ca.idms.io
Class NativeDataInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          ca.idms.io.NativeDataInputStream

All Implemented Interfaces:

java.io.Closeable, java.io.DataInput

Direct Known Subclasses:

FloDataInputStream, LoDataInputStream, UnicodeDataInputStream, UtfDataInputStream

public class NativeDataInputStream
extends java.io.FilterInputStream
implements java.io.DataInput

A NativeDataInputStream reads "native" data from a buffered input stream. This class combines a DataInputStream, a NativeFormat, and a TraceBufferInputStream, and provides additional features to those defined by the DataInput interface:

The data conversion methods are optimized to take advantage of the direct access to the byte array buffer provided by the TraceBufferInputStream.

The methods provided by the TraceBufferInputStream to access the underlying byte array are exposed to the caller.

The native data conversion options specifed in the NativeFormat are encapsulated and transparent to the caller in most cases.

Additional methods are provided to read and convert data, including native character set data and OS/390 formats, including packed decimal, zoned decimal, and DBCS.

Unlike DataInputStream, the methods are not final, so this class can be a base class for specialized data input classes. The exceptions are the same as those defined by the DataInput interface and the DataInputStream class.

Since:

CA IDMS Server 4.2 OS/390 Edition

Version:

1.00, 12/14/99

Author:

Dave Ross

See Also:

TraceBufferInputStream, NativeFormat, LoDataInputStream, FloDataInputStream, UtfDataInputStream, UnicodeDataInputStream

Field Summary

protected java.io.DataInputStream	dis Contains the default methods.
protected NativeFormat	fmt Describes the native data formats.

Fields inherited from class java.io.FilterInputStream

in

Method Summary

byte[]	getBuffer() Gets a reference to the buffer.
int	getCount() Gets the number of valid bytes in the buffer.
NativeFormat	getFormat() Gets the data formats in effect for this stream.
int	getPosition() Gets the index of the next character to be read.
boolean	readBoolean() Reads a boolean from the data input stream.
byte	readByte() Reads a signed 8-bit value from the data input stream.
java.lang.String	readBytes(int len) Reads a string from a stream as an array of bytes.
java.lang.String	readBytesInternal(int len) Reads an internal control block string from a stream as an array of bytes.
java.lang.String	readBytesKatakana(int len) Reads a single byte Katakana string from a stream as an array of bytes.
char	readChar() Reads a Unicode character from the underlying input stream, by calling the DataInputStream readChar method.
double	readDouble() Reads a double from the data input stream.
float	readFloat() Reads a float from the data input stream.
void	readFully(byte[] b) Reads b.length bytes from the data input stream.
void	readFully(byte[] b, int off, int len) Reads exactly len bytes from the data input stream.
java.lang.String	readGraphic(int len) Reads OS/390 DBCS data into String.
int	readInt() Reads an int from the data input stream.
java.lang.String	readLine() Deprecated. But specified by the DataInput interface.
long	readLong() Reads a long from the data input stream.
java.math.BigDecimal	readPacked(int prec, int scale) Reads a native format PACKED DECIMAL into a BigDecimal.
short	readShort() Reads a short from the data input stream.
int	readUnsignedByte() Reads an unsigned 8-bit number from the underlying data input stream.
int	readUnsignedShort() Reads an unsigned short from the data input stream.
java.lang.String	readUTF() Reads a string that has been encoded using a modified UTF-8 format from the data input stream.
java.math.BigDecimal	readZoned(int prec, int scale) Reads a Native format ZONED DECIMAL into a BigDecimal.
void	setSize(int len) Sets the size of the buffer.
int	skipBytes(int n) Skips exactly n bytes of input in the data input stream.
void	snap() Displays the contents of this buffer if tracing is enabled.
protected java.math.BigDecimal	toBigDecimal(char[] c, int scale) Creates a BigDecimal object from a "numeric" character array.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

dis

protected java.io.DataInputStream dis

Contains the default methods.

fmt

protected NativeFormat fmt

Describes the native data formats.

Method Detail

setSize

public void setSize(int len)

Sets the size of the buffer. This method allows optimization of the buffer size. The previous contents of the buffer are released.

getFormat

public NativeFormat getFormat()

Gets the data formats in effect for this stream.

Returns:

the format specifier.

getBuffer

public byte[] getBuffer()

Gets a reference to the buffer. This method allows access to the buffer without copying large byte arrays any more than necessary. Note that subsequent reads from the underlying input stream can change the contents of the buffer.

Returns:

TraceBufferInputStream.buf.

getCount

public int getCount()

Gets the number of valid bytes in the buffer.

Returns:

TraceBufferInputStream.count.

getPosition

public int getPosition()

Gets the index of the next character to be read.

Returns:

TraceBufferInputStream.pos.

snap

public void snap()

Displays the contents of this buffer if tracing is enabled.

Enabled by TraceObject.trace and TraceObject.snapBytes.

See Also:

TraceObject

readFully

public void readFully(byte[] b)
               throws java.io.IOException

Reads b.length bytes from the data input stream.

Specified by:

readFully in interface java.io.DataInput

Parameters:

b - the buffer into which the data is read.

Throws:

java.io.IOException

readFully

public void readFully(byte[] b,
                      int off,
                      int len)
               throws java.io.IOException

Reads exactly len bytes from the data input stream.

Specified by:

readFully in interface java.io.DataInput

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the number of bytes to read.

Throws:

java.io.IOException

skipBytes

public int skipBytes(int n)
              throws java.io.IOException

Skips exactly n bytes of input in the data input stream.

Specified by:

skipBytes in interface java.io.DataInput

Parameters:

n - the number of bytes to be skipped.

Returns:

the number of bytes skipped, which is always n.

Throws:

java.io.IOException

readBoolean

public boolean readBoolean()
                    throws java.io.IOException

Reads a boolean from the data input stream. Reads a single byte, 1 is true, 0 is false.

Specified by:

readBoolean in interface java.io.DataInput

Returns:

the boolean value read.

Throws:

java.io.EOFException - if this input stream has reached the end.

java.io.IOException - if an I/O error occurs.

readByte

public byte readByte()
              throws java.io.IOException

Reads a signed 8-bit value from the data input stream.

Specified by:

readByte in interface java.io.DataInput

Returns:

the next byte of this input stream as a signed 8-bit byte

Throws:

java.io.IOException

readUnsignedByte

public int readUnsignedByte()
                     throws java.io.IOException

Reads an unsigned 8-bit number from the underlying data input stream.

Specified by:

readUnsignedByte in interface java.io.DataInput

Returns:

the next byte of this input stream, interpreted as an unsigned 8-bit number.

Throws:

java.io.IOException

readShort

public short readShort()
                throws java.io.IOException

Reads a short from the data input stream.

Specified by:

readShort in interface java.io.DataInput

Returns:

the next two bytes of this input stream, interpreted as a signed 16-bit number.

Throws:

java.io.EOFException - if this input stream reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readUnsignedShort

public int readUnsignedShort()
                      throws java.io.IOException

Reads an unsigned short from the data input stream.

Specified by:

readUnsignedShort in interface java.io.DataInput

Returns:

the next two bytes of this input stream, interpreted as an unsigned 16-bit number.

Throws:

java.io.EOFException - if this input stream reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readChar

public char readChar()
              throws java.io.IOException

Reads a Unicode character from the underlying input stream, by calling the DataInputStream readChar method.

Specified by:

readChar in interface java.io.DataInput

Returns:

the next two bytes of this input stream as a Unicode character.

Throws:

java.io.EOFException - if this input stream reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readInt

public int readInt()
            throws java.io.IOException

Reads an int from the data input stream.

Specified by:

readInt in interface java.io.DataInput

Returns:

the next four bytes of this input stream, interpreted as an int.

Throws:

java.io.EOFException - if this input stream reaches the end before reading four bytes.

java.io.IOException - if an I/O error occurs.

readLong

public long readLong()
              throws java.io.IOException

Reads a long from the data input stream.

Specified by:

readLong in interface java.io.DataInput

Returns:

the next eight bytes of this input stream, interpreted as a long

Throws:

java.io.EOFException - if this input stream reaches the end before java.io.reading eight bytes.

java.io.IOException - if an I/O error occurs.

readFloat

public float readFloat()
                throws java.io.IOException

Reads a float from the data input stream.

Specified by:

readFloat in interface java.io.DataInput

Returns:

the next four bytes of this input stream, interpreted as a float.

Throws:

java.io.IOException

See Also:

readInt()

readDouble

public double readDouble()
                  throws java.io.IOException

Reads a double from the data input stream.

Specified by:

readDouble in interface java.io.DataInput

Returns:

the next eight bytes of this input stream, interpreted as a double.

Throws:

java.io.IOException

See Also:

readLong()

readLine

public java.lang.String readLine()
                          throws java.io.IOException

Deprecated. But specified by the DataInput interface.

Reads the next line of text from the underlying data input stream using its readLine() method.

Specified by:

readLine in interface java.io.DataInput

Returns:

next line of text (in theory)

Throws:

java.io.IOException - always, don't call it

readUTF

public java.lang.String readUTF()
                         throws java.io.IOException

Reads a string that has been encoded using a modified UTF-8 format from the data input stream.

Specified by:

readUTF in interface java.io.DataInput

Returns:

a Unicode string.

Throws:

java.io.IOException

readBytes

public java.lang.String readBytes(int len)
                           throws java.io.UnsupportedEncodingException,
                                  java.io.IOException

Reads a string from a stream as an array of bytes. An array of bytes is read from the input stream and converted to a String according to the encoding.

Parameters:

len - number of bytes to read from stream

Returns:

a String

Throws:

java.io.UnsupportedEncodingException - if the character set encoding is not supported

java.io.IOException - if an IO error occurs

See Also:

NativeDataOutputStream.writeBytes(String, int)

readBytesKatakana

public java.lang.String readBytesKatakana(int len)
                                   throws java.io.UnsupportedEncodingException,
                                          java.io.IOException

Reads a single byte Katakana string from a stream as an array of bytes. All lower case Latin characters in the array of bytes are first converted to upper case, then read from the input stream and converted to a String according to the encoding (which normally is Cp930).

Parameters:

len - number of bytes to read from stream

Returns:

a String

Throws:

java.io.UnsupportedEncodingException - if the character set encoding is not supported

java.io.IOException - if an IO error occurs

readBytesInternal

public java.lang.String readBytesInternal(int len)
                                   throws java.io.UnsupportedEncodingException,
                                          java.io.IOException

Reads an internal control block string from a stream as an array of bytes. An array of bytes is read from the input stream and converted to a String according to the internal control block encoding. When the "network" encoding is being used (UTF8 or Unicode) the string is converted "normally", that is, by the derived class method.

Parameters:

len - number of bytes to read from stream

Returns:

a String

Throws:

java.io.UnsupportedEncodingException - if the character set encoding is not supported

java.io.IOException - if an IO error occurs

See Also:

NativeDataOutputStream.writeBytesInternal(String, int)

readPacked

public java.math.BigDecimal readPacked(int prec,
                                       int scale)
                                throws java.io.IOException

Reads a native format PACKED DECIMAL into a BigDecimal. This reads an array of bytes representing a DECIMAL value and converts it to a BigDecimal object.

Parameters:

prec - total number of digits

scale - number of digits after the decimal

Returns:

a BigDecimal containing the DECIMAL value.

Throws:

java.io.IOException - if any error

See Also:

toBigDecimal(char[], int)

readZoned

public java.math.BigDecimal readZoned(int prec,
                                      int scale)
                               throws java.io.IOException

Reads a Native format ZONED DECIMAL into a BigDecimal. This reads a String representing a NUMERIC value and converts it to a BigDecimal object.

Parameters:

prec - total number of digits

scale - number of digits after the decimal

Returns:

a BigDecimal containing the NUMERIC value.

Throws:

java.io.IOException - if any error

See Also:

toBigDecimal(char[], int)

toBigDecimal

protected java.math.BigDecimal toBigDecimal(char[] c,
                                            int scale)
                                     throws DecimalFormatException

Creates a BigDecimal object from a "numeric" character array. This converts the internal representation of a numeric value used to read native packed and zone decimal data to a BigDecimal object. This representation consists of a character array with leading 0's to fill out the precision, the decimal point removed, and an explicit trailing sign (+/-).

Parameters:

c - an array of "numeric" characters.

scale - number of digits after the decimal.

Returns:

BigDecimal object.

Throws:

DecimalFormatException - if invalid

See Also:

readPacked(int, int), readZoned(int, int)

readGraphic

public java.lang.String readGraphic(int len)
                             throws java.io.IOException

Reads OS/390 DBCS data into String. This method reads OS/390 EBCDIC double byte characters from the input stream into a buffer prefixed with a "shift-out" character suffixed with a "shift-in" character, then converts the buffer to a String using the encoding in effect for this stream (which should be EBCDIC_DBCS).

Parameters:

len - the number of DBCS characters to read

Returns:

the converted string

Throws:

java.io.IOException - if an IO error occurs

See Also:

readBytes(int), UtfDataInputStream.readBytes(int), UnicodeDataInputStream.readBytes(int), NativeFormat.getString(byte[])