Android 特殊用法

转自：http://dev.10086.cn/cmdn/wiki/index.php?doc-view-2089.html 

 

 

1.让一个图片透明：

Bitmap buffer = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);buffer.eraseColor(Color.TRANSPARENT);

2.直接发送邮件：

Intent intent = new Intent(Intent.ACTION_SENDTO, Uri .fromParts("mailto", "[email protected]", null)); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); context.startActivity(intent);

3.程序控制屏幕变亮：
WindowManager.LayoutParams lp = getWindow().getAttributes(); lp.screenBrightness = 100 / 100.0f; getWindow().setAttributes(lp);

4.过滤特定文本

Filter filter = myAdapter.getFilter(); filter.filter(mySearchText);

5.scrollView scroll停止事件

setOnScrollListener(new OnScrollListener(){ public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { // TODO Auto-generated method stub } public void onScrollStateChanged(AbsListView view, int scrollState) { // TODO Auto-generated method stub if(scrollState == 0) Log.i("a", "scrolling stopped..."); } });}

6. 对于特定的程序 发起一个关联供打开

Bitmap bmp = getImageBitmap(jpg); String path = getFilesDir().getAbsolutePath() + "/test.png"; File file = new File(path); FileOutputStream fos = new FileOutputStream(file); bmp.compress( CompressFormat.PNG, 100, fos ); fos.close(); Intent intent = new Intent(); intent.setAction(android .content.Intent.ACTION_VIEW); intent.setDataAndType(Uri .fromFile(new File(path)), "image/png"); startActivity(intent); 对于图片上边的不适用索引格式会出错。 Intent intent = new Intent(); intent.setAction(android .content.Intent.ACTION_VIEW); File file = new File("/sdcard/test.mp4"); intent.setDataAndType(Uri .fromFile(file), "video/*"); startActivity(intent); Intent intent = new Intent(); intent.setAction(android .content.Intent.ACTION_VIEW); File file = new File("/sdcard/test.mp3"); intent.setDataAndType(Uri .fromFile(file), "audio/*"); startActivity(intent);

7.设置文本外观

setTextAppearance(context, android .R.style.TextAppearance_Medium); android :textAppearance="?android :attr/textAppearanceMedium"

8.设置单独的发起模式：

<activity android :name=".ArtistActivity" android :label="Artist" android :launchMode="singleTop"> </activity> Intent i = new Intent(); i.putExtra(EXTRA_KEY_ARTIST, id); i.setClass(this, ArtistActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP); startActivity(i);

9.创建一个圆角图片
这个的主要原理其实就是利用遮罩，先创建一个圆角方框 然后将图片放在下面：

Bitmap myCoolBitmap = ... ; int w = myCoolBitmap.getWidth(), h = myCoolBitmap.getHeight(); Bitmap rounder = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(rounder); Paint xferPaint = new Paint(Paint.ANTI_ALIAS_FLAG); xferPaint.setColor(Color.RED); canvas.drawRoundRect(new RectF(0,0,w,h), 20.0f, 20.0f, xferPaint); xferPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN)); //然后呢实现 canvas.drawBitmap(myCoolBitmap, 0,0, null); canvas.drawBitmap(rounder, 0, 0, xferPaint);

10.在notification 上的icon上加上数字 给人提示有多少个未读

Notification notification = new Notification (icon, tickerText, when); notification .number = 4;

11背景渐变：
首先建立文件drawable/shape.xml

<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android ="http://schemas.android .com/apk/res/android " android :shape="rectangle"> <gradient android :startColor="#FFFFFFFF" android :endColor="#FFFF0000" android :angle="270"/> </shape>

在该文件中设置渐变的开始颜色(startColor)、结束颜色(endColor)和角度(angle)

接着创建一个主题values/style.xml

<?xml version="1.0" encoding="utf-8"?> <resources> <mce:style name="NewTheme" parent="android :Theme"><!-- <item name="android :background">@drawable/shape</item> --></mce:style><style name="NewTheme" parent="android :Theme" mce_bogus="1"> <item name="android :background">@drawable/shape</item> </style> </resources>

然后在AndroidManifest.xml文件中的application或activity中引入该主题,如:

<activity android :name=".ShapeDemo" android :theme="@style/NewTheme">

该方法同样适用于控件  http://17f8.cn/trackback.php?tbID=259&extra=9d45e9
12. 储存数据 当你在一个实例中保存静态数据，此示例关闭后 下一个实例想引用 静态数据就会为null，这里呢必须重写applition
public class MyApplication extends Application{ private String thing = null; public String getThing(){ return thing; } public void setThing( String thing ){ this.thing = thing; } } public class MyActivity extends Activity { private MyApplication app; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); app = ((MyApplication)getApplication()); String thing = app.getThing(); } }