Package com.sun.xfile

Class XRandomAccessFile

java.lang.Object
com.sun.xfile.XRandomAccessFile
All Implemented Interfaces:
DataInput, DataOutput

public class XRandomAccessFile extends Object implements DataOutput, DataInput
Instances of this class support both reading and writing to a random access file. An application can modify the position in the file at which the next read or write occurs. This class provides a sense of security by offering methods that allow specified mode accesses of read-only or read-write to files.
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a random access file stream to read from, and optionally to write to, the file specified by the XFile argument.
    Creates a random access file to read from, and optionally to write to, a file with the specified name.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Closes this random access file and flushes any unwritten data to the file.
    void
    Forces any buffered output bytes to be written out.
    long
    Returns the current offset in this file.
    long
    Returns the length of this file.
    int
    Reads a byte of data from this file.
    int
    read(byte[] b)
    Reads up to b.length bytes of data from this file into an array of bytes.
    int
    read(byte[] b, int off, int len)
    Reads up to len bytes of data from this file into an array of bytes.
    final boolean
    Reads a boolean from this file.
    final byte
    Reads a signed 8-bit value from this file.
    final char
    Reads a Unicode character from this file.
    final double
    Reads a double from this file.
    final float
    Reads a float from this file.
    final void
    readFully(byte[] b)
    Reads b.length bytes from this file into the byte array.
    final void
    readFully(byte[] b, int off, int len)
    Reads exactly len bytes from this file into the byte array.
    final int
    Reads a signed 32-bit integer from this file.
    final String
    Reads the next line of text from this file.
    final long
    Reads a signed 64-bit integer from this file.
    final short
    Reads a signed 16-bit number from this file.
    final int
    Reads an unsigned 8-bit number from this file.
    final int
    Reads an unsigned 16-bit number from this file.
    final String
    Reads in a string from this file.
    void
    seek(long pos)
    Sets the offset from the beginning of this file at which the next read or write occurs.
    int
    skipBytes(int n)
    Skips exactly n bytes of input.
    void
    write(byte[] b)
    Writes b.length bytes from the specified byte array starting at offset off to this file.
    void
    write(byte[] b, int off, int len)
    Writes len bytes from the specified byte array starting at offset off to this file.
    void
    write(int b)
    Writes the specified byte to this file.
    final void
    writeBoolean(boolean v)
    Writes a boolean to the file as a 1-byte value.
    final void
    writeByte(int v)
    Writes a byte to the file as a 1-byte value.
    final void
    Writes the string to the file as a sequence of bytes.
    final void
    writeChar(int v)
    Writes a char to the file as a 2-byte value, high byte first.
    final void
    Writes a string to the file as a sequence of characters.
    final void
    writeDouble(double v)
    Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the file as an 8-byte quantity, high byte first.
    final void
    writeFloat(float v)
    Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the file as a 4-byte quantity, high byte first.
    final void
    writeInt(int v)
    Writes an int to the file as four bytes, high byte first.
    final void
    writeLong(long v)
    Writes a long to the file as eight bytes, high byte first.
    final void
    writeShort(int v)
    Writes a short to the file as two bytes, high byte first.
    final void
    Writes a string to the file using UTF-8 encoding in a machine-independent manner.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • XRandomAccessFile

      public XRandomAccessFile(XFile xf, String mode) throws IOException
      Creates a random access file stream to read from, and optionally to write to, the file specified by the XFile argument. The mode argument must either be equal to "r" or to "rw", indicating either to open the file for input, or for both input and output, respectively.
      Parameters:
      xf - the XFile object.
      mode - the access mode.
      Throws:
      IllegalArgumentException - if the mode argument is not equal to "r" or to "rw".
      IOException - if an I/O error occurs.
    • XRandomAccessFile

      public XRandomAccessFile(String name, String mode) throws IOException
      Creates a random access file to read from, and optionally to write to, a file with the specified name.

      The mode argument must either be equal to "r" or "rw", indicating either to open the file for input or for both input and output.

      Parameters:
      name - the native or URL file name.
      mode - the access mode.
      Throws:
      IllegalArgumentException - if the mode argument is not equal to "r" or to "rw".
      IOException - if an I/O error occurs.
  • Method Details

    • read

      public int read() throws IOException
      Reads a byte of data from this file.
      Returns:
      the next byte of data, or -1 if the end of the file is reached.
      Throws:
      IOException - if an I/O error occurs.
    • read

      public int read(byte[] b, int off, int len) throws IOException
      Reads up to len bytes of data from this file into an array of bytes.
      Parameters:
      b - the buffer into which the data is read.
      off - the start offset of the data.
      len - the maximum number of bytes read.
      Returns:
      the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.
      Throws:
      IOException - if an I/O error occurs.
    • read

      public int read(byte[] b) throws IOException
      Reads up to b.length bytes of data from this file into an array of bytes.
      Parameters:
      b - the buffer into which the data is read.
      Returns:
      the total number of bytes read into the buffer, or -1 if there is no more data because the end of this file has been reached.
      Throws:
      IOException - if an I/O error occurs.
    • readFully

      public final void readFully(byte[] b) throws IOException
      Reads b.length bytes from this file into the byte array.
      Specified by:
      readFully in interface DataInput
      Parameters:
      b - the buffer into which the data is read.
      Throws:
      EOFException - if this file reaches the end before reading all the bytes.
      IOException - if an I/O error occurs.
    • readFully

      public final void readFully(byte[] b, int off, int len) throws IOException
      Reads exactly len bytes from this file into the byte array.
      Specified by:
      readFully in interface 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:
      EOFException - if this file reaches the end before reading all the bytes.
      IOException - if an I/O error occurs.
    • skipBytes

      public int skipBytes(int n) throws IOException
      Skips exactly n bytes of input.

      Specified by:
      skipBytes in interface DataInput
      Parameters:
      n - the number of bytes to be skipped.
      Returns:
      the number of bytes skipped, which is always n.
      Throws:
      EOFException - if this file reaches the end before skipping all the bytes.
      IOException - if an I/O error occurs.
    • write

      public void write(int b) throws IOException
      Writes the specified byte to this file.
      Specified by:
      write in interface DataOutput
      Parameters:
      b - the byte to be written.
      Throws:
      IOException - if an I/O error occurs.
    • write

      public void write(byte[] b) throws IOException
      Writes b.length bytes from the specified byte array starting at offset off to this file.
      Specified by:
      write in interface DataOutput
      Parameters:
      b - the data.
      Throws:
      IOException - if an I/O error occurs.
    • write

      public void write(byte[] b, int off, int len) throws IOException
      Writes len bytes from the specified byte array starting at offset off to this file.
      Specified by:
      write in interface DataOutput
      Parameters:
      b - the data.
      off - the start offset in the data.
      len - the number of bytes to write.
      Throws:
      IOException - if an I/O error occurs.
    • getFilePointer

      public long getFilePointer() throws IOException
      Returns the current offset in this file.
      Returns:
      the offset from the beginning of the file, in bytes, at which the next read or write occurs.
      Throws:
      IOException - if an I/O error occurs.
    • seek

      public void seek(long pos) throws IOException
      Sets the offset from the beginning of this file at which the next read or write occurs.
      Parameters:
      pos - the absolute position.
      Throws:
      IOException - if an I/O error occurs.
    • length

      public long length() throws IOException
      Returns the length of this file.
      Returns:
      the length of this file.
      Throws:
      IOException - if an I/O error occurs.
    • flush

      public void flush() throws IOException
      Forces any buffered output bytes to be written out.
      Throws:
      IOException - if an I/O error occurs.
    • close

      public void close() throws IOException
      Closes this random access file and flushes any unwritten data to the file. After the file is closed further I/O operations may throw IOException.
      Throws:
      IOException - if an I/O error occurs.
    • readBoolean

      public final boolean readBoolean() throws IOException
      Reads a boolean from this file. This method reads a single byte from the file. A value of 0 represents false. Any other value represents true. This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
      Specified by:
      readBoolean in interface DataInput
      Returns:
      the boolean value read.
      Throws:
      EOFException - if this file has reached the end.
      IOException - if an I/O error occurs.
    • readByte

      public final byte readByte() throws IOException
      Reads a signed 8-bit value from this file. This method reads a byte from the file. If the byte read is b, where 0 <= b <= 255, then the result is:
        (byte)(b)

      This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readByte in interface DataInput
      Returns:
      the next byte of this file as a signed 8-bit byte.
      Throws:
      EOFException - if this file has reached the end.
      IOException - if an I/O error occurs.
    • readUnsignedByte

      public final int readUnsignedByte() throws IOException
      Reads an unsigned 8-bit number from this file. This method reads a byte from this file and returns that byte.

      This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readUnsignedByte in interface DataInput
      Returns:
      the next byte of this file, interpreted as an unsigned 8-bit number.
      Throws:
      EOFException - if this file has reached the end.
      IOException - if an I/O error occurs.
    • readShort

      public final short readShort() throws IOException
      Reads a signed 16-bit number from this file. The method reads 2 bytes from this file. If the two bytes read, in order, are b1 and b2, where each of the two values is between 0 and 255, inclusive, then the result is equal to:
        (short)((b1 << 8) | b2)

      This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readShort in interface DataInput
      Returns:
      the next two bytes of this file, interpreted as a signed 16-bit number.
      Throws:
      EOFException - if this file reaches the end before reading two bytes.
      IOException - if an I/O error occurs.
    • readUnsignedShort

      public final int readUnsignedShort() throws IOException
      Reads an unsigned 16-bit number from this file. This method reads two bytes from the file. If the bytes read, in order, are b1 and b2, where 0 <= b1, b2 <= 255, then the result is equal to:
        (b1 << 8) | b2

      This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readUnsignedShort in interface DataInput
      Returns:
      the next two bytes of this file, interpreted as an unsigned 16-bit integer.
      Throws:
      EOFException - if this file reaches the end before reading two bytes.
      IOException - if an I/O error occurs.
    • readChar

      public final char readChar() throws IOException
      Reads a Unicode character from this file. This method reads two bytes from the file. If the bytes read, in order, are b1 and b2, where 0 <= b1, b2 <= 255, then the result is equal to:
        (char)((b1 << 8) | b2)

      This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readChar in interface DataInput
      Returns:
      the next two bytes of this file as a Unicode character.
      Throws:
      EOFException - if this file reaches the end before reading two bytes.
      IOException - if an I/O error occurs.
    • readInt

      public final int readInt() throws IOException
      Reads a signed 32-bit integer from this file. This method reads 4 bytes from the file. If the bytes read, in order, are b1, b2, b3, and b4, where 0 <= b1, b2, b3, b4 <= 255, then the result is equal to:
        (b1 << 24) | (b2 << 16) + (b3 << 8) + b4

      This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readInt in interface DataInput
      Returns:
      the next four bytes of this file, interpreted as an int.
      Throws:
      EOFException - if this file reaches the end before reading four bytes.
      IOException - if an I/O error occurs.
    • readLong

      public final long readLong() throws IOException
      Reads a signed 64-bit integer from this file. This method reads eight bytes from the file. If the bytes read, in order, are b1, b2, b3, b4, b5, b6, b7, and b8, where:
        0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,

      then the result is equal to:

           ((long)b1 << 56) + ((long)b2 << 48)
           + ((long)b3 << 40) + ((long)b4 << 32)
           + ((long)b5 << 24) + ((long)b6 << 16)
           + ((long)b7 << 8) + b8
       

      This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readLong in interface DataInput
      Returns:
      the next eight bytes of this file, interpreted as a long.
      Throws:
      EOFException - if this file reaches the end before reading eight bytes.
      IOException - if an I/O error occurs.
    • readFloat

      public final float readFloat() throws IOException
      Reads a float from this file. This method reads an int value as if by the readInt method and then converts that int to a float using the intBitsToFloat method in class Float.

      This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readFloat in interface DataInput
      Returns:
      the next four bytes of this file, interpreted as a float.
      Throws:
      EOFException - if this file reaches the end before reading four bytes.
      IOException - if an I/O error occurs.
      See Also:
    • readDouble

      public final double readDouble() throws IOException
      Reads a double from this file. This method reads a long value as if by the readLong method and then converts that long to a double using the longBitsToDouble method in class Double.

      This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readDouble in interface DataInput
      Returns:
      the next eight bytes of this file, interpreted as a double.
      Throws:
      EOFException - if this file reaches the end before reading eight bytes.
      IOException - if an I/O error occurs.
      See Also:
    • readLine

      public final String readLine() throws IOException
      Reads the next line of text from this file. This method successively reads bytes from the file until it reaches the end of a line of text.

      A line of text is terminated by a carriage-return character ('\r'), a newline character ('\n'), a carriage-return character immediately followed by a newline character, or the end of the input stream. The line-terminating character(s), if any, are included as part of the string returned.

      This method blocks until a newline character is read, a carriage return and the byte following it are read (to see if it is a newline), the end of the stream is detected, or an exception is thrown.

      Specified by:
      readLine in interface DataInput
      Returns:
      the next line of text from this file.
      Throws:
      IOException - if an I/O error occurs.
    • readUTF

      public final String readUTF() throws IOException
      Reads in a string from this file. The string has been encoded using a modified UTF-8 format.

      The first two bytes are read as if by readUnsignedShort. This value gives the number of following bytes that are in the encoded string, not the length of the resulting string. The following bytes are then interpreted as bytes encoding characters in the UTF-8 format and are converted into characters.

      This method blocks until all the bytes are read, the end of the stream is detected, or an exception is thrown.

      Specified by:
      readUTF in interface DataInput
      Returns:
      a Unicode string.
      Throws:
      EOFException - if this file reaches the end before reading all the bytes.
      IOException - if an I/O error occurs.
      UTFDataFormatException - if the bytes do not represent valid UTF-8 encoding of a Unicode string.
      See Also:
    • writeBoolean

      public final void writeBoolean(boolean v) throws IOException
      Writes a boolean to the file as a 1-byte value. The value true is written out as the value (byte)1; the value false is written out as the value (byte)0.
      Specified by:
      writeBoolean in interface DataOutput
      Parameters:
      v - a boolean value to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeByte

      public final void writeByte(int v) throws IOException
      Writes a byte to the file as a 1-byte value.
      Specified by:
      writeByte in interface DataOutput
      Parameters:
      v - a byte value to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeShort

      public final void writeShort(int v) throws IOException
      Writes a short to the file as two bytes, high byte first.
      Specified by:
      writeShort in interface DataOutput
      Parameters:
      v - a short to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeChar

      public final void writeChar(int v) throws IOException
      Writes a char to the file as a 2-byte value, high byte first.
      Specified by:
      writeChar in interface DataOutput
      Parameters:
      v - a char value to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeInt

      public final void writeInt(int v) throws IOException
      Writes an int to the file as four bytes, high byte first.
      Specified by:
      writeInt in interface DataOutput
      Parameters:
      v - an int to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeLong

      public final void writeLong(long v) throws IOException
      Writes a long to the file as eight bytes, high byte first.
      Specified by:
      writeLong in interface DataOutput
      Parameters:
      v - a long to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeFloat

      public final void writeFloat(float v) throws IOException
      Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the file as a 4-byte quantity, high byte first.
      Specified by:
      writeFloat in interface DataOutput
      Parameters:
      v - a float value to be written.
      Throws:
      IOException - if an I/O error occurs.
      See Also:
    • writeDouble

      public final void writeDouble(double v) throws IOException
      Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the file as an 8-byte quantity, high byte first.
      Specified by:
      writeDouble in interface DataOutput
      Parameters:
      v - a double value to be written.
      Throws:
      IOException - if an I/O error occurs.
      See Also:
    • writeBytes

      public final void writeBytes(String s) throws IOException
      Writes the string to the file as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits.
      Specified by:
      writeBytes in interface DataOutput
      Parameters:
      s - a string of bytes to be written.
      Throws:
      IOException - if an I/O error occurs.
    • writeChars

      public final void writeChars(String s) throws IOException
      Writes a string to the file as a sequence of characters. Each character is written to the data output stream as if by the writeChar method.
      Specified by:
      writeChars in interface DataOutput
      Parameters:
      s - a String value to be written.
      Throws:
      IOException - if an I/O error occurs.
      See Also:
    • writeUTF

      public final void writeUTF(String str) throws IOException
      Writes a string to the file using UTF-8 encoding in a machine-independent manner.

      First, two bytes are written to the file as if by the writeShort method giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string. Following the length, each character of the string is output, in sequence, using the UTF-8 encoding for each character.

      Specified by:
      writeUTF in interface DataOutput
      Parameters:
      str - a string to be written.
      Throws:
      IOException - if an I/O error occurs.