【深蓝】Volley之Request 2

/**
     * Request method of this request. Currently supports GET, POST, PUT,
     * DELETE, HEAD, OPTIONS, TRACE, and PATCH.
     */
    private final int mMethod;

    /** URL of this request. */
    private final String mUrl;

    /** Default tag for {@link TrafficStats}. */
    private final int mDefaultTrafficStatsTag;  

    /** Listener interface for errors. */
    private final Response.ErrorListener mErrorListener;

    /** Sequence number of this request, used to enforce FIFO ordering. */
    private Integer mSequence;

    /** The request queue this request is associated with. */
    private RequestQueue mRequestQueue;

    /** Whether or not responses to this request should be cached. */
    private boolean mShouldCache = true;

    /** Whether or not this request has been canceled. */
    private boolean mCanceled = false;

    /** Whether or not a response has been delivered for this request yet. */
    private boolean mResponseDelivered = false;

    // A cheap variant of request tracing used to dump slow requests.
    private long mRequestBirthTime = 0;

    /**
     * Threshold at which we should log the request (even when debug logging is
     * not enabled).
     */
    private static final long SLOW_REQUEST_THRESHOLD_MS = 3000;

    /** The retry policy for this request. */
    private RetryPolicy mRetryPolicy;

    /**
     * When a request can be retrieved from cache but must be refreshed from the
     * network, the cache entry will be stored here so that in the event of a
     * "Not Modified" response, we can be sure it hasn‘t been evicted from
     * cache.
     */
    private Cache.Entry mCacheEntry = null;

    /** An opaque token tagging this request; used for bulk cancellation. */
    private Object mTag;