Android 一些功能代码详解编程语言

<Activity android:theme="@android:style/Theme.NoTitleBar.Fullscreen".. />

横屏

>setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

安装apk

private void install(File file) { 	Intent intent = new Intent(); 	intent.setAction(Intent.ACTION_VIEW); //	intent.setData(Uri.fromFile(file)); //	intent.setType("application/vnd.android.package-archive"); //mime的数据类型 plain/text image/jpeg  	intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");//该mime 表示 .apk 文件类型 	startActivity(intent); }

精确获取屏幕尺寸（例如：3.5、4.0、5.0寸屏幕） 

public static double getScreenPhysicalSize(Activity ctx) { 
	DisplayMetrics dm = new DisplayMetrics(); 
	ctx.getWindowManager().getDefaultDisplay().getMetrics(dm); 
	//对角线像素长 
	double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2)); 
	return diagonalPixels / (160 * dm.density); //160像素，density=1 
}

启动Apk的默认Activity

public static void startApkActivity(final Context ctx, String packageName) { 
	PackageManager pm = ctx.getPackageManager(); 
	PackageInfo pi; 
	try { 
	<span style="white-space:pre">	pi = pm.getPackageInfo(packageName, 0); 
		Intent intent = new Intent(Intent.ACTION_MAIN, null); 
		intent.addCategory(Intent.CATEGORY_LAUNCHER); 
		intent.setPackage(pi.packageName); 
 
		List<ResolveInfo> apps = pm.queryIntentActivities(intent, 0); 
 
		ResolveInfo ri = apps.iterator().next(); 
		if (ri != null) { 
			String className = ri.activityInfo.name; 
			intent.setComponent(new ComponentName(packageName, className)); 
			ctx.startActivity(intent); 
		} 
	} catch (NameNotFoundException e) { 
		Log.e("startActivity", e.getMessage()); 
	} 
}

 根据手机的分辨率从 dp 的单位 转成为 px(像素) 

public static int dip2px(Context context, float dpValue) {   
	final float scale = context.getResources().getDisplayMetrics().density;   
	return (int) (dpValue * scale + 0.5f);   
}  

根据手机的分辨率从 px(像素) 的单位 转成为dp   

public static int px2dip(Context context, float pxValue) {   
<span style="white-space:pre">	final float scale = context.getResources().getDisplayMetrics().density;   
	return (int) (pxValue / scale + 0.5f);   
}  

重启应用程序

Intent i = getBaseContext().getPackageManager()// 
	.getLaunchIntentForPackage(getBaseContext().getPackageName());  
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);  
startActivity(i);

判断字宽

public static float GetTextWidth(String text, float size) { 
	TextPaint fontPaint = new TextPaint(); 
	fontPaint.setTextSize(size); 
	return fontPaint.measureText(text); 
}