Example usage for com.google.gson TypeAdapter toJsonTree

List of usage examples for com.google.gson TypeAdapter toJsonTree

Introduction

In this page you can find the example usage for com.google.gson TypeAdapter toJsonTree.

Prototype

public final JsonElement toJsonTree(T value) 

Source Link

Document

Converts value to a JSON tree.

Usage

From source file:ca.ualberta.cs.team1travelexpenseapp.gsonUtils.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }// w w  w  . j av a 2 s  .  c  o m

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}

From source file:cc.kave.commons.utils.json.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }//from   w  w w .  j  a v  a2  s  .  co  m

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            // (kave adaptation) was: ".remove(typeFiledName)"
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that
            // subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            if (value == null) {
                Streams.write(null, out);
                return;
            }
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that
            // subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            // (kave adaptation) disabled check
            // if (jsonObject.has(typeFieldName)) {
            // throw new JsonParseException("cannot serialize " +
            // srcType.getName()
            // + " because it already defines a field named " +
            // typeFieldName);
            // }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}

From source file:co.aurasphere.botmill.kik.util.json.LowerCaseTypeAdapterFactory.java

License:Open Source License

public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
    final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
    final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);

    return new TypeAdapter<T>() {

        @Override/*ww w.  ja va 2  s. c  o  m*/
        public T read(JsonReader in) throws IOException {
            JsonElement tree = elementAdapter.read(in);
            afterRead(tree);
            return delegate.fromJsonTree(tree);
        }

        @Override
        public void write(JsonWriter out, T value) throws IOException {
            JsonElement tree = delegate.toJsonTree(value);
            beforeWrite(value, tree);
            elementAdapter.write(out, tree);
        }

        protected void beforeWrite(T source, JsonElement toSerialize) {
        }

        protected void afterRead(JsonElement deserialized) {
            if (deserialized instanceof JsonObject) {
                JsonObject jsonObject = ((JsonObject) deserialized);
                Set<Map.Entry<String, JsonElement>> entrySet = jsonObject.entrySet();
                for (Map.Entry<String, JsonElement> entry : entrySet) {
                    if (entry.getValue() instanceof JsonElement) {
                        if (entry.getKey().equalsIgnoreCase("type")) {
                            String val = jsonObject.get(entry.getKey()).toString();
                            jsonObject.addProperty(entry.getKey(), val.toLowerCase());
                        }
                    } else {
                        afterRead(entry.getValue());
                    }
                }
            }
        }
    };
}

From source file:com.cyanogenmod.account.gcm.model.MessageTypeAdapterFactory.java

License:Apache License

@Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
    if (!Message.class.isAssignableFrom(type.getRawType())) {
        return null;
    }//from  w  w w .ja  v  a  2  s .c  o  m

    final TypeAdapter<Message> rootAdapter = gson.getDelegateAdapter(this, TypeToken.get(Message.class));
    final TypeAdapter<PublicKeyMessage> keyExchangeAdapter = gson.getDelegateAdapter(this,
            TypeToken.get(PublicKeyMessage.class));
    final TypeAdapter<SymmetricKeyMessage> symmetricKeyAdapter = gson.getDelegateAdapter(this,
            TypeToken.get(SymmetricKeyMessage.class));
    final TypeAdapter<EncryptedMessage> secureMessageAdapter = gson.getDelegateAdapter(this,
            TypeToken.get(EncryptedMessage.class));
    final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);

    TypeAdapter<Message> result = new TypeAdapter<Message>() {
        @Override
        public void write(JsonWriter out, Message value) throws IOException {
            if (value instanceof PublicKeyMessage) {
                keyExchangeAdapter.write(out, (PublicKeyMessage) value);
            } else if (value instanceof SymmetricKeyMessage) {
                symmetricKeyAdapter.write(out, (SymmetricKeyMessage) value);
            } else if (value instanceof EncryptedMessage) {
                secureMessageAdapter.write(out, (EncryptedMessage) value);
            } else {
                JsonObject object = rootAdapter.toJsonTree(value).getAsJsonObject();
                elementAdapter.write(out, object);
            }
        }

        @Override
        public Message read(JsonReader in) throws IOException {
            JsonObject object = elementAdapter.read(in).getAsJsonObject();
            if (object.has("public_key")) {
                return keyExchangeAdapter.fromJsonTree(object);
            } else if (object.has("symmetric_key")) {
                return symmetricKeyAdapter.fromJsonTree(object);
            } else if (object.has("ciphertext")) {
                return secureMessageAdapter.fromJsonTree(object);
            } else {
                return rootAdapter.fromJsonTree(object);
            }
        }
    }.nullSafe();

    return (TypeAdapter<T>) result;
}

From source file:com.devicehive.json.adapters.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }/*from  w w  w  .j  a  v  a2  s  . co m*/

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            //                JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            //                if (jsonObject.has(typeFieldName)) {
            //                    throw new JsonParseException("cannot serialize " + srcType.getName()
            //                            + " because it already defines a field named " + typeFieldName);
            //                }
            //                JsonObject clone = new JsonObject();
            //                clone.add(typeFieldName, new JsonPrimitive(label));
            //                for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
            //                    clone.add(e.getKey(), e.getValue());
            //                }
            //                Streams.write(clone, out);
            Streams.write(jsonObject, out);
        }
    }.nullSafe();
}

From source file:com.etermax.conversations.repository.impl.elasticsearch.mapper.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }/*from  w  ww . jav  a 2  s . co m*/

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    }.nullSafe();
}

From source file:com.github.sheigutn.pushbullet.gson.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }/*from  w  ww  .  j  a  v  a  2  s .  co m*/

    if (baseDelegateAdapter == null) {
        baseDelegateAdapter = gson.getDelegateAdapter(RuntimeTypeAdapterFactory.this, TypeToken.get(baseType));
    }

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @SuppressWarnings("unchecked")
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName); //remove(typeFieldName) changed to get(typeFieldName)
            if (labelJsonElement == null) {
                return (R) baseDelegateAdapter.fromJsonTree(jsonElement);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            //if (jsonObject.has(typeFieldName)) {
            //    throw new JsonParseException("cannot serialize " + srcType.getName()
            //            + " because it already defines a field named " + typeFieldName); <-- Commented
            //}
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    }.nullSafe();
}

From source file:com.gsaul.AethonSimulator.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }/*  w  w w.  j a va 2  s . c o  m*/

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName); //used to be .remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    }.nullSafe();
}

From source file:com.kotcrab.vis.editor.serializer.json.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (baseType.isAssignableFrom(type.getRawType()) == false) {
        return null;
    }//from   ww w .  j  av  a  2s .c  om

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}

From source file:com.learn.mobile.library.dmobi.helper.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }//from   ww w .ja v a2  s .  co m

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            // JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            // Do not remove typeFieldName
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName);

            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    }.nullSafe();
}