Class JDBCBlobFile

java.lang.Object
org.hsqldb.jdbc.JDBCBlobFile
All Implemented Interfaces:
Blob
public class JDBCBlobFile extends Object implements Blob
A client-side file-based implementation of Blob.

HSQLDB-Specific Information:

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.

Since:
HSQLDB 2.1
Author:
Campbell Burnet (campbell-burnet@users dot sourceforge.net)

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final String
    TEMP_FILE_PREFIX
     
    static final String
    TEMP_FILE_SUFFIX
     

  • Constructor Summary

    Constructors
    Constructor
    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.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    free()
    This method frees the Blob object and releases the resources that it holds.
    InputStream
    getBinaryStream()
    Retrieves the BLOB value designated by this Blob instance as a stream.
    InputStream
    getBinaryStream(long pos, long length)
    Returns an InputStream object that contains a partial Blob value, 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 BLOB value that this Blob object 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 BLOB value designated by this Blob object.
    long
    position(byte[] pattern, long start)
    Retrieves the byte position at which the specified byte array pattern begins within the BLOB value that this Blob object represents.
    long
    position(Blob pattern, long start)
    Retrieves the byte position in the BLOB value designated by this Blob object at which pattern begins.
    OutputStream
    setBinaryStream(long pos)
    Retrieves a stream that can be used to write to the BLOB value that this Blob object represents.
    int
    setBytes(long pos, byte[] bytes)
    Writes the given array of bytes to the BLOB value that this Blob object represents, starting at position pos, and returns the number of bytes written.
    int
    setBytes(long pos, byte[] bytes, int offset, int len)
    Writes all or part of the given byte array to the BLOB value that this Blob object 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 BLOB value that this Blob object represents to be len bytes in length.

    Methods inherited from class Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

  • Constructor Details

    • JDBCBlobFile

      public JDBCBlobFile() throws SQLException
      Convenience constructor; equivalent to JDBCBlobFile(true);
      Throws:
      SQLException - If a file could not be created or if a security manager exists and its {@link java.lang.SecurityManager#checkWrite(java.lang.String)} method does not allow a file to be created.

    • JDBCBlobFile

      public JDBCBlobFile(boolean deleteOnFree) throws SQLException
      Constructs a new instance backed by a File object created in response to invoking File.createTempFile(TEMP_FILE_PREFIX,TEMP_FILE_SUFFIX).
      Parameters:
      deleteOnFree - Assigns whether an attempt to delete the backing file is to be made in response to invocation of free().
      Throws:
      SQLException - If a file could not be created or if a security manager exists and its {@link java.lang.SecurityManager#checkWrite(java.lang.String)} method does not allow a file to be created.

    • JDBCBlobFile

      public JDBCBlobFile(File file) throws SQLException
      Convenience constructor; equivalent to JDBCBlobFile(file, false);
      Parameters:
      file - used to back this BLOB instance.
      Throws:
      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 {@link java.lang.SecurityManager#checkRead} method denies read access to the file

    • JDBCBlobFile

      public JDBCBlobFile(File file, boolean deleteOnFree) throws SQLException
      Constructs a new instance backed by the given File object.
      Parameters:
      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().
      Throws:
      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 {@link java.lang.SecurityManager#checkRead} method denies read access to the file

  • Method Details

    • length

      public long length() throws SQLException
      Returns the number of bytes in the BLOB value designated by this Blob object.
      Specified by:
      length in interface Blob
      Returns:
      length of the BLOB in bytes
      Throws:
      SQLException - if there is an error accessing the length of the BLOB
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.2

    • getBytes

      public byte[] getBytes(long pos, int length) throws SQLException
      Retrieves all or part of the 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.
      Specified by:
      getBytes in interface Blob
      Parameters:
      pos - the ordinal position of the first byte in the BLOB value to be extracted; the first byte is at position 1
      length - the number of consecutive bytes to be copied; the value for length must be 0 or greater
      Returns:
      a byte array containing up to length consecutive bytes from the BLOB value designated by this Blob object, starting with the byte at position pos
      Throws:
      SQLException - if there is an error accessing the BLOB value; if pos is less than 1 or length is less than 0
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.2
      See Also:

    • getBinaryStream

      public InputStream getBinaryStream() throws SQLException
      Retrieves the BLOB value designated by this Blob instance as a stream.
      Specified by:
      getBinaryStream in interface Blob
      Returns:
      a stream containing the BLOB data
      Throws:
      SQLException - if there is an error accessing the BLOB value
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.2
      See Also:

    • position

      public long position(byte[] pattern, long start) throws SQLException
      Retrieves the byte position at which the specified byte array pattern begins within the BLOB value that this Blob object represents. The search for pattern begins at position start.
      Specified by:
      position in interface Blob
      Parameters:
      pattern - the byte array for which to search
      start - the position at which to begin searching; the first position is 1
      Returns:
      the position at which the pattern appears, else -1
      Throws:
      SQLException - if there is an error accessing the BLOB or if start is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.2

    • position

      public long position(Blob pattern, long start) throws SQLException
      Retrieves the byte position in the BLOB value designated by this Blob object at which pattern begins. The search begins at position start.
      Specified by:
      position in interface Blob
      Parameters:
      pattern - the Blob object designating the BLOB value for which to search
      start - the position in the BLOB value at which to begin searching; the first position is 1
      Returns:
      the position at which the pattern begins, else -1
      Throws:
      SQLException - if there is an error accessing the BLOB value or if start is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.2

    • setBytes

      public int setBytes(long pos, byte[] bytes) throws SQLException
      Writes the given array of bytes to the 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 than 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.

      HSQLDB-Specific Information:

      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.
      Specified by:
      setBytes in interface Blob
      Parameters:
      pos - the position in the BLOB object at which to start writing; the first position is 1
      bytes - the array of bytes to be written to the BLOB value that this Blob object represents
      Returns:
      the number of bytes written
      Throws:
      SQLException - if there is an error accessing the BLOB value or if pos is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.4
      See Also:

    • setBytes

      public int setBytes(long pos, byte[] bytes, int offset, int len) throws SQLException
      Writes all or part of the given 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 than 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.

      HSQLDB-Specific Information:

      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.
      Specified by:
      setBytes in interface Blob
      Parameters:
      pos - the position in the BLOB object at which to start writing; the first position is 1
      bytes - the array of bytes to be written to this BLOB object
      offset - the offset into the array bytes at which to start reading the bytes to be set
      len - the number of bytes to be written to the BLOB value from the array of bytes bytes
      Returns:
      the number of bytes written
      Throws:
      SQLException - if there is an error accessing the BLOB value or if pos is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.4
      See Also:

    • setBinaryStream

      public OutputStream setBinaryStream(long pos) throws SQLException
      Retrieves a stream that can be used to write to the 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 than 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.

      HSQLDB-Specific Information:

      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.
      Specified by:
      setBinaryStream in interface Blob
      Parameters:
      pos - the position in the BLOB value at which to start writing; the first position is 1
      Returns:
      a java.io.OutputStream object to which data can be written
      Throws:
      SQLException - if there is an error accessing the BLOB value or if pos is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.4
      See Also:

    • truncate

      public void truncate(long len) throws SQLException
      Truncates the BLOB value that this Blob object represents to be len bytes in length.

      Note: If the value specified for pos is greater than 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.

      HSQLDB-Specific Information:

      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.
      Specified by:
      truncate in interface Blob
      Parameters:
      len - the length, in bytes, to which the BLOB value that this Blob object represents should be truncated
      Throws:
      SQLException - if there is an error accessing the BLOB value or if len is less than 0
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.4

    • free

      public void free() throws SQLException
      This method frees the 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.

      HSQLDB-Specific Information:

      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.

      Specified by:
      free in interface Blob
      Throws:
      SQLException - if an error occurs releasing the Blob's resources
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.6
      See Also:

    • getBinaryStream

      public InputStream getBinaryStream(long pos, long length) throws SQLException
      Returns an InputStream object that contains a partial Blob value, starting with the byte specified by pos, which is length bytes in length.
      Specified by:
      getBinaryStream in interface Blob
      Parameters:
      pos - the offset to the first byte of the partial value to be retrieved. The first byte in the Blob is at position 1
      length - the length in bytes of the partial value to be retrieved
      Returns:
      InputStream through which the partial Blob value can be read.
      Throws:
      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 Blob
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      JDK 1.6

    • getFile

      public File getFile()
      Retrieves the canonical File object denoting the file that backs this BLOB.
      Returns:
      the file that backs this BLOB.

    • isDeleteOnFree

      public boolean isDeleteOnFree()
      Retrieves whether an attempt to delete the backing file is made in response to invocation of free().
      Returns:
      true if backing file deletion is attempted; otherwise false.

    • setDeleteOnFree

      public void setDeleteOnFree(boolean deleteOnFree)
      Assigns whether an attempt to delete the backing file is made in response to invocation of free().
      Parameters:
      deleteOnFree - the new value to assign