Interface Clob
- 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 TypeMethodDescriptionvoid
free()
This method releases the resources that theClob
object holds.Retrieves theCLOB
value designated by thisClob
object as an ascii stream.Retrieves theCLOB
value designated by thisClob
object as ajava.io.Reader
object (or as a stream of characters).getCharacterStream
(long pos, long length) Returns aReader
object that contains a partialClob
value, 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 theCLOB
value designated by thisClob
object.long
length()
Retrieves the number of characters in theCLOB
value designated by thisClob
object.long
Retrieves the character position at which the specified substringsearchstr
appears in the SQLCLOB
value represented by thisClob
object.long
Retrieves the character position at which the specifiedClob
objectsearchstr
appears in thisClob
object.setAsciiStream
(long pos) Retrieves a stream to be used to write Ascii characters to theCLOB
value that thisClob
object represents, starting at positionpos
.setCharacterStream
(long pos) Retrieves a stream to be used to write a stream of Unicode characters to theCLOB
value that thisClob
object represents, at positionpos
.int
Writes the given JavaString
to theCLOB
value that thisClob
object designates at the positionpos
.int
Writeslen
characters ofstr
, starting at characteroffset
, to theCLOB
value that thisClob
represents.void
truncate
(long len) Truncates theCLOB
value that thisClob
designates to have a length oflen
characters.
-
Method Details
-
length
Retrieves the number of characters in theCLOB
value designated by thisClob
object.- Returns:
- length of the
CLOB
in characters - Throws:
SQLException
- if there is an error accessing the length of theCLOB
valueSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
-
getSubString
Retrieves a copy of the specified substring in theCLOB
value designated by thisClob
object. The substring begins at positionpos
and has up tolength
consecutive 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
String
that is the specified substring in theCLOB
value designated by thisClob
object - Throws:
SQLException
- if there is an error accessing theCLOB
value; 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 theCLOB
value designated by thisClob
object as ajava.io.Reader
object (or as a stream of characters).- Returns:
- a
java.io.Reader
object containing theCLOB
data - Throws:
SQLException
- if there is an error accessing theCLOB
valueSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
-
getAsciiStream
Retrieves theCLOB
value designated by thisClob
object as an ascii stream.- Returns:
- a
java.io.InputStream
object containing theCLOB
data - Throws:
SQLException
- if there is an error accessing theCLOB
valueSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
-
position
Retrieves the character position at which the specified substringsearchstr
appears in the SQLCLOB
value represented by thisClob
object. 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 theCLOB
value 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 specifiedClob
objectsearchstr
appears in thisClob
object. The search begins at positionstart
.- Parameters:
searchstr
- theClob
object for which to searchstart
- the position at which to begin searching; the first position is 1- Returns:
- the position at which the
Clob
object appears or -1 if it is not present; the first position is 1 - Throws:
SQLException
- if there is an error accessing theCLOB
value or if start is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
-
setString
Writes the given JavaString
to theCLOB
value that thisClob
object designates at the positionpos
. The string will overwrite the existing characters in theClob
object starting at the positionpos
. If the end of theClob
value is reached while writing the given string, then the length of theClob
value will be increased to accommodate the extra characters.Note: If the value specified for
pos
is greater than the length+1 of theCLOB
value then the behavior is undefined. Some JDBC drivers may throw anSQLException
while other drivers may support this operation.- Parameters:
pos
- the position at which to start writing to theCLOB
value that thisClob
object represents; the first position is 1.str
- the string to be written to theCLOB
value that thisClob
designates- Returns:
- the number of characters written
- Throws:
SQLException
- if there is an error accessing theCLOB
value or if pos is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.4
-
setString
Writeslen
characters ofstr
, starting at characteroffset
, to theCLOB
value that thisClob
represents. The string will overwrite the existing characters in theClob
object starting at the positionpos
. If the end of theClob
value is reached while writing the given string, then the length of theClob
value will be increased to accommodate the extra characters.Note: If the value specified for
pos
is greater than the length+1 of theCLOB
value then the behavior is undefined. Some JDBC drivers may throw anSQLException
while other drivers may support this operation.- Parameters:
pos
- the position at which to start writing to thisCLOB
object; The first position is 1str
- the string to be written to theCLOB
value that thisClob
object representsoffset
- the offset intostr
to 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 theCLOB
value 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 theCLOB
value that thisClob
object represents, starting at positionpos
. Characters written to the stream will overwrite the existing characters in theClob
object starting at the positionpos
. If the end of theClob
value is reached while writing characters to the stream, then the length of theClob
value will be increased to accommodate the extra characters.Note: If the value specified for
pos
is greater than the length+1 of theCLOB
value then the behavior is undefined. Some JDBC drivers may throw anSQLException
while other drivers may support this operation.- Parameters:
pos
- the position at which to start writing to thisCLOB
object; The first position is 1- Returns:
- the stream to which ASCII encoded characters can be written
- Throws:
SQLException
- if there is an error accessing theCLOB
value 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 theCLOB
value that thisClob
object represents, at positionpos
. Characters written to the stream will overwrite the existing characters in theClob
object starting at the positionpos
. If the end of theClob
value is reached while writing characters to the stream, then the length of theClob
value will be increased to accommodate the extra characters.Note: If the value specified for
pos
is greater than the length+1 of theCLOB
value then the behavior is undefined. Some JDBC drivers may throw anSQLException
while other drivers may support this operation.- Parameters:
pos
- the position at which to start writing to theCLOB
value; The first position is 1- Returns:
- a stream to which Unicode encoded characters can be written
- Throws:
SQLException
- if there is an error accessing theCLOB
value or if pos is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.4
- See Also:
-
truncate
Truncates theCLOB
value that thisClob
designates to have a length oflen
characters.Note: If the value specified for
pos
is greater than the length+1 of theCLOB
value then the behavior is undefined. Some JDBC drivers may throw anSQLException
while other drivers may support this operation.- Parameters:
len
- the length, in characters, to which theCLOB
value should be truncated- Throws:
SQLException
- if there is an error accessing theCLOB
value 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 theClob
object holds. The object is invalid once thefree
method is called.After
free
has been called, any attempt to invoke a method other thanfree
will result in aSQLException
being thrown. Iffree
is called multiple times, the subsequent calls tofree
are 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 aReader
object that contains a partialClob
value, 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:
Reader
through which the partialClob
value 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 theClob
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.6
-