FileDocCategorySizeDatePackage
MemoryCacheImageInputStream.javaAPI DocJava SE 5 API3900Fri Aug 26 14:57:32 BST 2005javax.imageio.stream

MemoryCacheImageInputStream

public class MemoryCacheImageInputStream extends ImageInputStreamImpl
An implementation of ImageInputStream that gets its input from a regular InputStream. A memory buffer is used to cache at least the data between the discard position and the current read position.

In general, it is preferable to use a FileCacheImageInputStream when reading from a regular InputStream. This class is provided for cases where it is not possible to create a writable temporary file.

version
0.5

Fields Summary
private InputStream
stream
private MemoryCache
cache
Constructors Summary
public MemoryCacheImageInputStream(InputStream stream)
Constructs a MemoryCacheImageInputStream that will read from a given InputStream.

param
stream an InputStream to read from.
exception
IllegalArgumentException if stream is null.


                                
       
        if (stream == null) {
            throw new IllegalArgumentException("stream == null!");
        }        
        this.stream = stream;
Methods Summary
public voidclose()
Closes this MemoryCacheImageInputStream, freeing the cache. The source InputStream is not closed.

        super.close();
        cache.reset();
        stream = null;
public voidflushBefore(long pos)

        super.flushBefore(pos);
        cache.disposeBefore(pos);
public booleanisCached()
Returns true since this ImageInputStream caches data in order to allow seeking backwards.

return
true.
see
#isCachedMemory
see
#isCachedFile

        return true;
public booleanisCachedFile()
Returns false since this ImageInputStream does not maintain a file cache.

return
false.
see
#isCached
see
#isCachedMemory

        return false;
public booleanisCachedMemory()
Returns true since this ImageInputStream maintains a main memory cache.

return
true.
see
#isCached
see
#isCachedFile

        return true;
public intread()

        checkClosed();
        bitOffset = 0;
        long thisByte = streamPos;
        long pos = cache.loadFromStream(stream, streamPos+1);
        if (pos >= streamPos+1) {
            return cache.read(streamPos++);
        } else {
            return -1;
        }
public intread(byte[] b, int off, int len)

        checkClosed();
        // Will throw NullPointerException
        if (off < 0 || len < 0 || off + len > b.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > b.length!");
        }

        bitOffset = 0;

        if (len == 0) {
            return 0;
        }

        long pos = cache.loadFromStream(stream, streamPos+len);

        len = (int)(pos - streamPos);  // In case stream ended early

        if (len > 0) {
            cache.read(b, off, len, streamPos);
            streamPos += len;
            return len;
        } else {
            return -1;
        }