自定义Application使用示例——几个Activity共同操作某个变量

package cn.testapplication;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.app.Activity;
import android.content.Intent;
/**
* Demo描述:
* Application的基本使用
* 1 自定义OurApplication继承自Application
* 2 为AndroidManifest.xml下application结点新加个name属性
*   name的具体值即为OurApplication的路径
*
* 简单流程:
* 在MainActivity中点击按钮跳转到AnotherActivity.在AnotherActivity
* 中修改了OurApplication中所保存的值.然后按下Back键,回到MainActivity.
* 此时监测OurApplication中所保存的值.
*/
public class MainActivity extends Activity {
private Button mButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
}
private void init(){
mButton=(Button) findViewById(R.id.button);
mButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
Intent intent=new Intent(MainActivity.this, AnotherActivity.class);
startActivity(intent);
}
});
}

@Override
protected void onRestart() {
super.onRestart();
OurApplication ourApplication=(OurApplication) getApplication();
System.out.println("MainActivity中得到新的Password:"+ourApplication.getPassword());
}

}

package cn.testapplication;
import android.app.Activity;
import android.os.Bundle;
public class AnotherActivity extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.another);
init();
}
private void init(){
OurApplication ourApplication=(OurApplication) getApplication();
System.out.println("AnotherActivity中得到原来的Password:"+ourApplication.getPassword());
String newPassword="9527";
ourApplication.setPassword(newPassword);
System.out.println("AnotherActivity中设置新的Password:"+newPassword);
}
}

package cn.testapplication;

import android.app.Application;

public class OurApplication extends Application {
private String applicationPassword;
@Override
public void onCreate() {
super.onCreate();
applicationPassword="007";
}
public void setPassword(String password){
applicationPassword=password;
}
public String getPassword(){
return applicationPassword;
}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.testapplication"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="8" />

<application
android:name="cn.testapplication.OurApplication"
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="cn.testapplication.MainActivity"
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="cn.testapplication.AnotherActivity"></activity>
</application>
</manifest>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Click Me"
android:textSize="28sp"
android:layout_centerInParent="true"
/>

</RelativeLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Another Activity"
android:textSize="28sp"
android:layout_centerInParent="true"
/>

</RelativeLayout>