car/hardware/CarPropertyValue.java

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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 android.car.hardware;

import static java.lang.Integer.toHexString;

import android.annotation.IntDef;
import android.annotation.NonNull;
import android.os.Parcel;
import android.os.Parcelable;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

/**
 * Stores values broken down by area for a vehicle property.
 *
 * @param <T> refer to Parcel#writeValue(Object) to get a list of all supported types. The class
 * should be visible to framework as default class loader is being used here.
 *
 */
public final class CarPropertyValue<T> implements Parcelable {
    private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;

    private final int mPropertyId;
    private final int mAreaId;
    private final int mStatus;
    private final long mTimestamp;
    private final T mValue;

    @IntDef({
        STATUS_AVAILABLE,
        STATUS_UNAVAILABLE,
        STATUS_ERROR
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface PropertyStatus {}

    /**
     * CarPropertyValue is available.
     */
    public static final int STATUS_AVAILABLE = 0;

    /**
     * CarPropertyValue is unavailable.
     */
    public static final int STATUS_UNAVAILABLE = 1;

    /**
     * CarPropertyVale has an error.
     */
    public static final int STATUS_ERROR = 2;

    /**
     * Get an instance of CarPropertyValue
     * @param propertyId Property ID
     * @param areaId Area ID of Property
     * @param value Value of Property
     * @hide
     */
    public CarPropertyValue(int propertyId, int areaId, T value) {
        this(propertyId, areaId, 0, 0, value);
    }

    /**
     * Get an instance of CarPropertyValue
     * @param propertyId Property ID
     * @param areaId Area ID of Property
     * @param status Status of Property
     * @param timestamp Timestamp in nanosecond
     * @param value Value of Property
     * @hide
     */
    public CarPropertyValue(int propertyId, int areaId, int status, long timestamp, T value) {
        mPropertyId = propertyId;
        mAreaId = areaId;
        mStatus = status;
        mTimestamp = timestamp;
        mValue = value;
    }

    /**
     * Get an instance of CarPropertyValue
     * @param in Parcel to read
     * @hide
     */
    @SuppressWarnings("unchecked")
    public CarPropertyValue(Parcel in) {
        mPropertyId = in.readInt();
        mAreaId = in.readInt();
        mStatus = in.readInt();
        mTimestamp = in.readLong();
        String valueClassName = in.readString();
        Class<?> valueClass;
        try {
            valueClass = Class.forName(valueClassName);
        } catch (ClassNotFoundException e) {
            throw new IllegalArgumentException("Class not found: " + valueClassName);
        }

        if (String.class.equals(valueClass)) {
            byte[] bytes = in.readBlob();
            mValue = (T) new String(bytes, DEFAULT_CHARSET);
        } else if (byte[].class.equals(valueClass)) {
            mValue = (T) in.readBlob();
        } else {
            mValue = (T) in.readValue(valueClass.getClassLoader());
        }
    }

    public static final Creator<CarPropertyValue> CREATOR = new Creator<CarPropertyValue>() {
        @Override
        public CarPropertyValue createFromParcel(Parcel in) {
            return new CarPropertyValue(in);
        }

        @Override
        public CarPropertyValue[] newArray(int size) {
            return new CarPropertyValue[size];
        }
    };

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeInt(mPropertyId);
        dest.writeInt(mAreaId);
        dest.writeInt(mStatus);
        dest.writeLong(mTimestamp);

        Class<?> valueClass = mValue == null ? null : mValue.getClass();
        dest.writeString(valueClass == null ? null : valueClass.getName());

        // Special handling for String and byte[] to mitigate transaction buffer limitations.
        if (String.class.equals(valueClass)) {
            dest.writeBlob(((String) mValue).getBytes(DEFAULT_CHARSET));
        } else if (byte[].class.equals(valueClass)) {
            dest.writeBlob((byte[]) mValue);
        } else {
            dest.writeValue(mValue);
        }
    }

    /**
     * @return Property id of CarPropertyValue
     */
    public int getPropertyId() {
        return mPropertyId;
    }

    /**
     * @return Area id of CarPropertyValue
     */
    public int getAreaId() {
        return mAreaId;
    }

    /**
     * @return Status of CarPropertyValue
     */
    public @PropertyStatus int getStatus() {
        return mStatus;
    }

    /**
     * @return Timestamp of CarPropertyValue
     */
    public long getTimestamp() {
        return mTimestamp;
    }

    /**
     * @return Value of CarPropertyValue
     */
    @NonNull
    public T getValue() {
        return mValue;
    }

    /** @hide */
    @Override
    public String toString() {
        return "CarPropertyValue{"
                + "mPropertyId=0x" + toHexString(mPropertyId)
                + ", mAreaId=0x" + toHexString(mAreaId)
                + ", mStatus=" + mStatus
                + ", mTimestamp=" + mTimestamp
                + ", mValue=" + mValue
                + '}';
    }
}