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。

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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

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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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zuiniuwang.java

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。