which
* <code>pattern</code> begins. The search begins at position
* <code>start</code>.
*
* @param pattern the <code>Blob</code> object designating
* the <code>BLOB</code> value for which to search
* @param start the position in the <code>BLOB</code> value
* at which to begin searching; the first position is 1
* @return the position at which the pattern begins, else -1
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value or if start is less than 1
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.2, HSQLDB 1.7.2
*/
public long position(final Blob pattern, long start) throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
final int dlen = ldata.length;
if (start < MIN_POS) {
throw Util.outOfRangeArgument("start: " + start);
} else if (start > dlen || pattern == null) {
return -1L;
} else {
start--;
}
final long plen = pattern.length();
if (plen == 0 || start > ((long) dlen) - plen) {
return -1L;
}
// by now, we know plen <= Integer.MAX_VALUE
final int iplen = (int) plen;
byte[] bap;
if (pattern instanceof JDBCBlob) {
bap = ((JDBCBlob) pattern).data();
} else {
bap = pattern.getBytes(1L, iplen);
}
final int stop = dlen - iplen;
final byte b0 = bap[0];
outer_loop:
for (int i = (int) start; i <= stop; i++) {
if (ldata[i] != b0) {
continue;
}
int len = iplen;
int doffset = i;
int poffset = 0;
while (len-- > 0) {
if (ldata[doffset++] != bap[poffset++]) {
continue outer_loop;
}
}
return i + 1;
}
return -1L;
}
// -------------------------- JDBC 3.0 -----------------------------------
/**
* Writes the given array of bytes to the <code>BLOB</code> value that
* this <code>Blob</code> object represents, starting at position
* <code>pos</code>, and returns the number of bytes written.
* The array of bytes will overwrite the existing bytes
* in the <code>Blob</code> object starting at the position
* <code>pos</code>. If the end of the <code>Blob</code> value is reached
* while writing the array of bytes, then the length of the <code>Blob</code>
* value will be increased to accomodate the extra bytes.
* <p>
* <b>Note:</b> If the value specified for <code>pos</code>
* is greater then the length+1 of the <code>BLOB</code> value then the
* behavior is undefined. Some JDBC drivers may throw a
* <code>SQLException</code> while other drivers may support this
* operation.
*
* <!-- start release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* Starting with HSQLDB 1.9.0 this feature is supported. <p>
*
* When built under JDK 1.6+ and the Blob instance is constructed as a
* result of calling JDBCConnection.createBlob(), this operation affects
* only the client-side value; it has no effect upon a value stored in a
* database because JDBCConnection.createBlob() constructs disconnected,
* initially empty Blob instances. To propogate the Blob value to a database
* in this case, it is required to supply the Blob instance to an updating
* or inserting setXXX method of a Prepared or Callable Statement, or to
* supply the Blob instance to an updateXXX method of an updateable
* ResultSet. <p>
*
* <b>Implementation Notes:</b><p>
*
* No attempt is made to ensure precise thread safety. Instead, volatile
* member field and local variable snapshot isolation semantics are
* implemented. This is expected to eliminate most issues related
* to race conditions, with the possible exception of concurrent
* invocation of free(). <p>
*
* In general, however, if an application may perform concurrent
* JDBCBlob modifications and the integrity of the application depends on
* total order Blob modification semantics, then such operations
* should be synchronized on an appropriate monitor.<p>
*
* </div>
* <!-- end release-specific documentation -->
*
* @param pos the position in the <code>BLOB</code> object at which
* to start writing; the first position is 1
* @param bytes the array of bytes to be written to the <code>BLOB</code>
* value that this <code>Blob</code> object represents
* @return the number of bytes written
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value or if pos is less than 1
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @see #getBytes
* @since JDK 1.4, HSQLDB 1.7.2
* @revised JDK 1.6, HSQLDB 1.9.0
*/
public int setBytes(long pos, byte[] bytes) throws SQLException {
if (bytes == null) {
throw Util.nullArgument("bytes");
}
return (setBytes(pos, bytes, 0, bytes.length));
}
/**
* Writes all or part of the given <code>byte</code> array to the
* <code>BLOB</code> value that this <code>Blob</code> object represents
* and returns the number of bytes written.
* Writing starts at position <code>pos</code> in the <code>BLOB</code>
* value; <code>len</code> bytes from the given byte array are written.
* The array of bytes will overwrite the existing bytes
* in the <code>Blob</code> object starting at the position
* <code>pos</code>. If the end of the <code>Blob</code> value is reached
* while writing the array of bytes, then the length of the <code>Blob</code>
* value will be increased to accomodate the extra bytes.
* <p>
* <b>Note:</b> If the value specified for <code>pos</code>
* is greater then the length+1 of the <code>BLOB</code> value then the
* behavior is undefined. Some JDBC drivers may throw a
* <code>SQLException</code> while other drivers may support this
* operation.
*
* <!-- start release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* Starting with HSQLDB 1.9.0 this feature is supported. <p>
*
* When built under JDK 1.6+ and the Blob instance is constructed as a
* result of calling JDBCConnection.createBlob(), this operation affects
* only the client-side value; it has no effect upon a value stored in a
* database because JDBCConnection.createBlob() constructs disconnected,
* initially empty Blob instances. To propogate the Blob value to a database
* in this case, it is required to supply the Blob instance to an updating
* or inserting setXXX method of a Prepared or Callable Statement, or to
* supply the Blob instance to an updateXXX method of an updateable
* ResultSet. <p>
*
* <b>Implementation Notes:</b><p>
*
* If the value specified for <code>pos</code>
* is greater than the length of the <code>BLOB</code> value, then
* the <code>BLOB</code> value is extended in length to accept the
* written octets and the undefined region up to <code>pos</code> is
* filled with (byte)0. <p>
*
* No attempt is made to ensure precise thread safety. Instead, volatile
* member field and local variable snapshot isolation semantics are
* implemented. This is expected to eliminate most issues related
* to race conditions, with the possible exception of concurrent
* invocation of free(). <p>
*
* In general, however, if an application may perform concurrent
* JDBCBlob modifications and the integrity of the application depends on
* total order Blob modification semantics, then such operations
* should be synchronized on an appropriate monitor.<p>
*
* </div>
* <!-- end release-specific documentation -->
*
* @param pos the position in the <code>BLOB</code> object at which
* to start writing; the first position is 1
* @param bytes the array of bytes to be written to this <code>BLOB</code>
* object
* @param offset the offset into the array <code>bytes</code> at which
* to start reading the bytes to be set
* @param len the number of bytes to be written to the <code>BLOB</code>
* value from the array of bytes <code>bytes</code>
* @return the number of bytes written
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value or if pos is less than 1
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @see #getBytes
* @since JDK 1.4, HSQLDB 1.7.2
* @revised JDK 1.6, HSQLDB 1.9.0
*/
public int setBytes(long pos, byte[] bytes, int offset,
int len) throws SQLException {
if (!this.createdByConnection) {
/** @todo - better error message */
throw Util.notSupported();
}
if (bytes == null) {
throw Util.nullArgument("bytes");
}
if (offset < 0 || offset > bytes.length) {
throw Util.outOfRangeArgument("offset: " + offset);
}
if (len > bytes.length - offset) {
throw Util.outOfRangeArgument("len: " + len);
}
if (pos < MIN_POS || pos > 1L + (Integer.MAX_VALUE - len)) {
throw Util.outOfRangeArgument("pos: " + pos);
}
pos--;
byte[] ldata = this.data;
checkValid(ldata);
final int dlen = ldata.length;
if ((pos + len) > dlen) {
byte[] temp = new byte[(int) pos + len];
System.arraycopy(ldata, 0, temp, 0, dlen);
ldata = temp;
temp = null;
}
System.arraycopy(bytes, offset, ldata, (int) pos, len);
// paranoia, in case somone free'd us during the array copies.
checkValid(this.data);
this.data = ldata;
return len;
}
/**
* Retrieves a stream that can be used to write to the <code>BLOB</code>
* value that this <code>Blob</code> object represents. The stream begins
* at position <code>pos</code>.
* The bytes written to the stream will overwrite the existing bytes
* in the <code>Blob</code> object starting at the position
* <code>pos</code>. If the end of the <code>Blob</code> value is reached
* while writing to the stream, then the length of the <code>Blob</code>
* value will be increased to accomodate the extra bytes.
* <p>
* <b>Note:</b> If the value specified for <code>pos</code>
* is greater then the length+1 of the <code>BLOB</code> value then the
* behavior is undefined. Some JDBC drivers may throw a
* <code>SQLException</code> while other drivers may support this
* operation.
*
* <!-- start release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* Starting with HSQLDB 1.9.0 this feature is supported. <p>
*
* When built under JDK 1.6+ and the Blob instance is constructed as a
* result of calling JDBCConnection.createBlob(), this operation affects
* only the client-side value; it has no effect upon a value stored in a
* database because JDBCConnection.createBlob() constructs disconnected,
* initially empty Blob instances. To propogate the Blob value to a database
* in this case, it is required to supply the Blob instance to an updating
* or inserting setXXX method of a Prepared or Callable Statement, or to
* supply the Blob instance to an updateXXX method of an updateable
* ResultSet. <p>
*
* <b>Implementation Notes:</b><p>
*
* The data written to the stream does not appear in this
* Blob until the stream is closed <p>
*
* When the stream is closed, if the value specified for <code>pos</code>
* is greater than the length of the <code>BLOB</code> value, then
* the <code>BLOB</code> value is extended in length to accept the
* written octets and the undefined region up to <code>pos</code> is
* filled with (byte)0. <p>
*
* Also, no attempt is made to ensure precise thread safety. Instead,
* volatile member field and local variable snapshot isolation semantics
* are implemented. This is expected to eliminate most issues related
* to race conditions, with the possible exception of concurrent
* invocation of free(). <p>
*
* In general, however, if an application may perform concurrent
* JDBCBlob modifications and the integrity of the application depends on
* total order Blob modification semantics, then such operations
* should be synchronized on an appropriate monitor.<p>
*
* </div>
* <!-- end release-specific documentation -->
*
* @param pos the position in the <code>BLOB</code> value at which
* to start writing; the first position is 1
* @return a <code>java.io.OutputStream</code> object to which data can
* be written
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value or if pos is less than 1
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @see #getBinaryStream
* @since JDK 1.4, HSQLDB 1.7.2
* @revised JDK 1.6, HSQLDB 1.9.0
*/
public OutputStream setBinaryStream(final long pos) throws SQLException {
if (!this.createdByConnection) {
/** @todo - Better error message */
throw Util.notSupported();
}
if (pos < MIN_POS || pos > MAX_POS) {
throw Util.outOfRangeArgument("pos: " + pos);
}
checkValid(this.data);
return new java.io.ByteArrayOutputStream() {
public synchronized void close() throws java.io.IOException {
try {
JDBCBlob.this.setBytes(pos, toByteArray());
} catch (SQLException se) {
throw new java.io.IOException(se.toString());
} finally {
super.close();
}
}
};
}
/**
* Truncates the <code>BLOB</code> value that this <code>Blob</code>
* object represents to be <code>len</code> bytes in length.
* <p>
* <b>Note:</b> If the value specified for <code>pos</code>
* is greater then the length+1 of the <code>BLOB</code> value then the
* behavior is undefined. Some JDBC drivers may throw a
* <code>SQLException</code> while other drivers may support this
* operation.
*
* <!-- start release-specific documentation -->
* <div class="ReleaseSpecificDocumentation">
* <h3>HSQLDB-Specific Information:</h3> <p>
*
* Starting with HSQLDB 1.9.0 this feature is fully supported. <p>
*
* When built under JDK 1.6+ and the Blob instance is constructed as a
* result of calling JDBCConnection.createBlob(), this operation affects
* only the client-side value; it has no effect upon a value stored in a
* database because JDBCConnection.createBlob() constructs disconnected,
* initially empty Blob instances. To propogate the truncated Blob value to
* a database in this case, it is required to supply the Blob instance to
* an updating or inserting setXXX method of a Prepared or Callable
* Statement, or to supply the Blob instance to an updateXXX method of an
* updateable ResultSet. <p>
*
* </div>
* <!-- end release-specific documentation -->
*
* @param len the length, in bytes, to which the <code>BLOB</code> value
* that this <code>Blob</code> object represents should be truncated
* @exception SQLException if there is an error accessing the
* <code>BLOB</code> value or if len is less than 0
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.4, HSQLDB 1.7.2
* @revised JDK 1.6, HSQLDB 1.9.0
*/
public void truncate(final long len) throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
if (len < 0 || len > ldata.length) {
throw Util.outOfRangeArgument("len: " + len);
}
if (len == ldata.length) {
return;
}
byte[] newData = new byte[(int) len];
System.arraycopy(ldata, 0, newData, 0, (int) len);
checkValid(data); // limit possible race-condition with free()
data = newData;
}
//------------------------- JDBC 4.0 -----------------------------------
/**
* This method frees the <code>Blob</code> object and releases the resources that
* it holds. The object is invalid once the <code>free</code>
* method is called.
* <p>
* After <code>free</code> has been called, any attempt to invoke a
* method other than <code>free</code> will result in a <code>SQLException</code>
* being thrown. If <code>free</code> is called multiple times, the subsequent
* calls to <code>free</code> are treated as a no-op.
* <p>
*
* @throws SQLException if an error occurs releasing
* the Blob's resources
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.6, HSQLDB 1.9.0
*/
public void free() throws SQLException {
this.data = null;
}
/**
* Returns an <code>InputStream</code> object that contains a partial <code>Blob</code> value,
* starting with the byte specified by pos, which is length bytes in length.
*
* @param pos the offset to the first byte of the partial value to be retrieved.
* The first byte in the <code>Blob</code> is at position 1
* @param length the length in bytes of the partial value to be retrieved
* @return <code>InputStream</code> through which the partial <code>Blob</code> value can be read.
* @throws SQLException if pos is less than 1 or if pos is greater than the number of bytes
* in the <code>Blob</code> or if pos + length is greater than the number of bytes
* in the <code>Blob</code>
*
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since JDK 1.6, HSQLDB 1.9.0
*/
public InputStream getBinaryStream(long pos,
long length) throws SQLException {
final byte[] ldata = data;
checkValid(ldata);
final int dlen = ldata.length;
if (pos < MIN_POS || pos > dlen) {
throw Util.outOfRangeArgument("pos: " + pos);
}
pos--;
if (length < 0 || length > dlen - pos) {
throw Util.outOfRangeArgument("length: " + length);
}
if (pos == 0 && length == dlen) {
return new ByteArrayInputStream(ldata);
}
// Let client decide on policy.
//
// Zero-copy is (possibly much) faster because it does
// not allocate extra memory and does not involve copy
// processing.
//
// However, because it could lead to unexpected memory,
// stress, it is not polite to always pass back a stream
// whose buffer is the full size required to represent the
// underlying BLOB value.
// if (isGetBinaryStreamUsesCopy()) {
final byte[] out = new byte[(int) length];
System.arraycopy(ldata, (int) pos, out, 0, (int) length);
return new ByteArrayInputStream(out);
// } else {
// return new BinaryInputStream(ldata, pos, length);
// }
}
/**
* Assigns whether getBinaryStream() uses a copy of
* the underlying byte[].
*
* @param b when true, then getBinaryStream() uses a copy of
* the underlying byte[]
*/
public void setGetBinaryStreamUsesCopy(boolean b) {
getBinaryStreamUsesCopy = b;
}
/**
* Retrieves whether getBinaryStream() uses a copy of
* the underlying buffer.
*
* @return true if getBinaryStream() uses a copy of
* the underlying buffer; else false
*/
public boolean isGetBinaryStreamUsesCopy() {
return getBinaryStreamUsesCopy;
}
// ---------------------- internal implementation --------------------------
public static final long MIN_POS = 1L;
public static final long MAX_POS = 1L + (long) Integer.MAX_VALUE;
private volatile byte[] data;
private final boolean createdByConnection;
private boolean getBinaryStreamUsesCopy;
/**
* Constructs a new JDBCBlob instance wrapping the given octet sequence. <p>
*
* This constructor is used internally to retrieve result set values as
* Blob objects, yet it must 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 data the octet sequence representing the Blob value
* @throws SQLException if the argument is null
*/
public JDBCBlob(final byte[] data) throws SQLException {
init(data);
this.createdByConnection = false;
}
protected JDBCBlob() {
this.data = new byte[0];
this.createdByConnection = true;
}
protected void init(byte[] data) throws SQLException {
if (data == null) {
throw Util.nullArgument();
}
this.data = data; // (byte[]) data.clone();
}
protected void checkValid(final Object data) {
if (data == null) {
throw new RuntimeException("null data");
}
}
protected byte[] data() throws SQLException {
byte[] ldata = data;
checkValid(ldata);
return ldata;
}
}