Flutter web asset images not displaying when deployed to web server

问题

I have created a flutter web project which uses network images and asset images, everything works fine when debugging on my pc but when I deploy it to a web server, the network images work fine but the asset images dont show at all. When I Inspect the page in the web browsers consol, I get the error below:

$1 @ window.dart:120
/assets/slack.png:1 Failed to load resource: the server responded with a status of 503 ()
window.dart:120 Error while trying to load an asset: Failed to load asset at "assets/slack.png" (503)

$1 @ window.dart:120
/assets/flutterLogo.png:1 Failed to load resource: the server responded with a status of 503 ()
window.dart:120 Error while trying to load an asset: Failed to load asset at "assets/flutterLogo.png" (503)

$1 @ window.dart:120
/assets/kross.jpg:1 Failed to load resource: the server responded with a status of 503 ()
window.dart:120 Error while trying to load an asset: Failed to load asset at "assets/kross.jpg" (503)

$1 @ window.dart:120
/assets/codingRocket2.png:1 Failed to load resource: the server responded 

回答1:

You should add photos to pubspec.yaml file and upload your assets folder to web server. Probably it is about not uploading folder

回答2:

You should perhaps check if the file is available as part of your deployment. 404 is the usual error code you received for resource not found. 503 is something related to the server availability or server errors. I would do the following.

Step 1. Check the build folder

Try running the flutter build web command in your project and inspect the build folder. Assuming a pubspec.yaml with following asset configurations.

  assets:
    - js/plotly_hookup.js
    - js/plotly-latest.min.js
    - images/
    - screen_shot.png

I would expect the following inside my build\web\assets folder.

If this is not working as shown, then its time to inspect the pubspec.yaml file and correct the paths.

Step 2: check your hosted folder

Ensure the files as shown above are available in your server where this folder is hosted. Also verify if the server has any configurations to be made specifically for image files or types of images files.

来源：https://stackoverflow.com/questions/58878346/flutter-web-asset-images-not-displaying-when-deployed-to-web-server