javascript - 在 Angular2 中构建 multipart/form-data POST 请求并验证输入类型文件

Question

我有一张图片 (base64)，需要通过 POST 请求发送(并等待响应)。 POST 请求需要是 Content-Type:multipart/form-data。图片需要是Content-Type: image/jpg

POST 请求应该是这样的:

POST https://www.url... HTTP/1.1
Content-Type: multipart/form-data; boundary=-------------------------acebdf13572468
User-Agent: Fiddler
Host: www.host.com
Content-Length: 199640

---------------------------acebdf13572468
Content-Disposition: form-data; name="fieldNameHere"; filename="Nikon Digital SLR Camera D3100 14.2MP 2.jpg"
Content-Type: image/jpeg

以二进制图像数据为内容主体。

我正在尝试使用 Angular 2 的 Http Post 方法，但我不太确定如何生成请求。这是我的:

let body = atob(imageData);
let headers = new Headers({'Content-Type': 'multipart/form-data'});
let options = new RequestOptions({headers: headers});

this._http.post(url, body, options)
.map(res=>{
  //do stuff
});

我可以说我遗漏了其中的一部分，但我不确定我需要做什么才能为二进制图像数据提供 Content-Disposition & Type 等。

Answer 1

表单模板

<form id="form" name="file" [formGroup]="FileFormGroup"(submit)="addFrom($event, FileFormGroup)" method="post">  

   <input spellcheck="true" formControlName="Demo" name="Demo" type="text"/>
   <input type="file" accept="image/*" id="file" name="File"/>
   <input formControlName="File" type="hidden"/>

</form>

Ts

   import {FormGroup, FormBuilder, FormControl, Validators} from '@angular/forms';

   import {ValidatorFn} from '@angular/forms/src/directives/validators';

   public FileFormGroup: FormGroup; /* variable */

   constructor(public fb: FormBuilder) {}

   ngOnInit() {
      this.FileFormGroup = this.fb.group({
      Demo: ["", Validators.required],
      File: ["", this.fileExtension({msg: 'Please upload valid Image'})]
     });
   }

   public addFrom(event: Event, form: FormGroup): void {

   if(form.valid && form.dirty) {

   let formTemp: HTMLFormElement <HTMLFormElement>document.querySelector('#form');

   let formData: FormData = new FormData(formTemp);

   let xhr: XMLHttpRequest = this.foo(formData);

    xhr.onreadystatechange = () => {
      if(xhr.readyState === 4) {
        if(xhr.status === 201) {
           console.log("Success");
        } else {
           console.log("Error");
        }
      }
    }
  }}

    // Foo function
     public Foo(formData){
         let url: Foo;
         let xhr: XMLHttpRequest = new XMLHttpRequest();
         xhr.open('POST', url, true);

         // enctype For Multipart Request
          xhr.setRequestHeader("enctype", "multipart/form-data");

          // IE bug fixes to clear cache
          xhr.setRequestHeader("Cache-Control", "no-cache");
          xhr.setRequestHeader("Cache-Control", "no-store");
          xhr.setRequestHeader("Pragma", "no-cache"); 

          xhr.send(formData);
          return xhr;
     }

     /* validation function to check proper file extension */

  public fileExtension(config: any): ValidatorFn {
    return (control: FormControl) => {

      let urlRegEx: RegExp = /\.(jpe?g|png|gif)$/i;

      if(control.value && !control.value.match(urlRegEx)) {
        this.deleteImg = false;
        return {
          invalidUrl: config.msg
        };
      } else {
        return null;
      }
    };
  }