InputStream (Java Platform SE 7 ) (original) (raw)

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many aslen bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elementsb[off] through b[off+k-1], leaving elements b[off+k] throughb[off+len-1] unaffected.

In every case, elements b[0] throughb[off] and elements b[off+len] throughb[b.length-1] are unaffected.

The read(b, off, len) method for class InputStream simply calls the methodread() repeatedly. If the first such call results in anIOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in aIOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored intob and the number of bytes read before the exception occurred is returned. The default implementation of this method blocks until the requested amount of input data len has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.