Parcelable
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 theParcelable.Creator
interface.
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
- <?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。
- 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。
- 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
- 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:
![](http://qp.qq.com/cgi-bin/cgi_imgproxy?url=http%3A%2F%2Fhi.csdn.net%2Fattachment%2F201105%2F18%2F8630179_1305706042388L.png&size=0)
![](http://qp.qq.com/cgi-bin/cgi_imgproxy?url=http%3A%2F%2Fhi.csdn.net%2Fattachment%2F201105%2F18%2F8630179_1305706063Imir.png&size=0)
输出的log如下:
- 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。