實用代碼段（二）

1、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);
    }

2、 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);
    }

3、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()));
    }

4、保存恢復ListView當前位

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);
        }
    }

可以保存在Preference中或者是數據庫中，數據加載完後再設置。

5、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;
    }

6、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());
    }

7、 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());
                }
            }
        });
    }

8、發送不重複的通知（Notification）

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);
    }

代碼說明：
關鍵點在這個requestCode，這裏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。

9、代碼設置TextView的樣式

使用過自定義Dialog可能馬上會想到用如下代碼：

   new TextView(this,null,R.style.text_style); 

但你運行這代碼你會發現毫無作用。正確用法 ：

   new TextView(new ContextThemeWrapper(this, R.style.text_style))

10、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 "";
    }

11、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);

注意：setDisplayZoomControls是在API Level 11中新增。

12、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";
        }
    }

13、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

14、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;
    }