在Activity之间数据传递中还有一种比较实用的方式,就是全局对象,使用J2EE的读者来说都知道Java Web的四个作用域,这四个作用域从小到大分别是:Page、Request、Session和Application,其中Application域在应用程序的任何地方都可以使用和访问,除非是Web服务器停止,Android中的全局对象非常类似于Java Web中的Application域,除非是Android应用程序清除内存,否则全局对象将一直可以访问。
下面通过例子来分享一下它的实现:
建立的工程结构如下:
MainActivity运行截图:
OtherActivity运行截图:
源代码如下:
MyApp.java:
- package com.intent.activity;
- import android.app.Application;
- public class MyApp extends Application{
- public String name;
- public String getName() {
- return name;
- }
- public void setName(String name) {
- this.name = name;
- }
- }
MainActivity.java:
- package com.intent.activity;
- 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 MainActivity extends Activity implements OnClickListener{
- private MyApp myApp;
- private Button btn;
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- btn = (Button)findViewById(R.id.btOpenOtherActivity);
- btn.setOnClickListener(this);
- }
- @Override
- public void onClick(View v) {
- myApp = (MyApp)getApplication();
- myApp.setName("wulianghuan");
- //定义一个意图
- Intent intent = new Intent(MainActivity.this,OtherActivity.class);
- //启动意图
- startActivity(intent);
- }
- }
OtherActivity.java:
- package com.intent.activity;
- import android.app.Activity;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.TextView;
- public class OtherActivity extends Activity {
- private TextView text_name;
- private MyApp myApp;
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.other);
- text_name = (TextView) findViewById(R.id.name);
- //获取Intent传递的Bundle对象和它里面的数据
- myApp = (MyApp)getApplication();
- //设置文本框的数据
- text_name.setText("姓名:"+myApp.getName());
- }
- }
main.xml:
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:orientation="vertical" >
- <TextView
- android:layout_width="fill_parent"
- android:layout_height="wrap_content"
- android:text="这是:MainActivity" />
- <Button
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:id="@+id/btOpenOtherActivity"
- android:text="使用Application传递数据"/>
- </LinearLayout>
注意:在AndroidManifest.xml需要对MyApp对象进行声明:
- <?xml version="1.0" encoding="utf-8"?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="com.intent.activity"
- android:versionCode="1"
- android:versionName="1.0" >
- <uses-sdk android:minSdkVersion="8" />
- <application
- android:name=".MyApp"
- android:icon="@drawable/ic_launcher"
- android:label="@string/app_name" >
- <activity
- android:label="@string/app_name"
- android:name=".MainActivity" >
- <intent-filter >
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- <activity android:name=".OtherActivity"/>
- </application>
- </manifest>