Java 以角度 2 将图像转换为 base64

Converting an image to base64 in angular 2

提问by lakshmi

Converting an image to base64 in angular 2, image is uploaded from local . Current am using fileLoadedEvent.target.result. The problem is, when I send this base64 string through REST services to java, it is not able to decode it. When i try this base64 string with free online encoder-decoder, there also I cannot see decoded image. I tried using canvas also. Am not getting proper result. One thing is sure the base64 string what am getting is not proper one, do I need to add any package for this ? Or in angular 2 is there any perticular way to encode the image to base64 as it was there in angular 1 - angular-base64-upload package.

将图像转换为 angular 2 中的 base64，图像从本地上传。当前正在使用 fileLoadedEvent.target.result。问题是，当我通过 REST 服务将此 base64 字符串发送到 java 时，它无法对其进行解码。当我用免费的在线编码器-解码器尝试这个 base64 字符串时，我也看不到解码的图像。我也尝试使用画布。我没有得到正确的结果。有一件事是确定得到的 base64 字符串不正确，我需要为此添加任何包吗？或者在 angular 2 中是否有任何特定的方式将图像编码为 base64，就像它在 angular 1 - angular-base64-upload 包中一样。

Pls find below my sample code

请在我的示例代码下方找到

onFileChangeEncodeImageFileAsURL(event:any,imgLogoUpload:any,imageForLogo:any,imageDiv:any)
{
    var filesSelected = imgLogoUpload.files;
    var self = this;
    if (filesSelected.length > 0) {
      var fileToLoad = filesSelected[0]; 

      //Reading Image file, encode and display
       var  reader: FileReader = new FileReader();
       reader.onloadend = function(fileLoadedEvent:any) {

       //SECOND METHO
       var imgSrcData = fileLoadedEvent.target.result; // <--- data: base64 

        var newImage = imageForLogo;
        newImage.src = imgSrcData;
        imageDiv.innerHTML = newImage.outerHTML;

      }
      reader.readAsDataURL(fileToLoad);
    }
}

采纳答案by Parth Ghiya

Working plunkr for base64 String

用于 base64 字符串的工作 plunkr

https://plnkr.co/edit/PFfebmnqH0eQR9I92v0G?p=preview

https://plnkr.co/edit/PFfebmnqH0eQR9I92v0G?p=preview

  handleFileSelect(evt){
      var files = evt.target.files;
      var file = files[0];

    if (files && file) {
        var reader = new FileReader();

        reader.onload =this._handleReaderLoaded.bind(this);

        reader.readAsBinaryString(file);
    }
  }



  _handleReaderLoaded(readerEvt) {
     var binaryString = readerEvt.target.result;
            this.base64textString= btoa(binaryString);
            console.log(btoa(binaryString));
    }

回答by Ben Humphries

Have you tried using btoa or Crypto.js to encode the image to base64 ?

您是否尝试过使用 btoa 或 Crypto.js 将图像编码为 base64 ？

link to cryptojs - https://code.google.com/archive/p/crypto-js/

链接到cryptojs - https://code.google.com/archive/p/crypto-js/

var imgSrcData = window.btoa(fileLoadedEvent.target.result);

var imgSrcData = window.btoa(fileLoadedEvent.target.result);

or var imgSrcData = CryptoJS.enc.Base64.stringify(fileLoadedEvent.target.result);

或者 var imgSrcData = CryptoJS.enc.Base64.stringify(fileLoadedEvent.target.result);

回答by Ewertom Moraes

another solution thats works for base64 is something like this post https://stackoverflow.com/a/36281449/6420568

另一个适用于 base64 的解决方案类似于这篇文章 https://stackoverflow.com/a/36281449/6420568

in my case, i did

就我而言，我做到了

getImagem(readerEvt, midia){
    //console.log('change no input file', readerEvt);
    let file = readerEvt.target.files[0];
    var reader = new FileReader();
    reader.readAsDataURL(file);
    reader.onload = function () {
        //console.log('base64 do arquivo',reader.result);
        midia.binario = btoa(reader.result);
        //console.log('base64 do arquivo codificado',midia.binario);
    };
    reader.onerror = function (error) {
        console.log('Erro ao ler a imagem : ', error);
    };
}

and html component

和 html 组件

<input type="file" class="form-control"  (change)="getImagem($event, imagem)">

<img class="img-responsive"  src="{{imagem.binario | decode64 }}" alt="imagem..." style="width: 200px;"/>

to display the image, i created the pipe decode64

为了显示图像，我创建了管道 decode64

@Pipe({
  name: 'decode64'
})
export class Decode64Pipe implements PipeTransform {
  transform(value: any, args?: any): any {
    let a = '';
    if(value){
       a = atob(value);
    }
    return a;
  }
}

回答by Johansrk

I modified Parth Ghiya answer a bit, so you can upload 1- many images, and they are all stored in an array as base64 encoded strings

我稍微修改了 Parth Ghiya 的答案，因此您可以上传 1 张图片，并且它们都作为 base64 编码字符串存储在数组中

base64textString = [];

onUploadChange(evt: any) {
  const file = evt.target.files[0];

  if (file) {
    const reader = new FileReader();

    reader.onload = this.handleReaderLoaded.bind(this);
    reader.readAsBinaryString(file);
  }
}

handleReaderLoaded(e) {
  this.base64textString.push('data:image/png;base64,' + btoa(e.target.result));
}

HTML file

HTML文件

<input type="file" (change)="onUploadChange($event)" accept=".png, .jpg, .jpeg, .pdf" />
<img *ngFor="let item of base64textString"  src={{item}} alt="" id="img">

回答by Sithum Meegahapola

I have a come up with an answer with calling the HTTP request for post method with a json

我想出了一个答案，用 json 调用 post 方法的 HTTP 请求

1.event param is coming from the HTML input tag.
2. self.imagesrc is a component variable to store the data and to use that in the header file we need to cast the "this" to a self variable and use it in the reader. Onload function
3. this.server is the API calling service component variable I used in this component

1.event 参数来自 HTML 输入标签。
2. self.imagesrc 是一个组件变量，用于存储数据并在头文件中使用它，我们需要将“this”转换为 self 变量并在阅读器中使用它。onload函数3.this.server
是我在这个组件中使用的API调用服务组件变量

UploadImages(event) {
    var file = event.target.files[0];
    var reader = new FileReader();
    reader.readAsDataURL(file);
    var self = this;
    reader.onload = function() {
      self.imageSrc = reader.result.toString();
    };

    var image_data = {
      authentication_token: this.UD.getAuth_key ,
      fileToUpload: this.imageSrc,
      attachable_type: "Photo"
    };

    this.server.photo_Upload(image_data).subscribe(response => {
      if (response["success"]) {
        console.log(response);
      } else {
        console.log(response);
      }
    });
  }

回答by Massimo Variolo

Please consider using this package: image-to-base64

请考虑使用这个包：image-to-base64

Generate a image to base64, you can make this using a path or url.

将图像生成为 base64，您可以使用路径或 url 进行生成。

Or this accepted answer

或者这个接受的答案