JDK 中高效的实现

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/**     * See the general contract of the <code>readInt</code>     * method of <code>DataInput</code>.     * <p>     * Bytes     * for this operation are read from the contained     * input stream.     *     * @return     the next four bytes of this input stream, interpreted as an     *             <code>int</code>.     * @exception  EOFException  if this input stream reaches the end before     *               reading four bytes.     * @exception  IOException   the stream has been closed and the contained     *    input stream does not support reading after close, or     *    another I/O error occurs.     * @see        java.io.FilterInputStream#in     */    public final int readInt() throws IOException {        int ch1 = in.read();        int ch2 = in.read();        int ch3 = in.read();        int ch4 = in.read();        if ((ch1 | ch2 | ch3 | ch4) < 0)            throw new EOFException();        return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));    }