android Parcelable类表示该类可以用来序列化,打包为数据流对象Parcel,通常用于进程间通信传递自定义数据类型。
Parcel也相应的提供了一系列write/get方法方便打包和解包Parcel类。
需要实现的方法主要是如何打包和解包Parcel类,具体如下:
/** * 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);
在此方法中,需要将当前类需要保存的数据用Parcel.write*方法写入dest中,打包为Parcel对象。
同时在当前类中也需要定义一个全局static final常量CREATOR,同时实现其中的解包Parcel的方法
/** * 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); }
import android.os.Parcel; import android.os.Parcelable; public class Book implements Parcelable{ private String name; private int count; @Override public int describeContents() { return 0; } // write all parameters to parcel @Override public void writeToParcel(Parcel dest, int flags) { dest.writeString(name); dest.writeInt(count); } public static final Parcelable.Creator<Book> CREATOR = new Parcelable.Creator<Book>() { @Override public Book createFromParcel(Parcel source) { Book book = new Book(); book.name = source.readString(); book.count = source.readInt(); return book; } @Override public Book[] newArray(int size) { return new Book[size]; } }; }
需要注意的是打包/解包时数据应该尽量一致,即wirteToParcel和createFromParcel中读写的顺序应该一致。