cls("android.app.WallpaperManager", 壁纸类)
javax(壁纸管理器, null, 壁纸类, "getInstance", "android.content.Context", activity)
javax(a, 壁纸管理器, 壁纸类, "getDrawable")
us(1, "background", a)
.线性布局id
.放在载入事件