net.sourceforge.jtds.jdbc
Class Support

java.lang.Object
  |
  +--net.sourceforge.jtds.jdbc.Support

public class Support

extends java.lang.Object

This class contains static utility methods designed to support the main driver classes.

Implementation notes:

1. The methods in this class incorporate some code from previous versions of jTDS to handle dates, BLobs etc.
2. This class contains routines to generate runtime messages from the resource file.
3. The key data conversion logic used in Statements and result sets is implemented here.
4. There is nothing here which is TDS specific.

Version:

$Id: Support.java,v 1.39 2005/04/07 20:46:00 alin_sinpalean Exp $

Author:

Mike Hutchinson, jTDS project

Field Summary

private static java.math.BigDecimal	BIG_DECIMAL_ONE
private static java.math.BigDecimal	BIG_DECIMAL_ZERO
private static java.util.GregorianCalendar	cal Static utility Calendar object.
private static java.sql.Date	DATE_ZERO
private static java.lang.Double	DOUBLE_ONE
private static java.lang.Double	DOUBLE_ZERO
private static java.lang.Float	FLOAT_ONE
private static java.lang.Float	FLOAT_ZERO
private static char[]	hex Hex constants to use in conversion routines.
private static java.lang.Integer	INTEGER_ONE
private static java.lang.Integer	INTEGER_ZERO
private static java.lang.Long	LONG_ONE
private static java.lang.Long	LONG_ZERO
private static java.math.BigInteger	maxValue28
private static java.math.BigInteger	maxValue38
private static java.sql.Time	TIME_ZERO
private static java.util.HashMap	typeMap Convert java clases to java.sql.Type constant.

Constructor Summary

private

Support()

Method Summary

(package private) static void	()
private static java.lang.String	bigDecimalToString(java.math.BigDecimal x) Convert a BigDecimal value to String, stripping any trailing zeroes.
(package private) static java.lang.Object	convert(java.lang.Object callerReference, java.lang.Object x, int jdbcType, java.lang.String charSet) Convert an existing data object to the specified JDBC type.
(package private) static void	embedData(java.lang.StringBuffer buf, java.lang.Object value, boolean isUnicode, int tdsVersion) Embed the data object as a string literal in the buffer supplied.
(package private) static byte[]	encodeString(java.lang.String cs, java.lang.String value) Encode a string into a byte array using the specified character set.
(package private) static java.lang.String	getClassName(int jdbcType) Retrieve the fully qualified java class name for the supplied JDBC Types constant.
static ConnectionJDBC2	getConnection(java.lang.Object callerReference) Returns the connection for a given ResultSet, Statement or Connection object.
(package private) static int	getJdbcType(java.lang.Object value) Get the JDBC type constant which matches the supplied Object type.
(package private) static java.lang.String	getJdbcTypeName(int jdbcType) Get a String describing the supplied JDBC type constant.
(package private) static java.lang.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 java.lang.String	getStatementKey(java.lang.String sql, ParamInfo[] params, int serverType, java.lang.String catalog) Generates a unique statement key for a given SQL statement.
static java.sql.SQLException	linkException(java.sql.SQLException sqle, java.lang.Throwable cause) Link an the original cause exception to a SQL Exception.
(package private) static java.math.BigDecimal	normalizeBigDecimal(java.math.BigDecimal value, int maxPrecision) Normalize a BigDecimal value so that it fits within the available precision.
(package private) static java.lang.String	substituteParameters(java.lang.String sql, ParamInfo[] list, int tdsVersion) Substitute actual data for the parameter markers to simulate parameter substitution in a PreparedStatement.
(package private) static java.lang.String	substituteParamMarkers(java.lang.String sql, ParamInfo[] list) Update the SQL string and replace the ? markers with parameter names eg @P0, @P1 etc.
static long	timeFromZone(java.util.Date value, java.util.Calendar target) Convert a timestamp from a different Timezone.
static long	timeToZone(java.util.Date value, java.util.Calendar target) Convert a timestamp to a different Timezone.
static java.lang.String	toHex(byte[] bytes) Convert a byte[] object to a hex string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait

Field Detail

INTEGER_ZERO

private static final java.lang.Integer INTEGER_ZERO

INTEGER_ONE

private static final java.lang.Integer INTEGER_ONE

LONG_ZERO

private static final java.lang.Long LONG_ZERO

LONG_ONE

private static final java.lang.Long LONG_ONE

FLOAT_ZERO

private static final java.lang.Float FLOAT_ZERO

FLOAT_ONE

private static final java.lang.Float FLOAT_ONE

DOUBLE_ZERO

private static final java.lang.Double DOUBLE_ZERO

DOUBLE_ONE

private static final java.lang.Double DOUBLE_ONE

BIG_DECIMAL_ZERO

private static final java.math.BigDecimal BIG_DECIMAL_ZERO

BIG_DECIMAL_ONE

private static final java.math.BigDecimal BIG_DECIMAL_ONE

DATE_ZERO

private static final java.sql.Date DATE_ZERO

TIME_ZERO

private static final java.sql.Time TIME_ZERO

maxValue28

private static final java.math.BigInteger maxValue28

maxValue38

private static final java.math.BigInteger maxValue38

typeMap

private static final java.util.HashMap typeMap

Convert java clases to java.sql.Type constant.

hex

private static final char[] hex

Hex constants to use in conversion routines.

cal

private static final java.util.GregorianCalendar cal

Static utility Calendar object.

Constructor Detail

Support

private Support()

Method Detail

static void ()

toHex

public static java.lang.String toHex(byte[] bytes)

Convert a byte[] object to a hex string.

Parameters:

bytes - The byte array to convert.

Returns:

The hex equivalent as a String.

normalizeBigDecimal

static java.math.BigDecimal normalizeBigDecimal(java.math.BigDecimal value,
                                                int maxPrecision)
                                         throws java.sql.SQLException

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:

java.sql.SQLException - If the number is too big.

bigDecimalToString

private static java.lang.String bigDecimalToString(java.math.BigDecimal x)

Convert a BigDecimal value to String, stripping any trailing zeroes.

Parameters:

x - the BigDecimal value to convert

Returns:

the value converted to String

convert

static java.lang.Object convert(java.lang.Object callerReference,
                                java.lang.Object x,
                                int jdbcType,
                                java.lang.String charSet)
                         throws java.sql.SQLException

Convert an existing data object to the specified JDBC type.

Parameters:

callerReference - an object reference to the caller of this method; must be a Connection, Statement or ResultSet

x - the data object to convert

jdbcType - the required type constant from java.sql.Types

Returns:

the converted data object

Throws:

java.sql.SQLException - if the conversion is not supported or fails

getJdbcType

static int getJdbcType(java.lang.Object value)

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.

getJdbcTypeName

static java.lang.String getJdbcTypeName(int jdbcType)

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.

getClassName

static java.lang.String getClassName(int jdbcType)

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.

embedData

static void embedData(java.lang.StringBuffer buf,
                      java.lang.Object value,
                      boolean isUnicode,
                      int tdsVersion)
               throws java.sql.SQLException

Embed the data object as a string literal in the buffer supplied.

Parameters:

buf - The buffer in which the data will be embeded.

value - The data object.

getStatementKey

static java.lang.String getStatementKey(java.lang.String sql,
                                        ParamInfo[] params,
                                        int serverType,
                                        java.lang.String catalog)

Generates a unique statement key for a given SQL statement.

Parameters:

sql - the sql statment to generate the key for

params - the statement parameters

serverType - the type of server to generate the key for

catalog - the catalog is required for uniqueness on Microsoft SQL Server

Returns:

the unique statement key

getParameterDefinitions

static java.lang.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.

Parameters:

parameters - Parameters to construct the definition for

Returns:

a parameter definition string

substituteParamMarkers

static java.lang.String substituteParamMarkers(java.lang.String sql,
                                               ParamInfo[] list)

Update the SQL string and replace the ? markers with parameter names eg @P0, @P1 etc.

Parameters:

sql - the SQL containing markers to substitute

list - the parameter list

Returns:

the modified SQL as a String

substituteParameters

static java.lang.String substituteParameters(java.lang.String sql,
                                             ParamInfo[] list,
                                             int tdsVersion)
                                      throws java.sql.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.

Returns:

The modified SQL statement.

encodeString

static byte[] encodeString(java.lang.String cs,
                           java.lang.String value)

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[].

linkException

public static java.sql.SQLException linkException(java.sql.SQLException sqle,
                                                  java.lang.Throwable cause)

Link an the original cause exception to a SQL Exception.

If running under VM 1.4+ the Exception.initCause() method will be used to chain the exception. Modeled after the code written by Brian Heineman.

Parameters:

sqle - The SQLException to enhance.

cause - The child exception to link.

Returns:

The enhanced SQLException.

timeToZone

public static long timeToZone(java.util.Date value,
                              java.util.Calendar target)

Convert a timestamp to a different Timezone.

Parameters:

value - the timestamp value

target - the Calendar containing the TimeZone

Returns:

the new timestamp value as a long

timeFromZone

public static long timeFromZone(java.util.Date value,
                                java.util.Calendar target)

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.

getConnection

public static ConnectionJDBC2 getConnection(java.lang.Object callerReference)

Returns the connection for a given ResultSet, Statement or Connection object.

Parameters:

callerReference - an object reference to the caller of this method; must be a Connection, Statement or ResultSet

Returns:

a connection