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android之间传递多个对象

程序员文章站 2022-07-14 18:25:12
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Android中Intent中如何传递对象,就我目前所知道的有两种方法,一种是Bundle.putSerializable(Key,Object);另一种是Bundle.putParcelable(Key, Object);当然这些Object是有一定的条件的,前者是实现了Serializable接口,而后者是实现了Parcelable接口,为了让大家更容易理解我还是照常写了一个简单的Demo,大家就一步一步跟我来吧!

第一步:新建一个Android工程命名为ObjectTranDemo(类比较多哦!)目录结构如下图:


第二步:修改main.xml布局文件(这里我增加了两个按钮)代码如下
<?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="Welcome to Mr wei's blog."
/>
<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Serializable"
/>
<Button
android:id="@+id/button2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Parcelable"
/>
</LinearLayout>

第三步:新建两个类一个是Person.java实现Serializable接口,另一个Book.java实现Parcelable接口,代码分别如下:

Person.java:

package com.tutor.objecttran;
import java.io.Serializable;
public class Person implements Serializable {
private static final long serialVersionUID = -7060210544600464481L;
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;
}

}

Book.java:
package com.tutor.objecttran;  
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>() {
public Book createFromParcel(Parcel source) {
Book mBook = new Book();
mBook.bookName = source.readString();
mBook.author = source.readString();
mBook.publishTime = source.readInt();
return mBook;
}
public Book[] newArray(int size) {
return new Book[size];
}
};

public int describeContents() {
return 0;
}
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeString(bookName);
parcel.writeString(author);
parcel.writeInt(publishTime);
}
}


第四步:修改ObjectTranDemo.java,并且新建两个Activity,一个是ObjectTranDemo1.java,别一个是ObjectTranDemo2.java.分别用来显示Person对像数据,和Book对象数据:,代码分别如下:
ObjectTranDemo.java:
package com.tutor.objecttran;  
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class ObjectTranDemo extends Activity implements OnClickListener {

private Button sButton,pButton;
public final static String SER_KEY = "com.tutor.objecttran.ser";
public final static String PAR_KEY = "com.tutor.objecttran.par";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setupViews();

}

//我的一贯作风呵呵
public void setupViews(){
sButton = (Button)findViewById(R.id.button1);
pButton = (Button)findViewById(R.id.button2);
sButton.setOnClickListener(this);
pButton.setOnClickListener(this);
}
//Serializeable传递对象的方法
public void SerializeMethod(){
Person mPerson = new Person();
mPerson.setName("frankie");
mPerson.setAge(25);
Intent mIntent = new Intent(this,ObjectTranDemo1.class);
Bundle mBundle = new Bundle();
mBundle.putSerializable(SER_KEY,mPerson);
mIntent.putExtras(mBundle);

startActivity(mIntent);
}
//Pacelable传递对象方法
public void PacelableMethod(){
Book mBook = new Book();
mBook.setBookName("Android Tutor");
mBook.setAuthor("Frankie");
mBook.setPublishTime(2010);
Intent mIntent = new Intent(this,ObjectTranDemo2.class);
Bundle mBundle = new Bundle();
mBundle.putParcelable(PAR_KEY, mBook);
mIntent.putExtras(mBundle);

startActivity(mIntent);
}
//铵钮点击事件响应
public void onClick(View v) {
if(v == sButton){
SerializeMethod();
}else{
PacelableMethod();
}
}
}

ObjectTranDemo1.java:

package com.tutor.objecttran;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class ObjectTranDemo1 extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

TextView mTextView = new TextView(this);
Person mPerson = (Person)getIntent().getSerializableExtra(ObjectTranDemo.SER_KEY);
mTextView.setText("You name is: " + mPerson.getName() + "\n"+
"You age is: " + mPerson.getAge());

setContentView(mTextView);
}
} [/code

ObjectTranDemo2.java:
[code="java"]package com.tutor.objecttran;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class ObjectTranDemo2 extends Activity {

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TextView mTextView = new TextView(this);
Book mBook = (Book)getIntent().getParcelableExtra(ObjectTranDemo.PAR_KEY);
mTextView.setText("Book name is: " + mBook.getBookName()+"\n"+
"Author is: " + mBook.getAuthor() + "\n" +
"PublishTime is: " + mBook.getPublishTime());
setContentView(mTextView);
}
}



第五步:比较重要的一步啦,修改AndroidManifest.xml文件(将两个新增的Activity,ObjectTranDemo1,ObjectTranDemo2)申明一下

很多人知道在activity之间传递对象时有两个选择一个是Parcelable,另外一个是Serializable。但究竟我们该何时使用其中的一个呢?很多人不得而知,所以混用和滥用的情况就出现了。在这里我想给大家说清楚,以减少在程序中的不必要的风险。


1.在使用内存的时候,Parcelable 类比Serializable性能高,所以推荐使用Parcelable类。

2.Serializable在序列化的时候会产生大量的临时变量,从而引起频繁的GC。

3.Parcelable不能使用在要将数据存储在磁盘上的情况,因为Parcelable不能很好的保证数据的持续性在外界有变化的情况下。尽管Serializable效率低点, 也不提倡用,但在这种情况下,还是建议你用Serializable 。