Angular 5：如何使用 BLOB 头像保存用户

Question

我是 Angular 的新手，我想用头像保存一个新用户，那么如何将头像的 Blob 值传递给我的用户模型以便正确保存？

这是我的代码：

HTML

<input type="file" (change)="onSelectFile($event)" accept="image/x-png,image/gif,image/jpeg" value="{{image}}" id="avatar" ngModel name="avatar" #avatar="ngModel"/>

打字稿

image:any;

onSelectFile(event) {
  var reader ;
  reader = new FileReader;
  reader.onload = (event) => {
    console.log(reader.result);
    this.image = reader.result;
    console.log(this.image);
  }
  reader.readAsDataURL(event.target.files[0]);
}

保存用户时遇到的错误：

{"timestamp":"2018-11-24T13:29:13.222+0000","status":400,"error":"Bad Request","message":"JSON parse error: Cannot deserialize value of type `byte[]` from String \"\\fakepath\\IMG_20180808_023905.jpg\": Failed to decode VALUE_STRING as base64 (MIME-NO-LINEFEEDS): Illegal character ':' (code 0x3a) in base64 content; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `byte[]` from String \"\\fakepath\\IMG_20180808_023905.jpg\": Failed to decode VALUE_STRING as base64 (MIME-NO-LINEFEEDS): Illegal character ':' (code 0x3a) in base64 content\n at [Source: (PushbackInputStream); line: 1, column: 134] (through reference chain: org.vi.entities.User[\"avatar\"])","path":"/users"}

PS：user表中头像字段的类型是longblob

Answer 1

我不鼓励您将图像保存为数据库中的 blob，最好只保存头像的名称并让图像在之后显示。

如果您有兴趣尝试，我认为this tutorial 很适合。

Answer 2

onSelectFile(event) {
    let reader = new FileReader;
    reader.onload = this.handle.bind(this); 
    reader.readAsArrayBuffer(this.file);
}

handle(readerEvt: any) {

   let bytes = new Uint8Array(readerEvt.target.result);
   for (let index = 0; index < bytes.byteLength; index++) {
       this.image += String.fromCharCode(bytes[index]);
    }
 }

最好将图像作为文本写入数据库并将base64字符串发送到服务器。 那么你的函数应该是这样的：

handle(readerEvt: any) {

   let bytes = new Uint8Array(readerEvt.target.result);
   let binaryText = ''; 
   for (let index = 0; index < bytes.byteLength; index++) {
       let binaryText += String.fromCharCode(bytes[index]);
    }
   this.image = btoa(binaryText);
 }