public class JDBCBlobFile extends Object implements Blob
Starting with 2.1, in addition to HSQLDB driver support for both client-side in-memory and remote SQL CLOB data implementations, this class is provided to expose efficient, relatively high-performance BLOB operations over client accessible files.
Design Notes
Although it is possible to implement a transactional version of this class, the present implementation directly propagates changes to the underlying file such that changes become visible as soon as they are either implicitly or explicitly flushed to disk.
| Modifier and Type | Field and Description | 
|---|---|
| static String | TEMP_FILE_PREFIX | 
| static String | TEMP_FILE_SUFFIX | 
| Constructor and Description | 
|---|
| JDBCBlobFile()Convenience constructor; equivalent to JDBCBlobFile(true); | 
| JDBCBlobFile(boolean deleteOnFree)Constructs a new instance backed by a File object created in response
 to invoking File.createTempFile(TEMP_FILE_PREFIX,TEMP_FILE_SUFFIX) | 
| JDBCBlobFile(File file)Convenience constructor; equivalent to JDBCBlobFile(file, false); | 
| JDBCBlobFile(File file,
            boolean deleteOnFree)Constructs a new instance backed by the given File object. | 
| Modifier and Type | Method and Description | 
|---|---|
| void | free()This method frees the  Blobobject and releases the resources that
 it holds. | 
| InputStream | getBinaryStream()Retrieves the  BLOBvalue designated by thisBlobinstance as a stream. | 
| InputStream | getBinaryStream(long pos,
               long length)Returns an  InputStreamobject that contains a partialBlobvalue,
 starting  with the byte specified by pos, which is length bytes in length. | 
| byte[] | getBytes(long pos,
        int length)Retrieves all or part of the  BLOBvalue that thisBlobobject represents, as an array of
 bytes. | 
| File | getFile()Retrieves the canonical File object denoting the file that
 backs this BLOB. | 
| boolean | isDeleteOnFree()Retrieves whether an attempt to delete the backing file
 is made in response to invocation of  free(). | 
| long | length()Returns the number of bytes in the  BLOBvalue
 designated by thisBlobobject. | 
| long | position(Blob pattern,
        long start)Retrieves the byte position in the  BLOBvalue
 designated by thisBlobobject at whichpatternbegins. | 
| long | position(byte[] pattern,
        long start)Retrieves the byte position at which the specified byte array
  patternbegins within theBLOBvalue that thisBlobobject represents. | 
| OutputStream | setBinaryStream(long pos)Retrieves a stream that can be used to write to the  BLOBvalue that thisBlobobject represents. | 
| int | setBytes(long pos,
        byte[] bytes)Writes the given array of bytes to the  BLOBvalue that
 thisBlobobject represents, starting at positionpos, and returns the number of bytes written. | 
| int | setBytes(long pos,
        byte[] bytes,
        int offset,
        int len)Writes all or part of the given  bytearray to theBLOBvalue that thisBlobobject represents
 and returns the number of bytes written. | 
| void | setDeleteOnFree(boolean deleteOnFree)Assigns whether an attempt to delete the backing file
 is made in response to invocation of  free(). | 
| void | truncate(long len)Truncates the  BLOBvalue that thisBlobobject represents to belenbytes in length. | 
public static final String TEMP_FILE_PREFIX
public static final String TEMP_FILE_SUFFIX
public JDBCBlobFile()
             throws SQLException
SQLException - If a file could not be created or if a security
         manager exists and its SecurityManager.checkWrite(java.lang.String)public JDBCBlobFile(boolean deleteOnFree)
             throws SQLException
deleteOnFree - Assigns whether an attempt to delete the backing file
                     is to be made in response to invocation of free().SQLException - If a file could not be created or if a security
         manager exists and its SecurityManager.checkWrite(java.lang.String)public JDBCBlobFile(File file) throws SQLException
file - used to back this BLOB instance.SQLException - If an I/O error occurs, which is possible because
         the construction of the canonical pathname may require file system
         queries; if a required system property value cannot be accessed,
         or if a security manager exists and its SecurityManager.checkRead(java.io.FileDescriptor)public JDBCBlobFile(File file, boolean deleteOnFree) throws SQLException
file - used to back this BLOB instance.deleteOnFree - Assigns whether an attempt to delete the backing file
                     is to be made in response to invocation of free().SQLException - If an I/O error occurs, which is possible because
         the construction of the canonical pathname may require file system
         queries; if a required system property value cannot be accessed,
         or if a security manager exists and its SecurityManager.checkRead(java.io.FileDescriptor)public long length()
            throws SQLException
BLOB value
 designated by this Blob object.length in interface BlobBLOB in bytesSQLException - if there is an error accessing the
 length of the BLOBSQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodpublic byte[] getBytes(long pos,
                       int length)
                throws SQLException
BLOB
 value that this Blob object represents, as an array of
 bytes.  This byte array contains up to length
 consecutive bytes starting at position pos.getBytes in interface Blobpos - the ordinal position of the first byte in the
        BLOB value to be extracted; the first byte is at
        position 1length - the number of consecutive bytes to be copied; the value
 for length must be 0 or greaterlength
         consecutive bytes from the BLOB value designated
         by this Blob object, starting with the
         byte at position posSQLException - if there is an error accessing the
            BLOB value; if pos is less than 1 or length is
 less than 0SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodsetBytes(long, byte[])public InputStream getBinaryStream() throws SQLException
BLOB value designated by this
 Blob instance as a stream.getBinaryStream in interface BlobBLOB dataSQLException - if there is an error accessing the
            BLOB valueSQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodsetBinaryStream(long)public long position(byte[] pattern,
                     long start)
              throws SQLException
pattern begins within the BLOB
 value that this Blob object represents.  The
 search for pattern begins at position
 start.position in interface Blobpattern - the byte array for which to searchstart - the position at which to begin searching; the
        first position is 1SQLException - if there is an error accessing the
 BLOB or if start is less than 1SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodpublic long position(Blob pattern, long start) throws SQLException
BLOB value
 designated by this Blob object at which
 pattern begins.  The search begins at position
 start.position in interface Blobpattern - the Blob object designating
 the BLOB value for which to searchstart - the position in the BLOB value
        at which to begin searching; the first position is 1SQLException - if there is an error accessing the
            BLOB value or if start is less than 1SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodpublic int setBytes(long pos,
                    byte[] bytes)
             throws SQLException
BLOB value that
 this Blob object represents, starting at position
 pos, and returns the number of bytes written.
 The array of bytes will overwrite the existing bytes
 in the Blob object starting at the position
 pos.  If the end of the Blob value is reached
 while writing the array of bytes, then the length of the Blob
 value will be increased to accommodate the extra bytes.
 
 Note: If the value specified for pos
 is greater then the length+1 of the BLOB value then the
 behavior is undefined. Some JDBC drivers may throw a
 SQLException while other drivers may support this
 operation.
 
 
This operation affects only the content of the underlying file; it has no effect upon a value stored in a database. To propagate the updated Blob value to a database, 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 updatable ResultSet.
setBytes in interface Blobpos - the position in the BLOB object at which
        to start writing; the first position is 1bytes - the array of bytes to be written to the BLOB
        value that this Blob object representsSQLException - if there is an error accessing the
            BLOB value or if pos is less than 1SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodgetBytes(long, int)public int setBytes(long pos,
                    byte[] bytes,
                    int offset,
                    int len)
             throws SQLException
byte array to the
 BLOB value that this Blob object represents
 and returns the number of bytes written.
 Writing starts at position pos in the BLOB
 value; len bytes from the given byte array are written.
 The array of bytes will overwrite the existing bytes
 in the Blob object starting at the position
 pos.  If the end of the Blob value is reached
 while writing the array of bytes, then the length of the Blob
 value will be increased to accommodate the extra bytes.
 
 Note: If the value specified for pos
 is greater then the length+1 of the BLOB value then the
 behavior is undefined. Some JDBC drivers may throw a
 SQLException while other drivers may support this
 operation.
 
 
This operation affects only the content of the underlying file; it has no effect upon a value stored in a database. To propagate the updated Blob value to a database, 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 updatable ResultSet.
setBytes in interface Blobpos - the position in the BLOB object at which
        to start writing; the first position is 1bytes - the array of bytes to be written to this BLOB
        objectoffset - the offset into the array bytes at which
        to start reading the bytes to be setlen - the number of bytes to be written to the BLOB
        value from the array of bytes bytesSQLException - if there is an error accessing the
            BLOB value or if pos is less than 1SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodgetBytes(long, int)public OutputStream setBinaryStream(long pos) throws SQLException
BLOB
 value that this Blob object represents.  The stream begins
 at position pos.
 The  bytes written to the stream will overwrite the existing bytes
 in the Blob object starting at the position
 pos.  If the end of the Blob value is reached
 while writing to the stream, then the length of the Blob
 value will be increased to accommodate the extra bytes.
 
 Note: If the value specified for pos
 is greater then the length+1 of the BLOB value then the
 behavior is undefined. Some JDBC drivers may throw a
 SQLException while other drivers may support this
 operation.
 
 
Data written to the returned stream affects only the content of the underlying file; it has no effect upon a value stored in a database. To propagate the updated Blob value to a database, 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.
setBinaryStream in interface Blobpos - the position in the BLOB value at which
        to start writing; the first position is 1java.io.OutputStream object to which data can
         be writtenSQLException - if there is an error accessing the
            BLOB value or if pos is less than 1SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodgetBinaryStream()public void truncate(long len)
              throws SQLException
BLOB value that this Blob
 object represents to be len bytes in length.
 
 Note: If the value specified for pos
 is greater then the length+1 of the BLOB value then the
 behavior is undefined. Some JDBC drivers may throw a
 SQLException while other drivers may support this
 operation.
 
 
This operation affects only the length of the underlying file; it has no effect upon a value stored in a database. To propagate the truncated Blob value to a database, 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 updatable ResultSet.
truncate in interface Bloblen - the length, in bytes, to which the BLOB value
        that this Blob object represents should be truncatedSQLException - if there is an error accessing the
            BLOB value or if len is less than 0SQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodpublic void free()
          throws SQLException
Blob object and releases the resources that
 it holds. The object is invalid once the free
 method is called.
 
 After free has been called, any attempt to invoke a
 method other than free will result in a SQLException
 being thrown.  If free is called multiple times, the subsequent
 calls to free are treated as a no-op.
 
 
 This operation closes any input and/or output streams obtained
 via getBinaryStream(), getBinaryStream(long, long) or
 setBinaryStream(long). 
 Additionally, if the property isDeleteOnFree() is true, then
 an attempt is made to delete the backing file.
 
free in interface BlobSQLException - if an error occurs releasing
 the Blob's resourcesSQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodsetDeleteOnFree(boolean), 
isDeleteOnFree()public InputStream getBinaryStream(long pos, long length) throws SQLException
InputStream object that contains a partial Blob value,
 starting  with the byte specified by pos, which is length bytes in length.getBinaryStream in interface Blobpos - the offset to the first byte of the partial value to be retrieved.
  The first byte in the Blob is at position 1length - the length in bytes of the partial value to be retrievedInputStream through which the partial Blob value can be read.SQLException - if pos is less than 1 or if pos is greater than the number of bytes
 in the Blob or if pos + length is greater than the number of bytes
 in the BlobSQLFeatureNotSupportedException - if the JDBC driver does not support
 this methodpublic File getFile()
public boolean isDeleteOnFree()
free().public void setDeleteOnFree(boolean deleteOnFree)
free().deleteOnFree - the new value to assignCopyright © 2001 - 2017 HSQL Development Group.