Android中的Serialable和Parcelable的区别

转：http://blog.csdn.net/jiangwei0910410003/article/details/18988673

一．先从Serialize说起

我们都知道JAVA中的Serialize机制，译成串行化、序列化……，其作用是能将数据对象存入字节流当中，在需要时重新生成对象。主要应用是利用外部存储设备保存对象状态，以及通过网络传输对象等。

二、Android中的新的序列化机制

在Android系统中，定位为针对内存受限的设备，因此对性能要求更高，另外系统中采用了新的IPC（进程间通信）机制，必然要求使用性能更出色的对象传输方式。在这样的环境下，Parcel被设计出来，其定位就是轻量级的高效的对象序列化和反序列化机制。

三、Android中的Serialable和Parcelable的区别 

1、作用

Serializable的作用是为了保存对象的属性到本地文件、数据库、网络流、rmi以方便数据传输，当然这种传输可以是程序内的也可以是两个程序间的。而Android的Parcelable的设计初衷是因为Serializable效率过慢，为了在程序内不同组件间以及不同Android程序间(AIDL)高效的传输数据而设计，这些数据仅在内存中存在，Parcelable是通过IBinder通信的消息的载体。

从上面的设计上我们就可以看出优劣了。

2、效率及选择

Parcelable的性能比Serializable好，在内存开销方面较小，所以在内存间数据传输时推荐使用Parcelable，如activity间传输数据，而Serializable可将数据持久化方便保存，所以在需要保存或网络传输数据时选择Serializable，因为android不同版本Parcelable可能不同，所以不推荐使用Parcelable进行数据持久化

3、编程实现

对于Serializable，类只需要实现Serializable接口，并提供一个序列化版本id(serialVersionUID)即可。而Parcelable则需要实现writeToParcel、describeContents函数以及静态的CREATOR变量，实际上就是将如何打包和解包的工作自己来定义，而序列化的这些操作完全由底层实现。

Parcelable的一个实现例子如下

publicclass MyParcelable implements Parcelable {
privateint mData;
private String mStr;

publicint describeContents() {
return 0;
}

// 写数据进行保存
publicvoid writeToParcel(Parcel out, int flags) {
out.writeInt(mData);
out.writeString(mStr);
}

// 用来创建自定义的Parcelable的对象
publicstatic  final Parcelable.Creator CREATOR
=  new Parcelable.Creator() {
public MyParcelable createFromParcel(Parcel in) {
return new MyParcelable(in);
}

public MyParcelable[] newArray(int size) {
return new MyParcelable[size];
}
};

// 读数据进行恢复
private MyParcelable(Parcel in) {
mData = in.readInt();
mStr = in.readString();
}
}

publicclass MyParcelable implements Parcelable {
     privateint mData;
     private String mStr;
 
     publicint describeContents() {
         return 0;
     }
 
     // 写数据进行保存
     publicvoid writeToParcel(Parcel out, int flags) {
         out.writeInt(mData);
         out.writeString(mStr);
     }
 
     // 用来创建自定义的Parcelable的对象
     publicstatic final Parcelable.Creator CREATOR
             = new Parcelable.Creator() {
         public MyParcelable createFromParcel(Parcel in) {
             return new MyParcelable(in);
         }
 
         public MyParcelable[] newArray(int size) {
             return new MyParcelable[size];
         }
     };
    
     // 读数据进行恢复
     private MyParcelable(Parcel in) {
         mData = in.readInt();
         mStr = in.readString();
     }
 }

从上面我们可以看出Parcel的写入和读出顺序是一致的。如果元素是list读出时需要先new一个ArrayList传入，否则会报空指针异常。如下：

list= new ArrayList();

in.readStringList(list);

PS: 在自己使用时，read数据时误将前面int数据当作long读出，结果后面的顺序错乱，报如下异常，当类字段较多时务必保持写入和读取的类型及顺序一致。

11-2120:14:10.317: E/AndroidRuntime(21114): Caused by: java.lang.RuntimeException:Parcel android.os.Parcel@4126ed60: Unmarshalling unknown type code 3014773 atoffset 164

4、高级功能上

Serializable序列化不保存静态变量，可以使用Transient关键字对部分字段不进行序列化，也可以覆盖writeObject、readObject方法以实现序列化过程自定义

四、Parcelable应用

Parcelable是在内存中完成的序列化和反序列化，利用的是连续的内存空间，因此会更加高效。

我们接下来要说的是Parcel类如何应用。就应用程序而言，最常见使用Parcel类的场景就是在Activity间传递数据。没错，在Activity间使用Intent传递数据的时候，可以通过Parcelable机制传递复杂的对象。

下面来看一下简单的代码：

UserInfo类，实现了Parcelable接口:

package com.demo.entity;

import java.util.ArrayList;
import java.util.HashMap;

import android.os.Parcel;
import android.os.Parcelable;

/**
* 用户信息，实现Parcelable接口
* String,int,String[],ArrayList>这四种类型测试
* @author weijiang204321
*
*/
public class UserInfo implements Parcelable{

private String id;
private String name;
private int age;
private String[] boyfriendAry = new String[3];
private ArrayList> listData = new ArrayList>();
private SonInfo sonInfo;

public UserInfo(){
}

public UserInfo(String id,String name,int age,String[] boyfriendAry,ArrayList> listData){
this.id = id;
this.name = name;
this.age = age;
this.boyfriendAry = boyfriendAry;
this.listData = listData;
}

public UserInfo(Parcel source){
id = source.readString();
name = source.readString();
age = source.readInt();
sonInfo = source.readParcelable(SonInfo.class.getClassLoader());
source.readStringArray(boyfriendAry);
source.readList(listData, SonInfo.class.getClassLoader());
}

public String getId() {
return id;
}

public void setId(String id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public SonInfo getSonInfo(){
return sonInfo;
}

public void setSonInfo(SonInfo sonInfo){
this.sonInfo = sonInfo;
}

public String[] getBoyfriendAry() {
return boyfriendAry;
}

public void setBoyfriendAry(String[] boyfriendAry) {
this.boyfriendAry = boyfriendAry;
}

public ArrayList> getListData() {
return listData;
}

public void setListData(ArrayList> listData) {
this.listData = listData;
}


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

//进行序列化存储
@Override
public void writeToParcel(Parcel dest,  int flags) {
dest.writeString(id);
dest.writeString(name);
dest.writeInt(age);
dest.writeParcelable(sonInfo, Parcelable.PARCELABLE_WRITE_RETURN_VALUE);

dest.writeStringArray(boyfriendAry);
dest.writeList(listData);
}

public static final Parcelable.Creator CREATOR = new Creator() {
@Override
public UserInfo[] newArray(int size) {
return new UserInfo[size];
}

//将Parcel对象反序列化为UserInfo
@Override
public UserInfo createFromParcel(Parcel source) {
return new UserInfo(source);
}
};

}

package com.demo.entity;

import java.util.ArrayList;
import java.util.HashMap;

import android.os.Parcel;
import android.os.Parcelable;

/**
 * 用户信息，实现Parcelable接口
 * String,int,String[],ArrayList>这四种类型测试
 * @author weijiang204321
 *
 */
public class UserInfo implements Parcelable{

	private String id;
	private String name;
	private int age;
	private String[] boyfriendAry = new String[3];
	private ArrayList> listData = new ArrayList>();
	private SonInfo sonInfo;
	
	public UserInfo(){
	}
	
	public UserInfo(String id,String name,int age,String[] boyfriendAry,ArrayList> listData){
		this.id = id;
		this.name = name;
		this.age = age;
		this.boyfriendAry = boyfriendAry;
		this.listData = listData;
	}
	
	public UserInfo(Parcel source){
		id = source.readString();
		name = source.readString();
		age = source.readInt();
		sonInfo = source.readParcelable(SonInfo.class.getClassLoader());
		source.readStringArray(boyfriendAry);
		source.readList(listData, SonInfo.class.getClassLoader());
	}
	
	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	
	public SonInfo getSonInfo(){
		return sonInfo;
	}
	
	public void setSonInfo(SonInfo sonInfo){
		this.sonInfo = sonInfo;
	}
	
	public String[] getBoyfriendAry() {
		return boyfriendAry;
	}

	public void setBoyfriendAry(String[] boyfriendAry) {
		this.boyfriendAry = boyfriendAry;
	}

	public ArrayList> getListData() {
		return listData;
	}

	public void setListData(ArrayList> listData) {
		this.listData = listData;
	}

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

	//进行序列化存储
	@Override
	public void writeToParcel(Parcel dest, int flags) {
		dest.writeString(id);
		dest.writeString(name);
		dest.writeInt(age);
		dest.writeParcelable(sonInfo, Parcelable.PARCELABLE_WRITE_RETURN_VALUE);
		
		dest.writeStringArray(boyfriendAry);
		dest.writeList(listData);
	}
	
	public static final Parcelable.Creator CREATOR = new Creator() {   
        @Override  
        public UserInfo[] newArray(int size) {   
            return new UserInfo[size];   
        }   
           
        //将Parcel对象反序列化为UserInfo   
        @Override  
        public UserInfo createFromParcel(Parcel source) {   
            return new UserInfo(source);   
        }   
    };   

}

同样SonInfo类也要实现Parcelable接口:

package com.demo.entity;

import android.os.Parcel;
import android.os.Parcelable;

public class SonInfo implements Parcelable{

private String id;
private String name;

public SonInfo(){

}

public SonInfo(String id,String name){
this.id = id;
this.name = name;
}

public SonInfo(Parcel source){
this.id = source.readString();
this.name = source.readString();
}

public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

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

@Override
public void writeToParcel(Parcel dest,  int flags) {
dest.writeString(id);
dest.writeString(name);
}

public static final Parcelable.Creator CREATOR = new Creator() {
@Override
public SonInfo[] newArray(int size) {
return new SonInfo[size];
}

//将Parcel对象反序列化为UserInfo
@Override
public SonInfo createFromParcel(Parcel source) {
return new SonInfo(source);
}
};

}

package com.demo.entity;

import android.os.Parcel;
import android.os.Parcelable;

public class SonInfo implements Parcelable{

	private String id;
	private String name;
	
	public SonInfo(){
		
	}
	
	public SonInfo(String id,String name){
		this.id = id;
		this.name = name;
	}
	
	public SonInfo(Parcel source){
		this.id = source.readString();
		this.name = source.readString();
	}
	
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	
	@Override
	public int describeContents() {
		return 0;
	}
	
	@Override
	public void writeToParcel(Parcel dest, int flags) {
		dest.writeString(id);
		dest.writeString(name);
	}
	
	public static final Parcelable.Creator CREATOR = new Creator() {   
        @Override  
        public SonInfo[] newArray(int size) {   
            return new SonInfo[size];   
        }   
           
        //将Parcel对象反序列化为UserInfo   
        @Override  
        public SonInfo createFromParcel(Parcel source) {   
            return new SonInfo(source);   
        }   
    };   
	
}

下面来看一下测试类：

MainActivity类，在这里面进行数据的封装，然后传递到StubActivity类中：

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

Intent intent =  new Intent(this,StubActivity.class);
ArrayList> listData = new ArrayList>();
HashMap tempMap = new HashMap();
tempMap.put("one_child", new SonInfo("001_1","jiangwei_one_child"));
listData.add(tempMap);

UserInfo userInfo =  new UserInfo("001","jiangwei",24,new String[]{"张三","李四","王五"},listData);
SonInfo sonInfo = new SonInfo();
sonInfo.setId("001_1");
sonInfo.setName("jiangwei_child");
userInfo.setSonInfo(sonInfo);
intent.putExtra("userinfo", userInfo);
startActivity(intent);

}

}

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		Intent intent = new Intent(this,StubActivity.class);
		ArrayList> listData = new ArrayList>();
		HashMap tempMap = new HashMap();
		tempMap.put("one_child", new SonInfo("001_1","jiangwei_one_child"));
		listData.add(tempMap);
		
		UserInfo userInfo = new UserInfo("001","jiangwei",24,new String[]{"张三","李四","王五"},listData);
		SonInfo sonInfo = new SonInfo();
		sonInfo.setId("001_1");
		sonInfo.setName("jiangwei_child");
		userInfo.setSonInfo(sonInfo);
		intent.putExtra("userinfo", userInfo);
		startActivity(intent);
		
	}

}

下面就是StubActivity类，在这个类中将读出数据进行显示:

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class StubActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stub);

UserInfo userInfo = (UserInfo)this.getIntent().getParcelableExtra("userinfo");
SonInfo sonInfo = userInfo.getSonInfo();

String[] boyfriend = userInfo.getBoyfriendAry();
for(int i=0;i
Log.e("boyfriend_name:",boyfriend[i]);
}

ArrayList> listData = userInfo.getListData();
for(int j=0;j
SonInfo temp_soninfo = listData.get(j).get("one_child");
Log.e("OneChildId:",temp_soninfo.getId()+"");
Log.e("OneChildName:",temp_soninfo.getName()+"");
}



Log.e("UserId:",userInfo.getId()+"");
Log.e("UserName:",userInfo.getName()+"");
Log.e("UserAge:",userInfo.getAge()+"");
Log.e("Son_id:",sonInfo.getId()+"");
Log.e("Son_name:",sonInfo.getName()+"");

}

}

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class StubActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_stub);
		
		UserInfo userInfo = (UserInfo)this.getIntent().getParcelableExtra("userinfo");
		SonInfo sonInfo = userInfo.getSonInfo();
		
		String[] boyfriend = userInfo.getBoyfriendAry();
		for(int i=0;i> listData = userInfo.getListData();
		for(int j=0;j

运行结果：

这样就成功了使用了Parcelable进行数据的传输。