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Java - the image files are located in the bin directory, downloading new images will cause the application to restart

Popularity：901 ℃/2024-09-24 08:48:21

When an application needs to load an image file at runtime, if the image file is located in thebin directory, downloading a new image causes the application to restart because Java applications typically follow the following mechanism when loading resources:

  • Class Loader: Java applications use class loaders to load class files and resources.
  • Resource Loading: The class loader looks for resources based on the class path (classpath), and thebin The directory is usually included in the class path.
  • Caching mechanism: The class loader caches loaded resources for efficiency.

Specifically, when downloading a new image tobin When the catalog is used, the following occurs:

  1. Class Path Changes: due tobin The catalog is part of the class path, and downloading new images changes the class path.
  2. Cache invalidation: The class loader detects a change in the class path, causing the cache to be invalidated.
  3. Reload the resource: The class loader needs to reload all the classes that depend on thebin directory's resources, including image files.
  4. The application restarts: To ensure that the application is using the most up-to-date resources, a Java application may choose to reload or restart to reload all resources and update the cache.

Examples:

Assuming that the application uses thebin/images/ as a logo image and loads it on startup to be displayed on the UI. When downloading a new Pictures tobin/images Catalog time:

  • The application detects thebin A change in the directory that causes the cache to be invalidated.
  • The application reloadsbin/images/, using newly downloaded images.
  • To ensure that the UI is using the latest images, the application may choose to reload or restart.

Summary:

When an application relies on a file located in thebin When downloading image files in the directory, downloading new images will cause the class path to change, which in turn will cause the cache to become invalid and may eventually cause the application to restart. To avoid this, it is recommended to store images in thebin in a directory other than the directory, for exampleresources maybeimages Catalog.

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