blocks|key|1159745|text|一个Android+Context是一个Interface+(在一般意义上，不是在Java意义上；在Java中，Context实际上是一个抽象类！)这允许访问特定于应用程序的资源以及关于应用程序环境的类和信息。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1159746|如果你的android应用是一个web应用，你的上下文应该类似于ServletContext+(我在这里不做确切的比较)。|1159747|您的活动和服务还扩展了Context，因此它们继承了所有这些方法来访问应用程序运行的环境信息。|1159748|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/android/content/Context.html|1|http://en.wikipedia.org/wiki/Interface_%2528computing%2529^0|1K|7|A|7|0|K|9|1|0|W|E|0|B|7|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]|$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]|R|$5|M|N|O|E|$P|S]]]]

An Android <a href="http://developer.android.com/reference/android/content/Context.html" rel="noreferrer">Context</a> is an <a href="http://en.wikipedia.org/wiki/Interface_%28computing%29" rel="noreferrer">Interface</a> (in the general sense, not in the Java sense; in Java, <code>Context</code> is actually an abstract class!) that allows access to application specific resources and class and information about application environment.

If your android app was a web app, your context would be something similar to <code>ServletContext</code> (I am not making an exact comparison here).

Your activities and services also extend <code>Context</code>, so they inherit all those methods to access the environment information in which the app is running.

blocks|key|945941|text|上下文是对当前对象的引用，如下所示。此外，上下文还允许访问有关应用程序环境的信息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|945942|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Context is a reference to the current object as this. Also context allows access to information about the application environment.

blocks|key|946049|text|可以将其看作是孤立运行应用程序或服务的进程的虚拟机。竖井环境可以访问大量底层系统信息和某些允许的资源。您需要该上下文才能获得这些服务。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|946050|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Think of it as the VM that has siloed the process the app or service is running in. The siloed environment has access to a bunch of underlying system information and certain permitted resources. You need that context to get at those services.

blocks|key|1160035|text|android.content.Context类提供了到Android系统和项目资源的连接。它是访问有关应用程序环境的全局信息的接口。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1160036|上下文还提供对Android服务的访问，例如位置服务。|1160037|活动和服务扩展了Context类。|1160038|entityMap^0|0|N|0|0|8|7|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

The class <code>android.content.Context</code> provides the connection to the Android system and the resources of the project. It is the interface to global information about the application environment. 

The Context also provides access to Android Services, e.g. the Location Service. 

Activities and Services extend the <code>Context</code> class.

blocks|key|946375|text|Context是类android.content.Context的实例，它提供到执行应用程序的安卓系统的连接。例如，您可以通过上下文检查当前设备显示的大小。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|946376|它还提供了对项目资源的访问。它是访问有关应用程序环境的全局信息的接口。|946377|Context类还提供对Android服务的访问，例如警报管理器，以触发基于时间的事件。|946378|活动和服务扩展了Context类。因此，它们可以直接用于访问上下文。|946379|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Context is Instances of the the class android.content.Context provide the connection to the Android system which executes the application. For example, you can check the size of the current device display via the Context.

It also gives access to the resources of the project. It is the interface to global information about the application environment.

The Context class also provides access to Android services, e.g., the alarm manager to trigger time based events.

Activities and services extend the Context class. Therefore they can be directly used to access the Context.

blocks|key|945988|text|上下文基本上用于资源访问，并获取应用程序(应用程序上下文)或活动(活动上下文)或任何其他环境的详细信息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|945989|为了避免内存泄漏，您应该对每个需要上下文对象的组件使用应用程序上下文...有关更多信息，请单击here|offset|length|945990|entityMap|0|LINK|mutability|MUTABLE|url|http://www.curious-creature.org/2008/12/18/avoid-memory-leaks-on-android/^0|0|1B|4|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

Context is basically for resource access and getting the environment details of the application(for application context) or activity (for activity context) or any other...

In order to avoid memory leak you should use application context for every components that needs a context object.... for more click <a href="http://www.curious-creature.org/2008/12/18/avoid-memory-leaks-on-android/">here</a>

blocks|key|946256|text|上下文是应用程序/对象的当前状态的上下文。它是代表各种环境数据的实体。上下文帮助当前活动与外部android环境进行交互，如本地文件、数据库、与环境关联的类加载器、包括系统级服务在内的服务等。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|946257|上下文是系统的句柄。它提供诸如解析资源、获取对数据库和首选项的访问等服务。android应用程序具有activities。它就像是应用程序当前运行的环境的句柄。activity对象继承Context对象。|946258|您可以使用不同的调用方法来获取上下文1.+getApplicationContext()、2.+getContext()、3.+getBaseContext()+4.或this+(当在activity类中时)。|946259|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Context is context of current state of the application/object.Its an entity that represents various environment data . Context helps the current activity to interact with out side android environment like local files, databases, class loaders associated to the environment, services including system-level services, and more.

A Context is a handle to the system . It provides services like resolving resources, obtaining access to databases and preferences, and so on. An android app has activities. It’s like a handle to the environment your application is currently running in. The activity object inherits the Context object.

Different invoking methods by which you can get context
1. getApplicationContext(),
2. getContext(),
3. getBaseContext()
4. or this (when in the activity class).

blocks|key|1160502|text|上下文意味着Android可以知道我应该参加或参与的活动。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1160503|1-它在这里使用的Toast.makeText(context,+"Enter+All+Details",+Toast.LENGTH_SHORT).show();。Context+context+=+ActivityName.this;|offset|length|style|CODE|1160504|2+-startActivity(new+Intent(context,LoginActivity.class));|1160505|在这个上下文中意味着你想要从哪个活动转到其他活动。context或ActivityName.this比getContext和getApplicatinContext更快。|1160506|entityMap^0|0|9|20|2A|10|0|3|1J|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@$D|P|E|Q|F|G]|$D|R|E|S|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|W|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|M|$]]

Context means Android get to know in which activity I should go for or act in.

1 - <code>Toast.makeText(context, "Enter All Details", Toast.LENGTH_SHORT).show();</code>
it used in this.
<code>Context context = ActivityName.this;</code>

2 -<code>startActivity(new Intent(context,LoginActivity.class));</code>

in this context means from which activity you wanna go to other activity.
context or ActivityName.this is faster then , getContext and getApplicatinContext.

blocks|key|946312|text|类android.content.Context的实例提供到执行应用程序的安卓系统的连接。例如，您可以通过上下文检查当前设备显示的大小。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|946313|它还提供了对项目资源的访问。它是访问有关应用程序环境的全局信息的接口。|946314|Context类还提供对Android服务的访问，例如警报管理器，以触发基于时间的事件。|946315|活动和服务扩展了Context类。因此，它们可以直接用于访问上下文。|946316|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Instances of the the class android.content.Context provide the connection to the Android system which executes the application. For example, you can check the size of the current device display via the Context.

It also gives access to the resources of the project. It is the interface to global information about the application environment.

The Context class also provides access to Android services, e.g., the alarm manager to trigger time based events.

Activities and services extend the Context class. Therefore they can be directly used to access the Context.

blocks|key|1160387|text|上下文是针对每个应用程序Sandbox的安卓专用api，它提供对应用程序私有数据的访问，如访问资源、数据库、私有文件目录、首选项、设置……|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1160388|对于一个应用程序的所有活动/服务/广播侦听器，大多数privatedata都是相同的。|1160389|由于Application、Activity、Service实现了Context接口，因此可以在api调用需要Context参数的地方使用它们|1160390|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/Sandbox_(computer_security)^0|C|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

The Context is the android specific api to each app-s <a href="https://en.wikipedia.org/wiki/Sandbox_(computer_security)" rel="noreferrer">Sandbox</a>
that provides access app private data like to resources, database, private filedirectories, preferences, settings ... 

Most of the privatedata are the same for all activities/services/broadcastlisteners of one application.

Since Application, Activity, Service implement the Context interface they can be used where an api call needs a Context parameter

blocks|key|1160461|text|Context是指不同时间段的组件(或应用)。如果我确实在下午1点到2点之间吃了这么多的食物，那么我在那段时间的上下文就被用来访问我在这段时间内使用的所有方法(或资源)。内容是特定时间的组件(应用程序)。应用程序组件的Context会根据组件或应用程序的底层生命周期而不断变化。例如，在Activity的onCreate()中，|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1160462|getBaseContext()+--给出由activity的构造函数设置(创建)的Activity的context。getApplicationContext()+--在创建应用程序期间提供Context设置(已创建)。|1160463|注意：<application>包含所有的Android组件。|1160464|<application>
++++<activity>+..+</activity>+

++++<service>++..+</service>

++++<receiver>+..+</receiver>

++++<provider>+..+</provider>
</application>+|code-block|syntax|javascript|1160465|这意味着，当您从任何组件内部调用getApplicationContext()时，您都是在调用整个应用程序的公共上下文。|1160466|系统会根据组件的生命周期不断修改Context。|1160467|entityMap^0|0|7|31|7|3Z|8|0|0|G|16|8|1F|7|1N|N|2O|7|0|3|D|0|0|G|N|0|G|7|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]|$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1C|8|@$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1F|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1G|8|@$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1J|8|@$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|T|$]]

<code>Context</code> means component (or application) in various time-period. If I do eat so much food between 1 to 2 pm then my context of that time is used to access all methods (or resources) that I use during that time. Content is a component (application) for a particular time. The <code>Context</code> of components of the application keeps changing based on the underlying lifecycle of the components or application.
For instance, inside the onCreate() of an <code>Activity</code>, 

<code>getBaseContext()</code> -- gives the <code>context</code> of the <code>Activity</code> that is set (created) by the constructor of activity. 
<code>getApplicationContext()</code> -- gives the <code>Context</code> setup (created) during the creation of application. 

Note: <code>&lt;application&gt;</code> holds all Android Components. 

<pre><code>&lt;application&gt;
 &lt;activity&gt; .. &lt;/activity&gt; 

 &lt;service&gt; .. &lt;/service&gt;

 &lt;receiver&gt; .. &lt;/receiver&gt;

 &lt;provider&gt; .. &lt;/provider&gt;
&lt;/application&gt; 
</code></pre>

It means, when you call <code>getApplicationContext()</code> from inside whatever component, you are calling the common context of the whole application. 

<code>Context</code> keeps being modified by the system based on the lifecycle of components.

blocks|key|1160561|text|将上下文看作一个包含不同资源的盒子:字符串、颜色和字体。如果你需要一个资源，你可以求助于这个盒子。旋转屏幕时，此框会更改，因为方向会更改为横向。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1160562|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Think of Context as a box with different resources: string, colors, and fonts. If you need a resource, you turn to this box. When you rotate the screen, this box changes because the orientation changes to landscape.

In Android programming, what exactly is a <code>Context</code> class and what is it used for?

I read about it on the <a href="https://d.android.com/reference/android/content/Context" rel="noreferrer">developer site</a>, but I am unable to understand it clearly.

What is 'Context' on Android?

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在Android编程中，Context类到底是什么?它是用来做什么的？我在上读到了它，但我无法清楚地理解它。

问Android上的“上下文”是什么？
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