NetworkImage和Image.network的区别？ [英] Difference in NetworkImage and Image.network?

问题描述

两者是否有区别？

缺点是什么？在正常情况下，哪个更容易使用？

Whats the disadvantage and which one is easier to use for normal situation?

推荐答案

两者是否有区别？

Are there any difference in both of them?

是。它们是不同的。

• NetworkImage 类创建一个对象，该对象通过传递给它的 src URL提供图像。它不是小部件，也不会在屏幕上输出图像。



• Image.network 创建一个在屏幕上显示图像的小部件。它只是 Image 类（有状态的小部件）上的命名构造函数。 。它使用 NetworkImage 设置 image 属性。该 image 属性最终用于显示图像。

• NetworkImage class creates an object the provides an image from the src URL passed to it. It is not a widget and does not output an image to the screen.

• Image.network creates a widget that displays an image on the screen. It is just a named constructor on the Image class(a stateful widget). It sets the image property using the NetworkImage . This image property is used finally to display the image.

class Image extends StatefulWidget{
  Image(...){}; //default Constructor


  //the argument src is passed to the NetworkImage and assinged to the image property
  Image.network(String src, {...}) : image = NetworkImage(src, ...);


  final ImageProvider image;

  @override
  Widget build(BuildContext context){
    display the image
    return RawImage(image: image,
      ...
    );
  }
}

缺点是什么，在正常情况下哪个更容易使用？

Whats the disadvantage and which one is easier to use for normal situation?

没有缺点。您应该使用适合需要的那一种。例如，考虑：

There is no disadvantage. You should use the one the suits the need. For example consider:

1. CircleAvatar 小部件，该小部件显示一个表示用户的圆圈，并使用 backgroundImage 。它需要一个ImageProvider。因此，您传递了 NetworkImage（http://image.com）


2. FadeInImage 在加载原始图像时显示占位符，也需要 ImageProvider 其图片属性。因此，您可以提供它 NetworkImage（http://image.com）。

1. CircleAvatar widget that displays acircle that represents a user takes backgroundImage. It requires an ImageProvider. So you pass NetworkImage(http://image.com)
2. FadeInImage that displays a placeholder while the original image is loading also takes a ImageProvider for its image property. So you can provide it NetworkImage(http://image.com).

如果您只想在屏幕上将图像显示为小部件，请使用 Image.network 并在任何位置使用 NetworkImage 预计 ImageProvider 。

If you just want to display the image as a widget on screen use Image.network and use NetworkImage wherever an ImageProvider is expected.

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