android动态更改屏幕方向
在androd中要通过程序改变屏幕显示的方向，必须覆盖setRequestOrientation()方法，若要取得目前屏幕方向则需要用到getRequestOrientation()方法。
本例子实现了简单的改变屏幕方向，通过一个按钮点击事件，判断当前的屏幕方向，例如竖排（PORTRAIT），则改为横排（LANDSCAPE）;
本程序重写setRequestOrientation()方法，起目的是为了要捕捉设置屏幕放向的同时所触发的事件，并在更改的时候以Toast显示要更改的方向。
程序一开始闲判断getRequestOrentation()的值是否为-1，表示在Activity属性里没有设置android:screenOrientation="portrait"，这意味着即使点击按钮也无法判断屏幕的方向，不会进行更改方向的事件了。
布局文件main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" ><TextView android:id="@+id/textView01" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="" /><Button android:id="@+id/button01"android:layout_width="fill_parent"android:layout_height="wrap_content"android:gravity="center_horizontal"android:text="@string/button_text01"/></LinearLayout>
?OrientationActivity.java
public class OrientationActivity extends Activity {private TextView tv;private Button button;private Resources rs;private Display display;/** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); display = getWindow().getWindowManager().getDefaultDisplay(); tv = (TextView) this.findViewById(R.id.textView01); button = (Button) this.findViewById(R.id.button01); rs = this.getResources(); if(getRequestedOrientation() == -1){ tv.setText(rs.getText(R.string.err_msg)); } button.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {/* 方法一 */if(getRequestedOrientation() == -1){tv.setText(rs.getText(R.string.err_msg));}else{/* 方法一 *///if(getRequestedOrientation() == ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE){///* 若当前为横排则改为竖排 *///setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);//}else if(getRequestedOrientation() == ActivityInfo.SCREEN_ORIENTATION_PORTRAIT){///* 若当前为竖排则改为横排 *///setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);//}int h = display.getHeight();int w = display.getWidth();if(w < h){setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);}else{setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);}}} }); } /* (non-Javadoc) * @see android.app.Activity#setRequestedOrientation(int) */ @Override public void setRequestedOrientation(int requestedOrientation) { switch (requestedOrientation) {case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE:MakeTextToast.showToast(OrientationActivity.this,rs.getText(R.string.msg_2).toString() , true);break;case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:MakeTextToast.showToast(OrientationActivity.this,rs.getText(R.string.msg_2).toString() , true);break;default:break;} super.setRequestedOrientation(requestedOrientation); } /* (non-Javadoc) * @see android.app.Activity#getRequestedOrientation() */ @Override public int getRequestedOrientation() { // TODO Auto-generated method stub return super.getRequestedOrientation(); }}?MakeTextToast.java
public class MakeTextToast {/** * 显示Toast * @param context * @param msg 信息 * @param isLong 显示时间长短 */public static void showToast(Context context,String msg,boolean isLong){if(isLong){Toast.makeText(context, msg, Toast.LENGTH_LONG).show();}else{Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();}}}?
Manifest.xml
<application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".OrientationActivity" android:label="@string/app_name" android:screenOrientation="portrait"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application>
?运行结果图：
竖排：
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横排：
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