原文网址:http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2012/1211/694.html
Android中Bundle类的作用
Bundle类用作携带数据,它类似于Map,用于存放key-value名值对形式的值。相对于Map,它提供了各种常用类型的putXxx()/getXxx()方法,如:putString()/getString()和putInt()/getInt(),putXxx()用于往Bundle对象放入数据,getXxx()方法用于从Bundle对象里获取数据。Bundle的内部实际上是使用了HashMap类型的变量来存放putXxx()方法放入的值。
用Bundle可以在Activity中传递基本数据类型,比如int、float、string等,但是现在的需求是如何在Activity中传递对象实例呢?就我目前所知的有两种,分别是java中Serializable和Android新引进的Parcelable方法。
我们可以考虑采用Bundle.putSerializable(Key,Object);也可以考虑采用Bundle.putParcelable(Key, Object);其中前面一种方法中的Object必须要实现Serializable接口,后面一种方法中的Object必须要实现Parcelable接口。如果没有实现这两个接口之一,那么我们可以使用Bundle.putSerializable(Key,Object)或者Bundle.putParcelable(Key, Object),但起不到任何作用,下面我们以一个完整的例子来说明。
1.新建一个Android的工程,其中该工程的目录结构如下图:
2. 修改main.xml布局文件。布局文件的源码如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
<?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/hello" /> <Button android:id= "@+id/serButton" android:layout_width= "fill_parent" android:layout_height= "wrap_content" android:text= "Serializable" /> <Button android:id= "@+id/parButton" android:layout_width= "fill_parent" android:layout_height= "wrap_content" android:text= "Parcelable" /> </LinearLayout> |
3.在工程的src目录下新建一个实体类包,命名为com.andy.entity.同时在该package中添加两个实体类,一个是Person.java,该类实现Serializable接口;一个是Police.java,该类实现Parcelable接口。代码分别如下:
Person.java:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
package com.andy.entity; import java.io.Serializable; public class Person implements Serializable { private static final long serialVersionUID = -6919461967497580385L; 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; } } |
Police.java:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
package com.andy.entity; import android.os.Parcel; import android.os.Parcelable; public class Police implements Parcelable { private String name; private int workTime; public String getName() { return name; } public void setName(String name) { this .name = name; } public int getWorkTime() { return workTime; } public void setWorkTime(int workTime) { this .workTime = workTime; } public static final Parcelable.Creator<Police> CREATOR = new Creator<Police>() { @Override public Police createFromParcel(Parcel source) { Police police = new Police(); police.name = source.readString(); police.workTime = source.readInt(); return police; } @Override public Police[] newArray(int size) { return new Police[size]; } }; @Override public int describeContents() { return 0; } @Override public void writeToParcel(Parcel parcel, int flags) { parcel.writeString(name); parcel.writeInt(workTime); } } |
4.在包com.andy.testdemo中修改TestActivity.java类,同时在该包中添加类SerializableDemo和ParcelableDemo,分别继承了Activity类和分别显示Person对象和Police对象的数据。代码如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
package com.andy.testdemo; import com.andy.entity.Person; import com.andy.entity.Police; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; public class TestActivity extends Activity { private Button sButton,pButton; public final static String SER_KEY = "com.andy.ser" ; public final static String PAR_KEY = "com.andy.par" ; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.main); sButton = (Button)findViewById(R.id.serButton); sButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { SerializeMethod(); } }); pButton = (Button)findViewById(R.id.parButton); pButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { PacelableMethod(); } }); } /** * Serializeable传递对象的方法 */ private void SerializeMethod(){ Person mPerson = new Person(); mPerson.setName( "andy" ); mPerson.setAge(26); Intent mIntent = new Intent( this ,SerializableDemo.class); Bundle mBundle = new Bundle(); mBundle.putSerializable(SER_KEY,mPerson); mIntent.putExtras(mBundle); startActivity(mIntent); } /** * Pacelable传递对象方法 */ private void PacelableMethod(){ Police mPolice = new Police(); mPolice.setName( "I am Police" ); mPolice.setWorkTime(2008); Intent mIntent = new Intent( this ,ParcelableDemo.class); Bundle mBundle = new Bundle(); mBundle.putParcelable(PAR_KEY, mPolice); mIntent.putExtras(mBundle); startActivity(mIntent); } } |
SerializableDemo.java类
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
|
package com.andy.testdemo; import com.andy.entity.Person; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class SerializableDemo extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); TextView mTextView = new TextView( this ); Person mPerson = (Person)getIntent().getSerializableExtra(TestActivity.SER_KEY); mTextView.setText( "You name is: " + mPerson.getName() + "/n" + "You age is: " + mPerson.getAge()); setContentView(mTextView); } } |
ParcelableDemo.java类:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
package com.andy.testdemo; import com.andy.entity.Police; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class ParcelableDemo extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); TextView mTextView = new TextView( this ); Police mPolice = (Police)getIntent().getParcelableExtra(TestActivity.PAR_KEY); mTextView.setText( "Police name is: " + mPolice.getName()+ "/n" + "WorkTime is: " + mPolice.getWorkTime() + "/n" ); setContentView(mTextView); } } |
5.在AndroidManifest.xml文件中为新添加的两个Activity进行注册。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
<?xml version= "1.0" encoding= "utf-8" ?> <manifest xmlns:android= "http://schemas.android.com/apk/res/android" package= "com.andy.testdemo" android:versionCode= "1" android:versionName= "1.0" > <application android:icon= "@drawable/icon" android:label= "@string/app_name" > <activity android:name= ".TestActivity" 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= ".SerializableDemo" /> <activity android:name= ".ParcelableDemo" /> </application> <uses-sdk android:minSdkVersion= "8" /> </manifest> |