19个实用的Android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);

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);

6：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);

7: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();  
            }  
        }  
    };

8: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) {}   
}

9:获得手机UA

public String getUserAgent()  
{  
    String user_agent = ProductProperties.get(ProductProperties.USER_AGENT_KEY, null);  
    return user_agent;  
}

10：清空手机上Cookie

CookieSyncManager.createInstance(getApplicationContext());  
CookieManager.getInstance().removeAllCookie();

11：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”, “”, “”);  
        }  
}

12：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"/>

13: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(); 
                } 
    }

14:显示toast

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

15:在当前Activity中启动另外一个Activity

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

16:从当前ContentView从查找控件

(Button)findViewById(R.id.btnAbout)
R.id.btnAbout指控件id。

17: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

18: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。

19: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。