WEB端直传签名

{
    "msg": "操作成功",
    "code": 200,
    "data": {
        "accessKeyId": "LTAI5tBDFVar1hoq****",
        "policy": "eyJleHBpcmF0aW9uIjoiMjAxNS0xMS0wNVQyMDoyMzoyM1oiLCJjxb25kaXRpb25zIjpbWyJ************",
        "signature": "VsxOcOudx******z93CLaXPz+4s=",
        "dir": "ai-video-attached/",
        "host": "https://post-test.oss-cn-hangzhou.aliyuncs.com",
        "expire": 1446727949,
        "cdnDomain": "cdn.xxxxx.com"
    }
}