Android通过透明度设置背景变暗

变暗

WindowManager.LayoutParams lp=getWindow().getAttributes();

lp.alpha=0.3f;

getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);

getWindow().setAttributes(lp);

　　

变为原来的样子

WindowManager.LayoutParams lp=getWindow().getAttributes();

lp.alpha=1.0f;                  getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);

getWindow().setAttributes(lp);