- All Known Subinterfaces:
NClob
- All Known Implementing Classes:
SerialClob
CLOB type.
An SQL CLOB is a built-in type
that stores a Character Large Object as a column value in a row of
a database table.
By default drivers implement a Clob object using an SQL
locator(CLOB), which means that a Clob object
contains a logical pointer to the SQL CLOB data rather than
the data itself. A Clob object is valid for the duration
of the transaction in which it was created.
The Clob interface provides methods for getting the
length of an SQL CLOB (Character Large Object) value,
for materializing a CLOB value on the client, and for
searching for a substring or CLOB object within a
CLOB value.
Methods in the interfaces ResultSet,
CallableStatement, and PreparedStatement, such as
getClob and setClob allow a programmer to
access an SQL CLOB value. In addition, this interface
has methods for updating a CLOB value.
All methods on the Clob interface must be
fully implemented if the JDBC driver supports the data type.
- Since:
- 1.2
-
Method Summary
Modifier and TypeMethodDescriptionvoidfree()This method releases the resources that theClobobject holds.Retrieves theCLOBvalue designated by thisClobobject as an ascii stream.Retrieves theCLOBvalue designated by thisClobobject as ajava.io.Readerobject (or as a stream of characters).getCharacterStream(long pos, long length) Returns aReaderobject that contains a partialClobvalue, starting with the character specified by pos, which is length characters in length.getSubString(long pos, int length) Retrieves a copy of the specified substring in theCLOBvalue designated by thisClobobject.longlength()Retrieves the number of characters in theCLOBvalue designated by thisClobobject.longRetrieves the character position at which the specified substringsearchstrappears in the SQLCLOBvalue represented by thisClobobject.longRetrieves the character position at which the specifiedClobobjectsearchstrappears in thisClobobject.setAsciiStream(long pos) Retrieves a stream to be used to write Ascii characters to theCLOBvalue that thisClobobject represents, starting at positionpos.setCharacterStream(long pos) Retrieves a stream to be used to write a stream of Unicode characters to theCLOBvalue that thisClobobject represents, at positionpos.intWrites the given JavaStringto theCLOBvalue that thisClobobject designates at the positionpos.intWriteslencharacters ofstr, starting at characteroffset, to theCLOBvalue that thisClobrepresents.voidtruncate(long len) Truncates theCLOBvalue that thisClobdesignates to have a length oflencharacters.
-
Method Details
-
length
Retrieves the number of characters in theCLOBvalue designated by thisClobobject.- Returns:
- length of the
CLOBin characters - Throws:
SQLException- if there is an error accessing the length of theCLOBvalueSQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
-
getSubString
Retrieves a copy of the specified substring in theCLOBvalue designated by thisClobobject. The substring begins at positionposand has up tolengthconsecutive characters.- Parameters:
pos- the first character of the substring to be extracted. The first character is at position 1.length- the number of consecutive characters to be copied; the value for length must be 0 or greater- Returns:
- a
Stringthat is the specified substring in theCLOBvalue designated by thisClobobject - Throws:
SQLException- if there is an error accessing theCLOBvalue; if pos is less than 1 or length is less than 0SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
-
getCharacterStream
Retrieves theCLOBvalue designated by thisClobobject as ajava.io.Readerobject (or as a stream of characters).- Returns:
- a
java.io.Readerobject containing theCLOBdata - Throws:
SQLException- if there is an error accessing theCLOBvalueSQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
-
getAsciiStream
Retrieves theCLOBvalue designated by thisClobobject as an ascii stream.- Returns:
- a
java.io.InputStreamobject containing theCLOBdata - Throws:
SQLException- if there is an error accessing theCLOBvalueSQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
-
position
Retrieves the character position at which the specified substringsearchstrappears in the SQLCLOBvalue represented by thisClobobject. The search begins at positionstart.- Parameters:
searchstr- the substring for which to searchstart- the position at which to begin searching; the first position is 1- Returns:
- the position at which the substring appears or -1 if it is not present; the first position is 1
- Throws:
SQLException- if there is an error accessing theCLOBvalue or if pos is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
-
position
Retrieves the character position at which the specifiedClobobjectsearchstrappears in thisClobobject. The search begins at positionstart.- Parameters:
searchstr- theClobobject for which to searchstart- the position at which to begin searching; the first position is 1- Returns:
- the position at which the
Clobobject appears or -1 if it is not present; the first position is 1 - Throws:
SQLException- if there is an error accessing theCLOBvalue or if start is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.2
-
setString
Writes the given JavaStringto theCLOBvalue that thisClobobject designates at the positionpos. The string will overwrite the existing characters in theClobobject starting at the positionpos. If the end of theClobvalue is reached while writing the given string, then the length of theClobvalue will be increased to accommodate the extra characters.Note: If the value specified for
posis greater than the length+1 of theCLOBvalue then the behavior is undefined. Some JDBC drivers may throw anSQLExceptionwhile other drivers may support this operation.- Parameters:
pos- the position at which to start writing to theCLOBvalue that thisClobobject represents; the first position is 1.str- the string to be written to theCLOBvalue that thisClobdesignates- Returns:
- the number of characters written
- Throws:
SQLException- if there is an error accessing theCLOBvalue or if pos is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.4
-
setString
Writeslencharacters ofstr, starting at characteroffset, to theCLOBvalue that thisClobrepresents. The string will overwrite the existing characters in theClobobject starting at the positionpos. If the end of theClobvalue is reached while writing the given string, then the length of theClobvalue will be increased to accommodate the extra characters.Note: If the value specified for
posis greater than the length+1 of theCLOBvalue then the behavior is undefined. Some JDBC drivers may throw anSQLExceptionwhile other drivers may support this operation.- Parameters:
pos- the position at which to start writing to thisCLOBobject; The first position is 1str- the string to be written to theCLOBvalue that thisClobobject representsoffset- the offset intostrto start reading the characters to be writtenlen- the number of characters to be written- Returns:
- the number of characters written
- Throws:
SQLException- if there is an error accessing theCLOBvalue or if pos is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.4
-
setAsciiStream
Retrieves a stream to be used to write Ascii characters to theCLOBvalue that thisClobobject represents, starting at positionpos. Characters written to the stream will overwrite the existing characters in theClobobject starting at the positionpos. If the end of theClobvalue is reached while writing characters to the stream, then the length of theClobvalue will be increased to accommodate the extra characters.Note: If the value specified for
posis greater than the length+1 of theCLOBvalue then the behavior is undefined. Some JDBC drivers may throw anSQLExceptionwhile other drivers may support this operation.- Parameters:
pos- the position at which to start writing to thisCLOBobject; The first position is 1- Returns:
- the stream to which ASCII encoded characters can be written
- Throws:
SQLException- if there is an error accessing theCLOBvalue or if pos is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.4
- See Also:
-
setCharacterStream
Retrieves a stream to be used to write a stream of Unicode characters to theCLOBvalue that thisClobobject represents, at positionpos. Characters written to the stream will overwrite the existing characters in theClobobject starting at the positionpos. If the end of theClobvalue is reached while writing characters to the stream, then the length of theClobvalue will be increased to accommodate the extra characters.Note: If the value specified for
posis greater than the length+1 of theCLOBvalue then the behavior is undefined. Some JDBC drivers may throw anSQLExceptionwhile other drivers may support this operation.- Parameters:
pos- the position at which to start writing to theCLOBvalue; The first position is 1- Returns:
- a stream to which Unicode encoded characters can be written
- Throws:
SQLException- if there is an error accessing theCLOBvalue or if pos is less than 1SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.4
- See Also:
-
truncate
Truncates theCLOBvalue that thisClobdesignates to have a length oflencharacters.Note: If the value specified for
posis greater than the length+1 of theCLOBvalue then the behavior is undefined. Some JDBC drivers may throw anSQLExceptionwhile other drivers may support this operation.- Parameters:
len- the length, in characters, to which theCLOBvalue should be truncated- Throws:
SQLException- if there is an error accessing theCLOBvalue or if len is less than 0SQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.4
-
free
This method releases the resources that theClobobject holds. The object is invalid once thefreemethod is called.After
freehas been called, any attempt to invoke a method other thanfreewill result in aSQLExceptionbeing thrown. Iffreeis called multiple times, the subsequent calls tofreeare treated as a no-op.- Throws:
SQLException- if an error occurs releasing the Clob's resourcesSQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.6
-
getCharacterStream
Returns aReaderobject that contains a partialClobvalue, starting with the character specified by pos, which is length characters in length.- Parameters:
pos- the offset to the first character of the partial value to be retrieved. The first character in the Clob is at position 1.length- the length in characters of the partial value to be retrieved.- Returns:
Readerthrough which the partialClobvalue can be read.- Throws:
SQLException- if pos is less than 1; or if pos is greater than the number of characters in theClob; or if pos + length is greater than the number of characters in theClobSQLFeatureNotSupportedException- if the JDBC driver does not support this method- Since:
- 1.6
-