org.apache.commons.httpclient
Class ContentLengthInputStream

java.lang.Object
  java.io.InputStream
      org.apache.commons.httpclient.ContentLengthInputStream

All Implemented Interfaces:

Closeable

public class ContentLengthInputStream
extends InputStream

Cuts the wrapped InputStream off after a specified number of bytes.

Implementation note: Choices abound. One approach would pass through the InputStream.mark(int) and InputStream.reset() calls to the underlying stream. That's tricky, though, because you then have to start duplicating the work of keeping track of how much a reset rewinds. Further, you have to watch out for the "readLimit", and since the semantics for the readLimit leave room for differing implementations, you might get into a lot of trouble.

Alternatively, you could make this class extend BufferedInputStream and then use the protected members of that class to avoid duplicated effort. That solution has the side effect of adding yet another possible layer of buffering.

Then, there is the simple choice, which this takes - simply don't support InputStream.mark(int) and InputStream.reset(). That choice has the added benefit of keeping this class very simple.

Since:

2.0

Author:

Ortwin Glueck, Eric Johnson, Mike Bowler

Constructor Summary

ContentLengthInputStream(InputStream in, long contentLength)
Creates a new length limited stream

Method Summary

void	close() Reads until the end of the known length of content.
int	read() Read the next byte from the stream
int	read(byte[] b) Read more bytes from the stream.
int	read(byte[] b, int off, int len) Does standard InputStream.read(byte[], int, int) behavior, but also notifies the watcher when the contents have been consumed.
long	skip(long n) Skips and discards a number of bytes from the input stream.

Methods inherited from class java.io.InputStream

available, mark, markSupported, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ContentLengthInputStream

public ContentLengthInputStream(InputStream in,
                                long contentLength)

Creates a new length limited stream

Parameters:

in - The stream to wrap

contentLength - The maximum number of bytes that can be read from the stream. Subsequent read operations will return -1.

Since:

3.0

Method Detail

close

public void close()
           throws IOException

Reads until the end of the known length of content.

Does not close the underlying socket input, but instead leaves it primed to parse the next response.

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException - If an IO problem occurs.

read

public int read()
         throws IOException

Read the next byte from the stream

Specified by:

read in class InputStream

Returns:

The next byte or -1 if the end of stream has been reached.

Throws:

IOException - If an IO problem occurs

See Also:

InputStream.read()

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Does standard InputStream.read(byte[], int, int) behavior, but also notifies the watcher when the contents have been consumed.

Overrides:

read in class InputStream

Parameters:

b - The byte array to fill.

off - Start filling at this position.

len - The number of bytes to attempt to read.

Returns:

The number of bytes read, or -1 if the end of content has been reached.

Throws:

IOException - Should an error occur on the wrapped stream.

read

public int read(byte[] b)
         throws IOException

Read more bytes from the stream.

Overrides:

read in class InputStream

Parameters:

b - The byte array to put the new data in.

Returns:

The number of bytes read into the buffer.

Throws:

IOException - If an IO problem occurs

See Also:

InputStream.read(byte[])

skip

public long skip(long n)
          throws IOException

Skips and discards a number of bytes from the input stream.

Overrides:

skip in class InputStream

Parameters:

n - The number of bytes to skip.

Returns:

The actual number of bytes skipped. <= 0 if no bytes are skipped.

Throws:

IOException - If an error occurs while skipping bytes.

See Also:

InputStream.skip(long)