Package net.sourceforge.jtds.jdbc
Class Support
java.lang.Object
net.sourceforge.jtds.jdbc.Support
This class contains static utility methods designed to support the
main driver classes.
Implementation notes:
- The methods in this class incorporate some code from previous versions of jTDS to handle dates, BLobs etc.
- This class contains routines to generate runtime messages from the resource file.
- The key data conversion logic used in Statements and result sets is implemented here.
- There is nothing here which is TDS specific.
- Version:
- $Id: Support.java,v 1.56.2.6 2010-05-17 09:36:57 ickzon Exp $
- Author:
- Mike Hutchinson, jTDS project
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final BigDecimal
private static final BigDecimal
private static final Date
private static final Double
private static final Double
private static final Float
private static final Float
private static final char[]
Hex constants to use in conversion routines.private static final Integer
private static final Integer
private static final Long
private static final Long
private static final BigInteger
private static final BigInteger
private static final BigDecimal
private static final BigInteger
private static final BigDecimal
private static final BigInteger
private static final Time
private static final HashMap
Convert java clases to java.sql.Type constant. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescription(package private) static int
calculateNamedPipeBufferSize
(int tdsVersion, int packetSize) Calculate the buffer size to use when buffering theInputStream
for named pipes.(package private) static Object
castNumeric
(Object orig, int sourceType, int targetType) (package private) static Object
Convert an existing data object to the specified JDBC type.static Object
convertLOB
(Object value) Converts a LOB to the equivalent Java type, i.e.static int
convertLOBType
(int type) Converts a LOB type constant to the equivalent Java type constant, i.e.(package private) static void
embedData
(StringBuilder buf, Object value, boolean isUnicode, JtdsConnection connection) Embed the data object as a string literal in the buffer supplied.(package private) static byte[]
encodeString
(String cs, String value) Encode a string into a byte array using the specified character set.(package private) static String
getClassName
(int jdbcType) Retrieve the fully qualified java class name for the supplied JDBC Types constant.private static JtdsConnection
getConnection
(Object callerReference) Returns the connection for a givenResultSet
,Statement
orConnection
object.(package private) static int
getJdbcType
(Class typeClass) Get the JDBC type constant which matches the suppliedClass
.(package private) static int
getJdbcType
(Object value) Get the JDBC type constant which matches the supplied Object type.(package private) static String
getJdbcTypeName
(int jdbcType) Get a String describing the supplied JDBC type constant.(package private) static String
getParameterDefinitions
(ParamInfo[] parameters) Constructs a parameter definition string for use with sp_executesql, sp_prepare, sp_prepexec, sp_cursoropen, sp_cursorprepare and sp_cursorprepexec.(package private) static String
getStatementKey
(String sql, ParamInfo[] params, int serverType, String catalog, boolean autoCommit, boolean cursor) Generates a unique statement key for a given SQL statement.static boolean
Checks theos.name
system property to see if it starts with "windows".static Throwable
linkException
(Exception exception, Throwable cause) Link the original cause to anException
.static SQLException
linkException
(SQLException sqle, Throwable cause) Link the original cause to anSQLException
.static SQLWarning
linkException
(SQLWarning sqle, Throwable cause) Link the original cause to anSQLWarning
.(package private) static BigDecimal
normalizeBigDecimal
(BigDecimal value, int maxPrecision) Normalize a BigDecimal value so that it fits within the available precision.(package private) static String
substituteParameters
(String sql, ParamInfo[] list, JtdsConnection connection) Substitute actual data for the parameter markers to simulate parameter substitution in a PreparedStatement.(package private) static String
substituteParamMarkers
(String sql, ParamInfo[] list) Update the SQL string and replace the ? markers with parameter names eg @P0, @P1 etc.static long
timeFromZone
(Date value, Calendar target) Convert a timestamp from a different Timezone.static long
timeToZone
(Date value, Calendar target) Convert a timestamp to a different Timezone.static String
toHex
(byte[] bytes) Convert a byte[] object to a hex string.
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Field Details
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INTEGER_ZERO
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INTEGER_ONE
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LONG_ZERO
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LONG_ONE
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FLOAT_ZERO
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FLOAT_ONE
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DOUBLE_ZERO
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DOUBLE_ONE
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BIG_DECIMAL_ZERO
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BIG_DECIMAL_ONE
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DATE_ZERO
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TIME_ZERO
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MIN_VALUE_LONG_BI
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MAX_VALUE_LONG_BI
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MIN_VALUE_LONG_BD
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MAX_VALUE_LONG_BD
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MAX_VALUE_28
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MAX_VALUE_38
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typeMap
Convert java clases to java.sql.Type constant. -
hex
private static final char[] hexHex constants to use in conversion routines.
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Constructor Details
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Support
private Support()
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Method Details
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toHex
Convert a byte[] object to a hex string.- Parameters:
bytes
- The byte array to convert.- Returns:
- The hex equivalent as a
String
.
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normalizeBigDecimal
Normalize a BigDecimal value so that it fits within the available precision.- Parameters:
value
- The decimal value to normalize.maxPrecision
- The decimal precision supported by the server (assumed to be a value of either 28 or 38).- Returns:
- The possibly normalized decimal value as a
BigDecimal
. - Throws:
SQLException
- If the number is too big.
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castNumeric
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convert
static Object convert(Object callerReference, Object x, int jdbcType, String charSet) throws SQLException Convert an existing data object to the specified JDBC type.- Parameters:
callerReference
- an object reference to the caller of this method; must be aConnection
,Statement
orResultSet
x
- the data object to convertjdbcType
- the required type constant fromjava.sql.Types
- Returns:
- the converted data object
- Throws:
SQLException
- if the conversion is not supported or fails
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getJdbcType
Get the JDBC type constant which matches the supplied Object type.- Parameters:
value
- The object to analyse.- Returns:
- The JDBC type constant as an
int
.
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getJdbcType
Get the JDBC type constant which matches the suppliedClass
.- Parameters:
typeClass
- theClass
to analyse- Returns:
- the JDBC type constant as an
int
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getJdbcTypeName
Get a String describing the supplied JDBC type constant.- Parameters:
jdbcType
- The constant to be decoded.- Returns:
- The text decode of the type constant as a
String
.
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getClassName
Retrieve the fully qualified java class name for the supplied JDBC Types constant.- Parameters:
jdbcType
- The JDBC Types constant.- Returns:
- The fully qualified java class name as a
String
.
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embedData
static void embedData(StringBuilder buf, Object value, boolean isUnicode, JtdsConnection connection) throws SQLException Embed the data object as a string literal in the buffer supplied.- Parameters:
buf
- The buffer in which the data will be embedded.value
- The data object.isUnicode
- Set totrue
if Unicode strings should be used, elsefalse
.connection
- TheJtdsConnection
object.- Throws:
SQLException
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getStatementKey
static String getStatementKey(String sql, ParamInfo[] params, int serverType, String catalog, boolean autoCommit, boolean cursor) Generates a unique statement key for a given SQL statement.- Parameters:
sql
- the sql statement to generate the key forparams
- the statement parametersserverType
- the type of server to generate the key forcatalog
- the catalog is required for uniqueness on Microsoft SQL ServerautoCommit
- true if in auto commit modecursor
- true if this is a prepared cursor- Returns:
- the unique statement key
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getParameterDefinitions
Constructs a parameter definition string for use with sp_executesql, sp_prepare, sp_prepexec, sp_cursoropen, sp_cursorprepare and sp_cursorprepexec.- Parameters:
parameters
- Parameters to construct the definition for- Returns:
- a parameter definition string
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substituteParamMarkers
Update the SQL string and replace the ? markers with parameter names eg @P0, @P1 etc.- Parameters:
sql
- the SQL containing markers to substitutelist
- the parameter list- Returns:
- the modified SQL as a
String
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substituteParameters
static String substituteParameters(String sql, ParamInfo[] list, JtdsConnection connection) throws SQLException Substitute actual data for the parameter markers to simulate parameter substitution in a PreparedStatement.- Parameters:
sql
- The SQL containing parameter markers to substitute.list
- The parameter descriptors.connection
- The current connection.- Returns:
- The modified SQL statement.
- Throws:
SQLException
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encodeString
Encode a string into a byte array using the specified character set.- Parameters:
cs
- The Charset name.value
- The value to encode.- Returns:
- The value of the String as a
byte[]
.
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linkException
Link the original cause to anSQLWarning
.This convenience method calls
linkException(Exception, Throwable)
and casts the result for cleaner code elsewhere.- Parameters:
sqle
- TheSQLWarning
to enhance.cause
- TheThrowable
to link.- Returns:
- The original
SQLWarning
object.
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linkException
Link the original cause to anSQLException
.This convenience method calls
linkException(Exception, Throwable)
and casts the result for cleaner code elsewhere.- Parameters:
sqle
- TheSQLException
to enhance.cause
- TheThrowable
to link.- Returns:
- The original
SQLException
object.
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linkException
Link the original cause to anException
.If running under JVM 1.4+ the
Throwable.initCause(Throwable)
method will be invoked to chain the exception, else the exception is logged via theLogger
class. Modeled after the code written by Brian Heineman.- Parameters:
exception
- TheException
to enhance.cause
- TheThrowable
to link.- Returns:
- The original
Exception
object.
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timeToZone
Convert a timestamp to a different Timezone.- Parameters:
value
- the timestamp valuetarget
- theCalendar
containing the TimeZone- Returns:
- the new timestamp value as a
long
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timeFromZone
Convert a timestamp from a different Timezone.- Parameters:
value
- the timestamp value.target
- the Calendar containing the TimeZone.- Returns:
- The new timestamp value as a
long
.
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convertLOB
Converts a LOB to the equivalent Java type, i.e.Clob
toString
andBlob
tobyte[]
. If the value passed is not a LOB object, it is left unchanged and no exception is thrown; the idea is to transparently convert only LOBs.- Parameters:
value
- an object that may be a LOB- Returns:
- if the value was a LOB, the equivalent Java object, otherwise the original value
- Throws:
SQLException
- if an error occurs while reading the LOB contents
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convertLOBType
public static int convertLOBType(int type) Converts a LOB type constant to the equivalent Java type constant, i.e.Types.CLOB
toTypes.LONGVARCHAR
andTypes.BLOB
toTypes.LONGVARBINARY
. If the type passed is not that of a LOB, it is left unchanged and no exception is thrown; the idea is to transparently convert only LOB types.- Parameters:
type
- aTypes
constant defining a JDBC type, possibly a LOB- Returns:
- if the type was that of a LOB, the equivalent Java object type, otherwise the original type
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isWindowsOS
public static boolean isWindowsOS()Checks theos.name
system property to see if it starts with "windows".- Returns:
true
ifos.name
starts with "windows", elsefalse
.
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getConnection
Returns the connection for a givenResultSet
,Statement
orConnection
object.- Parameters:
callerReference
- an object reference to the caller of this method; must be aConnection
,Statement
orResultSet
- Returns:
- a connection
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calculateNamedPipeBufferSize
static int calculateNamedPipeBufferSize(int tdsVersion, int packetSize) Calculate the buffer size to use when buffering theInputStream
for named pipes. The buffer size is tied directly to the packet size because each request to theSmbNamedPipe
will send a request for a particular size of packet. In other words, if you only request 1 byte, theSmbNamedPipe
will send a request out and only ask for 1 byte back. Buffering the expected packet size ensures that all of the data will be returned in the buffer without wasting any space.- Parameters:
tdsVersion
- the TDS version for the connectionpacketSize
- requested packet size for the connection- Returns:
- minimum default packet size if
packetSize == 0
, elsepacketSize
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