Single-instance access to Android application objects
Last Update:2015-05-08
Source: Internet
Author: User
<span id="Label3"></p><p><p></p></p><p><p>1. Single Case Mode:</p></p><p><p>Singleton mode is a kind of common software design Pattern. In its core structure, it contains only a special class called a singleton class. The singleton mode can ensure that there is only one instance of a class in the system, and the instance is easy to be accessed by the outside world, thus it is convenient to control the number of instances and save system Resources. Singleton mode is the best solution if you want to have only one object for a class in the System.</p></p><p><p>2. Advantages of single case mode:</p></p><p><p>Reduced memory overhead because singleton mode has only one instance in memory</p></p><p><p>Singleton mode avoids multiple uses of Resources.</p></p><p><p>Singleton mode allows you to optimize and share resource access by setting global access points on the System.</p></p><p><p>2. Problem: need to access global data from Android app</p></p><p><p>Solution: Subclass Androdi.app.Application it as a singleton with a static access method, the sub-instantiated Android.app.Application. The pattern is to have all the global data for the instance, and then</p></p><p><p>The application instance is used as a singleton to illegally access various data and services with static access.</p></p><p><p>3. code:</p></p><p><p></p></p><pre><span style="color: #008080;"><span style="color: #008080;">1</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> public</span> <span style="color: #0000ff;"><span style="color: #0000ff;">class</span></span>Androidappliation<span style="color: #0000ff;"><span style="color: #0000ff;">extends</span></span><span style="color: #000000;"><span style="color: #000000;">Application {</span></span><span style="color: #008080;"><span style="color: #008080;">2</span></span> <span style="color: #008080;"><span style="color: #008080;">3</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">Private</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">Static</span></span><span style="color: #000000;"><span style="color: #000000;">androidappliation sinstance;</span></span><span style="color: #008080;"><span style="color: #008080;">4</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">Private</span></span><span style="color: #000000;"><span style="color: #000000;">Sessionhandler sessionhandler;</span></span><span style="color: #008080;"><span style="color: #008080;">5</span></span> <span style="color: #008080;"><span style="color: #008080;">6</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> public</span> <span style="color: #0000ff;"><span style="color: #0000ff;">Static</span></span><span style="color: #000000;"><span style="color: #000000;">androidappliation getinstance ()</span></span><span style="color: #008080;"><span style="color: #008080;">7</span></span> <span style="color: #000000;"><span style="color: #000000;"> {</span></span><span style="color: #008080;"><span style="color: #008080;">8</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span><span style="color: #000000;"><span style="color: #000000;">sinstance;</span></span><span style="color: #008080;"><span style="color: #008080;">9</span></span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;">Ten</span></span> <span style="color: #008080;"><span style="color: #008080;"></span> one</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> public</span><span style="color: #000000;"><span style="color: #000000;">Sessionhandler Getsessionhandler ()</span></span><span style="color: #008080;"><span style="color: #008080;"></span> a</span> <span style="color: #000000;"><span style="color: #000000;"> {</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span><span style="color: #000000;"><span style="color: #000000;">sessionhandler;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> the</span> <span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> public</span> <span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span><span style="color: #000000;"><span style="color: #000000;">OnCreate ()</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #000000;"><span style="color: #000000;"> {</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;">Super</span></span><span style="color: #000000;"><span style="color: #000000;">. OnCreate ();</span></span><span style="color: #008080;"><span style="color: #008080;"></span> +</span>Sinstance=<span style="color: #0000ff;"><span style="color: #0000ff;"></span> this</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #000000;"><span style="color: #000000;">sinstance.initializeinstance ();</span></span><span style="color: #008080;"><span style="color: #008080;"></span> +</span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> a</span> <span style="color: #008080;"><span style="color: #008080;"></span> at</span> <span style="color: #0000ff;"><span style="color: #0000ff;">Private</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span><span style="color: #000000;"><span style="color: #000000;">initializeinstance () {</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #008000;"><span style="color: #008000;">//</span></span><span style="color: #008000;">Do all <span style="color: #008000;">your initialization here;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span>Sessionhandler=<span style="color: #0000ff;"><span style="color: #0000ff;">New</span></span>Sessionhandler (<span style="color: #0000ff;"><span style="color: #0000ff;"></span> this</span>. getsharedpreferences ("press_private"<span style="color: #000000;"><span style="color: #000000;">, context.mode_private));</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #008080;"><span style="color: #008080;"></span> -</span>}</pre><p><p></p></p><p><p>Single-instance access to Android application objects</p></p></span>
