Java™ Platform
Standard Ed. 6

javax.imageio.stream
Class FileImageInputStream

java.lang.Object
  extended by javax.imageio.stream.ImageInputStreamImpl
      extended by javax.imageio.stream.FileImageInputStream
All Implemented Interfaces:
DataInput, ImageInputStream

public class FileImageInputStream
extends ImageInputStreamImpl

An implementation of ImageInputStream that gets its input from a File or RandomAccessFile. The file contents are assumed to be stable during the lifetime of the object.


Field Summary
 
Fields inherited from class javax.imageio.stream.ImageInputStreamImpl
bitOffset, byteOrder, flushedPos, streamPos
 
Constructor Summary
FileImageInputStream(File f)
          Constructs a FileImageInputStream that will read from a given File.
FileImageInputStream(RandomAccessFile raf)
          Constructs a FileImageInputStream that will read from a given RandomAccessFile.
 
Method Summary
 void close()
          Closes the stream.
protected  void finalize()
          Finalizes this object prior to garbage collection.
 long length()
          Returns the length of the underlying file, or -1 if it is unknown.
 int read()
          Reads a single byte from the stream and returns it as an int between 0 and 255.
 int read(byte[] b, int off, int len)
          Reads up to len bytes from the stream, and stores them into b starting at index off.
 void seek(long pos)
          Sets the current stream position to the desired location.
 
Methods inherited from class javax.imageio.stream.ImageInputStreamImpl
checkClosed, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, setByteOrder, skipBytes, skipBytes
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FileImageInputStream

public FileImageInputStream(File f)
                     throws FileNotFoundException,
                            IOException
Constructs a FileImageInputStream that will read from a given File.

The file contents must not change between the time this object is constructed and the time of the last call to a read method.

Parameters:
f - a File to read from.
Throws:
IllegalArgumentException - if f is null.
SecurityException - if a security manager exists and does not allow read access to the file.
FileNotFoundException - if f is a directory or cannot be opened for reading for any other reason.
IOException - if an I/O error occurs.

FileImageInputStream

public FileImageInputStream(RandomAccessFile raf)
Constructs a FileImageInputStream that will read from a given RandomAccessFile.

The file contents must not change between the time this object is constructed and the time of the last call to a read method.

Parameters:
raf - a RandomAccessFile to read from.
Throws:
IllegalArgumentException - if raf is null.
Method Detail

read

public int read()
         throws IOException
Description copied from class: ImageInputStreamImpl
Reads a single byte from the stream and returns it as an int between 0 and 255. If EOF is reached, -1 is returned.

Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

The bit offset within the stream must be reset to zero before the read occurs.

Specified by:
read in interface ImageInputStream
Specified by:
read in class ImageInputStreamImpl
Returns:
the value of the next byte in the stream, or -1 if EOF is reached.
Throws:
IOException - if the stream has been closed.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException
Description copied from class: ImageInputStreamImpl
Reads up to len bytes from the stream, and stores them into b starting at index off. If no bytes can be read because the end of the stream has been reached, -1 is returned.

The bit offset within the stream must be reset to zero before the read occurs.

Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

Specified by:
read in interface ImageInputStream
Specified by:
read in class ImageInputStreamImpl
Parameters:
b - an array of bytes to be written to.
off - the starting position within b to write to.
len - the maximum number of bytes to read.
Returns:
the number of bytes actually read, or -1 to indicate EOF.
Throws:
IOException - if an I/O error occurs.

length

public long length()
Returns the length of the underlying file, or -1 if it is unknown.

Specified by:
length in interface ImageInputStream
Overrides:
length in class ImageInputStreamImpl
Returns:
the file length as a long, or -1.

seek

public void seek(long pos)
          throws IOException
Description copied from interface: ImageInputStream
Sets the current stream position to the desired location. The next read will occur at this location. The bit offset is set to 0.

An IndexOutOfBoundsException will be thrown if pos is smaller than the flushed position (as returned by getflushedPosition).

It is legal to seek past the end of the file; an EOFException will be thrown only if a read is performed.

Specified by:
seek in interface ImageInputStream
Overrides:
seek in class ImageInputStreamImpl
Parameters:
pos - a long containing the desired file pointer position.
Throws:
IOException - if any other I/O error occurs.

close

public void close()
           throws IOException
Description copied from interface: ImageInputStream
Closes the stream. Attempts to access a stream that has been closed may result in IOExceptions or incorrect behavior. Calling this method may allow classes implementing this interface to release resources associated with the stream such as memory, disk space, or file descriptors.

Specified by:
close in interface ImageInputStream
Overrides:
close in class ImageInputStreamImpl
Throws:
IOException - if an I/O error occurs.

finalize

protected void finalize()
                 throws Throwable
Finalizes this object prior to garbage collection. The close method is called to close any open input source. This method should not be called from application code.

Overrides:
finalize in class ImageInputStreamImpl
Throws:
Throwable - if an error occurs during superclass finalization.

Java™ Platform
Standard Ed. 6

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