Android实用代码

Android实用代码

http://my.eoe.cn/861996/archive/1366.html?f_section=hot

1、 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);
        double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2));
        return diagonalPixels / (160 * dm.density);
   }

一般是7寸以上是平板

2、 判断是否是平板（官方用法） 

public static boolean isTablet(Context context) {
        return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configura tion.SCREENLAYOUT_SIZE_LARGE;
}
3、 文字根据状态更改颜色 android:textColor

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="#53c1bd" android:state_selected="true"/>
    <item android:color="#53c1bd" android:state_focused="true"/>
    <item android:color="#53c1bd" android:state_pressed="true"/>
    <item android:color="#777777"/>
</selector>
放在res/color/目录下

4、背景色根据状态更改颜色 android:backgroup

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_selected="true">
 <shape>
            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59 f" />
        </shape>
 </item>
    <item android:state_focused="true">
 <shape>
            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59 f" />
        </shape>
    </item>
    <item android:state_pressed="true">
 <shape>
            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59 f" />
        </shape>
 </item>
    <item>
 <shape>
            <gradient android:angle="0" android:centerColor="#00ff00" android:endColor="00ff00" android:startColor="00ff00" 		/>
        </shape>
 </item>
</selector>
如果直接给背景色color会报错。


5、 启动APK的默认Activity
public static void startApkActivity(final Context ctx, String packageName) {
        PackageManager pm = ctx.getPackageManager();
        PackageInfo pi;
        try {
            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);
        }
    }
7、计算字宽

public static float GetTextWidth(String text, float Size) {

TextPaint FontPaint = new TextPaint ();

FontPaint.setTextSize(Size);

returnFontPaint.measureText(text);

}