最近在开发中遇到一种个性化的需求，类似于QQ顶部的渐变状态栏的实现，如下图

首先我们要了解在Android5.0以后，系统API提供直接设置StatusBar来改变状态栏的颜色，然而在4.4上StatusBar变色的基本原理就是将StatusBar本身设置为透明，然后在StatusBar的位置添加一个相同大小的View并上色。没办法，我们要做的渐变颜色状态栏就是要兼容上下版本的差异

更多关于沉浸式状态栏的了解可参考洪洋大神的文章

Android 沉浸式状态栏攻略让你的状态栏变色吧

纯色兼容状态栏

代码如下


 /**
     * 设置状态栏颜色
     *
     * @param activity       需要设置的activity
     * @param color          状态栏颜色值
     * @param statusBarAlpha 状态栏透明度
     */
 
    public static void setColor(Activity activity, @ColorInt int color, @IntRange(from = 0, to = 255) int statusBarAlpha) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            //5.0以上版本
 
            //设置FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS属性才能调用setStatusBarColor方法来设置状态栏颜色
            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            //设置FLAG_TRANSLUCENT_STATUS透明状态栏
            activity.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            //根据输入的颜色和透明度显示
            activity.getWindow().setStatusBarColor(calculateStatusColor(color, statusBarAlpha));
 
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            //低版本
 
            //添加透明状态栏
            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            //获取顶级视图
            ViewGroup decorView = (ViewGroup) activity.getWindow().getDecorView();
            //获取顶部的StatusBarView,自定义StatusBarView的Id(在resources中创建Id)
            View fakeStatusBarView = decorView.findViewById(R.id.statusbarutil_fake_status_bar_view);
            if (fakeStatusBarView != null) {
                if (fakeStatusBarView.getVisibility() == View.GONE) {
                    fakeStatusBarView.setVisibility(View.VISIBLE);
                }
                //设置顶层颜色
                fakeStatusBarView.setBackgroundColor(calculateStatusColor(color, statusBarAlpha));
            } else {
                //上述不符合，则创建一个View添加到顶级视图中
                decorView.addView(createStatusBarView(activity, color, statusBarAlpha));
            }
            setRootView(activity);
        }
    }

calculateStatusColor（计算状态栏颜色）

 /**
     * 计算状态栏颜色
     *
     * @param color color值
     * @param alpha alpha值
     * @return 最终的状态栏颜色
     */
    private static int calculateStatusColor(@ColorInt int color, int alpha) {
        if (alpha == 0) {
            return color;
        }
        float a = 1 - alpha / 255f;
        int red = color >> 16 & 0xff;
        int green = color >> 8 & 0xff;
        int blue = color & 0xff;
        red = (int) (red * a + 0.5);
        green = (int) (green * a + 0.5);
        blue = (int) (blue * a + 0.5);
        return 0xff << 24 | red << 16 | green << 8 | blue;
    }

自定义View状态栏


 /**
     * 自定义View状态栏
     *
     * @param activity 需要设置的activity
     * @param color    状态栏颜色值
     * @param alpha    透明值
     * @return 状态栏矩形条
     */
    private static View createStatusBarView(Activity activity, @ColorInt int color, int alpha) {
        // 绘制一个和状态栏一样高的矩形
        View statusBarView = new View(activity);
        LinearLayout.LayoutParams params =
                new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, getStatusBarHeight(activity));
        statusBarView.setLayoutParams(params);
        statusBarView.setBackgroundColor(calculateStatusColor(color, alpha));
        //自定义的StatusBarView的Id
        statusBarView.setId(FAKE_STATUS_BAR_VIEW_ID);
        return statusBarView;
    }

最后重新规划布局

setRootView

/**
     * 设置根布局参数
     */
    private static void setRootView(Activity activity) {
        //ViewGroup容器存放UI组件
        ViewGroup parent = (ViewGroup) activity.findViewById(android.R.id.content);
        for (int i = 0, count = parent.getChildCount(); i < count; i++) {
            View childView = parent.getChildAt(i);
            if (childView instanceof ViewGroup) {
                childView.setFitsSystemWindows(true);
                ((ViewGroup) childView).setClipToPadding(true);
            }
        }
    }

由此纯色状态栏的基本配置就可以了，只需要创建Utils工具类在Activity中调用即可，

 //设置纯色状态栏
 StatusBarUtil.setColor(this, AppUtils.getColor(R.color.colorPrimary));

渐变色兼容状态栏

关于渐变颜色的状态栏，实现方法有很多种，比如（反射拿到StatusBar并设置setBackgroundResource将shape渐变颜色添加进来即可，创建View填充状态栏），这里我们介绍的是第二种方法，创建View填充状态栏（有没有方法跟上面的方法很类似）

代码如下

  /**
     * 为界面设置自定义透明View
     *
     * @param activity       需要设置的activity
     * @param statusBarAlpha 状态栏透明度
     * @param needOffsetView 需要向下偏移的 View
    public static void setTranslucentForWindow(Activity activity, @IntRange(from = 0, to = 255) int statusBarAlpha,
                                                  View needOffsetView) {
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT) {
            //5.0以上版本
            setTransparentForWindow(activity);
            addTranslucentView(activity, statusBarAlpha);
            if (needOffsetView != null) {
                Object haveSetOffset = needOffsetView.getTag(TAG_KEY_HAVE_SET_OFFSET);
                if (haveSetOffset != null && (Boolean) haveSetOffset) {
                    return;
                }
                ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) needOffsetView.getLayoutParams();
                layoutParams.setMargins(layoutParams.leftMargin, layoutParams.topMargin + getStatusBarHeight(activity),
                        layoutParams.rightMargin, layoutParams.bottomMargin);
                needOffsetView.setTag(TAG_KEY_HAVE_SET_OFFSET, true);
            }
        } else {
            //低版本
 
            //添加透明状态栏
            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            //获取顶级视图
            ViewGroup decorView = (ViewGroup) activity.getWindow().getDecorView();
            //获取顶部的StatusBarView,自定义id
            View fakeStatusBarView = decorView.findViewById(FAKE_STATUS_BAR_VIEW_ID);
            if (fakeStatusBarView != null) {
                if (fakeStatusBarView.getVisibility() == View.GONE) {
                    fakeStatusBarView.setVisibility(View.VISIBLE);
                }
                //设置顶层颜色
                fakeStatusBarView.setBackgroundResource(R.drawable.shape_gradient);
            } else {
                //上述不符合，则创建一个View添加到顶级视图中
                View statusBarView = new View(activity);
                LinearLayout.LayoutParams params =
                        new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, getStatusBarHeight(activity));
                statusBarView.setLayoutParams(params);
                fakeStatusBarView.setBackgroundResource(R.drawable.shape_gradient);
                statusBarView.setId(FAKE_STATUS_BAR_VIEW_ID);
                decorView.addView(statusBarView);
            }
            setRootView(activity);
        }
 
    }

getStatusBarHeight

 /**
     * 获取状态栏高度
     *
     * @param context context
     * @return 状态栏高度
     */
    public static int getStatusBarHeight(Context context) {
        // 获得状态栏高度
        int resourceId = context.getResources().getIdentifier("status_bar_height", "dimen", "android");
        return context.getResources().getDimensionPixelSize(resourceId);
    }

setTransparentForWindow


/**
     * 设置透明
     */
    public static void setTransparentForWindow(Activity activity) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            activity.getWindow().setStatusBarColor(Color.TRANSPARENT);
            activity.getWindow()
                    .getDecorView()
                    .setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            activity.getWindow()
                    .setFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS, WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        }

addTranslucentView


/**
     * 添加半透明矩形条
     *
     * @param activity       需要设置的 activity
     * @param statusBarAlpha 透明值
     */
    private static void addTranslucentView(Activity activity, @IntRange(from = 0, to = 255) int statusBarAlpha) {
        ViewGroup contentView = (ViewGroup) activity.findViewById(android.R.id.content);//系统Id
        View fakeTranslucentView = contentView.findViewById(FAKE_TRANSLUCENT_VIEW_ID);
        if (fakeTranslucentView != null) {
            if (fakeTranslucentView.getVisibility() == View.GONE) {
                fakeTranslucentView.setVisibility(View.VISIBLE);
            }
            fakeTranslucentView.setBackgroundColor(Color.argb(statusBarAlpha, 0, 0, 0));
        } else {
            contentView.addView(createTranslucentStatusBarView(activity, statusBarAlpha));
        }
    }

由此渐变颜色的状态栏设置，只需要将toolbar作为View传入，调用如下

//设置渐变颜色状态栏
StatusBarUtil.setTransparentForWindow(this, mToolbar);
 
 
//布局如下
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
 
    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/shape_gradient"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:elevation="@dimen/dp0">
 
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ToolbarPopupTheme"
            app:title="@string/main_toolbar_title_top"
            app:titleTextColor="@color/colorPrimary">
 
 
        </android.support.v7.widget.Toolbar>
    </android.support.design.widget.AppBarLayout>
</LinearLayout>

Demo Link

至此，渐变色状态栏的配置已经介绍完全了