Android使用Parcelable传递对象方法及注意事项

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

1. describeContents()返回0就可以 、

2. writeToParcel(Parcel parcel, int flag) 把需要写入的数据写入Parcel中，然后框架调用此方法发送给接收端的Activity

3. public static final Parcelable.Creator<ParcelableObject> CREATOR 外部类反序列化该类时调用此方法

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。

 ^?[Copy to clipboard]Download zuiniuwang.java

 

 

 /**
 * 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

^?[Copy to clipboard] Download zuiniuwang.java

 

 

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

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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"));

    }

}

傻蛋经过测试发现，当使用Intent传递数据时，如果你自己创建了一个Bundle，则无论要传的数据是否放入Bundle（如直接intent.putExtra("xx" , "xx")），都会放到放到此Bundle中。如果没有创建此Bundle，则会默认创建一个Bundle来存放数据。当取数据时可以先取Bundle再从Bundle中取数据，或者直接取就好了。

如果要发送对象最简单的方法是： 把要发的数据直接当做对象发送，接收也不用Bundle，因为已经默认创建。

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