枚举类型的数据存入到map中
原文来自http://fokman.iteye.com/blog/1568905

public enum IdeasCMD {    RESERVED(0), PING(1), PING_ACK(2), KEY_EXCHANGE(3), KEY_EXCHANGE_ACK(4), CONNECT(5), CONNECT_ACK(6), DISCONNECT(7), KEEP_ALIVE(            8), KEEP_ALIVE_ACK(9)   ;    private final int value;    /**     * enum lookup map     */    private static final Map<Integer, IdeasCMD> lookup = new HashMap<Integer, IdeasCMD>();    static {        for (IdeasCMD s : EnumSet.allOf(IdeasCMD.class)) {            lookup.put(s.getValue(), s);        }    }    IdeasCMD(int value) {        this.value = value;    }    public int getValue() {        return value;    }    public static IdeasCMD lookup(int value) {        return lookup.get(value);    }}