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。
1 /** 2 * ParcelableObject.java 3 * com.androidtest.parcelable 4 * 5 * Function： TODO 6 * 7 * ver date author 8 * ────────────────────────────────── 9 * 2011-5-11 Leon 10 * 11 * Copyright (c) 2011, TNT All Rights Reserved. 12 */ 13 14 package com.androidtest.parcelable; 15 16 import android.os.Parcel; 17 import android.os.Parcelable; 18 19 /** 20 * ClassName:ParcelableObject 需要实现三个方法，describeContents()返回0就可以 、 writeToParcel(Parcel parcel, int flag) 21 * 写入Parcel和public static final Parcelable.Creator 22 <parcelableobject><span style="font-size: 14px"> CREATOR 供外部类反序列化该类 23 * 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 24 * Function: TODO 25 * Reason: TODO ADD REASON 26 * 27 * @author Leon 28 * @version 29 * @since Ver 1.1 30 * @Date 2011-5-11 31 */ 32 public class ParcelableObject implements Parcelable{ 33 private String name ; 34 private String surName ; 35 private int age ; 36 37 public String getName() { 38 return name; 39 } 40 41 public void setName(String name) { 42 this.name = name; 43 } 44 45 public String getSurName() { 46 return surName; 47 } 48 49 public void setSurName(String surName) { 50 this.surName = surName; 51 } 52 53 public int getAge() { 54 return age; 55 } 56 57 public void setAge(int age) { 58 this.age = age; 59 } 60 61 @Override 62 public int describeContents() { 63 64 // TODO Auto-generated method stub 65 return 0; 66 67 } 68 69 @Override 70 public void writeToParcel(Parcel dest, int flag) { 71 72 // TODO Auto-generated method stub 73 74 dest.writeInt(age); 75 dest.writeString(name); 76 dest.writeString(surName); 77 78 } 79 public static final Parcelable.Creator CREATOR = new Creator() { 80 81 @Override 82 public ParcelableObject createFromParcel(Parcel source) { 83 84 // TODO Auto-generated method stub 85 ParcelableObject parcelableObj = new ParcelableObject(); 86 parcelableObj.age=source.readInt(); 87 parcelableObj.surName=source.readString(); 88 parcelableObj.name = source.readString(); 89 return parcelableObj; 90 91 } 92 93 @Override 94 public ParcelableObject[] newArray(int size) { 95 96 // TODO Auto-generated method stub 97 return new ParcelableObject[size]; 98 99 } 100 101 }; 102 }
ParcelableActivity1 发送的代码
1 package com.androidtest.parcelable; 2 3 import android.app.Activity; 4 import android.content.Intent; 5 import android.os.Bundle; 6 import android.view.View; 7 import android.view.View.OnClickListener; 8 import android.widget.Button; 9 import android.widget.LinearLayout; 10 public class ParcelableActivity1 extends Activity { 11 12 @Override 13 protected void onCreate(Bundle savedInstanceState) { 14 // TODO Auto-generated method stub 15 super.onCreate(savedInstanceState); 16 LinearLayout linearLayout = new LinearLayout(this); 17 Button button = new Button(this); 18 button.setText("Send Parcelable Object"); 19 linearLayout.addView(button); 20 button.setOnClickListener(new OnClickListener(){ 21 @Override 22 public void onClick(View arg0) { 23 ParcelableObject passObject = new ParcelableObject(); 24 passObject.setName("Leon Zhang"); 25 passObject.setAge(18); 26 passObject.setSurName("xxx"); 27 28 Intent intent = new Intent(ParcelableActivity1.this,ParcelableActivity2.class); 29 // 使用Bundle发送 30 // Bundle bundle = new Bundle(); 31 // bundle.putParcelable("key", passObject); 32 intent.putExtra("key", passObject); 33 // intent.putExtras(bundle); 34 intent.putExtra("key2", "out of bundle"); 35 startActivity(intent); 36 } 37 }); 38 this.setContentView(linearLayout); 39 } 40 41 }
ParcelableActivity2 接收的代码
1 package com.androidtest.parcelable; 2 3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.util.Log; 6 7 public class ParcelableActivity2 extends Activity { 8 9 private static final String TAG = ParcelableActivity2.class.getSimpleName(); 10 11 @Override 12 protected void onCreate(Bundle savedInstanceState) { 13 14 // TODO Auto-generated method stub 15 super.onCreate(savedInstanceState); 16 ParcelableObject passObject = this.getIntent() 17 .getParcelableExtra("key"); 18 19 Log.v(TAG, "Name: " + passObject.getName() + " Surname: " 20 + passObject.getSurName() + " Age: " 21 + String.valueOf(passObject.getAge()) 22 + " out of bundle is :" 23 + this.getIntent().getStringExtra("key2")); 24 Bundle myBundle = this.getIntent().getExtras(); 25 Log.v(TAG,"XX: " 26 + ((ParcelableObject) myBundle.getParcelable("key")) 27 .getName()+ " Key2 :"+ myBundle.getString("key2")); 28 29 } 30 31 }