Android使用Parcelable传递对象方法及注意事项

android提供了一种新的类型：Parcel。本类被用作封装数据的容器，封装后的数据可以通过Intent或IPC传递。 除了基本类型以外，只有实现了Parcelable接口的类才能被放入Parcel中。

Intent 可以携带对象来在不同的Activity中传递数据，要传递的数据必须实现三个方法

Parcelable实现要点：需要实现三个东西

1）writeToParcel 方法。该方法将类的数据写入外部提供的Parcel中.声明如下：

　　writeToParcel (Parcel dest, int flags) 具体参数含义见javadoc

2）describeContents方法。没搞懂有什么用，反正直接返回0也可以

3）静态的Parcelable.Creator接口，本接口有两个方法：

　　createFromParcel(Parcel in) 实现从in中创建出类的实例的功能

　　newArray(int size) 创建一个类型为T，长度为size的数组，仅一句话（return new T[size])即可。估计本方法是供外部类反序列化本类数组使用。

 

一定要注意：写入parcel和反序列化parcel时顺序一定要相同，不然数据会出错。

 

 /**
 * ParcelableObject.java
 * com.androidtest.parcelable
 *
 * Function： TODO
 *
 *   ver     date              author
 * ──────────────────────────────────
 *            2011-5-11         Leon
 *
 * Copyright (c) 2011, TNT All Rights Reserved.
*/
 
package com.androidtest.parcelable;
 
import android.os.Parcel;
import android.os.Parcelable;
 
/**
 * ClassName:ParcelableObject 需要实现三个方法，describeContents()返回0就可以 、 writeToParcel(Parcel parcel, int flag)
 * 写入Parcel和public static final Parcelable.Creator
<parcelableobject><span style="font-size: 14px"> CREATOR 供外部类反序列化该类
 * 一定要注意顺序后面这个两个函数读和写的顺序要相同，不然数据会出错
 * Function: TODO
 * Reason:     TODO ADD REASON
 *
 * @author   Leon
 * @version
 * @since    Ver 1.1
 * @Date     2011-5-11
 */
public class ParcelableObject implements Parcelable{
    private  String  name  ;
    private  String  surName ;
    private  int     age ; 
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getSurName() {
        return surName;
    }
 
    public void setSurName(String surName) {
        this.surName = surName;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
 
    @Override
    public int describeContents() {
 
        // TODO Auto-generated method stub
        return 0;
 
    }
 
    @Override
    public void writeToParcel(Parcel dest, int flag) {
 
        // TODO Auto-generated method stub
 
        dest.writeInt(age);
        dest.writeString(name);
        dest.writeString(surName);
 
    }
    public static final Parcelable.Creator CREATOR = new Creator() {
 
        @Override
        public ParcelableObject createFromParcel(Parcel source) {
 
            // TODO Auto-generated method stub
            ParcelableObject parcelableObj = new ParcelableObject();
            parcelableObj.age=source.readInt();
            parcelableObj.surName=source.readString();
            parcelableObj.name = source.readString();
            return parcelableObj;
 
        }
 
        @Override
        public ParcelableObject[] newArray(int size) {
 
            // TODO Auto-generated method stub
            return new ParcelableObject[size];
 
        } 
 
    };
}

 

ParcelableActivity1 发送的代码

package com.androidtest.parcelable;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
public class ParcelableActivity1 extends Activity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        LinearLayout linearLayout = new LinearLayout(this);
        Button button = new Button(this);
        button.setText("Send Parcelable Object");
        linearLayout.addView(button);
        button.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View arg0) {
                ParcelableObject passObject = new ParcelableObject();
                passObject.setName("Leon Zhang");
                passObject.setAge(18);
                passObject.setSurName("xxx");
 
                Intent intent = new Intent(ParcelableActivity1.this,ParcelableActivity2.class);
//              使用Bundle发送
//                Bundle bundle = new Bundle();
//                bundle.putParcelable("key", passObject);
                intent.putExtra("key", passObject);
//                intent.putExtras(bundle);
                intent.putExtra("key2", "out of bundle");
                startActivity(intent);
            }
        });
       this.setContentView(linearLayout);
    }
 
}

ParcelableActivity2 接收的代码

package com.androidtest.parcelable;
 
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
 
public class ParcelableActivity2 extends Activity {
 
    private static final String TAG = ParcelableActivity2.class.getSimpleName();
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
 
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        ParcelableObject passObject = this.getIntent()
                .getParcelableExtra("key");
 
        Log.v(TAG, "Name: " + passObject.getName() + " Surname: "
                        + passObject.getSurName() + " Age: "
                        + String.valueOf(passObject.getAge())
                        + " out of bundle is :"
                        + this.getIntent().getStringExtra("key2"));
        Bundle myBundle = this.getIntent().getExtras();
        Log.v(TAG,"XX: "
                        + ((ParcelableObject) myBundle.getParcelable("key"))
                                .getName()+ " Key2 :"+ myBundle.getString("key2"));
 
    }
 
}