Android_CodeWiki_01

 记录常用代码片，以备不时之需..wkakak，开始：

   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);
     }

 一般小于7寸的，都是非平板，属于正常智能机系列

  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) >= Configuration.SCREENLAYOUT_SIZE_L         ARGE;
    }

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>

放在工程 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="#00a59f" />
         </shape></item>
     <item android:state_focused="true"><shape>
             <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />
         </shape></item>
     <item android:state_pressed="true"><shape>
             <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />
         </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);
         return FontPaint.measureText(text);
     }

8、获取应用程序下所有Activity 

　　

  public static ArrayList<String> getActivities(Context ctx) {
       ArrayList<String> result = new ArrayList<String>();
       Intent intent = new Intent(Intent.ACTION_MAIN, null);
       intent.setPackage(ctx.getPackageName());
       for (ResolveInfo info : ctx.getPackageManager().queryIntentActivities(intent, 0)) {
           result.add(info.activityInfo.name);
       }
       return result;
   }

9、检测字符串中是否包含汉字

　　

public static boolean checkChinese(String sequence) {
        final String format = "[\\u4E00-\\u9FA5\\uF900-\\uFA2D]";
        boolean result = false;
        Pattern pattern = Pattern.compile(format);
        Matcher matcher = pattern.matcher(sequence);
        result = matcher.find();
        return result;
    }

检测字符串中只能包含：中文、数字、下划线(_)、横线(-)

 public static boolean checkNickname(String sequence) {
        final String format = "[^\\u4E00-\\u9FA5\\uF900-\\uFA2D\\w-_]";
        Pattern pattern = Pattern.compile(format);
        Matcher matcher = pattern.matcher(sequence);
        return !matcher.find();
    } 

10、检查有没有应用程序来接受处理你发出的intent

　　

  public static boolean isIntentAvailable(Context context, String action) {
         final PackageManager packageManager = context.getPackageManager();
         final Intent intent = new Intent(action);
         List<ResolveInfo> list = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
         return list.size() > 0;
     }

参考：http://www.cnblogs.com/over140/archive/2013/03/05/2706068.html