Android 集成支付宝报4000错误

{resultStatus=4000, result=, memo=系统繁忙，请稍后再试} "alipay_sdk=alipay-sdk-java-3.3.49.ALL&app_id=2019121369839932&biz_content=%7B%22body%22%3A%22%E6%B5%8B%E8%AF%95%E5%95%86%E5%93%81%22%2C%22out_trade_no%22%3A%2212019121817052811991080598%22%2C%22passback_params%22%3A%22recharge%22%2C%22product_code%22%3A%22QUICK_MSECURITY_PAY%22%2C%22subject%22%3A%22%E6%99%BA%E6%85%A7%E7%89%A9%E4%B8%9A%E5%9B%A2%E8%B4%AD%E6%B6%88%E8%B4%B9%22%2C%22timeout_express%22%3A%2230m%22%2C%22total_amount%22%3A%220.01%22%7D&charset=utf-8&format=json&method=alipay.trade.app.pay&notify_url=http%3A%2F%2Fm7tcup.natappfree.cc%2Fgroupbuy%2FalipayNotify&sign=KIcL2rzCHiR1fDbZKLr1oBGuZ5xZirN%2BOc7ojz0lXscnDUqAlATbu8kJTzGuilw7M8krAeBinYTZ9DMs1iqO6RrYKQavsADc8huPgBJiPrI%2FSs%2BavKhp7GnXSf90poXTCqWH1fsGRAw407lz6Z6QpiSu05mPx%2F4cS0BZluyWPeRaVLB0fDu7E3RjgcTWf6qVEWP0ZYqkxFRSnJDltUWqeeWEVryW7zSPN4dEPiZ8zH9c1WR16eTXuuJ6P0BanCI%2FLPDi%2BUUV4mwy7FpJbjAynGlkohFa83qXFYzSWUKK41iaIrCrrSlQgDgx0GSs%2FQNZJULTCW4TmXkCVTHELZM4WA%3D%3D&sign_type=RSA2&timestamp=2019-12-20+13%3A10%3A42&version=1.0"