签名原串 ：appid=xxx&mch_id=xxx&nonce_str=5186d12965324a0e875f75d9acdbc611&receiver={"account":"xxx","name":"小程序","relation_type":"PARTNER","type":"MERCHANT_ID"}&key=B1E00C7752444B49A338C278CB338BDF

xml : <xml><appid>xxx</appid><mch_id>xxx</mch_id><nonce_str>5186d12965324a0e875f75d9acdbc611</nonce_str><receiver>{"account":"xxx","name":"小程序","relation_type":"PARTNER","type":"MERCHANT_ID"}</receiver><sign>E6EC3F2CC1038F7BD4347FDAA7A017897F0CB3FDA569126C386C518634467302</sign></xml>

在微信签名工具验证都是通过的(sha256签名)，但是远程调用的时候死活报验证签名失败。对比签名的5条规则，都符合啊。