传递字节流

方法1

var aaa= urlBase64ToUint8Array(encrypt);
    var bb=new Uint8Array(aaa)    
    var xhr = new XMLHttpRequest;
    xhr.open("POST", "http://localhost:1111/XXXX", false);
    xhr.send(bb);
    xhr.onreadystatechange= function() {
                     alert("returned:"+ xhr.responseText);
                   }

方法2 微信小程序

var data=stringtobyte.urlBase64ToUint8Array(encrypt)
 app.wxPRequest(
      'POST',url,data.buffer,(data)=>{
      wx.hideLoading({
        success: (res) => {},
      })

     responseType:'arraybuffer',
      header: {
        'content-type': 'application/x-www-form-urlencoded',
      },