File	Doc	Category	Size	Date	Package
InputStream.java	API Doc	Apache Lucene 1.4.3	7396	Tue Mar 30 00:48:06 BST 2004	org.apache.lucene.store

InputStream

• java.lang.Object

Fields Summary
static final int	BUFFER_SIZE
private byte[]	buffer
private char[]	chars
private long	bufferStart
private int	bufferLength
private int	bufferPosition
protected long	length

Constructors Summary

Methods Summary
public java.lang.Object	clone() Returns a clone of this stream. Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from. Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from. InputStream clone = null; try { clone = (InputStream)super.clone(); } catch (CloneNotSupportedException e) {} if (buffer != null) { clone.buffer = new byte[BUFFER_SIZE]; System.arraycopy(buffer, 0, clone.buffer, 0, bufferLength); } clone.chars = null; return clone;
public abstract void	close() Closes the stream to futher operations.
public final long	getFilePointer() Returns the current position in this file, where the next read will occur. see #seek(long) return bufferStart + bufferPosition;
public final long	length() The number of bytes in the file. return length;
public final byte	readByte() Reads and returns a single byte. see OutputStream#writeByte(byte) // set by subclasses if (bufferPosition >= bufferLength) refill(); return buffer[bufferPosition++];
public final void	readBytes(byte[] b, int offset, int len) Reads a specified number of bytes into an array at the specified offset. param b the array to read bytes into param offset the offset in the array to start storing bytes param len the number of bytes to read see OutputStream#writeBytes(byte[],int) if (len < BUFFER_SIZE) { for (int i = 0; i < len; i++) // read byte-by-byte b[i + offset] = (byte)readByte(); } else { // read all-at-once long start = getFilePointer(); seekInternal(start); readInternal(b, offset, len); bufferStart = start + len; // adjust stream variables bufferPosition = 0; bufferLength = 0; // trigger refill() on read }
public final void	readChars(char[] buffer, int start, int length) Reads UTF-8 encoded characters into an array. param buffer the array to read characters into param start the offset in the array to start storing characters param length the number of characters to read see OutputStream#writeChars(String,int,int) final int end = start + length; for (int i = start; i < end; i++) { byte b = readByte(); if ((b & 0x80) == 0) buffer[i] = (char)(b & 0x7F); else if ((b & 0xE0) != 0xE0) { buffer[i] = (char)(((b & 0x1F) << 6) | (readByte() & 0x3F)); } else buffer[i] = (char)(((b & 0x0F) << 12) | ((readByte() & 0x3F) << 6) | (readByte() & 0x3F)); }
public final int	readInt() Reads four bytes and returns an int. see OutputStream#writeInt(int) return ((readByte() & 0xFF) << 24) | ((readByte() & 0xFF) << 16) | ((readByte() & 0xFF) << 8) | (readByte() & 0xFF);
protected abstract void	readInternal(byte[] b, int offset, int length) Expert: implements buffer refill. Reads bytes from the current position in the input. param b the array to read bytes into param offset the offset in the array to start storing bytes param length the number of bytes to read
public final long	readLong() Reads eight bytes and returns a long. see OutputStream#writeLong(long) return (((long)readInt()) << 32) | (readInt() & 0xFFFFFFFFL);
public final java.lang.String	readString() Reads a string. see OutputStream#writeString(String) int length = readVInt(); if (chars == null || length > chars.length) chars = new char[length]; readChars(chars, 0, length); return new String(chars, 0, length);
public final int	readVInt() Reads an int stored in variable-length format. Reads between one and five bytes. Smaller values take fewer bytes. Negative numbers are not supported. see OutputStream#writeVInt(int) byte b = readByte(); int i = b & 0x7F; for (int shift = 7; (b & 0x80) != 0; shift += 7) { b = readByte(); i |= (b & 0x7F) << shift; } return i;
public final long	readVLong() Reads a long stored in variable-length format. Reads between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported. byte b = readByte(); long i = b & 0x7F; for (int shift = 7; (b & 0x80) != 0; shift += 7) { b = readByte(); i |= (b & 0x7FL) << shift; } return i;
private void	refill() long start = bufferStart + bufferPosition; long end = start + BUFFER_SIZE; if (end > length) // don't read past EOF end = length; bufferLength = (int)(end - start); if (bufferLength == 0) throw new IOException("read past EOF"); if (buffer == null) buffer = new byte[BUFFER_SIZE]; // allocate buffer lazily readInternal(buffer, 0, bufferLength); bufferStart = start; bufferPosition = 0;
public final void	seek(long pos) Sets current position in this file, where the next read will occur. see #getFilePointer() if (pos >= bufferStart && pos < (bufferStart + bufferLength)) bufferPosition = (int)(pos - bufferStart); // seek within buffer else { bufferStart = pos; bufferPosition = 0; bufferLength = 0; // trigger refill() on read() seekInternal(pos); }
protected abstract void	seekInternal(long pos) Expert: implements seek. Sets current position in this file, where the next {@link #readInternal(byte[],int,int)} will occur. see #readInternal(byte[],int,int)