一个Activity的层级关系之Window、DecoreView
//设置窗体全屏
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
//设置窗体始终点亮
getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
//设置窗体背景模糊， android 4.0以后不支持了。
getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND, WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
window的设置都可以在Activity的theme的style中配置，比如：
<resources>
<style name="MyTransparent">
<item name="android:windowBackground">@color/transparent_background</item> 这个是设置 decoreView的背景色
<item name="android:windowNoTitle">true</item> 设置decoreView是否有title那个FrameLayout布局
<item name="android:windowIsTranslucent">true</item> window默认是黑色配置是否透明(<strong><span style="color:#cc0000;">window是最顶级，在decoreView的外面</span></strong>)
<item name="android:windowAnimationStyle">@+android:style/Animation.Translucent</item> 窗口动画设置，非常有用。
<code class="xml plain" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;"> <</code><code class="xml keyword" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-weight: bold !important; min-height: inherit !important; color: rgb(0, 102, 153) !important;">item</code><span style="color: rgb(46, 46, 46); font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; line-height: 13.1875px; white-space: pre;"> </span><code class="xml color1" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important; color: gray !important;">name</code><code class="xml plain" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">=</code><code class="xml string" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important; color: blue !important;">"android:backgroundDimEnabled"</code><code class="xml plain" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">>true</</code><code class="xml keyword" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-weight: bold !important; min-height: inherit !important; color: rgb(0, 102, 153) !important;">item</code><code class="xml plain" style="line-height: 13.1875px; white-space: pre; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">> 设置窗口是否变暗(当该窗口是个对话框时很明显看到，把Activity弄小也看得到)</code>
<span style="color: rgb(51, 51, 51); font-family: 宋体; font-size: 14px; line-height: 28px; text-indent: 28px;"> <item name="android:windowIsFloating">true</item> 表示浮在屏幕上的，如果在这里使用了，整个layout就会在 屏幕中心，相当于浮在屏幕上，所以这个只适用于dialog </span> </style> </resources>
<code class="xml plain" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;"><</code><code class="xml keyword" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-weight: bold !important; min-height: inherit !important; color: rgb(0, 102, 153) !important;">item</code><span style="color: rgb(46, 46, 46); font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; line-height: 13.1875px;"> </span><code class="xml color1" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important; color: gray !important;">name</code><code class="xml plain" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">=</code><code class="xml string" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important; color: blue !important;">"android:backgroundDimEnabled"</code><code class="xml plain" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">>true</</code><code class="xml keyword" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-weight: bold !important; min-height: inherit !important; color: rgb(0, 102, 153) !important;">item</code><code class="xml plain" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">> 默认变暗等级50%，如果在代码中setContentView()之前可以设置窗口特征。①和②缺一不可。</code>
<code class="xml plain" style="line-height: 13.1875px; border: 0px !important; margin: 0px !important; padding: 0px !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; border-top-left-radius: 0px !important; border-top-right-radius: 0px !important; border-bottom-right-radius: 0px !important; border-bottom-left-radius: 0px !important; background-image: none !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: inherit !important;">①
mActivity.getWindow().setFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND,WindowManager.LayoutParams.FLAG_DIM_BEHIND);
</code>
②
WindowManager.LayoutParams lp_=mActivity.getWindow().getAttributes();
lp_.dimAmount = 0.3f;
mActivity.getWindow().setAttributes(lp_);
mActivity. getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
// dimAmount在0.0f和1.0f之间，0.0f完全不暗，1.0f全暗
更多相关的内容看博客：
http://2960629.blog.51cto.com/2950629/742499
http://blog.jobbole.com/65531/