Android - Parcelable 序列化操作数据

Android -- Parcelable 序列化操作数据
序列化数据原理：
序列化的过程就是对象写入字节流和从字节流中读取对象。将对象状态转换成字节流之后，可以用java.io包中的各种字节流类将其保存到文件中，管道到另一线程中或通过网络连接将对象数据发送到另一主机。
简单说就是将数据对象存入字节流当中，在需要时重新生成对象。

Android中的序列化机制:
首先android系统利用Binder进行IPC通讯，且定位为针对内存受限的设备，所以则要求使用高效的对象传输方式，因为Parcel应运而生。

代码分析：
frameworks\base\core\java\android\os\Parcel.java
frameworks\base\core\jni\android_util_Binder.cpp JNI函数

以典型代码片段举例:
package test.com.parcel;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.os.Parcel;import android.os.Parcelable;import android.util.Log;public class TestParcelActivity extends Activity {ComplexDataStruct complexData = null;/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);testComplexDS();}public void testComplexDS(){complexData = new ComplexDataStruct();Intent intent=new Intent(TestParcelActivity.this,TestParcelActivity.class);complexData.a = 10;complexData.b = 20;complexData.str1 = " hello...";complexData.str2 = " world...";intent.putExtra("complexData", complexData);ComplexDataStruct test = (ComplexDataStruct)intent.getParcelableExtra("complexData");Log.i("","a="+test.a);Log.i("","b="+test.b);Log.i("","str1="+test.str1);Log.i("","str2="+test.str2);}/* 一个复杂的Parcelable对象传递 */public class ComplexDataStruct {public int a = 0;public int b = 0;public String str1 = null;public String str2 = null;/* 内部实现静态CREATOR类 */public static final Parcelable.Creator<ComplexDataStruct> CREATOR = new Parcelable.Creator<ComplexDataStruct>() {// 从Parcel中读取数据，返回ComplexDataStruct对象public ComplexDataStruct createFromParcel(Parcel in) {return new ComplexDataStruct(in);}public ComplexDataStruct[] newArray(int size) {return new ComplexDataStruct[size]; // 传递数组}};ComplexDataStruct(){//TODO}public ComplexDataStruct(ComplexDataStruct other) {this.a = other.a;this.b = other.b;this.str1 = other.str1;this.str2 = other.str2;}private ComplexDataStruct(Parcel in) {readFromParcel(in);}public void readFromParcel(Parcel in) {a = in.readInt();b = in.readInt();str1 = in.readString();str2 = in.readString();}public int describeContents() {// TODO Auto-generated method stubreturn 0;}public void writeToParcel(Parcel arg0, int arg1) {// TODO Auto-generated method stubarg0.writeInt(a);arg0.writeInt(b);arg0.writeString(str1);arg0.writeString(str2);}}}