android中application 关于全局变量

转自:http://blog.csdn.net/leilu2008/article/details/6199961

android中application关于全局变量

android编程中,application这样的名词似乎变得那样的不常见,而让大家更为熟悉的是activity、intent、provider、broadcast和service。但其实android中的application也有着它自身的用处。

打开manifest文件,会看到有一个application配置标签,这就是有关application的使用了。那究竟application有什么用处呢?来看看SDK中是如何描述的:

Baseclassforthosewhoneedtomaintainglobalapplicationstate.YoucanprovideyourownimplementationbyspecifyingitsnameinyourAndroidManifest.xml's<application>tag,whichwillcausethatclasstobeinstantiatedforyouwhentheprocessforyourapplication/packageiscreated.

就是说application是用来保存全局变量的,并且是在package创建的时候就跟着存在了。所以当我们需要创建全局变量的时候,不需要再像j2se那样需要创建public权限的static变量,而直接在application中去实现。只需要调用Context的getApplicationContext或者Activity的getApplication方法来获得一个application对象,再做出相应的处理。

因小工程中涉及到的文件比较多,这里就贴代码撒。

application文件:

Java代码

publicclassTestApplicationextendsApplication{

privateintcurIndex;

publicintgetCurIndex(){

returncurIndex;

}

publicvoidsetCurIndex(intcurIndex){

this.curIndex=curIndex;

}

@Override

publicvoidonCreate(){

super.onCreate();

}

@Override

publicvoidonTerminate(){

super.onTerminate();

}

}

application中有一个curIndex和settergetter方法。

第一个acitivty中对application进行的操作:

Java代码

1.TestApplicationapplication=(TestApplication)this.getApplication();

2.Log.i("data",""+application.getCurIndex());

3.application.setCurIndex(5);

TestApplicationapplication=(TestApplication)this.getApplication();

Log.i("data",""+application.getCurIndex());

application.setCurIndex(5);

第二个Activity:

Java代码

1.TestApplicationapplication=(TestApplication)this.getApplication();

2.Log.i("data",""+application.getCurIndex());

3.application.setCurIndex(6);

TestApplicationapplication=(TestApplication)this.getApplication();

Log.i("data",""+application.getCurIndex());

application.setCurIndex(6);

第三个Activity:

Java代码

1.finalTestApplicationapplication=(TestApplication)this.getApplication();

2.Log.i("data",""+application.getCurIndex());

finalTestApplicationapplication=(TestApplication)this.getApplication();

Log.i("data",""+application.getCurIndex());

PS:<applicationandroid:icon="@drawable/icon"android:label="@string/app_name"android:name=".TestApplication">

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