File	Doc	Category	Size	Date	Package
SharedFileInputStream.java	API Doc	Glassfish v2 API	16356	Mon May 14 15:28:50 BST 2007	javax.mail.util

SharedFileInputStream

• java.lang.Object
  • java.io.InputStream
    • java.io.FilterInputStream
      • java.io.BufferedInputStream

Fields Summary
private static int	defaultBufferSize
protected RandomAccessFile	in The file containing the data. Shared by all related SharedFileInputStreams.
protected int	bufsize The normal size of the read buffer.
protected long	bufpos The file offset that corresponds to the first byte in the read buffer.
protected long	start The file offset of the start of data in this subset of the file.
protected long	datalen The amount of data in this subset of the file.
private boolean	master True if this is a top level stream created directly by "new". False if this is a derived stream created by newStream.
private SharedFile	sf

Constructors Summary
public SharedFileInputStream(File file) Creates a SharedFileInputStream for the file. param file the file this(file, defaultBufferSize);
public SharedFileInputStream(String file) Creates a SharedFileInputStream for the named file param file the file this(file, defaultBufferSize);
public SharedFileInputStream(File file, int size) Creates a SharedFileInputStream with the specified buffer size. param file the file param size the buffer size. exception IllegalArgumentException if size <= 0. super(null); // XXX - will it NPE? if (size <= 0) throw new IllegalArgumentException("Buffer size <= 0"); init(new SharedFile(file), size);
public SharedFileInputStream(String file, int size) Creates a SharedFileInputStream with the specified buffer size. param file the file param size the buffer size. exception IllegalArgumentException if size <= 0. super(null); // XXX - will it NPE? if (size <= 0) throw new IllegalArgumentException("Buffer size <= 0"); init(new SharedFile(file), size);
private SharedFileInputStream(SharedFile sf, long start, long len, int bufsize) Used internally by the newStream method. super(null); this.master = false; this.sf = sf; this.in = sf.open(); this.start = start; this.bufpos = start; this.datalen = len; this.bufsize = bufsize; buf = new byte[bufsize];

Methods Summary
public synchronized int	available() Returns the number of bytes that can be read from this input stream without blocking. return the number of bytes that can be read from this input stream without blocking. exception IOException if an I/O error occurs. ensureOpen(); return (count - pos) + in_available();
public void	close() Closes this input stream and releases any system resources associated with the stream. exception IOException if an I/O error occurs. if (in == null) return; try { if (master) sf.forceClose(); else sf.close(); } finally { sf = null; in = null; buf = null; }
private void	ensureOpen() Check to make sure that this stream has not been closed if (in == null) throw new IOException("Stream closed");
private void	fill() Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks. Assumes that it is being called by a synchronized method. This method also assumes that all data has already been read in, hence pos > count. if (markpos < 0) { pos = 0; /* no mark: throw away the buffer */ bufpos += count; } else if (pos >= buf.length) /* no room left in buffer */ if (markpos > 0) { /* can throw away early part of the buffer */ int sz = pos - markpos; System.arraycopy(buf, markpos, buf, 0, sz); pos = sz; bufpos += markpos; markpos = 0; } else if (buf.length >= marklimit) { markpos = -1; /* buffer got too big, invalidate mark */ pos = 0; /* drop buffer contents */ bufpos += count; } else { /* grow buffer */ int nsz = pos * 2; if (nsz > marklimit) nsz = marklimit; byte nbuf[] = new byte[nsz]; System.arraycopy(buf, 0, nbuf, 0, pos); buf = nbuf; } count = pos; in.seek(bufpos + pos); // limit to datalen int len = buf.length - pos; if (bufpos - start + pos + len > datalen) len = (int)(datalen - (bufpos - start + pos)); int n = in.read(buf, pos, len); if (n > 0) count = n + pos;
protected void	finalize() Force this stream to close. super.finalize(); close();
public long	getPosition() Return the current position in the InputStream, as an offset from the beginning of the InputStream. return the current position //System.out.println("getPosition: start " + start + " pos " + pos + " bufpos " + bufpos + " = " + (bufpos + pos - start)); if (in == null) throw new RuntimeException("Stream closed"); return bufpos + pos - start;
private int	in_available() // XXX - overflow return (int)((start + datalen) - (bufpos + count));
private void	init(javax.mail.util.SharedFileInputStream$SharedFile sf, int size) this.sf = sf; this.in = sf.open(); this.start = 0; this.datalen = in.length(); // XXX - file can't grow this.bufsize = size; buf = new byte[size];
public synchronized void	mark(int readlimit) See the general contract of the mark method of InputStream. param readlimit the maximum limit of bytes that can be read before the mark position becomes invalid. see #reset() marklimit = readlimit; markpos = pos;
public boolean	markSupported() Tests if this input stream supports the mark and reset methods. The markSupported method of SharedFileInputStream returns true. return a boolean indicating if this stream type supports the mark and reset methods. see java.io.InputStream#mark(int) see java.io.InputStream#reset() return true;
public java.io.InputStream	newStream(long start, long end) Return a new InputStream representing a subset of the data from this InputStream, starting at start (inclusive) up to end (exclusive). start must be non-negative. If end is -1, the new stream ends at the same place as this stream. The returned InputStream will also implement the SharedInputStream interface. param start the starting position param end the ending position + 1 return the new stream if (in == null) throw new RuntimeException("Stream closed"); if (start < 0) throw new IllegalArgumentException("start < 0"); if (end == -1) end = datalen; return new SharedFileInputStream(sf, this.start + (int)start, (int)(end - start), bufsize);
public synchronized int	read(byte[] b, int off, int len) Reads bytes from this stream into the specified byte array, starting at the given offset. This method implements the general contract of the corresponding {@link java.io.InputStream#read(byte[], int, int) read} method of the {@link java.io.InputStream} class. param b destination buffer. param off offset at which to start storing bytes. param len maximum number of bytes to read. return the number of bytes read, or -1 if the end of the stream has been reached. exception IOException if an I/O error occurs. ensureOpen(); if ((off | len | (off + len) | (b.length - (off + len))) < 0) { throw new IndexOutOfBoundsException(); } else if (len == 0) { return 0; } int n = read1(b, off, len); if (n <= 0) return n; while ((n < len) /* && (in.available() > 0) */) { int n1 = read1(b, off + n, len - n); if (n1 <= 0) break; n += n1; } return n;
public synchronized int	read() See the general contract of the read method of InputStream. return the next byte of data, or -1 if the end of the stream is reached. exception IOException if an I/O error occurs. ensureOpen(); if (pos >= count) { fill(); if (pos >= count) return -1; } return buf[pos++] & 0xff;
private int	read1(byte[] b, int off, int len) Read characters into a portion of an array, reading from the underlying stream at most once if necessary. int avail = count - pos; if (avail <= 0) { if (false) { /* If the requested length is at least as large as the buffer, and if there is no mark/reset activity, do not bother to copy the bytes into the local buffer. In this way buffered streams will cascade harmlessly. */ if (len >= buf.length && markpos < 0) { // XXX - seek, update bufpos - how? return in.read(b, off, len); } } fill(); avail = count - pos; if (avail <= 0) return -1; } int cnt = (avail < len) ? avail : len; System.arraycopy(buf, pos, b, off, cnt); pos += cnt; return cnt;
public synchronized void	reset() See the general contract of the reset method of InputStream. If markpos is -1 (no mark has been set or the mark has been invalidated), an IOException is thrown. Otherwise, pos is set equal to markpos. exception IOException if this stream has not been marked or if the mark has been invalidated. see #mark(int) ensureOpen(); if (markpos < 0) throw new IOException("Resetting to invalid mark"); pos = markpos;
public synchronized long	skip(long n) See the general contract of the skip method of InputStream. param n the number of bytes to be skipped. return the actual number of bytes skipped. exception IOException if an I/O error occurs. ensureOpen(); if (n <= 0) { return 0; } long avail = count - pos; if (avail <= 0) { // If no mark position set then don't keep in buffer /* if (markpos <0) return in.skip(n); */ // Fill in buffer to save bytes for reset fill(); avail = count - pos; if (avail <= 0) return 0; } long skipped = (avail < n) ? avail : n; pos += skipped; return skipped;