Android中如何使用Bundle传递对象[使用Serializable或者Parcelable]
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:
<?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:
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:
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:
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
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:
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。
<?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>