---
banner_title: "Flash - Dynamic File Server"
banner_description: "Learn how to serve files in a dynamic context."
---

# 📁 Dynamic File Server

Sometimes we need to serve files in a dynamic context, in this sense a static file server is limiting.
Imagine we have a frontend application that is compiled down to a single `index.html` file, and we want to serve it with Flash
alongside it's javascript and css bundles. The way these compiled applications work is that they rely heavily on
client-side routing, so when the user navigates to a different page, the frontend application will try to fetch the
corresponding file from the server. This is where a dynamic file server comes in handy, as no route is pre-registered.

::: warning
The dynamic file server relies heavily on the concept of dynamic handlers, which are handlers that will resolve for
any subpath of the endpoint they are registered to (see [Handler Types](/flash/core-concepts/handlers) for more info).
:::

## Usage

To serve static files in Flash, you need to call the `server.serveDynamic()` method with the endpoint path and an instance of `DynamicFileServerConfig`.
The configuration object is instanced like so :

```java
DynamicFileServerConfiguration(
    boolean enableFileWatcher,
    String destinationPath,
    String dynamicEntrypoint,
    SourceType sourceType
)
```

- `enableFileWatcher` : If set to `true`, the server will watch for changes in the served files and reload them automatically.
- `destinationPath` : The path to the directory containing the files to be served.
- `dynamicEntrypoint` : The path to the file that will be served when the client navigates to the endpoint eg. `index.html`.
- `sourceType` : The type of source to serve files from. It can be either `FILESYSTEM` or `RESOURCESTREAM`.

Registering the dynamic file server is as simple as calling the `server.serveDynamic()` method with the desired path and configuration object:

```java
public class Example {
    public static void main(String[] args) {
        FlashServer server = new FlashServer(8080);

        server.serveDynamic("/*", new DynamicFileServerConfiguration(
            true,
            "path/to/my/files",
            "index.html",
            SourceType.FILESYSTEM
        ));
    }
}
```

Now you can access the files (or frontend) in the specified directory by navigating to `http://localhost:8080/<file-name>`.

Similarly, you can serve the same content from the jar's resources folder by setting the `sourceType` to `RESOURCESTREAM`:

```java
public class Example {
    public static void main(String[] args) {
        FlashServer server = new FlashServer(8080);

        server.serveStatic("/static", new DynamicFileServerConfiguration(
            true,
            "path/to/my/files",
            "index.html",
            SourceType.RESOURCESTREAM
        ));
    }
}
```