把后端返回的文件流格式转换成正常数据格式
断点调试返回值

network查看返回值

一、blob类型
let stringData:any = await this.blobToString(res);
blobToString(blob) {
return new Promise((resolve, reject) => {
const reader = new FileReader();
reader.onloadend = () => {
resolve(reader.result);
};
reader.onerror = reject;
reader.readAsText(blob);
});
}
二、类型为arraybuffer

 let enc = new TextDecoder('utf-8')
 res = JSON.parse(enc.decode(new Uint8Array(res))) //转化成json对象
 if(res.errcode){
   this.$message.error(res.errmsg);
 }