ewe.io
Class DataInputStream

java.lang.Object
  ewe.io.InputStream
      ewe.io.FilterInputStream
          ewe.io.DataInputStream

All Implemented Interfaces:

DataInput, Streamable

public class DataInputStream

extends FilterInputStream

implements DataInput

Field Summary

protected byte[]	buffer
boolean	closeUnderlying Set this to false if you don't want a close of this DataInputStream to close the underlying Stream.
protected Lock	lock

Fields inherited from class ewe.io.InputStream

atEOF, closed, in, rs, stream

Constructor Summary

DataInputStream(InputStream s)

DataInputStream(Stream s)

Method Summary

void	close()
int	read() Reads the next byte of data from this input stream.
int	read(byte[] bytes) Read in a number of bytes of data from the input stream equal to the length of the provided buffer.
int	read(byte[] bytes, int offset, int length) Read in a number of bytes of data from the input stream.
protected void	readAll(byte[] bytes, int offset, int length)
protected long	readALong()
protected int	readAnInt(int numBytes)
boolean	readBoolean() This method reads a Java boolean value from an input stream.
byte	readByte() This method reads a Java byte value from an input stream.
char	readChar() This method reads a Java char value from an input stream.
double	readDouble() This method reads a Java double value from an input stream.
float	readFloat() This method reads a Java float value from an input stream.
void	readFully(byte[] data) This method reads raw bytes into the passed array until the array is full.
void	readFully(byte[] data, int offset, int length) This method reads raw bytes into the passed array buf starting offset bytes into the buffer.
int	readInt() This method reads a Java int value from an input stream It operates by reading four bytes from the stream and converting them to a single Java int.
long	readLong() This method reads a Java long value from an input stream It operates by reading eight bytes from the stream and converting them to a single Java long.
short	readShort() This method reads a signed 16-bit value into a Java in from the stream.
int	readUnsignedByte() This method reads 8 unsigned bits into a Java int value from the stream.
int	readUnsignedShort() This method reads 16 unsigned bits into a Java int value from the stream.
String	readUTF() This method reads a String from an input stream that is encoded in a modified UTF-8 format.
int	skipBytes(int length) This method skips and discards the specified number of bytes in an input stream.

Methods inherited from class ewe.io.InputStream

available, getFastStream, getName, mark, markSupported, readSingleByteFromMultiByteRead, reset, shutdown, skip, toReadableStream, toStream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, toString

Field Detail

closeUnderlying

public boolean closeUnderlying

Set this to false if you don't want a close of this DataInputStream to close the underlying Stream.

buffer

protected byte[] buffer

lock

protected Lock lock

Constructor Detail

DataInputStream

public DataInputStream(Stream s)

DataInputStream

public DataInputStream(InputStream s)

Method Detail

read

public int read(byte[] bytes,
                int offset,
                int length)
         throws IOException

Description copied from class: InputStream

Read in a number of bytes of data from the input stream.

Overrides:

read in class InputStream

Parameters:

bytes - a destination buffer for the data.

offset - The start offset in the destination buffer.

length - The number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs during reading.

read

public int read()
         throws IOException

Description copied from class: InputStream

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Overrides:

read in class InputStream

Returns:

the byte read or -1 on end of stream.

Throws:

IOException - if an I/O error occured.

read

public int read(byte[] bytes)
         throws IOException

Description copied from class: InputStream

Read in a number of bytes of data from the input stream equal to the length of the provided buffer. Additional verbose

Overrides:

read in class InputStream

Parameters:

bytes - a destination buffer for the data.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs during reading.

readAll

protected void readAll(byte[] bytes,
                       int offset,
                       int length)
                throws IOException,
                       EOFException

Throws:

IOException

EOFException

readAnInt

protected int readAnInt(int numBytes)
                 throws IOException

Throws:

IOException

readALong

protected long readALong()
                  throws IOException

Throws:

IOException

readByte

public byte readByte()
              throws IOException

Description copied from interface: DataInput

This method reads a Java byte value from an input stream. The value is in the range of -128 to 127.

This method can read a byte written by an object implementing the writeByte() method in the DataOutput interface.

Specified by:

readByte in interface DataInput

Returns:

The byte value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeByte(int)

readShort

public short readShort()
                throws IOException

Description copied from interface: DataInput

This method reads a signed 16-bit value into a Java in from the stream. It operates by reading two bytes from the stream and converting them to a single 16-bit Java short. The two bytes are stored most significant byte first (i.e., "big endian") regardless of the native host byte ordering.

As an example, if byte1 and byte2 represent the first and second byte read from the stream respectively, they will be transformed to a short in the following manner:

(short)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))

The value returned is in the range of -32768 to 32767.

This method can read a short written by an object implementing the writeShort() method in the DataOutput interface.

Specified by:

readShort in interface DataInput

Returns:

The short value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeShort(int)

readChar

public char readChar()
              throws IOException

Description copied from interface: DataInput

This method reads a Java char value from an input stream. It operates by reading two bytes from the stream and converting them to a single 16-bit Java char. The two bytes are stored most significant byte first (i.e., "big endian") regardless of the native host byte ordering.

As an example, if byte1 and byte2 represent the first and second byte read from the stream respectively, they will be transformed to a char in the following manner:

(char)((byte1 << 8) + byte2)

This method can read a char written by an object implementing the writeChar() method in the DataOutput interface.

Specified by:

readChar in interface DataInput

Returns:

The char value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeChar(int)

readInt

public int readInt()
            throws IOException

Description copied from interface: DataInput

This method reads a Java int value from an input stream It operates by reading four bytes from the stream and converting them to a single Java int. The bytes are stored most significant byte first (i.e., "big endian") regardless of the native host byte ordering.

As an example, if byte1 through byte4 represent the first four bytes read from the stream, they will be transformed to an int in the following manner:

(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + ((byte3 & 0xFF)<< 8) + (byte4 & 0xFF)))

The value returned is in the range of -2147483648 to 2147483647.

This method can read an int written by an object implementing the writeInt() method in the DataOutput interface.

Specified by:

readInt in interface DataInput

Returns:

The int value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeInt(int)

readLong

public long readLong()
              throws IOException

Description copied from interface: DataInput

This method reads a Java long value from an input stream It operates by reading eight bytes from the stream and converting them to a single Java long. The bytes are stored most significant byte first (i.e., "big endian") regardless of the native host byte ordering.

As an example, if byte1 through byte8 represent the first eight bytes read from the stream, they will be transformed to an long in the following manner:

(long)(((byte1 & 0xFF) << 56) + ((byte2 & 0xFF) << 48) + ((byte3 & 0xFF) << 40) + ((byte4 & 0xFF) << 32) + ((byte5 & 0xFF) << 24) + ((byte6 & 0xFF) << 16) + ((byte7 & 0xFF) << 8) + (byte8 & 0xFF)))

The value returned is in the range of -9223372036854775808 to 9223372036854775807.

This method can read an long written by an object implementing the writeLong() method in the DataOutput interface.

Specified by:

readLong in interface DataInput

Returns:

The long value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeLong(long)

readUnsignedByte

public int readUnsignedByte()
                     throws IOException

Description copied from interface: DataInput

This method reads 8 unsigned bits into a Java int value from the stream. The value returned is in the range of 0 to 255.

This method can read an unsigned byte written by an object implementing the writeByte() method in the DataOutput interface.

Specified by:

readUnsignedByte in interface DataInput

Returns:

The unsigned bytes value read as a Java int.

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeByte(int)

readBoolean

public boolean readBoolean()
                    throws IOException

Description copied from interface: DataInput

This method reads a Java boolean value from an input stream. It does so by reading a single byte of data. If that byte is zero, then the value returned is false. If the byte is non-zero, then the value returned is true.

This method can read a boolean written by an object implementing the writeBoolean() method in the DataOutput interface.

Specified by:

readBoolean in interface DataInput

Returns:

The boolean value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeBoolean(boolean)

readFloat

public float readFloat()
                throws IOException

Description copied from interface: DataInput

This method reads a Java float value from an input stream. It operates by first reading an int value from the stream by calling the readInt() method in this interface, then converts that int to a float using the intBitsToFloat method in the class java.lang.Float.

This method can read a float written by an object implementing the writeFloat() method in the DataOutput interface.

Specified by:

readFloat in interface DataInput

Returns:

The float value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeFloat(float), Float.intBitsToFloat(int)

readDouble

public double readDouble()
                  throws IOException

Description copied from interface: DataInput

This method reads a Java double value from an input stream. It operates by first reading a long value from the stream by calling the readLong() method in this interface, then converts that long to a double using the longBitsToDouble method in the class java.lang.Double.

This method can read a double written by an object implementing the writeDouble() method in the DataOutput interface.

Specified by:

readDouble in interface DataInput

Returns:

The double value read

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeDouble(double), Double.longBitsToDouble(long)

readFully

public void readFully(byte[] data,
                      int offset,
                      int length)
               throws IOException

Description copied from interface: DataInput

This method reads raw bytes into the passed array buf starting offset bytes into the buffer. The number of bytes read will be exactly len. Note that this method blocks until the data is available and throws an exception if there is not enough data left in the stream to read len bytes. Note also that zero length buffers are permitted. In this case, the method will return immediately without reading any bytes from the stream.

Specified by:

readFully in interface DataInput

Parameters:

data - The buffer into which to read the data

offset - The offset into the buffer to start storing data

length - The number of bytes to read into the buffer

Throws:

IOException - If any other error occurs

readFully

public void readFully(byte[] data)
               throws IOException

Description copied from interface: DataInput

This method reads raw bytes into the passed array until the array is full. Note that this method blocks until the data is available and throws an exception if there is not enough data left in the stream to fill the buffer. Note also that zero length buffers are permitted. In this case, the method will return immediately without reading any bytes from the stream.

Specified by:

readFully in interface DataInput

Parameters:

data - The buffer into which to read the data

Throws:

IOException - If any other error occurs

readUnsignedShort

public int readUnsignedShort()
                      throws IOException

Description copied from interface: DataInput

This method reads 16 unsigned bits into a Java int value from the stream. It operates by reading two bytes from the stream and converting them to a single Java int. The two bytes are stored most significant byte first (i.e., "big endian") regardless of the native host byte ordering.

As an example, if byte1 and byte2 represent the first and second byte read from the stream respectively, they will be transformed to an int in the following manner:

(int)(((byte1 0xFF) << 8) + (byte2 & 0xFF))

The value returned is in the range of 0 to 65535.

This method can read an unsigned short written by an object implementing the writeShort() method in the DataOutput interface.

Specified by:

readUnsignedShort in interface DataInput

Returns:

The unsigned short value read as a Java int.

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeShort(int)

readUTF

public String readUTF()
               throws IOException

Description copied from interface: DataInput

This method reads a String from an input stream that is encoded in a modified UTF-8 format. This format has a leading two byte sequence that contains the remaining number of bytes to read. This two byte sequence is read using the readUnsignedShort() method of this interface. After the number of remaining bytes have been determined, these bytes are read an transformed into char values. These char values are encoded in the stream using either a one, two, or three byte format. The particular format in use can be determined by examining the first byte read.

If the first byte has a high order bit of 0, then that character consists on only one byte. This character value consists of seven bits that are at positions 0 through 6 of the byte. As an example, if byte1 is the byte read from the stream, it would be converted to a char like so:

(char)byte1

If the first byte has 110 as its high order bits, then the character consists of two bytes. The bits that make up the character value are in positions 0 through 4 of the first byte and bit positions 0 through 5 of the second byte. (The second byte should have 10 as its high order bits). These values are in most significant byte first (i.e., "big endian") order.

As an example, if byte1 and byte2 are the first two bytes read respectively, and the high order bits of them match the patterns which indicate a two byte character encoding, then they would be converted to a Java char like so:

(char)(((byte1 & 0x1F) << 6) + (byte2 & 0x3F))

If the first byte has a 1110 as its high order bits, then the character consists of three bytes. The bits that make up the character value are in positions 0 through 3 of the first byte and bit positions 0 through 5 of the other two bytes. (The second and third bytes should have 10 as their high order bits). These values are in most significant byte first (i.e., "big endian") order.

As an example, if byte1, byte2, and byte3 are the three bytes read, and the high order bits of them match the patterns which indicate a three byte character encoding, then they would be converted to a Java char like so: (char)(((byte1 & 0x0F) << 12) + ((byte2 & 0x3F) + (byte3 & 0x3F)) Note that all characters are encoded in the method that requires the fewest number of bytes with the exception of the character with the value of \u0000 which is encoded as two bytes. This is a modification of the UTF standard used to prevent C language style NUL values from appearing in the byte stream.

This method can read data that was written by an object implementing the writeUTF() method in DataOutput.

Specified by:

readUTF in interface DataInput

Throws:

IOException - If any other error occurs

See Also:

DataOutput.writeUTF(java.lang.String)

skipBytes

public int skipBytes(int length)
              throws IOException

Description copied from interface: DataInput

This method skips and discards the specified number of bytes in an input stream. Note that this method may skip less than the requested number of bytes. The actual number of bytes skipped is returned. No bytes are skipped if a negative number is passed to this method.

Specified by:

skipBytes in interface DataInput

Parameters:

length - The number of bytes to skip

Returns:

The number of bytes actually skipped, which will always be numBytes

Throws:

IOException - If any other error occurs

close

public void close()
           throws IOException

Overrides:

close in class InputStream

Throws:

IOException