import net.dean.jraw.http.oauth.OAuthHelper; //导入依赖的package包/类
public static Completable userAuthentication(
        final RedditClient reddit,
        final Credentials credentials,
        final String url) {
    return Completable.create(new CompletableOnSubscribe() {
        @Override
        public void subscribe(CompletableEmitter e) throws Exception {
            OAuthHelper oAuthHelper = reddit.getOAuthHelper();

            try {
                OAuthData oAuthData = oAuthHelper.onUserChallenge(url, credentials);
                reddit.authenticate(oAuthData);
                AuthenticationManager.get().onAuthenticated(oAuthData);
                e.onComplete();
            } catch (Exception ex) {
                e.onError(ex);
            }
        }
    });
}
 

import net.dean.jraw.http.oauth.OAuthHelper; //导入依赖的package包/类
private  URL getAuthorizationUrl() {
    OAuthHelper oAuthHelper = AuthenticationManager.get().getRedditClient().getOAuthHelper();
    Credentials credentials = ((MyApplication) getApplication()).getInstalledAppCredentials();
    String[] scopes = {"identity", "edit", "flair", "mysubreddits", "read", "vote",
            "submit", "subscribe", "history", "save"};
    return oAuthHelper.getAuthorizationUrl(credentials, true, true, scopes);
}
 

import net.dean.jraw.http.oauth.OAuthHelper; //导入依赖的package包/类
public UserChallengeTask(OAuthHelper helper, Credentials creds){
    this.helper = helper;
    this.creds = creds;
}
 

import net.dean.jraw.http.oauth.OAuthHelper; //导入依赖的package包/类
public UserChallengeTask(OAuthHelper oAuthHelper, Credentials credentials) {
    Log.v(LogUtil.getTag(), "UserChallengeTask()");
    mOAuthHelper = oAuthHelper;
    mCredentials = credentials;
}
 

import net.dean.jraw.http.oauth.OAuthHelper; //导入依赖的package包/类
@Override
public void onCreate(Bundle savedInstance) {
    overrideSwipeFromAnywhere();
    super.onCreate(savedInstance);
    applyColorTheme("");
    try {
        setContentView(R.layout.activity_login);
    } catch(Exception e){
        finish();
        return;
    }
    setupAppBar(R.id.toolbar, R.string.title_login, true, true);

    String[] scopes = {
            "identity", "modcontributors", "modconfig", "modothers", "modwiki", "creddits",
            "livemanage", "account", "privatemessages", "modflair", "modlog", "report",
            "modposts", "modwiki", "read", "vote", "edit", "submit", "subscribe", "save",
            "wikiread", "flair", "history", "mysubreddits"
    };
    if (Authentication.reddit == null) {
        new Authentication(getApplicationContext());
    }
    final OAuthHelper oAuthHelper = Authentication.reddit.getOAuthHelper();
    final Credentials credentials = Credentials.installedApp(CLIENT_ID, REDIRECT_URL);
    String authorizationUrl =
            oAuthHelper.getAuthorizationUrl(credentials, true, scopes).toExternalForm();
    authorizationUrl = authorizationUrl.replace("www.", "i.");
    authorizationUrl = authorizationUrl.replace("%3A%2F%2Fi", "://www");
    Log.v(LogUtil.getTag(), "Auth URL: " + authorizationUrl);
    final WebView webView = (WebView) findViewById(R.id.web);
    webView.clearCache(true);
    webView.clearHistory();
    WebSettings webSettings = webView.getSettings();
    webSettings.setSaveFormData(false);
    webSettings.setSavePassword(false); // Not needed for API level 18 or greater (deprecated)

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
        CookieManager.getInstance().removeAllCookies(null);
        CookieManager.getInstance().flush();
    } else {
        CookieSyncManager cookieSyncMngr = CookieSyncManager.createInstance(this);
        cookieSyncMngr.startSync();
        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.removeAllCookie();
        cookieManager.removeSessionCookie();
        cookieSyncMngr.stopSync();
        cookieSyncMngr.sync();
    }

    webView.setWebViewClient(new WebViewClient() {
        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            if (url.contains("code=")) {
                Log.v(LogUtil.getTag(), "WebView URL: " + url);
                // Authentication code received, prevent HTTP call from being made.
                webView.stopLoading();
                new UserChallengeTask(oAuthHelper, credentials).execute(url);
                webView.setVisibility(View.GONE);
            }
        }
    });

    webView.loadUrl(authorizationUrl);
}