Java tutorial
/* * Copyright (C) 2011 Google Inc. * * 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.google.gson.internal.bind; import java.io.IOException; import java.math.BigDecimal; import java.math.BigInteger; import java.net.InetAddress; import java.net.URI; import java.net.URISyntaxException; import java.net.URL; import java.sql.Timestamp; import java.util.ArrayList; import java.util.BitSet; import java.util.Calendar; import java.util.Currency; import java.util.Date; import java.util.GregorianCalendar; import java.util.HashMap; import java.util.List; import java.util.Locale; import java.util.Map; import java.util.StringTokenizer; import java.util.UUID; import java.util.concurrent.atomic.AtomicBoolean; import java.util.concurrent.atomic.AtomicInteger; import java.util.concurrent.atomic.AtomicIntegerArray; import com.google.gson.Gson; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonIOException; import com.google.gson.JsonNull; import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import com.google.gson.JsonSyntaxException; import com.google.gson.TypeAdapter; import com.google.gson.TypeAdapterFactory; import com.google.gson.annotations.SerializedName; import com.google.gson.internal.LazilyParsedNumber; import com.google.gson.reflect.TypeToken; import com.google.gson.stream.JsonReader; import com.google.gson.stream.JsonToken; import com.google.gson.stream.JsonWriter; /** * Type adapters for basic types. */ public final class TypeAdapters { private TypeAdapters() { throw new UnsupportedOperationException(); } @SuppressWarnings("rawtypes") public static final TypeAdapter<Class> CLASS = new TypeAdapter<Class>() { @Override public void write(JsonWriter out, Class value) throws IOException { throw new UnsupportedOperationException("Attempted to serialize java.lang.Class: " + value.getName() + ". Forgot to register a type adapter?"); } @Override public Class read(JsonReader in) throws IOException { throw new UnsupportedOperationException( "Attempted to deserialize a java.lang.Class. Forgot to register a type adapter?"); } }.nullSafe(); public static final TypeAdapterFactory CLASS_FACTORY = newFactory(Class.class, CLASS); public static final TypeAdapter<BitSet> BIT_SET = new TypeAdapter<BitSet>() { @Override public BitSet read(JsonReader in) throws IOException { BitSet bitset = new BitSet(); in.beginArray(); int i = 0; JsonToken tokenType = in.peek(); while (tokenType != JsonToken.END_ARRAY) { boolean set; switch (tokenType) { case NUMBER: set = in.nextInt() != 0; break; case BOOLEAN: set = in.nextBoolean(); break; case STRING: String stringValue = in.nextString(); try { set = Integer.parseInt(stringValue) != 0; } catch (NumberFormatException e) { throw new JsonSyntaxException( "Error: Expecting: bitset number value (1, 0), Found: " + stringValue); } break; default: throw new JsonSyntaxException("Invalid bitset value type: " + tokenType); } if (set) { bitset.set(i); } ++i; tokenType = in.peek(); } in.endArray(); return bitset; } @Override public void write(JsonWriter out, BitSet src) throws IOException { out.beginArray(); for (int i = 0, length = src.length(); i < length; i++) { int value = (src.get(i)) ? 1 : 0; out.value(value); } out.endArray(); } }.nullSafe(); public static final TypeAdapterFactory BIT_SET_FACTORY = newFactory(BitSet.class, BIT_SET); public static final TypeAdapter<Boolean> BOOLEAN = new TypeAdapter<Boolean>() { @Override public Boolean read(JsonReader in) throws IOException { JsonToken peek = in.peek(); if (peek == JsonToken.NULL) { in.nextNull(); return null; } else if (peek == JsonToken.STRING) { // support strings for compatibility with GSON 1.7 return Boolean.parseBoolean(in.nextString()); } return in.nextBoolean(); } @Override public void write(JsonWriter out, Boolean value) throws IOException { out.value(value); } }; /** * Writes a boolean as a string. Useful for map keys, where booleans aren't * otherwise permitted. */ public static final TypeAdapter<Boolean> BOOLEAN_AS_STRING = new TypeAdapter<Boolean>() { @Override public Boolean read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return Boolean.valueOf(in.nextString()); } @Override public void write(JsonWriter out, Boolean value) throws IOException { out.value(value == null ? "null" : value.toString()); } }; public static final TypeAdapterFactory BOOLEAN_FACTORY = newFactory(boolean.class, Boolean.class, BOOLEAN); public static final TypeAdapter<Number> BYTE = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { int intValue = in.nextInt(); return (byte) intValue; } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapterFactory BYTE_FACTORY = newFactory(byte.class, Byte.class, BYTE); public static final TypeAdapter<Number> SHORT = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { return (short) in.nextInt(); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapterFactory SHORT_FACTORY = newFactory(short.class, Short.class, SHORT); public static final TypeAdapter<Number> INTEGER = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { return in.nextInt(); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapterFactory INTEGER_FACTORY = newFactory(int.class, Integer.class, INTEGER); public static final TypeAdapter<AtomicInteger> ATOMIC_INTEGER = new TypeAdapter<AtomicInteger>() { @Override public AtomicInteger read(JsonReader in) throws IOException { try { return new AtomicInteger(in.nextInt()); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, AtomicInteger value) throws IOException { out.value(value.get()); } }.nullSafe(); public static final TypeAdapterFactory ATOMIC_INTEGER_FACTORY = newFactory(AtomicInteger.class, TypeAdapters.ATOMIC_INTEGER); public static final TypeAdapter<AtomicBoolean> ATOMIC_BOOLEAN = new TypeAdapter<AtomicBoolean>() { @Override public AtomicBoolean read(JsonReader in) throws IOException { return new AtomicBoolean(in.nextBoolean()); } @Override public void write(JsonWriter out, AtomicBoolean value) throws IOException { out.value(value.get()); } }.nullSafe(); public static final TypeAdapterFactory ATOMIC_BOOLEAN_FACTORY = newFactory(AtomicBoolean.class, TypeAdapters.ATOMIC_BOOLEAN); public static final TypeAdapter<AtomicIntegerArray> ATOMIC_INTEGER_ARRAY = new TypeAdapter<AtomicIntegerArray>() { @Override public AtomicIntegerArray read(JsonReader in) throws IOException { List<Integer> list = new ArrayList<Integer>(); in.beginArray(); while (in.hasNext()) { try { int integer = in.nextInt(); list.add(integer); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } in.endArray(); int length = list.size(); AtomicIntegerArray array = new AtomicIntegerArray(length); for (int i = 0; i < length; ++i) { array.set(i, list.get(i)); } return array; } @Override public void write(JsonWriter out, AtomicIntegerArray value) throws IOException { out.beginArray(); for (int i = 0, length = value.length(); i < length; i++) { out.value(value.get(i)); } out.endArray(); } }.nullSafe(); public static final TypeAdapterFactory ATOMIC_INTEGER_ARRAY_FACTORY = newFactory(AtomicIntegerArray.class, TypeAdapters.ATOMIC_INTEGER_ARRAY); public static final TypeAdapter<Number> LONG = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { return in.nextLong(); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapter<Number> FLOAT = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return (float) in.nextDouble(); } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapter<Number> DOUBLE = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return in.nextDouble(); } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapter<Number> NUMBER = new TypeAdapter<Number>() { @Override public Number read(JsonReader in) throws IOException { JsonToken jsonToken = in.peek(); switch (jsonToken) { case NULL: in.nextNull(); return null; case NUMBER: case STRING: return new LazilyParsedNumber(in.nextString()); default: throw new JsonSyntaxException("Expecting number, got: " + jsonToken); } } @Override public void write(JsonWriter out, Number value) throws IOException { out.value(value); } }; public static final TypeAdapterFactory NUMBER_FACTORY = newFactory(Number.class, NUMBER); public static final TypeAdapter<Character> CHARACTER = new TypeAdapter<Character>() { @Override public Character read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } String str = in.nextString(); if (str.length() != 1) { throw new JsonSyntaxException("Expecting character, got: " + str); } return str.charAt(0); } @Override public void write(JsonWriter out, Character value) throws IOException { out.value(value == null ? null : String.valueOf(value)); } }; public static final TypeAdapterFactory CHARACTER_FACTORY = newFactory(char.class, Character.class, CHARACTER); public static final TypeAdapter<String> STRING = new TypeAdapter<String>() { @Override public String read(JsonReader in) throws IOException { JsonToken peek = in.peek(); if (peek == JsonToken.NULL) { in.nextNull(); return null; } /* coerce booleans to strings for backwards compatibility */ if (peek == JsonToken.BOOLEAN) { return Boolean.toString(in.nextBoolean()); } return in.nextString(); } @Override public void write(JsonWriter out, String value) throws IOException { out.value(value); } }; public static final TypeAdapter<BigDecimal> BIG_DECIMAL = new TypeAdapter<BigDecimal>() { @Override public BigDecimal read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { return new BigDecimal(in.nextString()); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, BigDecimal value) throws IOException { out.value(value); } }; public static final TypeAdapter<BigInteger> BIG_INTEGER = new TypeAdapter<BigInteger>() { @Override public BigInteger read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { return new BigInteger(in.nextString()); } catch (NumberFormatException e) { throw new JsonSyntaxException(e); } } @Override public void write(JsonWriter out, BigInteger value) throws IOException { out.value(value); } }; public static final TypeAdapterFactory STRING_FACTORY = newFactory(String.class, STRING); public static final TypeAdapter<StringBuilder> STRING_BUILDER = new TypeAdapter<StringBuilder>() { @Override public StringBuilder read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return new StringBuilder(in.nextString()); } @Override public void write(JsonWriter out, StringBuilder value) throws IOException { out.value(value == null ? null : value.toString()); } }; public static final TypeAdapterFactory STRING_BUILDER_FACTORY = newFactory(StringBuilder.class, STRING_BUILDER); public static final TypeAdapter<StringBuffer> STRING_BUFFER = new TypeAdapter<StringBuffer>() { @Override public StringBuffer read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return new StringBuffer(in.nextString()); } @Override public void write(JsonWriter out, StringBuffer value) throws IOException { out.value(value == null ? null : value.toString()); } }; public static final TypeAdapterFactory STRING_BUFFER_FACTORY = newFactory(StringBuffer.class, STRING_BUFFER); public static final TypeAdapter<URL> URL = new TypeAdapter<URL>() { @Override public URL read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } String nextString = in.nextString(); return "null".equals(nextString) ? null : new URL(nextString); } @Override public void write(JsonWriter out, URL value) throws IOException { out.value(value == null ? null : value.toExternalForm()); } }; public static final TypeAdapterFactory URL_FACTORY = newFactory(URL.class, URL); public static final TypeAdapter<URI> URI = new TypeAdapter<URI>() { @Override public URI read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } try { String nextString = in.nextString(); return "null".equals(nextString) ? null : new URI(nextString); } catch (URISyntaxException e) { throw new JsonIOException(e); } } @Override public void write(JsonWriter out, URI value) throws IOException { out.value(value == null ? null : value.toASCIIString()); } }; public static final TypeAdapterFactory URI_FACTORY = newFactory(URI.class, URI); public static final TypeAdapter<InetAddress> INET_ADDRESS = new TypeAdapter<InetAddress>() { @Override public InetAddress read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } // regrettably, this should have included both the host name and the host address return InetAddress.getByName(in.nextString()); } @Override public void write(JsonWriter out, InetAddress value) throws IOException { out.value(value == null ? null : value.getHostAddress()); } }; public static final TypeAdapterFactory INET_ADDRESS_FACTORY = newTypeHierarchyFactory(InetAddress.class, INET_ADDRESS); public static final TypeAdapter<UUID> UUID = new TypeAdapter<UUID>() { @Override public UUID read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return java.util.UUID.fromString(in.nextString()); } @Override public void write(JsonWriter out, UUID value) throws IOException { out.value(value == null ? null : value.toString()); } }; public static final TypeAdapterFactory UUID_FACTORY = newFactory(UUID.class, UUID); public static final TypeAdapter<Currency> CURRENCY = new TypeAdapter<Currency>() { @Override public Currency read(JsonReader in) throws IOException { return Currency.getInstance(in.nextString()); } @Override public void write(JsonWriter out, Currency value) throws IOException { out.value(value.getCurrencyCode()); } }.nullSafe(); public static final TypeAdapterFactory CURRENCY_FACTORY = newFactory(Currency.class, CURRENCY); public static final TypeAdapterFactory TIMESTAMP_FACTORY = new TypeAdapterFactory() { @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { if (typeToken.getRawType() != Timestamp.class) { return null; } final TypeAdapter<Date> dateTypeAdapter = gson.getAdapter(Date.class); return (TypeAdapter<T>) new TypeAdapter<Timestamp>() { @Override public Timestamp read(JsonReader in) throws IOException { Date date = dateTypeAdapter.read(in); return date != null ? new Timestamp(date.getTime()) : null; } @Override public void write(JsonWriter out, Timestamp value) throws IOException { dateTypeAdapter.write(out, value); } }; } }; public static final TypeAdapter<Calendar> CALENDAR = new TypeAdapter<Calendar>() { private static final String YEAR = "year"; private static final String MONTH = "month"; private static final String DAY_OF_MONTH = "dayOfMonth"; private static final String HOUR_OF_DAY = "hourOfDay"; private static final String MINUTE = "minute"; private static final String SECOND = "second"; @Override public Calendar read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } in.beginObject(); int year = 0; int month = 0; int dayOfMonth = 0; int hourOfDay = 0; int minute = 0; int second = 0; while (in.peek() != JsonToken.END_OBJECT) { String name = in.nextName(); int value = in.nextInt(); if (YEAR.equals(name)) { year = value; } else if (MONTH.equals(name)) { month = value; } else if (DAY_OF_MONTH.equals(name)) { dayOfMonth = value; } else if (HOUR_OF_DAY.equals(name)) { hourOfDay = value; } else if (MINUTE.equals(name)) { minute = value; } else if (SECOND.equals(name)) { second = value; } } in.endObject(); return new GregorianCalendar(year, month, dayOfMonth, hourOfDay, minute, second); } @Override public void write(JsonWriter out, Calendar value) throws IOException { if (value == null) { out.nullValue(); return; } out.beginObject(); out.name(YEAR); out.value(value.get(Calendar.YEAR)); out.name(MONTH); out.value(value.get(Calendar.MONTH)); out.name(DAY_OF_MONTH); out.value(value.get(Calendar.DAY_OF_MONTH)); out.name(HOUR_OF_DAY); out.value(value.get(Calendar.HOUR_OF_DAY)); out.name(MINUTE); out.value(value.get(Calendar.MINUTE)); out.name(SECOND); out.value(value.get(Calendar.SECOND)); out.endObject(); } }; public static final TypeAdapterFactory CALENDAR_FACTORY = newFactoryForMultipleTypes(Calendar.class, GregorianCalendar.class, CALENDAR); public static final TypeAdapter<Locale> LOCALE = new TypeAdapter<Locale>() { @Override public Locale read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } String locale = in.nextString(); StringTokenizer tokenizer = new StringTokenizer(locale, "_"); String language = null; String country = null; String variant = null; if (tokenizer.hasMoreElements()) { language = tokenizer.nextToken(); } if (tokenizer.hasMoreElements()) { country = tokenizer.nextToken(); } if (tokenizer.hasMoreElements()) { variant = tokenizer.nextToken(); } if (country == null && variant == null) { return new Locale(language); } else if (variant == null) { return new Locale(language, country); } else { return new Locale(language, country, variant); } } @Override public void write(JsonWriter out, Locale value) throws IOException { out.value(value == null ? null : value.toString()); } }; public static final TypeAdapterFactory LOCALE_FACTORY = newFactory(Locale.class, LOCALE); public static final TypeAdapter<JsonElement> JSON_ELEMENT = new TypeAdapter<JsonElement>() { @Override public JsonElement read(JsonReader in) throws IOException { switch (in.peek()) { case STRING: return new JsonPrimitive(in.nextString()); case NUMBER: String number = in.nextString(); return new JsonPrimitive(new LazilyParsedNumber(number)); case BOOLEAN: return new JsonPrimitive(in.nextBoolean()); case NULL: in.nextNull(); return JsonNull.INSTANCE; case BEGIN_ARRAY: JsonArray array = new JsonArray(); in.beginArray(); while (in.hasNext()) { array.add(read(in)); } in.endArray(); return array; case BEGIN_OBJECT: JsonObject object = new JsonObject(); in.beginObject(); while (in.hasNext()) { object.add(in.nextName(), read(in)); } in.endObject(); return object; case END_DOCUMENT: case NAME: case END_OBJECT: case END_ARRAY: default: throw new IllegalArgumentException(); } } @Override public void write(JsonWriter out, JsonElement value) throws IOException { if (value == null || value.isJsonNull()) { out.nullValue(); } else if (value.isJsonPrimitive()) { JsonPrimitive primitive = value.getAsJsonPrimitive(); if (primitive.isNumber()) { out.value(primitive.getAsNumber()); } else if (primitive.isBoolean()) { out.value(primitive.getAsBoolean()); } else { out.value(primitive.getAsString()); } } else if (value.isJsonArray()) { out.beginArray(); for (JsonElement e : value.getAsJsonArray()) { write(out, e); } out.endArray(); } else if (value.isJsonObject()) { out.beginObject(); for (Map.Entry<String, JsonElement> e : value.getAsJsonObject().entrySet()) { out.name(e.getKey()); write(out, e.getValue()); } out.endObject(); } else { throw new IllegalArgumentException("Couldn't write " + value.getClass()); } } }; public static final TypeAdapterFactory JSON_ELEMENT_FACTORY = newTypeHierarchyFactory(JsonElement.class, JSON_ELEMENT); private static final class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapter<T> { private final Map<String, T> nameToConstant = new HashMap<String, T>(); private final Map<T, String> constantToName = new HashMap<T, String>(); public EnumTypeAdapter(Class<T> classOfT) { try { for (T constant : classOfT.getEnumConstants()) { String name = constant.name(); SerializedName annotation = classOfT.getField(name).getAnnotation(SerializedName.class); if (annotation != null) { name = annotation.value(); for (String alternate : annotation.alternate()) { nameToConstant.put(alternate, constant); } } nameToConstant.put(name, constant); constantToName.put(constant, name); } } catch (NoSuchFieldException e) { throw new AssertionError(e); } } @Override public T read(JsonReader in) throws IOException { if (in.peek() == JsonToken.NULL) { in.nextNull(); return null; } return nameToConstant.get(in.nextString()); } @Override public void write(JsonWriter out, T value) throws IOException { out.value(value == null ? null : constantToName.get(value)); } } public static final TypeAdapterFactory ENUM_FACTORY = new TypeAdapterFactory() { @SuppressWarnings({ "rawtypes", "unchecked" }) @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { Class<? super T> rawType = typeToken.getRawType(); if (!Enum.class.isAssignableFrom(rawType) || rawType == Enum.class) { return null; } if (!rawType.isEnum()) { rawType = rawType.getSuperclass(); // handle anonymous subclasses } return (TypeAdapter<T>) new EnumTypeAdapter(rawType); } }; public static <TT> TypeAdapterFactory newFactory(final TypeToken<TT> type, final TypeAdapter<TT> typeAdapter) { return new TypeAdapterFactory() { @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { return typeToken.equals(type) ? (TypeAdapter<T>) typeAdapter : null; } }; } public static <TT> TypeAdapterFactory newFactory(final Class<TT> type, final TypeAdapter<TT> typeAdapter) { return new TypeAdapterFactory() { @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { return typeToken.getRawType() == type ? (TypeAdapter<T>) typeAdapter : null; } @Override public String toString() { return "Factory[type=" + type.getName() + ",adapter=" + typeAdapter + "]"; } }; } public static <TT> TypeAdapterFactory newFactory(final Class<TT> unboxed, final Class<TT> boxed, final TypeAdapter<? super TT> typeAdapter) { return new TypeAdapterFactory() { @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { Class<? super T> rawType = typeToken.getRawType(); return (rawType == unboxed || rawType == boxed) ? (TypeAdapter<T>) typeAdapter : null; } @Override public String toString() { return "Factory[type=" + boxed.getName() + "+" + unboxed.getName() + ",adapter=" + typeAdapter + "]"; } }; } public static <TT> TypeAdapterFactory newFactoryForMultipleTypes(final Class<TT> base, final Class<? extends TT> sub, final TypeAdapter<? super TT> typeAdapter) { return new TypeAdapterFactory() { @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { Class<? super T> rawType = typeToken.getRawType(); return (rawType == base || rawType == sub) ? (TypeAdapter<T>) typeAdapter : null; } @Override public String toString() { return "Factory[type=" + base.getName() + "+" + sub.getName() + ",adapter=" + typeAdapter + "]"; } }; } /** * Returns a factory for all subtypes of {@code typeAdapter}. We do a runtime check to confirm * that the deserialized type matches the type requested. */ public static <T1> TypeAdapterFactory newTypeHierarchyFactory(final Class<T1> clazz, final TypeAdapter<T1> typeAdapter) { return new TypeAdapterFactory() { @SuppressWarnings("unchecked") @Override public <T2> TypeAdapter<T2> create(Gson gson, TypeToken<T2> typeToken) { final Class<? super T2> requestedType = typeToken.getRawType(); if (!clazz.isAssignableFrom(requestedType)) { return null; } return (TypeAdapter<T2>) new TypeAdapter<T1>() { @Override public void write(JsonWriter out, T1 value) throws IOException { typeAdapter.write(out, value); } @Override public T1 read(JsonReader in) throws IOException { T1 result = typeAdapter.read(in); if (result != null && !requestedType.isInstance(result)) { throw new JsonSyntaxException("Expected a " + requestedType.getName() + " but was " + result.getClass().getName()); } return result; } }; } @Override public String toString() { return "Factory[typeHierarchy=" + clazz.getName() + ",adapter=" + typeAdapter + "]"; } }; } }