Android——Android Bundle详解

1 Bundle介绍

Bundle主要用于传递数据；它保存的数据，是以key-value(键值对)的形式存在的。

我们经常使用Bundle在Activity之间传递数据，传递的数据可以是boolean、byte、int、long、float、double、string等基本类型或它们对应的数组，也可以是对象或对象数组。当Bundle传递的是对象或对象数组时，必须实现Serializable 或Parcelable接口。下面分别介绍Activity之间如何传递基本类型、传递对象。

2传递基本类型

Bundle提供了各种常用类型的putXxx()/getXxx()方法，用于读写基本类型的数据。Bundle操作基本数据类型的API表格如下所示：

写数据的方法如下：

// "com.test" is the package name of the destination class  
// "com.test.Activity02" is the full class path of the destination class  
Intent intent = new Intent().setClassName("com.bundletest", "com.bundletest.Bundle02");  
  
Bundle bundle = new Bundle();  
bundle.putString("name", "skywang");  
bundle.putInt("height", 175);  
intent.putExtras(bundle);  
  
startActivity(intent);  
  
// end current class  
finish();

对应的读数据的方法如下：

Bundle bundle = this.getIntent().getExtras();    
    
String name = bundle.getString("name");    
int height = bundle.getInt("height");

3传递Parcelable类型的对象

3.1 Parcelable说明

Parcelable是Android自定义的一个接口，它包括了将数据写入Parcel和从Parcel中读出的API。一个实体（用类来表示），如果需要封装到bundle消息中去，可以通过实现Parcelable接口来实现。

Parcelable和Serializable的API如下表：

3.2 Parcelable接口说明

public interface Parcelable {  
    //内容描述接口，基本不用管  
    public int describeContents();  
    //写入接口函数，打包  
    public void writeToParcel(Parcel dest, int flags);  
    //读取接口，目的是要从Parcel中构造一个实现了Parcelable的类的实例处理。因为实现类在这里还是不可知的，所以需要用到模板的方式，继承类名通过模板参数传入。  
    //为了能够实现模板参数的传入，这里定义Creator嵌入接口,内含两个接口函数分别返回单个和多个继承类实例。  
    public interface Creator<T> {  
        public T createFromParcel(Parcel source);  
        public T[] newArray(int size);  
 }  
}

3.3 Parcelable接口的实现方法

从parcelable接口定义中，我们可以看到，实现parcelable接口，需要我们实现下面几个方法：
(01)describeContents方法。内容接口描述，默认返回0就可以;
(02)writeToParcel 方法。该方法将类的数据写入外部提供的Parcel中.即打包需要传递的数据到Parcel容器保存，以便从parcel容器获取数据，该方法声明如下：
writeToParcel(Parcel dest, int flags) 具体参数含义见doc文档
(3.)静态的Parcelable.Creator接口，本接口有两个方法：
createFromParcel(Parcelin) 从Parcel容器中读取传递数据值，封装成Parcelable对象返回逻辑层。
newArray(int size) 创建一个类型为T，长度为size的数组，仅一句话（returnnew T[size])即可。方法是供外部类反序列化本类数组使用。

4传递Serializable类型的对象

4.1 Serializable说明

Serializable是一个对象序列化的接口。一个类只有实现了Serializable接口，它的对象才是可序列化的。因此如果要序列化某些类的对象，这些类就必须实现Serializable接口。而实际上，Serializable是一个空接口，没有什么具体内容，它的目的只是简单的标识一个类的对象可以被序列化。

4.2 Serializable接口的实现方法

很简单，只要implements Serializable接口就可以了

5 demo演示程序

下面是对实现上述三种数据传递方式的BundleTest(demo程序)进行简要介绍

5.1 demo概要

BundleTest共包含了4个java文件和2个layout文件(main.xml和main2.xml)

Bundle01.java —— 默认的主Activity窗口。

Bundle02.java —— 主Activity用于跳转的目的窗口。

Book.java —— 实现Parcelable接口的类

Person.java —— 实现Serializable接口的类

main.xml —— Bundle01.java的layout文件

main2.xml —— Bundle02.java的layout文件

工程文件结构如下所示：

5.2代码

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>  
<manifest xmlns:android="http://schemas.android.com/apk/res/android"  
      package="com.bundletest"  
      android:versionCode="1"  
      android:versionName="1.0">  
      
    <application android:icon="@drawable/icon" android:label="@string/app_name">  
        <activity android:name=".Bundle01"  
                  android:label="@string/app_name">  
            <intent-filter>  
                <action android:name="android.intent.action.MAIN" />  
                <category android:name="android.intent.category.LAUNCHER" />  
            </intent-filter>  
        </activity>  
        <activity android:name=".Bundle02"> </activity>  
    </application>  
    <uses-sdk android:minSdkVersion="11" />  
</manifest>

main.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"  
    >  
    <TextView    
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/app_01"  
        />  
  
    <Button    
        android:id="@+id/btnBasic"   
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/text_basic"  
        />  
  
    <Button    
        android:id="@+id/btnPar"   
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/text_par"  
        />  
  
    <Button    
        android:id="@+id/btnSer"   
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/text_ser"  
        />  
  
  
  
</LinearLayout>

main2.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"  
    >  
    <TextView    
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/app_02"  
        />  
  
    <Button    
        android:id="@+id/btnBack"   
        android:layout_width="fill_parent"   
        android:layout_height="wrap_content"   
        android:text="@string/text_jump_back"  
        />  
      
</LinearLayout>

strings.xml

<?xml version="1.0" encoding="utf-8"?>  
<resources>  
    <string name="hello">Hello MyBundleTest!</string>  
    <string name="app_name">MyBundleTest</string>  
    <string name="app_01">Bundle_01</string>  
    <string name="app_02">Bundle_02</string>  
    <string name="text_basic">Bundle Basic Data</string>  
    <string name="text_par">Bundle Parcelable Data</string>  
    <string name="text_ser">Bundle Seriable Data</string>  
    <string name="text_jump_back">Jump Back to Bundler01</string>  
</resources>

Bundle01.java

package com.bundletest;  
  
import android.app.Activity;  
import android.os.Bundle;    
import android.view.View;  
import android.view.View.OnClickListener;  
import android.widget.Button;  
import android.content.Intent;  
import android.util.Log;  
  
public class Bundle01 extends Activity implements View.OnClickListener{  
  
    private static final String TAG = "skywang-->Bundle01";  
  
    private Button mBtnBasic = null;  
    private Button mBtnPar = null;  
    private Button mBtnSer = null;  
  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
  
        mBtnBasic = (Button) findViewById(R.id.btnBasic);  
        mBtnBasic.setOnClickListener(this);  
  
        mBtnPar = (Button) findViewById(R.id.btnPar);  
        mBtnPar.setOnClickListener(this);  
  
        mBtnSer = (Button) findViewById(R.id.btnSer);  
        mBtnSer.setOnClickListener(this);  
    }  
  
  
    @Override  
    public void onClick(View view) {  
        switch (view.getId()) {  
            case R.id.btnBasic:  
                sendBasicDataThroughBundle();  
                break;  
            case R.id.btnPar:  
                sendParcelableDataThroughBundle();  
                break;  
            case R.id.btnSer:  
                sendSeriableDataThroughBundle();  
                break;  
            default:  
                break;  
  
        }  
    }  
  
    // sent basic data, such as int, strin, etc...  through bundle  
    private void sendBasicDataThroughBundle(){    
        // "com.test" is the package name of the destination class  
        // "com.test.Activity02" is the full class path of the destination class  
        Intent intent = new Intent().setClassName("com.bundletest", "com.bundletest.Bundle02");  
          
        Bundle bundle = new Bundle();  
        bundle.putString("name", "skywang");  
        bundle.putInt("height", 175);  
        intent.putExtras(bundle);  
          
        startActivity(intent);  
  
        // end current class  
        finish();  
    }  
  
    // sent object through Pacelable  
    private void sendParcelableDataThroughBundle(){    
        Intent intent = new Intent().setClassName("com.bundletest", "com.bundletest.Bundle02");  
  
        Book mBook = new Book();  
        mBook.setBookName("Android");  
        mBook.setAuthor("skywang");  
        mBook.setPublishTime(2013);  
  
        Bundle mBundle = new Bundle();  
        mBundle.putParcelable("ParcelableValue", mBook);  
        intent.putExtras(mBundle);  
            
        startActivity(intent);  
        finish();  
    }  
  
    // sent object through seriable  
    private void sendSeriableDataThroughBundle(){    
        Intent intent = new Intent().setClassName("com.bundletest", "com.bundletest.Bundle02");  
  
        Person mPerson = new Person();  
        mPerson.setName("skywang");  
        mPerson.setAge(24);  
  
        Bundle mBundle = new Bundle();  
        mBundle.putSerializable("SeriableValue",mPerson);  
        intent.putExtras(mBundle);  
            
        startActivity(intent);  
        finish();  
    }  
  
}

Bundle02.java

package com.bundletest;  
  
import android.app.Activity;  
import android.os.Bundle;    
import android.view.View;  
import android.view.View.OnClickListener;  
import android.widget.Button;  
import android.content.Intent;  
import android.util.Log;  
  
public class Bundle02 extends Activity implements View.OnClickListener {  
  
    private static final String TAG = "skywang-->Bundle02";  
  
    private Button mBtnBack = null;  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main2);  
  
        mBtnBack = (Button) findViewById(R.id.btnBack);  
        mBtnBack.setOnClickListener(this);  
  
        receiveBasicData();  
        receiveParcelableData();  
        receiveSeriableData();  
    }  
  
    private void receiveBasicData() {  
        Bundle bundle = this.getIntent().getExtras();    
            
        String name = bundle.getString("name");    
        int height = bundle.getInt("height");  
        if (name != null && height != 0)  
        Log.d(TAG, "receice basic data -- " +  
                   "name="+name+", height="+height);  
    }  
  
    private void receiveParcelableData() {  
        Book mBook = (Book)getIntent().getParcelableExtra("ParcelableValue");  
        if (mBook != null)  
            Log.d(TAG, "receice parcel data -- " +  
                       "Book name is: " + mBook.getBookName()+", "+  
                       "Author is: " + mBook.getAuthor() + ", "+  
                       "PublishTime is: " + mBook.getPublishTime());  
    }  
  
    private void receiveSeriableData() {  
        Person mPerson = (Person)getIntent().getSerializableExtra("SeriableValue");    
        if (mPerson != null)  
            Log.d(TAG, "receice serial data -- " +  
                       "The name is:" + mPerson.getName() + ", "+  
                       "age is:" + mPerson.getAge());    
    }  
  
    @Override  
    public void onClick(View view) {  
        switch (view.getId()) {  
            case R.id.btnBack:  
            {  
                // "com.test" is the package name of the destination class  
                // "com.test.Activity01" is the full class path of the destination class  
                Intent intent = new Intent().setClassName("com.bundletest", "com.bundletest.Bundle01");  
                startActivity(intent);  
                // end current class  
                finish();  
            }  
                break;  
            default:  
                break;  
  
        }  
    }  
  
}

Book.java

package com.bundletest;  
  
import android.os.Parcel;    
import android.os.Parcelable;    
  
public class Book implements Parcelable {    
    private String bookName;    
    private String author;    
    private int publishTime;    
        
    public String getBookName() {    
        return bookName;    
    }    
    public void setBookName(String bookName) {    
        this.bookName = bookName;    
    }    
    public String getAuthor() {    
        return author;    
    }    
    public void setAuthor(String author) {    
        this.author = author;    
    }    
    public int getPublishTime() {    
        return publishTime;    
    }    
    public void setPublishTime(int publishTime) {    
        this.publishTime = publishTime;    
    }    
        
    public static final Parcelable.Creator<Book> CREATOR = new Creator<Book>() {    
        @Override  
        public Book createFromParcel(Parcel source) {    
            Book mBook = new Book();    
            mBook.bookName = source.readString();    
            mBook.author = source.readString();    
            mBook.publishTime = source.readInt();    
            return mBook;    
        }    
        @Override  
        public Book[] newArray(int size) {    
            return new Book[size];    
        }    
    };    
        
    @Override  
    public int describeContents() {    
        return 0;    
    }    
  
    @Override  
    public void writeToParcel(Parcel parcel, int flags) {    
        parcel.writeString(bookName);    
        parcel.writeString(author);    
        parcel.writeInt(publishTime);    
    }    
}

Person.java

package com.bundletest;  
  
import java.io.Serializable;    
  
public class Person implements Serializable {    
  
    private static final long serialVersionUID = 1L;   
  
    private String name;    
    private int age;    
    public String getName() {    
        return name;    
    }    
    public void setName(String name) {    
        this.name = name;    
    }    
    public int getAge() {    
        return age;    
    }    
    public void setAge(int age) {    
        this.age = age;    
    }    
        
}