Angular 2 - 检查图片网址是否有效或损坏

Question

我正在从 API 获取大量图像 URL，并将它们显示在 Angular 2 Web 应用程序中。某些 URL 已损坏，我想将它们替换为本地存储在我的网络服务器上的默认图片。有没有人建议如何测试 url 并在状态码 404 的情况下替换损坏的图像？

谢谢！

Answer 1

监听图片元素的error事件：

<img [src]="someUrl" (error)="updateUrl($event)">

其中updateUrl(event) { ... } 为this.someUrl 分配了一个新值。

Plunker example

如果你只想签入代码，可以使用Checking if image does exists using javascript中解释的方法

@Directive({
  selector: 'img[default]',
  host: {
    '(error)':'updateUrl()',
    '[src]':'src'
   }
})
class DefaultImage {
  @Input() src:string;
  @Input() default:string;

  updateUrl() {
    this.src = this.default;
  }
}

Directive Plunker example

Answer 2

您可以通过这种方式使用 onError 事件来处理 invalid url 或 broken url。

• https://plnkr.co/edit/fD8zxd?p=preview

<img [src]="invalidPath" onError="this.src='images/angular.png'"/> 

这样就可以通过 onError 事件直接将 img 路径分配给 src

Answer 3

我在 Angular 4 上的示例

<img [src]="img" (error)="img.src = errorImg" #img>

1. 其中 img - 图像路径；
2. 错误 - 错误发出
3. errorImg - 默认 img 的路径
4. #img - 链接到 img 对象

Answer 4

我使用 base64 加载微调器：

<img [src]="photoContainer.photo.url | secure" onError="this.src='data:image/svg+xml;base64,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'">

Answer 5

我找到了一个对我有用的非常简单的解决方案。这不会检查 404，但是我有可能具有 .image 属性的对象。我知道这不是他问题的答案，但希望它可以帮助一些人。

<img class="list-thumb-img" [attr.src]="item.image?.url ? item.image.url : 'assets/img/140-100.png'">

Answer 6

一个完美的 Angular 8 指令：

import {AfterViewInit, Directive, ElementRef, Input} from '@angular/core';

@Directive({
    selector: '[appImage]'
})
export class ImageDirective implements AfterViewInit {

    @Input() src;

    constructor(private imageRef: ElementRef) {
    }

    ngAfterViewInit(): void {
        const img = new Image();
        img.onload = () => {
            this.setImage(this.src);
        };

        img.onerror = () => {
            // Set a placeholder image 
            this.setImage('assets/placeholder.png');
        };

        img.src = this.src;
    }

    private setImage(src: string) {
        this.imageRef.nativeElement.setAttribute('src', src);
    }
}

现在，HTML 将是：

<img [src]="'/some/valid-image.png'" appImage>

Answer 7

如果要更改未加载的图像或源已损坏... Angular 8，只需将此目标的 src 更改为默认资产：

• 组件 HTML

  <...>

• 组件 TS

  pictNotLoading(事件) { event.target.src = 'assets/nopicture.png'; }

Answer 8

这是我在多图像上的后备解决方案。 我们基本上在解析图像后分离 ChangeDetector，以便在解析图像后减少 CPU 的 vm 检查周期。

import {Component, ChangeDetectionStrategy, ChangeDetectorRef} from 'angular2/core';
import {AppStore} from "angular2-redux-util/dist/index";



@Component({
    selector: 'logoCompany',
    changeDetection: ChangeDetectionStrategy.Default,
    template: `
            <div style="padding-top: 7px" > 
              <span style="color: gainsboro; font-family: Roboto">{{getBusinessInfo('companyName')}}</span>
              <!--<img style="width: 35px" class="img-circle" src="http://galaxy.example.me/Resources/Resellers/{{getBusinessInfo('businessId')}}/{{getBusinessInfo('fileName')}}" />-->
              <img style="width: 35px" class="img-circle" [src]="getImageUrl()" (load)="onImageLoaded()" (error)="onImageError()" />
            </div>
    `
})

export class LogoCompany {

    constructor(private cdr:ChangeDetectorRef) {    
    }
    private imageRetries:number = 0;
    private unsub;


    private detach() {
        this.cdr.detach();
    }

    private getImageUrl() {          
        var url = '';
        switch (this.imageRetries){
            case 0: {
                url = 'http://galaxy.example.me/Resources/Resellers/' + this.getBusinessInfo('businessId') + '/Logo.jpg'
                break;
            }
            case 1: {
                url = 'http://galaxy.example.me/Resources/Resellers/' + this.getBusinessInfo('businessId') + '/Logo.png'
                break;
            }
            default: {
                url = 'assets/person.png'
                break;
            }

        }
        return url;
    }

    private onImageLoaded() {
        this.detach();
    }

    private onImageError() {
        this.imageRetries++;
    }

    private getBusinessInfo(field):string {
          return '12345';
    }





}

Answer 9

只有当 url 不正确时才会发生错误事件， 如果 url 正确但文件不存在，则可以在此代码中使用

javascript check if file exists on server:

（注意404是数字而不是字符串）

function doesFileExist(urlToFile) {
var xhr = new XMLHttpRequest();
xhr.open('HEAD', urlToFile, false);
xhr.send();
 
if (xhr.status == 404) {
    return false;
} else {
    return true;
}}

Answer 10

对于这个用例，您可以简单地使用三元运算符。 我假设您正在从远程服务器获取响应

<img src="{{ res.image ? res.image : onErrorFunction() }}"

如果您不想让来自服务器的图像在单引号 '' 中写入路径。

这里如果链接被破坏，那么它将转到 onErrorFunction 如果它没有被破坏，res.image 将被加载。