转 20个Android很有用的代码片断

1：查看是否有存储卡插入

String status=Environment.getExternalStorageState();

if(status.equals(Enviroment.MEDIA_MOUNTED))

{

?? 说明有SD卡插入

}

2：让某个Activity透明

OnCreate 中不设Layout

this.setTheme(R.style.Theme_Transparent);

以下是 Theme_Transparent的定义（注意transparent_bg是一副透明的图片）

3：在屏幕元素中设置句柄

使用Activity.findViewById来取得屏幕上的元素的句柄. 使用该句柄您可以设置或获取任何该对象外露的

值.

TextView msgTextView = (TextView)findViewById(R.id.msg);

?? msgTextView.setText(R.string.push_me);

4:发送短信

????????????String body=”this is mms demo”;

?????????? Intent mmsintent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”smsto”,

number, null));

?????????? mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body);

?????????? mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, true);

?????????? mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, true);

????????????startActivity(mmsintent);

5:发送彩信

?????????? StringBuilder sb = new StringBuilder();

????????????sb.append(”file://”);

????????????sb.append(fd.getAbsoluteFile());

????????????Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”mmsto”, number,

null));

????????????// Below extra datas are all optional.

????????????intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_SUBJECT, subject);

????????????intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body);

????????????intent.putExtra(Messaging.KEY_ACTION_SENDTO_CONTENT_URI, sb.toString());

????????????intent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, composeMode);

????????????intent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, exitOnSent);

????????????startActivity(intent);

7：发送Mail

???????????? mime = “img/jpg”;

????????????shareIntent.setDataAndType(Uri.fromFile(fd), mime);

????????????shareIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(fd));

????????????shareIntent.putExtra(Intent.EXTRA_SUBJECT, subject);

????????????shareIntent.putExtra(Intent.EXTRA_TEXT, body);

8:注册一个 BroadcastReceiver

registerReceiver(mMasterResetReciever, new IntentFilter(”oms.action.MASTERRESET”));

private BroadcastReceiver mMasterResetReciever = new BroadcastReceiver() {

????????public void onReceive(Context context, Intent intent){

????????????String action = intent.getAction();

????????????if(”oms.action.MASTERRESET”.equals(action)){

????????????????RecoverDefaultConfig();

????????????}

????????}

????};

9:定义ContentObserver，监听某个数据表

private ContentObserver mDownloadsObserver = new DownloadsChangeObserver

(Downloads.CONTENT_URI);

private class DownloadsChangeObserver extends ContentObserver {

????????public DownloadsChangeObserver(Uri uri) {

????????????super(new Handler());

????????}

[email protected]

????????public void onChange(boolean selfChange) {｝??

????????}

??

10:获得 手机UA

public String getUserAgent()

????{

?????????? String user_agent = ProductProperties.get(ProductProperties.USER_AGENT_KEY, null);

????????????return user_agent;

????}

11：清空手机上Cookie

CookieSyncManager.createInstance(getApplicationContext());

????????CookieManager.getInstance().removeAllCookie();

12：建立GPRS 连接

?? //Dial the GPRS link.

????private boolean openDataConnection() {

????????// Set up data connection.

????????DataConnection conn = DataConnection.getInstance();????

????????????if (connectMode == 0) {

????????????????ret = conn.openConnection(mContext, “cmwap”, “cmwap”, “cmwap”);

????????????} else {

????????????????ret = conn.openConnection(mContext, “cmnet”, “”, “”);

????????????}

????}

13：PreferenceActivity 用法

public class Setting extends PreferenceActivity

｛

????public void onCreate(Bundle savedInstanceState) {

????????super.onCreate(savedInstanceState);

????????addPreferencesFromResource(R.xml.settings)；

????}

｝

Setting.xml:

????????????android:key=”seting2″

????????????android:[email protected]/seting2″

????????????android:[email protected]/seting2″/>

????????????android:key=”seting1″

????????????android:[email protected]/seting1″

????????????android:[email protected]/seting1summaryOff”

????????????android:[email protected]/>

14:通过 HttpClient从指定server获取数据

???????????? DefaultHttpClient httpClient = new DefaultHttpClient();

????????????HttpGet method = new HttpGet(“http://www.baidu.com/1.html”);

????????????HttpResponse resp;

????????????Reader reader = null;

????????????try {

????????????????// AllClientPNames.TIMEOUT

????????????????HttpParams params = new BasicHttpParams();

????????????????params.setIntParameter(AllClientPNames.CONNECTION_TIMEOUT, 10000);

????????????????httpClient.setParams(params);

????????????????resp = httpClient.execute(method);

????????????????int status = resp.getStatusLine().getStatusCode();

????????????????if (status != HttpStatus.SC_OK) return false;

????????????????// HttpStatus.SC_OK;

????????????????return true;

????????????} catch (ClientProtocolException e) {

????????????????// TODO Auto-generated catch block

????????????????e.printStackTrace();

????????????} catch (IOException e) {

????????????????// TODO Auto-generated catch block

????????????????e.printStackTrace();

????????????} finally {

????????????????if (reader != null) try {

????????????????????reader.close();

????????????????} catch (IOException e) {

????????????????????// TODO Auto-generated catch block

????????????????????e.printStackTrace();

????????????????}

????????????}

15:显示toast

Toast.makeText(this._getApplicationContext(), R.string._item, Toast.LENGTH_SHORT).show();

16:在当前Activity中启动另外一个Activity

startActivity(new Intent(this,目标Activity.class));

17:从当前ContentView从查找控件

(Button)findViewById(R.id.btnAbout)????

R.id.btnAbout指控件id。

18:获取屏幕宽高

DisplayMetrics dm = new DisplayMetrics();??

//获取窗口属性

getWindowManager().getDefaultDisplay().getMetrics(dm);????

int screenWidth = dm.widthPixels;//320??

int screenHeight = dm.heightPixels;//480

19:无标题栏、全屏

//无标题栏??

requestWindowFeature(Window.FEATURE_NO_TITLE);??

//全屏模式??

getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,

??WindowManager.LayoutParams.FLAG_FULLSCREEN);

注意在setContentView()之前调用，否则无效。

20注册activity

所有用到的Activity都必须在AndroidManifest.xml中注册，否则会报空指针错误。

如：，注意是包名+类名。