Android 特殊用法--来自中国移动开发社区

1.让一个图片透明：

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

2.直接发送邮件：

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

3.程序控制屏幕变亮：

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

4.过滤特定文本

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

5.scrollView scroll停止事件

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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

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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

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

8.设置单独的发起模式：

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<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：

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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));

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//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

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

11背景渐变：
首先建立文件drawable/shape.xml

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<?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

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<?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:

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<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

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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();
      }
      }