Uniapp converts graphic verification codes in the form of file streams into images

              uni.request({
				    url: 'http://10.1.11.165:8000/code/', // Just for the sample , Not the real interface address .
					responseType: 'arraybuffer',
				    success: (res) => {
				       	this.urls = 'data:image/png;base64,' + btoa(
				             new Uint8Array(res.data)
				               .reduce((data, byte) => data + String.fromCharCode(byte), '')
				           );
				       	console.log(this.urls)
				    }
				});

Be careful ：
responseType: ‘arraybuffer’, Must specify
uniapp Address ：https://uniapp.dcloud.io/api/request/request