Android中的基本认证登录

Question

First of all: I'm new to programming and this is a school project.

My Problem: I've got a basic login mask using strings to save the users credentials. The credentials, if true, are saved via SharedPrefences. Now I want to compare the users input to the Basic Authentication credentials of my webserver http://fost19.tk/ (user: fost19, pw: 12345) to log the user into the app or give him an error message. Everything is working so far, but I'm stuck at connecting to my webserver and comparing the credentials.

I've read some questions on the internet, but to be honest I am completely lost right now, which is the best method to achieve this in the current android build. I'm aware that I need to decrypt the given credentials from my webserver, but I don't know how to do this in Java and I don't know which "plugins" need to be added to my project.

Thanks for your help: :)

Answer 1

In the next step you probably want to download the content from your website and process it in the app. First of all, your app needs the permission Internet. Add the following line to your manifest file below the application tag:

<uses-permission android:name="android.permission.INTERNET" />

Your website requires http authentication. To do this, you need to include your username and password in the headers of your request. However, Android does not allow syncronous network traffic. Therefore we download the content from the website in the background and can then update the user interface via a callback. You can add my class DownloadContent to your project:

import android.os.AsyncTask;
import android.util.Base64;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import javax.net.ssl.HttpsURLConnection;

public class DownloadContent extends AsyncTask<String, Void, String> {
private final Callback callback;
private final String username, password;

private DownloadContent(@NonNull String username, @NonNull String password, @NonNull Callback callback) {
    this.callback = callback;
    this.username = username;
    this.password = password;
}

public static void run(@NonNull String username, @NonNull String password, @NonNull Callback callback) {
    DownloadContent loader = new DownloadContent(username, password, callback);
    // runs doInBackground asynchronous
    loader.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}

@Override
protected String doInBackground(String... strings) {
    try {
        String credentials = username + ":" + password;
        URL url = new URL ("https://vertretungsplanbbscux.000webhostapp.com/auth/index.html");
        // encode to 64 encoded string (necessary for authorization header)
        String base64 = Base64.encodeToString(credentials.getBytes(), Base64.NO_WRAP);
        // perform a post request
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setDoOutput(true);
        // append encoded username and password as authorization header
        connection.setRequestProperty  ("Authorization", "Basic " + base64);
        InputStream stream = connection.getInputStream();
        BufferedReader reader = new BufferedReader (new InputStreamReader(stream));
        String inputLine;
        StringBuilder response = new StringBuilder();
        // read html of website
        while ((inputLine = reader.readLine()) != null)
            response.append(inputLine);
        reader.close();
        return response.toString();
    } catch(Exception e) {
        e.printStackTrace();
    }
    // return null if an error has occurred
    return null;
}

@Override
protected void onPostExecute(@Nullable String content) {
    // called after doInBackground has finished, synchronous again
    if (content == null) {
        callback.onNotLoaded();
    } else {
        callback.onLoaded(content);
    }
}

public interface Callback {
    void onLoaded(String content);
    void onNotLoaded();
}
}

Here is how you can access the content:

DownloadContent.run("fost19", "12345", new DownloadContent.Callback() {
        @Override
        public void onLoaded(String content) {
            Log.d("DownloadContent", content);
            //TODO display content in user interface
        }

        @Override
        public void onNotLoaded() {
            Log.d("DownloadContent", "could not fetch content from website");
            // TODO show error message
        }
    });

I hope that I could help you with your substitution plan app.

Edit1: You should only use a secure connection (https). So instead of using your.tk address, I used the actual secure address from your website.