編輯:關於android開發
一些不常見確又很實用的代碼塊。
1.精確獲取屏幕尺寸(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); }
2.判斷是否是平板(官方用法)
public static boolean isTablet(Context context) { return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE; }
3.文字根據狀態更改顏色 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>
4.背景色根據狀態更改顏色 android:backgroup(如果直接給背景色color會報錯)
<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>
5.啟動APK的默認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); } }
6.計算字寬(注意如果設置了textStyle,還需要進一步設置TextPaint)
public static float GetTextWidth(String text, float Size) { TextPaint FontPaint = new TextPaint(); FontPaint.setTextSize(Size); return FontPaint.measureText(text); }
7.獲取應用程序下所有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; }
8.檢測字符串中是否包含漢字
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; }
9.檢測字符串中只能包含:中文、數字、下劃線(_)、橫線(-)
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.檢查有沒有應用程序來接受處理你發出的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; }
11.使用TransitionDrawable實現漸變效果(比使用AlphaAnimation效果要好,可避免出現閃爍問題)
private void setImageBitmap(ImageView imageView, Bitmap bitmap) { // Use TransitionDrawable to fade in. final TransitionDrawable td = new TransitionDrawable(new Drawable[] { new ColorDrawable(android.R.color.transparent), new BitmapDrawable(mContext.getResources(), bitmap) }); //noinspection deprecation imageView.setBackgroundDrawable(imageView.getDrawable()); imageView.setImageDrawable(td); td.startTransition(200); }
12.掃描指定的文件(用途:從本軟件新增、修改、刪除圖片、文件某一個文件(音頻、視頻)需要更新系統媒體庫時使用,不必掃描整個SD卡)
sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
13.Dip轉px(難免在Activity代碼中設置位置、大小等,本方法就很有用了)
public static int dipToPX(final Context ctx, float dip) { return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, ctx.getResources().getDisplayMetrics()); }
14.獲取已經安裝APK的路徑
PackageManager pm = getPackageManager(); for (ApplicationInfo app : pm.getInstalledApplications(0)) { Log.d("PackageList", "package: " + app.packageName + ", sourceDir: " + app.sourceDir); }
15.多進程Preferences數據共享
public static void putStringProcess(Context ctx, String key, String value) { SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS); Editor editor = sharedPreferences.edit(); editor.putString(key, value); editor.commit(); } public static String getStringProcess(Context ctx, String key, String defValue) { SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS); return sharedPreferences.getString(key, defValue); }
16.泛型ArrayList轉數組
@SuppressWarnings("unchecked") public static <T> T[] toArray(Class<?> cls, ArrayList<T> items) { if (items == null || items.size() == 0) { return (T[]) Array.newInstance(cls, 0); } return items.toArray((T[]) Array.newInstance(cls, items.size())); }
17.保存恢復ListView當前位置(可以保存在Preference中或者是數據庫中,數據加載完後再設置)
private void saveCurrentPosition() { if (mListView != null) { int position = mListView.getFirstVisiblePosition(); View v = mListView.getChildAt(0); int top = (v == null) ? 0 : v.getTop(); //保存position和top } } private void restorePosition() { if (mFolder != null && mListView != null) { int position = 0;//取出保存的數據 int top = 0;//取出保存的數據 mListView.setSelectionFromTop(position, top); } }
18.調用便攜式熱點和數據共享設置
public static Intent getHotspotSetting() { Intent intent = new Intent(); intent.setAction(Intent.ACTION_MAIN); ComponentName com = new ComponentName("com.android.settings", "com.android.settings.TetherSettings"); intent.setComponent(com); return intent; }
19.格式化輸出IP地址
public static String getIp(Context ctx) { return Formatter.formatIpAddress((WifiManager) ctx.getSystemService(Context.WIFI_SERVICE).getConnectionInfo().getIpAddress()); }
20.文件夾排序(先文件夾排序,後文件排序)
public static void sortFiles(File[] files) { Arrays.sort(files, new Comparator<File>() { @Override public int compare(File lhs, File rhs) { //返回負數表示o1 小於o2,返回0 表示o1和o2相等,返回正數表示o1大於o2。 boolean l1 = lhs.isDirectory(); boolean l2 = rhs.isDirectory(); if (l1 && !l2) return -1; else if (!l1 && l2) return 1; else { return lhs.getName().compareTo(rhs.getName()); } } }); }
21.發送不重復的通知Notification(關鍵點在這個requestCode,這裡使用的是當前系統時間,巧妙的保證了每次都是一個新的Notification產生)
public static void sendNotification(Context context, String title, String message, Bundle extras) { Intent mIntent = new Intent(context, FragmentTabsActivity.class); mIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); mIntent.putExtras(extras); int requestCode = (int) System.currentTimeMillis(); PendingIntent mContentIntent = PendingIntent.getActivity(context, requestCode, mIntent, 0); Notification mNotification = new NotificationCompat.Builder(context) .setContentTitle(title).setSmallIcon(R.drawable.app_icon) .setContentIntent(mContentIntent).setContentText(message) .build(); mNotification.flags |= Notification.FLAG_AUTO_CANCEL; mNotification.defaults = Notification.DEFAULT_ALL; NotificationManager mNotificationManager = (NotificationManager) context .getSystemService(Context.NOTIFICATION_SERVICE); mNotificationManager.notify(requestCode, mNotification); }
22.代碼設置TextView的樣式
new TextView(new ContextThemeWrapper(this, R.style.text_style))
23.ip地址轉成8位十六進制串
/** ip轉16進制 */ public static String ipToHex(String ips) { StringBuffer result = new StringBuffer(); if (ips != null) { StringTokenizer st = new StringTokenizer(ips, "."); while (st.hasMoreTokens()) { String token = Integer.toHexString(Integer.parseInt(st.nextToken())); if (token.length() == 1) token = "0" + token; result.append(token); } } return result.toString(); } /** 16進制轉ip */ public static String texToIp(String ips) { try { StringBuffer result = new StringBuffer(); if (ips != null && ips.length() == 8) { for (int i = 0; i < 8; i += 2) { if (i != 0) result.append('.'); result.append(Integer.parseInt(ips.substring(i, i + 2), 16)); } } return result.toString(); } catch (NumberFormatException ex) { Logger.e(ex); } return ""; }
24.WebView保留縮放功能但隱藏縮放控件
mWebView.getSettings().setSupportZoom(true); mWebView.getSettings().setBuiltInZoomControls(true); if (DeviceUtils.hasHoneycomb()) mWebView.getSettings().setDisplayZoomControls(false);
25.獲取網絡類型名稱
public static String getNetworkTypeName(Context context) { if (context != null) { ConnectivityManager connectMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); if (connectMgr != null) { NetworkInfo info = connectMgr.getActiveNetworkInfo(); if (info != null) { switch (info.getType()) { case ConnectivityManager.TYPE_WIFI: return "WIFI"; case ConnectivityManager.TYPE_MOBILE: return getNetworkTypeName(info.getSubtype()); } } } } return getNetworkTypeName(TelephonyManager.NETWORK_TYPE_UNKNOWN); } public static String getNetworkTypeName(int type) { switch (type) { case TelephonyManager.NETWORK_TYPE_GPRS: return "GPRS"; case TelephonyManager.NETWORK_TYPE_EDGE: return "EDGE"; case TelephonyManager.NETWORK_TYPE_UMTS: return "UMTS"; case TelephonyManager.NETWORK_TYPE_HSDPA: return "HSDPA"; case TelephonyManager.NETWORK_TYPE_HSUPA: return "HSUPA"; case TelephonyManager.NETWORK_TYPE_HSPA: return "HSPA"; case TelephonyManager.NETWORK_TYPE_CDMA: return "CDMA"; case TelephonyManager.NETWORK_TYPE_EVDO_0: return "CDMA - EvDo rev. 0"; case TelephonyManager.NETWORK_TYPE_EVDO_A: return "CDMA - EvDo rev. A"; case TelephonyManager.NETWORK_TYPE_EVDO_B: return "CDMA - EvDo rev. B"; case TelephonyManager.NETWORK_TYPE_1xRTT: return "CDMA - 1xRTT"; case TelephonyManager.NETWORK_TYPE_LTE: return "LTE"; case TelephonyManager.NETWORK_TYPE_EHRPD: return "CDMA - eHRPD"; case TelephonyManager.NETWORK_TYPE_IDEN: return "iDEN"; case TelephonyManager.NETWORK_TYPE_HSPAP: return "HSPA+"; default: return "UNKNOWN"; } }
26.Android解壓Zip包
/** * 解壓一個壓縮文檔 到指定位置 * * @param zipFileString 壓縮包的名字 * @param outPathString 指定的路徑 * @throws Exception */ public static void UnZipFolder(String zipFileString, String outPathString) throws Exception { java.util.zip.ZipInputStream inZip = new java.util.zip.ZipInputStream(new java.io.FileInputStream(zipFileString)); java.util.zip.ZipEntry zipEntry; String szName = ""; while ((zipEntry = inZip.getNextEntry()) != null) { szName = zipEntry.getName(); if (zipEntry.isDirectory()) { // get the folder name of the widget szName = szName.substring(0, szName.length() - 1); java.io.File folder = new java.io.File(outPathString + java.io.File.separator + szName); folder.mkdirs(); } else { java.io.File file = new java.io.File(outPathString + java.io.File.separator + szName); file.createNewFile(); // get the output stream of the file java.io.FileOutputStream out = new java.io.FileOutputStream(file); int len; byte[] buffer = new byte[1024]; // read (len) bytes into buffer while ((len = inZip.read(buffer)) != -1) { // write (len) byte from buffer at the position 0 out.write(buffer, 0, len); out.flush(); } out.close(); } }//end of while inZip.close(); }//end of func
27.從assets中讀取文本和圖片資源
/** 從assets 文件夾中讀取文本數據 */ public static String getTextFromAssets(final Context context, String fileName) { String result = ""; try { InputStream in = context.getResources().getAssets().open(fileName); // 獲取文件的字節數 int lenght = in.available(); // 創建byte數組 byte[] buffer = new byte[lenght]; // 將文件中的數據讀到byte數組中 in.read(buffer); result = EncodingUtils.getString(buffer, "UTF-8"); in.close(); } catch (Exception e) { e.printStackTrace(); } return result; } /** 從assets 文件夾中讀取圖片 */ public static Drawable loadImageFromAsserts(final Context ctx, String fileName) { try { InputStream is = ctx.getResources().getAssets().open(fileName); return Drawable.createFromStream(is, null); } catch (IOException e) { if (e != null) { e.printStackTrace(); } } catch (OutOfMemoryError e) { if (e != null) { e.printStackTrace(); } } catch (Exception e) { if (e != null) { e.printStackTrace(); } } return null; }
28.展開、收起狀態欄(可用於點擊Notifacation之後收起狀態欄)
public static final void collapseStatusBar(Context ctx) { Object sbservice = ctx.getSystemService("statusbar"); try { Class<?> statusBarManager = Class.forName("android.app.StatusBarManager"); Method collapse; if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) { collapse = statusBarManager.getMethod("collapsePanels"); } else { collapse = statusBarManager.getMethod("collapse"); } collapse.invoke(sbservice); } catch (Exception e) { e.printStackTrace(); } } public static final void expandStatusBar(Context ctx) { Object sbservice = ctx.getSystemService("statusbar"); try { Class<?> statusBarManager = Class.forName("android.app.StatusBarManager"); Method expand; if (Build.VERSION.SDK_INT >= 17) { expand = statusBarManager.getMethod("expandNotificationsPanel"); } else { expand = statusBarManager.getMethod("expand"); } expand.invoke(sbservice); } catch (Exception e) { e.printStackTrace(); } }
29.獲取狀態欄高度
public static int getStatusBarHeight(Context context){ Class<?> c = null; Object obj = null; Field field = null; int x = 0, statusBarHeight = 0; try { c = Class.forName("com.android.internal.R$dimen"); obj = c.newInstance(); field = c.getField("status_bar_height"); x = Integer.parseInt(field.get(obj).toString()); statusBarHeight = context.getResources().getDimensionPixelSize(x); } catch (Exception e1) { e1.printStackTrace(); } return statusBarHeight; }
30.ListView使用ViewHolder極簡寫法
public static <T extends View> T getAdapterView(View convertView, int id) { SparseArray<View> viewHolder = (SparseArray<View>) convertView.getTag(); if (viewHolder == null) { viewHolder = new SparseArray<View>(); convertView.setTag(viewHolder); } View childView = viewHolder.get(id); if (childView == null) { childView = convertView.findViewById(id); viewHolder.put(id, childView); } return (T) childView; } //用法 @Override public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { convertView = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_feed_item, parent, false); } ImageView thumnailView = getAdapterView(convertView, R.id.video_thumbnail); ImageView avatarView = getAdapterView(convertView, R.id.user_avatar); ImageView appIconView = getAdapterView(convertView, R.id.app_icon);
31.設置Activity透明
<style name="TransparentActivity" parent="AppBaseTheme"> <item name="android:windowBackground">@android:color/transparent</item> <item name="android:colorBackgroundCacheHint">@null</item> <item name="android:windowIsTranslucent">true</item> <item name="android:windowNoTitle">true</item> <item name="android:windowContentOverlay">@null</item> </style>
說明:AppBaseTheme一般是你application指定的android:theme是啥這裡就是啥,否則Activity內部的空間風格可能不一致。
用途:用於模擬Dialog效果,比如再Service中沒法用Dialog,就可以用Activity來模擬
32.代碼切換全屏
//切換到全屏 getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN); getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); //切換到非全屏 getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); getWindow().addFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
注意:切換到全屏時,底部的虛擬按鍵仍然是顯示的。次方法可多次調用用於切換
用途:播放器界面經常會用到
33.調用開發者選項中顯示觸摸位置功能(設置1顯示,設置0不顯示)
android.provider.Settings.System.putInt(getContentResolver(), "show_touches", 1);
34.獲取設備上已安裝並且可啟動的應用列表(使用getInstalledApplications會返回很多無法啟動甚至沒有圖標的系統應用。ResolveInfo.activityInfo.applicationInfo也能取到你想要的數據)
Intent intent = new Intent(Intent.ACTION_MAIN); intent.addCategory(Intent.CATEGORY_LAUNCHER); List<ResolveInfo> activities = getPackageManager().queryIntentActivities(intent, 0)
轉載自 農民伯伯: http://over140.cnblogs.com
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