Android 特殊用法--来自中国移动开发社区

1.让一个图片透明：

复制到剪贴板   Java代码

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

2.直接发送邮件：

复制到剪贴板   Java代码

 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：

复制到剪贴板   Java代码

 WindowManager.LayoutParams lp = getWindow().getAttributes();
 lp.screenBrightness =  100  /  100 .0f;
 getWindow().setAttributes(lp);

4.过滤特定文本

复制到剪贴板   Java代码

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

5.scrollView scroll停止事件

复制到剪贴板   Java代码

 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

复制到剪贴板   C/C++代码

 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

复制到剪贴板   Java代码

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

8.设置单独的发起模式：

复制到剪贴板   Java代码

 <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：

复制到剪贴板   Java代码

 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));

复制到剪贴板   Java代码

 //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

复制到剪贴板   Java代码

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

11背景渐变：
首先建立文件drawable/shape.xml

复制到剪贴板   Java代码

 <?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

复制到剪贴板   Java代码

 <?xml version= "1.0"  encoding= "utf-8" ?>
 <resources>
 <style name= "NewTheme"  parent= "android :Theme" >
 <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:

复制到剪贴板   Java代码

 <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

复制到剪贴板   Java代码

 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();
       }
       }