Android 一些非常实用的 Android 开发资源
jopen
11年前
一、获取已经安装APK的路径
PackageManager pm = getPackageManager(); for (ApplicationInfo app : pm.getInstalledApplications(0)) { Log.d("PackageList", "package: " + app.packageName + ", sourceDir: " + app.sourceDir); } 输出如下：
package: com.tmobile.thememanager, sourceDir: /system/app/ThemeManager.apk package: com.touchtype.swiftkey, sourceDir: /data/app/com.touchtype.swiftkey-1.apk
二、 多进程Preferences数据共享
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); } 三、泛型ArrayList转数组
@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())); } 四、 保存恢复ListView当前位置
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;//取出保存的数据 int top = 0;//取出保存的数据 mListView.setSelectionFromTop(position, top); } } 可以保存在Preference中或者是数据库中，数据加载完后再设置。
五、调用 便携式热点和数据共享 设置
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; } 六、 格式化输出IP地址
public static String getIp(Context ctx) { return Formatter.formatIpAddress((WifiManager) ctx.getSystemService(Context.WIFI_SERVICE).getConnectionInfo().getIpAddress()); } 七、 文件夹排序（先文件夹排序，后文件排序）
public static void sortFiles(File[] files) { Arrays.sort(files, new Comparator<File>() { @Override public int compare(File lhs, File rhs) { //返回负数表示o1 小于o2，返回0 表示o1和o2相等，返回正数表示o1大于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()); } } }); } 一、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; } 二、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; } 三、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(); } 四、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; } 五、使用TransitionDrawable实现渐变效果
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); } 比使用AlphaAnimation效果要好，可避免出现闪烁问题。
六、 扫描指定的文件
sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
用途：从本软件新增、修改、删除图片、文件某一个文件（音频、视频）需要更新系统媒体库时使用，不必扫描整个SD卡。
七、Dip转px
public static int dipToPX(final Context ctx, float dip) { return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, ctx.getResources().getDisplayMetrics()); } 用途：难免在Activity代码中设置位置、大小等，本方法就很有用了！
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) >= Configuration.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="#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); } } 6、计算字宽
public static float GetTextWidth(String text, float Size) { TextPaint FontPaint = new TextPaint(); FontPaint.setTextSize(Size); return FontPaint.measureText(text); } 注意如果设置了textStyle，还需要进一步设置TextPaint。