Volley重复请求数据的问题

request.setRetryPolicy(new DefaultRetryPolicy(50000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

/**
* Constructs a new retry policy.
* @param initialTimeoutMs The initial timeout for the policy. 默认超时时间
* @param maxNumRetries The maximum number of retries. 默认最大尝试次数
* @param backoffMultiplier Backoff multiplier for the policy. 对于请求失败之后的请求，不以相同的时间间隔去请求Server，而是以一个曲线增长，一次比一次长，如果backoff因子是2，当前超时为3，即下次再请求隔6s
*/
public DefaultRetryPolicy(int initialTimeoutMs, int maxNumRetries, float backoffMultiplier) {
mCurrentTimeoutMs = initialTimeoutMs;
mMaxNumRetries = maxNumRetries;
mBackoffMultiplier = backoffMultiplier;
}