Package org.apache.http.impl.io

Class ContentLengthInputStream

java.lang.Object
java.io.InputStream
org.apache.http.impl.io.ContentLengthInputStream
All Implemented Interfaces:
Closeable, AutoCloseable
public class ContentLengthInputStream
extends InputStream
Stream that cuts off after a specified number of bytes. Note that this class NEVER closes the underlying stream, even when close gets called. Instead, it will read until the "end" of its chunking on close, which allows for the seamless execution of subsequent HTTP 1.1 requests, while not requiring the client to remember to read the entire contents of the response.

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:
4.0
Author:
Ortwin Glueck, Eric Johnson, Mike Bowler

  • Constructor Details

    • ContentLengthInputStream

      public ContentLengthInputStream​(SessionInputBuffer in, long contentLength)
      Creates a new length limited stream
      Parameters:
      in - The session input buffer to wrap
      contentLength - The maximum number of bytes that can be read from the stream. Subsequent read operations will return -1.

  • Method Details

    • 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 AutoCloseable
      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)