Loading of external resources containing by a document Leave feedback
If the document contains external resources, such as images, GroupDocs.Viewer loads them when rendering a document. This allows the document to display correctly, but is a potential security risk.
GroupDocs.Viewer allows you to manage loading of external resources contained by a document. These features are supported for the following formats:
Use the LoadOptions object to manage loading of external resources.
The following code snippet shows how to deny loading of external resources:
LoadOptions loadOptions = new LoadOptions();
loadOptions.setSkipExternalResources(true); // Skip loading of external resources
try (Viewer viewer = new Viewer("business-flyer.docx", loadOptions)) {
HtmlViewOptions viewOptions = HtmlViewOptions.forEmbeddedResources();
viewer.view(viewOptions);
}
val loadOptions = LoadOptions()
loadOptions.isSkipExternalResources = true // Skip loading of external resources
Viewer("business-flyer.docx", loadOptions).use { viewer ->
val viewOptions = HtmlViewOptions.forEmbeddedResources()
viewer.view(viewOptions)
}
The following images show the output file with and without external resources (see top right corner):
| loadOptions.setSkipExternalResources(false) | loadOptions.setSkipExternalResources(true) |
|---|---|
 |  |
The following code snippet shows how to allow loading of external resources from specific URLs:
LoadOptions loadOptions = new LoadOptions();
loadOptions.setSkipExternalResources(true); // Skip loading of all external resources
loadOptions.getWhitelistedResources().add("avatars.githubusercontent.com"); // Enable loading of external resources that has `avatars.githubusercontent.com` fragment in resource URL.
try (Viewer viewer = new Viewer("business-flyer.docx", loadOptions)) {
HtmlViewOptions viewOptions = HtmlViewOptions.forEmbeddedResources();
viewer.view(viewOptions);
}
val loadOptions = LoadOptions()
loadOptions.isSkipExternalResources = true // Skip loading of all external resources
loadOptions.whitelistedResources.add("avatars.githubusercontent.com") // Enable loading of external resources that has `avatars.githubusercontent.com` fragment in resource URL.
val viewer = Viewer("business-flyer.docx", loadOptions)
val viewOptions = HtmlViewOptions.forEmbeddedResources()
viewer.use {
it.view(viewOptions)
}
The default timeout is 10 seconds. GroupDocs.Viewer allows you to change this value.
The following code snippet shows how to set a timeout to load external resources:
// Specify a timeout.
LoadOptions loadOptions = new LoadOptions();
loadOptions.setResourceLoadingTimeout(5000);
// Render a file.
try (Viewer viewer = new Viewer("sample.docx", loadOptions)) {
HtmlViewOptions viewOptions = HtmlViewOptions.forEmbeddedResources();
viewer.view(viewOptions);
}
// Specify a timeout.
val loadOptions = LoadOptions()
loadOptions.setResourceLoadingTimeout(5000)
// Render a file.
Viewer("sample.docx", loadOptions).use { viewer ->
val viewOptions = HtmlViewOptions.forEmbeddedResources()
viewer.view(viewOptions)
}
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