阅读Android官网示例的笔记

未分类

1. Fragment嵌入在Acitvity中时，需要在OnCreate中添加

if (savedInstanceState == null) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            RecyclerViewFragment fragment = new RecyclerViewFragment();
            transaction.replace(R.id.sample_content_fragment, fragment);
            transaction.commit();
        }

2. Fragment中在onCreateView，或onViewCreated中初始化View数据

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
            // 。。。
        return inflater.inflate(R.layout.fragment_notification_builder, container, false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mNotificationManager = (NotificationManager) getActivity().getSystemService(
                Context.NOTIFICATION_SERVICE);
        mNumberOfNotifications = (TextView) view.findViewById(R.id.number_of_notifications);
        // Supply actions to the button that is displayed on screen.
        View.OnClickListener onClickListener = new View.OnClickListener() {};
        view.findViewById(R.id.add_notification).setOnClickListener(onClickListener);
    }

3. 基本网络操作

得到流

    private InputStream downloadUrl(String urlString) throws IOException {
        // BEGIN_INCLUDE(get_inputstream)
        URL url = new URL(urlString);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setReadTimeout(10000 /* milliseconds */);
        conn.setConnectTimeout(15000 /* milliseconds */);
        conn.setRequestMethod("GET");
        conn.setDoInput(true);
        // Start the query
        conn.connect();
        InputStream stream = conn.getInputStream();
        return stream;
        // END_INCLUDE(get_inputstream)
    }

流转化为字符串

    private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
        Reader reader = null;
        reader = new InputStreamReader(stream, "UTF-8");
        char[] buffer = new char[len];
        reader.read(buffer);
        return new String(buffer);
    }

封装操作

    /** Initiates the fetch operation. */
    private String loadFromNetwork(String urlString) throws IOException {
        InputStream stream = null;
        String str ="";
        try {
            stream = downloadUrl(urlString);
            str = readIt(stream, 500);
       } finally {
           if (stream != null) {
               stream.close();
            }
        }
        return str;
    }

通过AysncTask执行

    private class DownloadTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {
            try {
                return loadFromNetwork(urls[0]);
            } catch (IOException e) {
              return getString(R.string.connection_error);
            }
        }
        /**
         * Uses the logging framework to display the output of the fetch
         * operation in the log fragment.
         */
        @Override
        protected void onPostExecute(String result) {
          Log.i(TAG, result);
        }
    }

4. 在OnCreate里面需使用Intent传递的数据时，最好在onNewIntent中也加入处理。

相关介绍：
http://www.cnblogs.com/zenfly/archive/2012/02/10/2345196.html
http://gundumw100.iteye.com/blog/2160467

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sample_main);
        if (getIntent() != null) {
            handleIntent(getIntent());
        }
    }

    @Override
    protected void onNewIntent(Intent intent) {
        handleIntent(intent);
    }

    private void handleIntent(Intent intent) {
        if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
            String query = intent.getStringExtra(SearchManager.QUERY);
            Bundle bundle = new Bundle();
            bundle.putString(QUERY_KEY, query);
            ContactablesLoaderCallbacks loaderCallbacks = new ContactablesLoaderCallbacks(this);
            getLoaderManager().restartLoader(CONTACT_QUERY_LOADER, bundle, loaderCallbacks);
        }
    }