Home Backend Development PHP Tutorial java,android里的context都是什么意思啊该如何处理

java,android里的context都是什么意思啊该如何处理

Jun 13, 2016 am 10:23 AM
context java jndi

java,android里的context都是什么意思啊
java,android里的context都是什么意思啊。说是上下文,这是什么东西啊

------解决方案--------------------
发错地方了,错就错了吧

Context在Java中的出现是如此频繁,但其中文翻译“上下文”又是如此诡异拗口,因此导致很多人不是很了解Context的具体含义是指什么,所以很有必要来深究一下这词的含义。先来举几个JAVA中用到Context的例子 (1)JNDI的一个类javax.naming.InitialContext,它读取JNDI的一些配置信息,并内含对象和其在JNDI中的注册名称的映射信息。请看下面的代码

InitialContext ic=new InitialContext();
RMIAdaptor server=(RMIAdaptor)ic.lookup("jmx/invoker/RMIAdaptor");

这是一段JBoss中获取MBean的远程调用类的代码。在这里面通过InitialContext中JNDI注册的名称“jmx/invoker/RMIAdaptor”来获得RMIAdaptor
对象。这和JAVA集合中的MAP有点象,有一个String的key,key对映着它的对象。(2)再来看看下面Spring中最常见的几句代码。ApplicationContext 是内含configuration.xml配置文件的信息,使得可以通过getBean用名称得到相应的注册对象。

ApplicationContext ctx= new FileSystemXmlApplicationContext("configuration.xml");
Object obj= ctx.getBean("Object_Name");

从上面的代码,我很能体会到Context所代表的意义:公用信息、环境、容器....。所以我觉得Context翻译成上下文并不直观,按照语言使用的环境,翻译成“环境”、“容器”可能更好。 把Context翻译成“上下文”只是不直观罢了,不过也没大错。我们来看看中文的“上下文”是什么意思。我们常说听话传话不能“断章取义”,而要联系它的“上下文”来看。比如,小丽对王老五说“我爱你”,光看这句还以为在说情话呢。但一看上下文--“虽然我爱你,但你太穷了,我们还是分手吧”,味道就完全变了。从这里来看“上下文”也有“环境”的意思,就是语言的环境。

 PS:

 上下文其实是一个抽象的概念。我们常见的上下文有Servlet中的pageContext,访问JNDI时候用的Context。写过这些代码的人可能比较容易理解,其实他们真正的作用就是承上启下。比如说pageContext他的上层是WEB容器,下层是你写的那个Servlet类,pageContext作为中间的通道让Servlet 和Web容器进行交互。再比如访问JNDI的Context,他的上层是JNDI服务器(可能是远程的),下层是你的应用程序,他的作用也是建立一个通道让你能访问JNDI服务器,同时也让JNDI服务器接受你的请求,同样起到交互作用。
------解决方案--------------------

探讨

发错地方了,错就错了吧

Context在Java中的出现是如此频繁,但其中文翻译“上下文”又是如此诡异拗口,因此导致很多人不是很了解Context的具体含义是指什么,所以很有必要来深究一下这词的含义。先来举几个JAVA中用到Context的例子 (1)JNDI的一个类javax.naming.InitialContext,它读取JNDI的一些配置信息,并内含对象和其在JNDI中的注册名称的……

------解决方案--------------------
那你就错了,这就是赤裸裸的copy.
探讨

引用:

发错地方了,错就错了吧

Context在Java中的出现是如此频繁,但其中文翻译“上下文”又是如此诡异拗口,因此导致很多人不是很了解Context的具体含义是指什么,所以很有必要来深究一下这词的含义。先来举几个JAVA中用到Context的例子 (1)JNDI的一个类javax.naming.InitialContext,它读取JNDI的一……

------解决方案--------------------
探讨

那你就错了,这就是赤裸裸的copy.
引用:

引用:

发错地方了,错就错了吧

Context在Java中的出现是如此频繁,但其中文翻译“上下文”又是如此诡异拗口,因此导致很多人不是很了解Context的具体含义是指什么,所以很有必要来深究一下这词的含义。先来举几个JAVA中用到Context的例子 (1)……

------解决方案--------------------
就android来说,目前的水平只知道Context一般表示当前Activity类实例。Activity的Override方法里如果需要传Context,就直接传this,有些需要传 Activity名.this,比如事件类方法的实现需要传的Context.
话说你咋发到这了,csdn有android版的,移动平台 > Android。
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