funf.config.ContextInjectorTypeAdapaterFactory.java Source code

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Here is the source code for funf.config.ContextInjectorTypeAdapaterFactory.java

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/**
 * 
 * Funf: Open Sensing Framework
 * Copyright (C) 2010-2011 Nadav Aharony, Wei Pan, Alex Pentland.
 * Acknowledgments: Alan Gardner
 * Contact: nadav@media.mit.edu
 * 
 * This file is part of Funf.
 * 
 * Funf is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 * 
 * Funf is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with Funf. If not, see <http://www.gnu.org/licenses/>.
 * 
 */
package funf.config;

import static funf.util.LogUtil.TAG;

import java.io.IOException;
import java.lang.reflect.Field;

import android.content.Context;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

import funf.util.AnnotationUtil;
import funf.util.LogUtil;

public class ContextInjectorTypeAdapaterFactory implements TypeAdapterFactory {

    public static final String CONTEXT_FIELD = "context";

    private Context context;
    private TypeAdapterFactory delegate;

    public ContextInjectorTypeAdapaterFactory(Context context, TypeAdapterFactory delegate) {
        if (context == null) {
            throw new RuntimeException("Context cannot be null.");
        }
        this.context = context;
        this.delegate = delegate;
    }

    @Override
    public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
        final TypeAdapter<T> delegateAdapter = delegate.create(gson, type);
        if (delegateAdapter == null) {
            return null;
        } else {
            return new TypeAdapter<T>() {

                @Override
                public void write(JsonWriter out, T value) throws IOException {
                    delegateAdapter.write(out, value);
                }

                @Override
                public T read(JsonReader in) throws IOException {
                    T value = delegateAdapter.read(in);
                    if (value != null) {
                        try {
                            Field contextField = AnnotationUtil.getField(CONTEXT_FIELD, value.getClass());
                            if (contextField != null && Context.class.isAssignableFrom(contextField.getType())) {
                                boolean isAccessible = contextField.isAccessible();
                                contextField.setAccessible(true);
                                contextField.set(value, context);
                                contextField.setAccessible(isAccessible);
                            }
                        } catch (SecurityException e) {
                            // Swallow
                            Log.v(LogUtil.TAG, e.getMessage());
                        } catch (IllegalArgumentException e) {
                            // Swallow
                            Log.v(LogUtil.TAG, e.getMessage());
                        } catch (IllegalAccessException e) {
                            // Swallow
                            Log.v(LogUtil.TAG, e.getMessage());
                        }
                    }
                    return value;
                }
            };
        }
    }

}