android检查网络是否正常

/**
     * 检查网络是否正常.
     *
     * @return true: 正常，false 不正常
     */
public boolean checkNetwork() {
boolean flag = false;
ConnectivityManager cwjManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
if (cwjManager.getActiveNetworkInfo() != null) {
flag = cwjManager.getActiveNetworkInfo().isAvailable();
}
return flag;
}