Android编程14个很有用的代码片段

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);
 

6、显示toast

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

 

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(“/templets/default/index.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(); 
               } 
        }