java socket 的参数选项解读

 public void setInterface(InetAddress inf) throws SocketException {
    if (isClosed()) {
        throw new SocketException("Socket is closed");
    }
    checkAddress(inf, "setInterface");
    synchronized (infLock) {
        getImpl().setOption(SocketOptions.IP_MULTICAST_IF, inf);
        infAddress = inf;
    }
    }

/**
     * Disable/Enable local loopback of multicast datagrams
     * The option is used by the platform‘s networking code as a hint 
     * for setting whether multicast data will be looped back to 
     * the local socket.
     *
     * <p>Because this option is a hint, applications that want to
     * verify what loopback mode is set to should call 
     * {@link #getLoopbackMode()}
     * @param disable <code>true</code> to disable the LoopbackMode
     * @throws SocketException if an error occurs while setting the value
     * @since 1.4
     * @see #getLoopbackMode
     */
    public void setLoopbackMode(boolean disable) throws SocketException {
    getImpl().setOption(SocketOptions.IP_MULTICAST_LOOP, Boolean.valueOf(disable));
    }

/**
     * Sets traffic class or type-of-service octet in the IP
     * header for packets sent from this Socket.
     * As the underlying network implementation may ignore this
     * value applications should consider it a hint.
     *
     * <P> The tc <B>must</B> be in the range <code> 0 <= tc <=
     * 255</code> or an IllegalArgumentException will be thrown.
     * <p>Notes:
     * <p> For Internet Protocol v4 the value consists of an octet
     * with precedence and TOS fields as detailed in RFC 1349. The
     * TOS field is bitset created by bitwise-or‘ing values such
     * the following :-
     * <p>
     * <UL>
     * <LI><CODE>IPTOS_LOWCOST (0x02)</CODE></LI>
     * <LI><CODE>IPTOS_RELIABILITY (0x04)</CODE></LI>
     * <LI><CODE>IPTOS_THROUGHPUT (0x08)</CODE></LI>
     * <LI><CODE>IPTOS_LOWDELAY (0x10)</CODE></LI>
     * </UL>
     * The last low order bit is always ignored as this
     * corresponds to the MBZ (must be zero) bit.
     * <p>
     * Setting bits in the precedence field may result in a
     * SocketException indicating that the operation is not
     * permitted.
     * <p>
     * As RFC 1122 section 4.2.4.2 indicates, a compliant TCP
     * implementation should, but is not required to, let application
     * change the TOS field during the lifetime of a connection.
     * So whether the type-of-service field can be changed after the
     * TCP connection has been established depends on the implementation
     * in the underlying platform. Applications should not assume that
     * they can change the TOS field after the connection.
     * <p>
     * For Internet Protocol v6 <code>tc</code> is the value that
     * would be placed into the sin6_flowinfo field of the IP header.
     *
     * @param tc        an <code>int</code> value for the bitset.
     * @throws SocketException if there is an error setting the
     * traffic class or type-of-service
     * @since 1.4
     * @see #getTrafficClass
     */
    public void setTrafficClass(int tc) throws SocketException {
    if (tc < 0 || tc > 255)
        throw new IllegalArgumentException("tc is not in range 0 -- 255");

    if (isClosed())
        throw new SocketException("Socket is closed");
        getImpl().setOption(SocketOptions.IP_TOS, new Integer(tc));
    }

/**
     * Enable/disable SO_LINGER with the specified linger time in seconds. 
     * The maximum timeout value is platform specific.
     *
     * The setting only affects socket close.
     * 
     * @param on     whether or not to linger on.
     * @param linger how long to linger for, if on is true.
     * @exception SocketException if there is an error
     * in the underlying protocol, such as a TCP error. 
     * @exception IllegalArgumentException if the linger value is negative.
     * @since JDK1.1
     * @see #getSoLinger()
     */
    public void setSoLinger(boolean on, int linger) throws SocketException {
    if (isClosed())
        throw new SocketException("Socket is closed");
    if (!on) {
        getImpl().setOption(SocketOptions.SO_LINGER, new Boolean(on));
    } else {
        if (linger < 0) {
        throw new IllegalArgumentException("invalid value for SO_LINGER");
        }
            if (linger > 65535)
                linger = 65535;
        getImpl().setOption(SocketOptions.SO_LINGER, new Integer(linger));
    }
    }

/**
     *  Enable/disable SO_TIMEOUT with the specified timeout, in
     *  milliseconds.  With this option set to a non-zero timeout,
     *  a read() call on the InputStream associated with this Socket
     *  will block for only this amount of time.  If the timeout expires,
     *  a <B>java.net.SocketTimeoutException</B> is raised, though the
     *  Socket is still valid. The option <B>must</B> be enabled
     *  prior to entering the blocking operation to have effect. The
     *  timeout must be > 0.
     *  A timeout of zero is interpreted as an infinite timeout.
     * @param timeout the specified timeout, in milliseconds.
     * @exception SocketException if there is an error
     * in the underlying protocol, such as a TCP error. 
     * @since   JDK 1.1
     * @see #getSoTimeout()
     */
    public synchronized void setSoTimeout(int timeout) throws SocketException {
    if (isClosed())
        throw new SocketException("Socket is closed");
    if (timeout < 0)
      throw new IllegalArgumentException("timeout can‘t be negative");

    getImpl().setOption(SocketOptions.SO_TIMEOUT, new Integer(timeout));
    }