===2019-09-13 03:13:55.690 ERROR cn.vcfilm.sts.callback.handler.PayCallbackHandler Line:210 - 微信sdk解析错误：
org.xml.sax.SAXParseException: Premature end of file.
    at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257)
    at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
    at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121)
    at com.github.wxpay.sdk.WXPayUtil.xmlToMap(WXPayUtil.java:43)
    at cn.vcfilm.sts.callback.handler.PayCallbackHandler.requestHandle(PayCallbackHandler.java:205)
    at cn.vcfilm.sts.callback.handler.PayCallbackHandler.verifyParams(PayCallbackHandler.java:119)

请问这是怎么回事？微信支付回调有的时候是成功，但有时候就这样了，导致回调不成功