Using nanohttpd for server on localhost, how to serve the static HTML code in the whole directory?

Question

I can't make nanohttpd work. It seems not be able to find the www directory in app's root.

My code is at https://github.com/tlkahn/neonx

My code at MainActivity.java:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        BottomNavigationView navView = findViewById(R.id.nav_view);
        mWebView = findViewById(R.id.webkit);
        navView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setMixedContentMode(WebSettings.MIXED_CONTENT_ALWAYS_ALLOW);
        webSettings.setDomStorageEnabled(true);
        mWebView.getSettings().setLoadsImagesAutomatically(true);
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
                return false;
            }
        });
        if (!haveNetworkConnection()) {
            new AlertDialog.Builder(this)
                .setTitle("You are not connected to internet.")
                .setMessage("Are you sure you want to exit?")
                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finishAffinity();
                        System.exit(0);
                    }
                }).setNegativeButton("No", null).show();
        }
        startLocalServer(3000, "www", true, true );
    }

  public void startLocalServer(int port, String root, Boolean localhost, Boolean keepAlive) {
      try {
          File www_root = new File(root);
          server = new WebServer("localhost", port, www_root.getAbsoluteFile());
          server.start();
          printIp();
      } catch (IOException e) {
          e.printStackTrace();
      }
  }

When I tried to visit localhost:3000, I got the error: given path is not a directory. The error seems to come from this line: https://git.io/fjS3f

I guess the way I initialize the rootDir is wrong (this line: https://git.io/fjS3v). But how can I make this work? I mean to serve the whole directory, which means all CSS/JS/hypyerlinks should work, once nanohttpd starts serving...

Answer 1

The problem is that you cannot access files in the assets folder as if they were local files. You have to extend NanoHTTPD and override serve(IHTTPSession) in order to serve assets. Here is an example in Kotlin. Let me know if you cannot read it and I will port it to Java.

class FileServer(private val context: Context, port: Int) : NanoHTTPD(port) {
override fun serve(session: IHTTPSession): Response {
    val uri = session.uri.removePrefix("/").ifEmpty { "index.html" }
    println("Loading $uri")
    try {
        val mime = when (uri.substringAfterLast(".")) {
            "ico" -> "image/x-icon"
            "css" -> "text/css"
            "htm" -> "text/html"
            "html" -> "text/html"
            else -> "application/javascript"
        }

        return NanoHTTPD.newChunkedResponse(
            Response.Status.OK,
            mime,
            context.assets.open("www/$uri") // prefix with www because your files are not in the root folder in assets
        )
    } catch (e: Exception) {
        val message = "Failed to load asset $uri because $e"
        println(message)
        e.printStackTrace()
        return NanoHTTPD.newFixedLengthResponse(message)
    }
}