Class 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 1.56.2.6 2010-05-17 09:36:57 ickzon Exp $
    Author:
    Mike Hutchinson, jTDS project
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Support()  
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) static int calculateNamedPipeBufferSize​(int tdsVersion, int packetSize)
      Calculate the buffer size to use when buffering the InputStream for named pipes.
      (package private) static java.lang.Object castNumeric​(java.lang.Object orig, int sourceType, int targetType)  
      (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.
      static java.lang.Object convertLOB​(java.lang.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​(java.lang.StringBuilder buf, java.lang.Object value, boolean isUnicode, JtdsConnection connection)
      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.
      private static JtdsConnection getConnection​(java.lang.Object callerReference)
      Returns the connection for a given ResultSet, Statement or Connection object.
      (package private) static int getJdbcType​(java.lang.Class typeClass)
      Get the JDBC type constant which matches the supplied Class.
      (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, boolean autoCommit, boolean cursor)
      Generates a unique statement key for a given SQL statement.
      static boolean isWindowsOS()
      Checks the os.name system property to see if it starts with "windows".
      static java.lang.Throwable linkException​(java.lang.Exception exception, java.lang.Throwable cause)
      Link the original cause to an Exception.
      static java.sql.SQLException linkException​(java.sql.SQLException sqle, java.lang.Throwable cause)
      Link the original cause to an SQLException.
      static java.sql.SQLWarning linkException​(java.sql.SQLWarning sqle, java.lang.Throwable cause)
      Link the original cause to an SQLWarning.
      (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, JtdsConnection connection)
      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, 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
      • MIN_VALUE_LONG_BI

        private static final java.math.BigInteger MIN_VALUE_LONG_BI
      • MAX_VALUE_LONG_BI

        private static final java.math.BigInteger MAX_VALUE_LONG_BI
      • MIN_VALUE_LONG_BD

        private static final java.math.BigDecimal MIN_VALUE_LONG_BD
      • MAX_VALUE_LONG_BD

        private static final java.math.BigDecimal MAX_VALUE_LONG_BD
      • MAX_VALUE_28

        private static final java.math.BigInteger MAX_VALUE_28
      • MAX_VALUE_38

        private static final java.math.BigInteger MAX_VALUE_38
      • 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.
    • Constructor Detail

      • Support

        private Support()
    • Method Detail

      • 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.
      • castNumeric

        static java.lang.Object castNumeric​(java.lang.Object orig,
                                            int sourceType,
                                            int targetType)
      • 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.
      • getJdbcType

        static int getJdbcType​(java.lang.Class typeClass)
        Get the JDBC type constant which matches the supplied Class.
        Parameters:
        typeClass - the Class 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.StringBuilder buf,
                              java.lang.Object value,
                              boolean isUnicode,
                              JtdsConnection connection)
                       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 embedded.
        value - The data object.
        isUnicode - Set to true if Unicode strings should be used, else false.
        connection - The JtdsConnection object.
        Throws:
        java.sql.SQLException
      • getStatementKey

        static java.lang.String getStatementKey​(java.lang.String sql,
                                                ParamInfo[] params,
                                                int serverType,
                                                java.lang.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 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
        autoCommit - true if in auto commit mode
        cursor - true if this is a prepared cursor
        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,
                                                     JtdsConnection connection)
                                              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.
        connection - The current connection.
        Returns:
        The modified SQL statement.
        Throws:
        java.sql.SQLException
      • 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.SQLWarning linkException​(java.sql.SQLWarning sqle,
                                                        java.lang.Throwable cause)
        Link the original cause to an SQLWarning.

        This convenience method calls linkException(Exception, Throwable) and casts the result for cleaner code elsewhere.

        Parameters:
        sqle - The SQLWarning to enhance.
        cause - The Throwable to link.
        Returns:
        The original SQLWarning object.
      • linkException

        public static java.sql.SQLException linkException​(java.sql.SQLException sqle,
                                                          java.lang.Throwable cause)
        Link the original cause to an SQLException.

        This convenience method calls linkException(Exception, Throwable) and casts the result for cleaner code elsewhere.

        Parameters:
        sqle - The SQLException to enhance.
        cause - The Throwable to link.
        Returns:
        The original SQLException object.
      • linkException

        public static java.lang.Throwable linkException​(java.lang.Exception exception,
                                                        java.lang.Throwable cause)
        Link the original cause to an Exception.

        If running under JVM 1.4+ the Throwable.initCause(Throwable) method will be invoked to chain the exception, else the exception is logged via the Logger class. Modeled after the code written by Brian Heineman.

        Parameters:
        exception - The Exception to enhance.
        cause - The Throwable to link.
        Returns:
        The original Exception object.
      • 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.
      • convertLOB

        public static java.lang.Object convertLOB​(java.lang.Object value)
                                           throws java.sql.SQLException
        Converts a LOB to the equivalent Java type, i.e. Clob to String and Blob to byte[]. 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:
        java.sql.SQLException - if an error occurs while reading the LOB contents
      • convertLOBType

        public static int convertLOBType​(int type)
        Converts a LOB type constant to the equivalent Java type constant, i.e. Types.CLOB to Types.LONGVARCHAR and Types.BLOB to Types.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 - a Types 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
      • isWindowsOS

        public static boolean isWindowsOS()
        Checks the os.name system property to see if it starts with "windows".
        Returns:
        true if os.name starts with "windows", else false.
      • getConnection

        private static JtdsConnection 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
      • calculateNamedPipeBufferSize

        static int calculateNamedPipeBufferSize​(int tdsVersion,
                                                int packetSize)
        Calculate the buffer size to use when buffering the InputStream for named pipes.

        The buffer size is tied directly to the packet size because each request to the SmbNamedPipe will send a request for a particular size of packet. In other words, if you only request 1 byte, the SmbNamedPipe 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 connection
        packetSize - requested packet size for the connection
        Returns:
        minimum default packet size if packetSize == 0, else packetSize