转 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。