Java tutorial
/** * Copyright 2010-present Facebook. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.facebook; import android.content.Context; import android.content.SharedPreferences; import android.os.Bundle; import android.util.Log; import com.facebook.internal.Logger; import com.facebook.internal.Utility; import com.facebook.internal.Validate; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.util.ArrayList; import java.util.List; import java.util.Map; /* * <p> * An implementation of {@link TokenCachingStrategy TokenCachingStrategy} that uses Android SharedPreferences * to persist information. * </p> * <p> * The data to be cached is passed in via a Bundle. Only non-null key-value-pairs where * the value is one of the following types (or an array of the same) are persisted: * boolean, byte, int, long, float, double, char. In addition, String and List<String> * are also supported. * </p> */ public class SharedPreferencesTokenCachingStrategy extends TokenCachingStrategy { private static final String DEFAULT_CACHE_KEY = "com.facebook.SharedPreferencesTokenCachingStrategy.DEFAULT_KEY"; private static final String TAG = SharedPreferencesTokenCachingStrategy.class.getSimpleName(); private static final String JSON_VALUE_TYPE = "valueType"; private static final String JSON_VALUE = "value"; private static final String JSON_VALUE_ENUM_TYPE = "enumType"; private static final String TYPE_BOOLEAN = "bool"; private static final String TYPE_BOOLEAN_ARRAY = "bool[]"; private static final String TYPE_BYTE = "byte"; private static final String TYPE_BYTE_ARRAY = "byte[]"; private static final String TYPE_SHORT = "short"; private static final String TYPE_SHORT_ARRAY = "short[]"; private static final String TYPE_INTEGER = "int"; private static final String TYPE_INTEGER_ARRAY = "int[]"; private static final String TYPE_LONG = "long"; private static final String TYPE_LONG_ARRAY = "long[]"; private static final String TYPE_FLOAT = "float"; private static final String TYPE_FLOAT_ARRAY = "float[]"; private static final String TYPE_DOUBLE = "double"; private static final String TYPE_DOUBLE_ARRAY = "double[]"; private static final String TYPE_CHAR = "char"; private static final String TYPE_CHAR_ARRAY = "char[]"; private static final String TYPE_STRING = "string"; private static final String TYPE_STRING_LIST = "stringList"; private static final String TYPE_ENUM = "enum"; private String cacheKey; private SharedPreferences cache; /** * Creates a default {@link SharedPreferencesTokenCachingStrategy SharedPreferencesTokenCachingStrategy} * instance that provides access to a single set of token information. * * @param context * The Context object to use to get the SharedPreferences object. * * @throws NullPointerException if the passed in Context is null */ public SharedPreferencesTokenCachingStrategy(Context context) { this(context, null); } /** * Creates a {@link SharedPreferencesTokenCachingStrategy SharedPreferencesTokenCachingStrategy} instance * that is distinct for the passed in cacheKey. * * @param context * The Context object to use to get the SharedPreferences object. * * @param cacheKey * Identifies a distinct set of token information. * * @throws NullPointerException if the passed in Context is null */ public SharedPreferencesTokenCachingStrategy(Context context, String cacheKey) { Validate.notNull(context, "context"); this.cacheKey = Utility.isNullOrEmpty(cacheKey) ? DEFAULT_CACHE_KEY : cacheKey; // If the application context is available, use that. However, if it isn't // available (possibly because of a context that was created manually), use // the passed in context directly. Context applicationContext = context.getApplicationContext(); context = applicationContext != null ? applicationContext : context; this.cache = context.getSharedPreferences(this.cacheKey, Context.MODE_PRIVATE); } /** * Returns a Bundle that contains the information stored in this cache * * @return A Bundle with the information contained in this cache */ public Bundle load() { Bundle settings = new Bundle(); Map<String, ?> allCachedEntries = cache.getAll(); for (String key : allCachedEntries.keySet()) { try { deserializeKey(key, settings); } catch (JSONException e) { // Error in the cache. So consider it corrupted and return null Logger.log(LoggingBehavior.CACHE, Log.WARN, TAG, "Error reading cached value for key: '" + key + "' -- " + e); return null; } } return settings; } /** * Persists all supported data types present in the passed in Bundle, to the * cache * * @param bundle * The Bundle containing information to be cached */ public void save(Bundle bundle) { Validate.notNull(bundle, "bundle"); SharedPreferences.Editor editor = cache.edit(); for (String key : bundle.keySet()) { try { serializeKey(key, bundle, editor); } catch (JSONException e) { // Error in the bundle. Don't store a partial cache. Logger.log(LoggingBehavior.CACHE, Log.WARN, TAG, "Error processing value for key: '" + key + "' -- " + e); // Bypass the commit and just return. This cancels the entire edit transaction return; } } editor.apply(); } /** * Clears out all token information stored in this cache. */ public void clear() { cache.edit().clear().apply(); } private void serializeKey(String key, Bundle bundle, SharedPreferences.Editor editor) throws JSONException { Object value = bundle.get(key); if (value == null) { // Cannot serialize null values. return; } String supportedType = null; JSONArray jsonArray = null; JSONObject json = new JSONObject(); if (value instanceof Byte) { supportedType = TYPE_BYTE; json.put(JSON_VALUE, ((Byte) value).intValue()); } else if (value instanceof Short) { supportedType = TYPE_SHORT; json.put(JSON_VALUE, ((Short) value).intValue()); } else if (value instanceof Integer) { supportedType = TYPE_INTEGER; json.put(JSON_VALUE, ((Integer) value).intValue()); } else if (value instanceof Long) { supportedType = TYPE_LONG; json.put(JSON_VALUE, ((Long) value).longValue()); } else if (value instanceof Float) { supportedType = TYPE_FLOAT; json.put(JSON_VALUE, ((Float) value).doubleValue()); } else if (value instanceof Double) { supportedType = TYPE_DOUBLE; json.put(JSON_VALUE, ((Double) value).doubleValue()); } else if (value instanceof Boolean) { supportedType = TYPE_BOOLEAN; json.put(JSON_VALUE, ((Boolean) value).booleanValue()); } else if (value instanceof Character) { supportedType = TYPE_CHAR; json.put(JSON_VALUE, value.toString()); } else if (value instanceof String) { supportedType = TYPE_STRING; json.put(JSON_VALUE, value); } else if (value instanceof Enum<?>) { supportedType = TYPE_ENUM; json.put(JSON_VALUE, value.toString()); json.put(JSON_VALUE_ENUM_TYPE, value.getClass().getName()); } else { // Optimistically create a JSONArray. If not an array type, we can null // it out later jsonArray = new JSONArray(); if (value instanceof byte[]) { supportedType = TYPE_BYTE_ARRAY; for (byte v : (byte[]) value) { jsonArray.put((int) v); } } else if (value instanceof short[]) { supportedType = TYPE_SHORT_ARRAY; for (short v : (short[]) value) { jsonArray.put((int) v); } } else if (value instanceof int[]) { supportedType = TYPE_INTEGER_ARRAY; for (int v : (int[]) value) { jsonArray.put(v); } } else if (value instanceof long[]) { supportedType = TYPE_LONG_ARRAY; for (long v : (long[]) value) { jsonArray.put(v); } } else if (value instanceof float[]) { supportedType = TYPE_FLOAT_ARRAY; for (float v : (float[]) value) { jsonArray.put((double) v); } } else if (value instanceof double[]) { supportedType = TYPE_DOUBLE_ARRAY; for (double v : (double[]) value) { jsonArray.put(v); } } else if (value instanceof boolean[]) { supportedType = TYPE_BOOLEAN_ARRAY; for (boolean v : (boolean[]) value) { jsonArray.put(v); } } else if (value instanceof char[]) { supportedType = TYPE_CHAR_ARRAY; for (char v : (char[]) value) { jsonArray.put(String.valueOf(v)); } } else if (value instanceof List<?>) { supportedType = TYPE_STRING_LIST; @SuppressWarnings("unchecked") List<String> stringList = (List<String>) value; for (String v : stringList) { jsonArray.put((v == null) ? JSONObject.NULL : v); } } else { // Unsupported type. Clear out the array as a precaution even though // it is redundant with the null supportedType. jsonArray = null; } } if (supportedType != null) { json.put(JSON_VALUE_TYPE, supportedType); if (jsonArray != null) { // If we have an array, it has already been converted to JSON. So use // that instead. json.putOpt(JSON_VALUE, jsonArray); } String jsonString = json.toString(); editor.putString(key, jsonString); } } private void deserializeKey(String key, Bundle bundle) throws JSONException { String jsonString = cache.getString(key, "{}"); JSONObject json = new JSONObject(jsonString); String valueType = json.getString(JSON_VALUE_TYPE); if (valueType.equals(TYPE_BOOLEAN)) { bundle.putBoolean(key, json.getBoolean(JSON_VALUE)); } else if (valueType.equals(TYPE_BOOLEAN_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); boolean[] array = new boolean[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = jsonArray.getBoolean(i); } bundle.putBooleanArray(key, array); } else if (valueType.equals(TYPE_BYTE)) { bundle.putByte(key, (byte) json.getInt(JSON_VALUE)); } else if (valueType.equals(TYPE_BYTE_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); byte[] array = new byte[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = (byte) jsonArray.getInt(i); } bundle.putByteArray(key, array); } else if (valueType.equals(TYPE_SHORT)) { bundle.putShort(key, (short) json.getInt(JSON_VALUE)); } else if (valueType.equals(TYPE_SHORT_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); short[] array = new short[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = (short) jsonArray.getInt(i); } bundle.putShortArray(key, array); } else if (valueType.equals(TYPE_INTEGER)) { bundle.putInt(key, json.getInt(JSON_VALUE)); } else if (valueType.equals(TYPE_INTEGER_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); int[] array = new int[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = jsonArray.getInt(i); } bundle.putIntArray(key, array); } else if (valueType.equals(TYPE_LONG)) { bundle.putLong(key, json.getLong(JSON_VALUE)); } else if (valueType.equals(TYPE_LONG_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); long[] array = new long[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = jsonArray.getLong(i); } bundle.putLongArray(key, array); } else if (valueType.equals(TYPE_FLOAT)) { bundle.putFloat(key, (float) json.getDouble(JSON_VALUE)); } else if (valueType.equals(TYPE_FLOAT_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); float[] array = new float[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = (float) jsonArray.getDouble(i); } bundle.putFloatArray(key, array); } else if (valueType.equals(TYPE_DOUBLE)) { bundle.putDouble(key, json.getDouble(JSON_VALUE)); } else if (valueType.equals(TYPE_DOUBLE_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); double[] array = new double[jsonArray.length()]; for (int i = 0; i < array.length; i++) { array[i] = jsonArray.getDouble(i); } bundle.putDoubleArray(key, array); } else if (valueType.equals(TYPE_CHAR)) { String charString = json.getString(JSON_VALUE); if (charString != null && charString.length() == 1) { bundle.putChar(key, charString.charAt(0)); } } else if (valueType.equals(TYPE_CHAR_ARRAY)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); char[] array = new char[jsonArray.length()]; for (int i = 0; i < array.length; i++) { String charString = jsonArray.getString(i); if (charString != null && charString.length() == 1) { array[i] = charString.charAt(0); } } bundle.putCharArray(key, array); } else if (valueType.equals(TYPE_STRING)) { bundle.putString(key, json.getString(JSON_VALUE)); } else if (valueType.equals(TYPE_STRING_LIST)) { JSONArray jsonArray = json.getJSONArray(JSON_VALUE); int numStrings = jsonArray.length(); ArrayList<String> stringList = new ArrayList<String>(numStrings); for (int i = 0; i < numStrings; i++) { Object jsonStringValue = jsonArray.get(i); stringList.add(i, jsonStringValue == JSONObject.NULL ? null : (String) jsonStringValue); } bundle.putStringArrayList(key, stringList); } else if (valueType.equals(TYPE_ENUM)) { try { String enumType = json.getString(JSON_VALUE_ENUM_TYPE); @SuppressWarnings({ "unchecked", "rawtypes" }) Class<? extends Enum> enumClass = (Class<? extends Enum>) Class.forName(enumType); @SuppressWarnings("unchecked") Enum<?> enumValue = Enum.valueOf(enumClass, json.getString(JSON_VALUE)); bundle.putSerializable(key, enumValue); } catch (ClassNotFoundException e) { } catch (IllegalArgumentException e) { } } } }