Android 三步簡單適配齊劉海系統狀態欄

個人思路：

說到齊劉海適配，最典型的就是MainActivity的幾個fragment中有的需要透明系統狀態欄 有的不需要， 而一般需要透明系統狀態欄的fragment頂部都會放個輪播圖，然後在輪播圖上放搜索框，所謂適配，就是指搜索框的位置根據系統狀態欄高度設置，達到在齊劉海手機上搜索框不被覆蓋；

如上圖所示，下面對如動態圖所示系統狀態欄進行三步分析

一、獲取系統狀態欄高度

兩行代碼就能獲取當前系統狀態欄的高度

      int resourceId = mContext.getResources().getIdentifier("status_bar_height", "dimen", "android");
      int viewHeight = mContext.getResources().getDimensionPixelSize(resourceId);

二、設置顏色

根據UI的需求，我的做法是先設置系統狀態欄透明，監聽手勢動作，開始滑動時，增加一個系統狀態欄同高的view，更改背景色漸變（漸變值爲0-100%，百分比同 滑動距離/輪播圖高度），更改系統狀態欄圖標顏色爲深色，再重寫scrollview，監聽滑動置頂時，設置透明系統狀態欄，隱藏佔位view；

/**
 * 設置透明系統狀態欄
 */
View decorView = getActivity().getWindow().getDecorView();
decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
        | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
getActivity().getWindow().setStatusBarColor(Color.parseColor("#00000000"));//設置透明

/**
 * 設置系統狀態欄圖標顏色，用false和true 設置顏色爲白色或者深色
 */
 StatusBarCompat.setLightStatusBar(getActivity().getWindow(), false);

/**
 * 滑動監聽
 */
 private MyScrollView.OnMyScrollListener listener;

 listener = new MyScrollView.OnMyScrollListener() {
                @Override
                public void onScrollStateChanged(MyScrollView view, int state) {
                    String str;
                    if (state == 0) {
                        str = "IDLE";
                    } else if (state == 1) {
                        str = "DRAG";
                    } else if (state == 2) {
                        str = "FLING";
                    } else {
                        str = "ERROR";
                    }
                    Log.d("brycegao", "滑動狀態：" + str);
                }

                @Override
                public void onScroll(MyScrollView view, int y) {
                    int height = banner.getHeight();
                    if (scroll_view.getScrollY() > 0) {
                        if (scroll_view.getScrollY() < height) {
                            float scale = (float) scroll_view.getScrollY() / height;
                            float alpha = (255 * scale);
                            //百分比漸變
                            view_placeholder.setBackgroundColor(Color.argb((int) alpha, 0xff, 0xff, 0xff));
                            //獲取系統狀態欄高度
                            int resourceId = mContext.getResources().getIdentifier("status_bar_height", "dimen", "android");
                            //獲取屏幕寬度
                            int viewWidth = (int) (ScreenUtils.getScreenWidth(mContext));
                            if (resourceId > 0) {
                                int viewHeight = mContext.getResources().getDimensionPixelSize(resourceId);
                                RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(viewWidth, viewHeight);
                                view_placeholder.setLayoutParams(params);
                            }
                            StatusBarCompat.setLightStatusBar(getActivity().getWindow(), true);//設置導航欄字體顏色
                        }
                    }

                }

                @Override
                public void onScrollToTop() {
                    Log.d("brycegao", "滑到頂部");
                    view_placeholder.setLayoutParams(new RelativeLayout.LayoutParams(0, 0));
                    StatusBarCompat.setLightStatusBar(getActivity().getWindow(), false);//設置導航欄字體顏色
                }

                @Override
                public void onScrollToBottom() {
                    Log.d("brycegao", "滑動底部");
                }
            };

/**
 * 自定義scrollview 監聽滑動事件，網上找的，親測可用，不過原文地址忘了 勿怪、見諒
 */
public class MyScrollView extends ScrollView {

    private ArrayList<OnMyScrollListener> listeners;

    private int currentState;
    private boolean isLastBottom;  //上次刷新是否底部
    private int lastDrawPos;     //上次刷新的縱向位移

    public interface OnMyScrollListener {
        int SCROLL_STATE_FLING = 2;   //手指滑動後鬆開，自動滑動
        int SCROLL_STATE_IDLE = 0;   //不滑動
        int SCROLL_STATE_TOUCH_SCROLL = 1;   //手指按着屏幕滑動

        void onScrollStateChanged(MyScrollView view, int state);

        void onScroll(MyScrollView view, int y); //滑動距離

        void onScrollToTop();   //滑到頂部

        void onScrollToBottom(); //滑到底部
    }

    public MyScrollView(Context context) {
        super(context);
    }

    public MyScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        listeners = new ArrayList<>();
    }

    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override public boolean onTouchEvent(MotionEvent ev) {
        boolean lastDragState = getDragState();

        boolean ret = super.onTouchEvent(ev);
        if (ev.getActionMasked() == MotionEvent.ACTION_MOVE) {
            for (OnMyScrollListener listener:listeners) {
                listener.onScroll(this, getScrollY());
            }
        }

        if ((ev.getActionMasked() == MotionEvent.ACTION_UP
                || ev.getActionMasked() == MotionEvent.ACTION_CANCEL)
                && currentState == OnMyScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
            //取消滑動
            currentState = OnMyScrollListener.SCROLL_STATE_IDLE;
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollStateChanged(this, OnMyScrollListener.SCROLL_STATE_IDLE);
            }

        }
        boolean curDragState = getDragState();

        //拖動
        if (!lastDragState && curDragState) {
            currentState = OnMyScrollListener.SCROLL_STATE_TOUCH_SCROLL;
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollStateChanged(this, OnMyScrollListener.SCROLL_STATE_TOUCH_SCROLL);
            }
        }
        return ret;
    }

    @Override protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (lastDrawPos == getScrollY()
                && getScrollY() > 0
                && currentState == OnMyScrollListener.SCROLL_STATE_FLING ) {
            currentState = OnMyScrollListener.SCROLL_STATE_IDLE;  //設置狀態爲空閒
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollStateChanged(this, OnMyScrollListener.SCROLL_STATE_IDLE);
            }
        }

        if (getScrollY() == 0 && lastDrawPos == 0
                && currentState != OnMyScrollListener.SCROLL_STATE_IDLE) {
            currentState = OnMyScrollListener.SCROLL_STATE_IDLE;  //設置狀態爲空閒
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollStateChanged(this, OnMyScrollListener.SCROLL_STATE_IDLE);
                listener.onScrollToTop();
            }
        }

        lastDrawPos = getScrollY();

        if (isCurrentBottom()
                && !isLastBottom) {
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollToBottom();
            }
        }
        isLastBottom = isCurrentBottom();
    }

    @Override public void fling(int velocityY) {
        super.fling(velocityY);

        if (getChildCount() > 0) {
            currentState = OnMyScrollListener.SCROLL_STATE_FLING;
            for (OnMyScrollListener listener:listeners) {
                listener.onScrollStateChanged(this, OnMyScrollListener.SCROLL_STATE_FLING);
            }
        }
    }

    //判斷是否滑到底部
    private boolean isCurrentBottom() {
        boolean ret = false;

        int targetSdkVersion = getContext().getApplicationInfo().targetSdkVersion;
        int heightPadding;  //scrollview上下padding之和
        View child = getChildAt(0);
        final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();
        if (targetSdkVersion >= Build.VERSION_CODES.M) {
            heightPadding = getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin;
        } else {
            heightPadding = getPaddingTop() + getPaddingBottom();
        }

        if (getMeasuredHeight() - heightPadding + getScrollY() == child.getMeasuredHeight()) {
            ret = true;
        }
        return ret;
    }

    //反射查詢mIsBeingDragged
    private boolean getDragState() {
        boolean state = false;
        try {
            Class clz = ScrollView.class;
            Field field = clz.getDeclaredField("mIsBeingDragged");
            field.setAccessible(true);
            state = field.getBoolean(this);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return state;
    }

    //滑動加速器是否停止
    private boolean isfinishScroll() {
        boolean isfinish=false;
        Class scrollview=ScrollView.class;
        try {
            Field scrollField=scrollview.getDeclaredField("mScroller");
            scrollField.setAccessible(true);
            Object scroller=scrollField.get(this);
            Class overscroller= scrollField.getType();
            Method finishField=overscroller.getMethod("isFinished");
            finishField.setAccessible(true);
            isfinish= (boolean) finishField.invoke(scroller);
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {

        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        return isfinish;
    }

    /**
     * 添加滑動監聽
     * @param listener
     */
    public void addOnScrollListner(OnMyScrollListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("invalid listener");
        }

        if (!listeners.contains(listener)) {
            listeners.add(listener);
        }
    }

    public void removeOnScrollListener(OnMyScrollListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("invalid listener");
        }

        listeners.remove(listener);
    }
}

三、UI適配

其實這個UI適配也很簡單的，就是設置搜索框的paddingTop爲系統狀態欄的高度+xdp，這裏就不寫代碼了

以上就是本人對齊劉海適配的思路，歡迎指正，共同學習，共勉