android 笔记 --- Android中开发中常用代码

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.获取android屏幕大小

Log.d("tag1", "width>>"
                + this.getWindow().getWindowManager().getDefaultDisplay()
                        .getWidth()
                + " height>>"
                + this.getWindow().getWindowManager().getDefaultDisplay()
                        .getHeight());

在Nexus one下测试，结果是w：480，h：800，这个数值不随屏幕横向或纵向而变化。

这里牵扯到多个对象：

* Activity
* Window：Activity打开一个Window（可以认为Activity包含一个Window），可以在Window中加入View，目前只有一个实现Window的类，PhoneWindow，以后也许会有PadWindow？
* WindowManager：Activity包含一个WindowManager，可以通过它立即删除window中的view，还可通过它得到Display
* Display，应该是代表显示器，可以得到长、宽，以及屏幕的方向（横向还是纵向）等。

17.界面无标题栏和全屏效果的实现方式
使用xml的方式，在manifest文件中，在需要的Activity元素中加入属性：

<activity android:name=".TextButtonActivity" android:label="@string/app_name"
    android:theme="@android:style/Theme.NoTitleBar.Fullscreen">

这是全屏的。

如果只是不要标题栏：

这样的好处是不需要写程序语句。程序的写法是，无标题栏：

requestWindowFeature(Window.FEATURE_NO_TITLE);全屏：

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

程序的写法，适用于动态配置是否全屏的情况下。