20个Android很有用的代码片段

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());

}

@Override
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:title=”@string/seting2″
android:summary=”@string/seting2″/>

android:key=”seting1″
android:title=”@string/seting1″
android:summaryOff=”@string/seting1summaryOff”
android:summaryOn=”@stringseting1summaryOff”/>

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。