Android 特殊用法介绍

核心提示：startActivity(intent);Intent intent = new Intent();intent.setAction(android .content.Intent.ACTION_VIEW);File file = new File("/sdcard/test.mp3");inte

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"? >