Android:Parcelable 和 Serializable 之间的区别？

Question

为什么Android提供2个接口(interface)来序列化对象？可序列化对象是否与 Android Binder 和 AIDL 文件互操作？

Answer 1

在 Android 中，我们不能只将对象传递给 Activity 。为此，对象必须实现 Serializable 或 Parcelable 接口(interface)。

可序列化

Serializable 是标准的Java 接口(interface)。您可以只实现 Serializable 接口(interface)并添加覆盖方法。这种方法的问题是使用了反射，而且这是一个缓慢的过程。此方法会创建大量临时对象并导致大量垃圾收集。但是，Serializable接口(interface)更容易实现。

看下面的例子(Serializable):

// MyObjects Serializable class

import java.io.Serializable;
import java.util.ArrayList;
import java.util.TreeMap;

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

public class MyObjects implements Serializable {

    private String name;
    private int age;
    public ArrayList<String> address;

    public MyObjects(String name, int age, ArrayList<String> address) {
        super();
        this.name = name;
        this.age = age;
        this.address = address;
    }

    public ArrayList<String> getAddress() {
        if (!(address == null))
            return address;
        else
            return new ArrayList<String>();
    }

    public String getName() {
        return name;
    }

    // return age
    public int getAge() {
        return age;
    }
}

// MyObjects instance
MyObjects mObjects = new MyObjects("name", "age", "Address array here");

// Passing MyObjects instance via intent
Intent mIntent = new Intent(FromActivity.this, ToActivity.class);
mIntent.putExtra("UniqueKey", mObjects);
startActivity(mIntent);

// Getting MyObjects instance
Intent mIntent = getIntent();
MyObjects workorder = (MyObjects)    mIntent.getSerializableExtra("UniqueKey");

可打包

Parcelable 过程比Serializable 快得多。造成这种情况的原因之一是我们对序列化过程是明确的，而不是使用反射来推断它。也有理由为此目的对代码进行了大量优化。

看下面的例子(Parcelable):

// MyObjects Parcelable class

import java.util.ArrayList;

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

public class MyObjects implements Parcelable {

    private int age;
    private String name;
    private ArrayList<String> address;

    public MyObjects(String name, int age, ArrayList<String> address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }

    public MyObjects(Parcel source) {
        age = source.readInt();
        name = source.readString();
        address = source.createStringArrayList();
    }

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

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeInt(age);
        dest.writeString(name);
        dest.writeStringList(address);
    }

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

    public ArrayList<String> getAddress() {
        if (!(address == null))
            return address;
        else
            return new ArrayList<String>();
    }

    public static final Creator<MyObjects> CREATOR = new Creator<MyObjects>() {
        @Override
        public MyObjects[] newArray(int size) {
            return new MyObjects[size];
        }

        @Override
        public MyObjects createFromParcel(Parcel source) {
            return new MyObjects(source);
        }
    };
}

// MyObjects instance
MyObjects mObjects = new MyObjects("name", "age", "Address array here");

// Passing MyOjects instance
Intent mIntent = new Intent(FromActivity.this, ToActivity.class);
mIntent.putExtra("UniqueKey", mObjects);
startActivity(mIntent);

// Getting MyObjects instance
Intent mIntent = getIntent();
MyObjects workorder = (MyObjects) mIntent.getParcelableExtra("UniqueKey");

您可以传递 ArrayList 的 Parcelable 对象，如下所示:

// Array of MyObjects
ArrayList<MyObjects> mUsers;

// Passing MyOjects instance
Intent mIntent = new Intent(FromActivity.this, ToActivity.class);
mIntent.putParcelableArrayListExtra("UniqueKey", mUsers);
startActivity(mIntent);

// Getting MyObjects instance
Intent mIntent = getIntent();
ArrayList<MyObjects> mUsers = mIntent.getParcelableArrayList("UniqueKey");

结论

1. Parcelable 比 Serializable 接口(interface)快
2. Parcelable 接口(interface)相比 Serializable 接口(interface)需要更多时间来实现
3. Serializable接口(interface)更容易实现
4. Serializable 接口(interface)会创建大量临时对象并导致大量垃圾回收
5. Parcelable数组可以通过android中的Intent传递