public int readLength() throws IOException {
		int length = 0;

		byte b = (byte) this.read();

		// This is short form. The short form can be used if the number of
		// octets in the Value part is less than or
		// equal to 127, and can be used whether the Value part is primitive or
		// constructed. This form is identified by
		// encoding bit 8 as zero, with the length count in bits 7 to 1 (as
		// usual, with bit 7 the most significant bit
		// of the length).
		if ((b & 0x80) == 0) {
			return b;
		}

		// This is indefinite form. The indefinite form of length can only be
		// used (but does not have to be) if the V
		// part is constructed, that
		// is to say, consists of a series of TLVs. In the indefinite form of
		// length the first bit of the first octet is
		// set to 1, as for the long form, but the value N is set to zero.
		b = (byte) (b & 0x7F);
		if (b == 0) {
			return Tag.Indefinite_Length;
		}

		// If bit 8 of the first length octet is set to 1, then we have the long
		// form of length. In long form, the first
		// octet encodes in its remaining seven bits a value N which is the
		// length of a series of octets that themselves
		// encode the length of the Value part.
		byte temp;
		for (int i = 0; i < b; i++) {
			temp = (byte) this.read();
			length = (length << 8) | (0x00FF & temp);
		}

		return length;
	}
public int readLength ( ) throws IOException { int length = 0 ; byte b = ( byte ) this . read ( ) ; if ( ( b & 0x80 ) == 0 ) { return b ; } b = ( byte ) ( b & 0x7F ) ; if ( b == 0 ) { return Tag . Indefinite_Length ; } byte temp ; for ( int i = 0 ; i < b ; i ++ ) { temp = ( byte ) this . read ( ) ; length = ( length << 8 ) | ( 0x00FF & temp ) ; } return length ; }
Reads and returns the length field.
In case of indefinite length returns Tag.Indefinite_Length value

@return
@throws IOException