Android Parcelable的使用
2013-07-26 09:47
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转自:http://blog.csdn.net/zyc13701469860/article/details/6429934
在SDK中 Parcelable类的概述是这样的:Interface for classes whose instances can be written to and restored from a
a static field called
这个接口的实例是通过Parcel进行存储的,在使用Parcelable的时候必须使用Parcelable.Creator。
下面上代码:
首先修改main.xml,增加一个button
[html]
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<?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:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Parcelable">
</Button>
</LinearLayout>
然后是主Activity ParcelableTest.java,这个类显示UI,并通过button点击事件启动另一个Activity -- ParcelableTest2,同时通过Parcelable接口传递一些数据。
[java]
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package parcelable_test.com;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class ParcelableTest extends Activity implements OnClickListener{
public static final String KEY = "key";
private Button button;
public static final String TAG = "Parcelable";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
Log.d(TAG, "ParcelableTest");
}
private void init(){
button = (Button)findViewById(R.id.button);
button.setOnClickListener(this);
}
private void fun(){
Log.d(TAG, "fun");
Person mPerson = new Person();
mPerson.setName("tom");
mPerson.setAge(25);
Intent mIntent = new Intent(this,parcelable_test.com.ParcelableTest2.class);
Bundle mBundle = new Bundle();
mBundle.putParcelable(KEY, mPerson);
mIntent.putExtras(mBundle);
startActivity(mIntent);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button:
fun();
break;
default:
break;
}
}
}
ParcelableTest2.java,这个类用于获取ParcelableTest传出的数据,并显示在UI上。
[java]
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package parcelable_test.com;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public
cdcd
class ParcelableTest2 extends Activity{
private static final String TAG = ParcelableTest.TAG;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d(TAG, "ParcelableTest2");
TextView textView = new TextView(this);
Person mPerson = (Person)getIntent().getParcelableExtra(ParcelableTest.KEY);
textView.setText("name = " + mPerson.getName() + " age = " + mPerson.getAge());
setContentView(textView);
}
}
下面就是最重要的类Person,Person类引用了Parcelable接口
[java]
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package parcelable_test.com;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;
public class Person implements Parcelable{
private String name;
private int age;
private static final String TAG = ParcelableTest.TAG;
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;
}
public static final Parcelable.Creator<Person> CREATOR = new Creator<Person>() {
@Override
public Person createFromParcel(Parcel source) {
Log.d(TAG,"createFromParcel");
Person mPerson = new Person();
mPerson.name = source.readString();
mPerson.age = source.readInt();
return mPerson;
}
@Override
public Person[] newArray(int size) {
// TODO Auto-generated method stub
return new Person[size];
}
};
@Override
public int describeContents() {
// TODO Auto-generated method stub
Log.d(TAG,"describeContents");
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
// TODO Auto-generated method stub
Log.d(TAG,"writeToParcel");
dest.writeString(name);
dest.writeInt(age);
}
}
最后在AndroidManifest.xml加入<activity android:name=".ParcelableTest2"></activity>
程序运行效果如下:
输出的log如下:
[plain]
view plaincopyprint?
05-18 16:09:47.243 I/ActivityManager( 59): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=parcelable_test.com/.ParcelableTest }
05-18 16:09:47.383 D/Parcelable( 337): ParcelableTest
05-18 16:09:48.003 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest: 724 ms (total 724 ms)
05-18 16:09:49.263 D/Parcelable( 337): fun
05-18 16:09:49.263 D/Parcelable( 337): writeToParcel
05-18 16:09:49.273 I/ActivityManager( 59): Starting activity: Intent { cmp=parcelable_test.com/.ParcelableTest2 (has extras) }
05-18 16:09:49.453 D/Parcelable( 337): ParcelableTest2
05-18 16:09:49.453 D/Parcelable( 337): createFromParcel
05-18 16:09:49.952 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest2: 562 ms (total 562 ms)
通过log可知程序的运行情况,在mBundle.putParcelable(KEY, mPerson);时,调用了Person类中的public void writeToParcel(Parcel dest, int flags)方法,并向dest写数据,在 Person mPerson = (Person)getIntent().getParcelableExtra(ParcelableTest.KEY);的时候,调用了Person类中的public Person createFromParcel(Parcel
source) 方法,创建了一个Person对象,并给这个对象的属性赋值,这里的Parcel source和Parcel dest,是相同的,然后返回这个Person对象。最后就可以打印出mPerson的属性信息了。
在SDK中 Parcelable类的概述是这样的:Interface for classes whose instances can be written to and restored from a
Parcel. Classes implementing the Parcelable interface must also have
a static field called
CREATOR, which is an object implementing the
Parcelable.Creatorinterface.
这个接口的实例是通过Parcel进行存储的,在使用Parcelable的时候必须使用Parcelable.Creator。
下面上代码:
首先修改main.xml,增加一个button
[html]
view plaincopyprint?
<?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:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Parcelable">
</Button>
</LinearLayout>
<?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:id="@+id/text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Parcelable"> </Button> </LinearLayout>
然后是主Activity ParcelableTest.java,这个类显示UI,并通过button点击事件启动另一个Activity -- ParcelableTest2,同时通过Parcelable接口传递一些数据。
[java]
view plaincopyprint?
package parcelable_test.com;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class ParcelableTest extends Activity implements OnClickListener{
public static final String KEY = "key";
private Button button;
public static final String TAG = "Parcelable";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
Log.d(TAG, "ParcelableTest");
}
private void init(){
button = (Button)findViewById(R.id.button);
button.setOnClickListener(this);
}
private void fun(){
Log.d(TAG, "fun");
Person mPerson = new Person();
mPerson.setName("tom");
mPerson.setAge(25);
Intent mIntent = new Intent(this,parcelable_test.com.ParcelableTest2.class);
Bundle mBundle = new Bundle();
mBundle.putParcelable(KEY, mPerson);
mIntent.putExtras(mBundle);
startActivity(mIntent);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button:
fun();
break;
default:
break;
}
}
}
package parcelable_test.com; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class ParcelableTest extends Activity implements OnClickListener{ public static final String KEY = "key"; private Button button; public static final String TAG = "Parcelable"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); init(); Log.d(TAG, "ParcelableTest"); } private void init(){ button = (Button)findViewById(R.id.button); button.setOnClickListener(this); } private void fun(){ Log.d(TAG, "fun"); Person mPerson = new Person(); mPerson.setName("tom"); mPerson.setAge(25); Intent mIntent = new Intent(this,parcelable_test.com.ParcelableTest2.class); Bundle mBundle = new Bundle(); mBundle.putParcelable(KEY, mPerson); mIntent.putExtras(mBundle); startActivity(mIntent); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.button: fun(); break; default: break; } } }
ParcelableTest2.java,这个类用于获取ParcelableTest传出的数据,并显示在UI上。
[java]
view plaincopyprint?
package parcelable_test.com;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public
cdcd
class ParcelableTest2 extends Activity{
private static final String TAG = ParcelableTest.TAG;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d(TAG, "ParcelableTest2");
TextView textView = new TextView(this);
Person mPerson = (Person)getIntent().getParcelableExtra(ParcelableTest.KEY);
textView.setText("name = " + mPerson.getName() + " age = " + mPerson.getAge());
setContentView(textView);
}
}
package parcelable_test.com; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.widget.TextView; public class ParcelableTest2 extends Activity{ private static final String TAG = ParcelableTest.TAG; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Log.d(TAG, "ParcelableTest2"); TextView textView = new TextView(this); Person mPerson = (Person)getIntent().getParcelableExtra(ParcelableTest.KEY); textView.setText("name = " + mPerson.getName() + " age = " + mPerson.getAge()); setContentView(textView); } }
下面就是最重要的类Person,Person类引用了Parcelable接口
[java]
view plaincopyprint?
package parcelable_test.com;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;
public class Person implements Parcelable{
private String name;
private int age;
private static final String TAG = ParcelableTest.TAG;
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;
}
public static final Parcelable.Creator<Person> CREATOR = new Creator<Person>() {
@Override
public Person createFromParcel(Parcel source) {
Log.d(TAG,"createFromParcel");
Person mPerson = new Person();
mPerson.name = source.readString();
mPerson.age = source.readInt();
return mPerson;
}
@Override
public Person[] newArray(int size) {
// TODO Auto-generated method stub
return new Person[size];
}
};
@Override
public int describeContents() {
// TODO Auto-generated method stub
Log.d(TAG,"describeContents");
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
// TODO Auto-generated method stub
Log.d(TAG,"writeToParcel");
dest.writeString(name);
dest.writeInt(age);
}
}
package parcelable_test.com; import android.os.Parcel; import android.os.Parcelable; import android.util.Log; public class Person implements Parcelable{ private String name; private int age; private static final String TAG = ParcelableTest.TAG; 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; } public static final Parcelable.Creator<Person> CREATOR = new Creator<Person>() { @Override public Person createFromParcel(Parcel source) { Log.d(TAG,"createFromParcel"); Person mPerson = new Person(); mPerson.name = source.readString(); mPerson.age = source.readInt(); return mPerson; } @Override public Person[] newArray(int size) { // TODO Auto-generated method stub return new Person[size]; } }; @Override public int describeContents() { // TODO Auto-generated method stub Log.d(TAG,"describeContents"); return 0; } @Override public void writeToParcel(Parcel dest, int flags) { // TODO Auto-generated method stub Log.d(TAG,"writeToParcel"); dest.writeString(name); dest.writeInt(age); } }
最后在AndroidManifest.xml加入<activity android:name=".ParcelableTest2"></activity>
程序运行效果如下:
输出的log如下:
[plain]
view plaincopyprint?
05-18 16:09:47.243 I/ActivityManager( 59): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=parcelable_test.com/.ParcelableTest }
05-18 16:09:47.383 D/Parcelable( 337): ParcelableTest
05-18 16:09:48.003 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest: 724 ms (total 724 ms)
05-18 16:09:49.263 D/Parcelable( 337): fun
05-18 16:09:49.263 D/Parcelable( 337): writeToParcel
05-18 16:09:49.273 I/ActivityManager( 59): Starting activity: Intent { cmp=parcelable_test.com/.ParcelableTest2 (has extras) }
05-18 16:09:49.453 D/Parcelable( 337): ParcelableTest2
05-18 16:09:49.453 D/Parcelable( 337): createFromParcel
05-18 16:09:49.952 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest2: 562 ms (total 562 ms)
05-18 16:09:47.243 I/ActivityManager( 59): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=parcelable_test.com/.ParcelableTest } 05-18 16:09:47.383 D/Parcelable( 337): ParcelableTest 05-18 16:09:48.003 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest: 724 ms (total 724 ms) 05-18 16:09:49.263 D/Parcelable( 337): fun 05-18 16:09:49.263 D/Parcelable( 337): writeToParcel 05-18 16:09:49.273 I/ActivityManager( 59): Starting activity: Intent { cmp=parcelable_test.com/.ParcelableTest2 (has extras) } 05-18 16:09:49.453 D/Parcelable( 337): ParcelableTest2 05-18 16:09:49.453 D/Parcelable( 337): createFromParcel 05-18 16:09:49.952 I/ActivityManager( 59): Displayed activity parcelable_test.com/.ParcelableTest2: 562 ms (total 562 ms)
通过log可知程序的运行情况,在mBundle.putParcelable(KEY, mPerson);时,调用了Person类中的public void writeToParcel(Parcel dest, int flags)方法,并向dest写数据,在 Person mPerson = (Person)getIntent().getParcelableExtra(ParcelableTest.KEY);的时候,调用了Person类中的public Person createFromParcel(Parcel
source) 方法,创建了一个Person对象,并给这个对象的属性赋值,这里的Parcel source和Parcel dest,是相同的,然后返回这个Person对象。最后就可以打印出mPerson的属性信息了。
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