android parcelable 详细介绍
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android parcelable 详细介绍
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????? 想要在兩個activity之間傳遞對象，那么這個對象必須序列化，Android中序列化一個對象有兩種方式，一種是實現Serializable接口，這個非常簡單，只需要聲明一下就可以了，不痛不癢。但是android中還有一種特有的序列化方法，那就是實現Parcelable接口，使用這種方式來序列化的效率要高于實現Serializable接口。不過Serializable接口實在是太方便了，因此在某些情況下實現這個接口還是非常不錯的選擇。?
使用Parcelable步驟：?
1.實現Parcelable接口?
2.實現接口中的兩個方法
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第一個方法是內容接口描述，默認返回0就可以了?
第二個方法是將我們的對象序列化一個Parcel對象，也就是將我們的對象存入Parcel中?
3.實例化靜態內部對象CREATOR實現接口Parcelable.Creator，實例化CREATOR時要實現其中的兩個方法，其中createFromParcel的功能就是從Parcel中讀取我們的對象。
也就是說我們先利用writeToParcel方法寫入對象，再利用createFromParcel方法讀取對象，因此這兩個方法中的讀寫順序必須一致，否則會出現數據紊亂，一會我會舉例子。?
看一個代碼示例：
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最后貼上Parcelable源碼，Google已經給了一個示例了：
/** Copyright (C) 2006 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.os;/*** Interface for classes whose instances can be written to* and restored from a {@link Parcel}. Classes implementing the Parcelable* interface must also have a static field called <code>CREATOR</code>, which* is an object implementing the {@link Parcelable.Creator Parcelable.Creator}* interface.* * <p>A typical implementation of Parcelable is:</p>* * <pre>* public class MyParcelable implements Parcelable {* private int mData;** public int describeContents() {* return 0;* }** public void writeToParcel(Parcel out, int flags) {* out.writeInt(mData);* }** public static final Parcelable.Creator<MyParcelable> CREATOR* = new Parcelable.Creator<MyParcelable>() {* public MyParcelable createFromParcel(Parcel in) {* return new MyParcelable(in);* }** public MyParcelable[] newArray(int size) {* return new MyParcelable[size];* }* };* * private MyParcelable(Parcel in) {* mData = in.readInt();* }* }</pre>*/ public interface Parcelable {/*** Flag for use with {@link #writeToParcel}: the object being written* is a return value, that is the result of a function such as* "<code>Parcelable someFunction()</code>",* "<code>void someFunction(out Parcelable)</code>", or* "<code>void someFunction(inout Parcelable)</code>". Some implementations* may want to release resources at this point.*/public static final int PARCELABLE_WRITE_RETURN_VALUE = 0x0001;/*** Bit masks for use with {@link #describeContents}: each bit represents a* kind of object considered to have potential special significance when* marshalled.*/public static final int CONTENTS_FILE_DESCRIPTOR = 0x0001;/*** Describe the kinds of special objects contained in this Parcelable's* marshalled representation.* * @return a bitmask indicating the set of special object types marshalled* by the Parcelable.*/public int describeContents();/*** Flatten this object in to a Parcel.* * @param dest The Parcel in which the object should be written.* @param flags Additional flags about how the object should be written.* May be 0 or {@link #PARCELABLE_WRITE_RETURN_VALUE}.*/public void writeToParcel(Parcel dest, int flags);/*** Interface that must be implemented and provided as a public CREATOR* field that generates instances of your Parcelable class from a Parcel.*/public interface Creator<T> {/*** Create a new instance of the Parcelable class, instantiating it* from the given Parcel whose data had previously been written by* {@link Parcelable#writeToParcel Parcelable.writeToParcel()}.* * @param source The Parcel to read the object's data from.* @return Returns a new instance of the Parcelable class.*/public T createFromParcel(Parcel source);/*** Create a new array of the Parcelable class.* * @param size Size of the array.* @return Returns an array of the Parcelable class, with every entry* initialized to null.*/public T[] newArray(int size);}/*** Specialization of {@link Creator} that allows you to receive the* ClassLoader the object is being created in.*/public interface ClassLoaderCreator<T> extends Creator<T> {/*** Create a new instance of the Parcelable class, instantiating it* from the given Parcel whose data had previously been written by* {@link Parcelable#writeToParcel Parcelable.writeToParcel()} and* using the given ClassLoader.** @param source The Parcel to read the object's data from.* @param loader The ClassLoader that this object is being created in.* @return Returns a new instance of the Parcelable class.*/public T createFromParcel(Parcel source, ClassLoader loader);} } 《新程序員》：云原生和全面數字化實踐50位技術專家共同創作，文字、視頻、音頻交互閱讀總結
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