思路

要求

ScrollView 巢狀 位址列 和 WebView

手指滑屏向下滾動（網頁向上），如果網頁有滾動條，首先把 位址列 滾動到消失，然後 WebView 才開始滾動；

手指滑屏向上滾動（網頁向下），如果位址列隱藏，那麼 位址列 首先慢慢顯示，然後 WebView 才開始滾動。

實現方案

• 根據 View 的 onInterceptTouchEvent 和 onTouchEvent 原理。把 ScrollView 設定為 WebView 的一個變數，在 WebView的 onInterceptTouchEvent 方法裡檢測到 MotionEvent.ACTION_DOWN

  事件後中斷事件，在 WebView 的 onTouchEvent 事件中根據具體情況決定是把 MotionEvent.ACTION_MOVE 事件傳送給 ScrollView 還是留給自己
  • 由於MotionEvent.ACTION_MOVE 事件傳送給 ScrollView 後無法在一次 Touch 事件中再接收，所以會導致如果有位址列，向下滑動第一次只能滑動到 ScrollView 消失
  +

• Hack網頁，加入JS指令碼，前行讓網頁頂部空出來一段空白，空白處覆蓋位址列

  • 優點是WebView大小不變化，容易控制

  • 缺點是比較複雜要處理各種網頁元素,各種 position 情況，實現複雜，效率低

• 由手勢接管所有觸發操作，再由它分發給需要滾動的控制元件

  • 本文方法

資源

SrollView下面包含節點位址列,WebView控制元件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    android:id="@+id/root"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width
 
="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">

    <samples.zjc.com.testbrowserfeature.MyScrollView
        android:id="@+id/scrollView"
        android:scrollbars="none"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <LinearLayout
                android:id="@+id/toolBar"
                android:background="#5ff0"
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
                <EditText
                    android:id="@+id/urlEdit"
                    android:layout_weight="1"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"/>
                <Button
                    android:id="@+id/goButton"
                    android:text="Go"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"/>
            </LinearLayout>

            <samples.zjc.com.testbrowserfeature.MyWebView
                android:id="@+id/webView"
                android:layout_width="match_parent"
                android:layout_height="100dp" />
        </LinearLayout>
    </samples.zjc.com.testbrowserfeature.MyScrollView>
</RelativeLayout>

ScrollView繼承自 ScrollView

• onTouchEvent 中阻止 MotionEvent.ACTION_MOVE 事件

public class MyScrollView extends ScrollView {
    public MyScrollView(Context context) {
        super(context);
    }

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

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

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if(ev.getAction() == MotionEvent.ACTION_MOVE) {
            return true;
        }
        return super.onTouchEvent(ev);
    }
}

MyWebView繼承自 WebView

• onTouchEvent 中阻止 MotionEvent.ACTION_MOVE 事件

• onDrawListner

• 計算豎直滾動範圍

public class MyWebView extends WebView {
    public interface MyWebViewListener {
        void afterDraw(WebView webView);
    }

    private MyWebViewListener mListener;
    private int mMoveCheckedCnt;

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

    public MyWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

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

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public MyWebView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    public MyWebView(Context context, AttributeSet attrs, int defStyleAttr, boolean privateBrowsing) {
        super(context, attrs, defStyleAttr, privateBrowsing);
    }

    public void setListener(MyWebViewListener listener) {
        mListener = listener;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mMoveCheckedCnt = 0;
                flingScroll(0, 0);
                break;
            case MotionEvent.ACTION_MOVE:
                mMoveCheckedCnt++;
                return false;
            case MotionEvent.ACTION_UP:
                if(mMoveCheckedCnt >= 2) {
                    event.setAction(MotionEvent.ACTION_CANCEL);
                    mMoveCheckedCnt = 0;
                }
                break;
        }
        return super.onTouchEvent(event);
    }

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

        MyWebViewListener listener = mListener;
        if(listener != null) {
            listener.afterDraw(this);
        }
    }

    public int getVScrollRange() {
        int v = computeVerticalScrollRange() - computeVerticalScrollExtent();
        if(v < 0) {
            v = 0;
        }
        return v;
    }
}

主視窗

• GlobalLayoutListener 獲取位址列和滾動檢視高度

• GestureDetector 邏輯分發 - 決定是滑動webview還是改變webview高度從而改變ScrollView滾動範圍（ScrollView總是滾動到最底）

• WebView 重畫之後檢測當前位址列偏移

public class MainActivity extends AppCompatActivity implements MyWebView.MyWebViewListener {

    MyWebView mWebView;
    GestureDetector mGesture = null;

    View mToolBar;
    int mToolBarHeight;
    MyScrollView mScrollView;
    int mScrollViewHeight;
    int mScrollOffset;
    EditText mUrlEdit;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mWebView = (MyWebView) findViewById(R.id.webView);
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                return false;
            }
        });

        mWebView.setListener(this);

        mWebView.loadUrl("http://www.sohu.com");

        mUrlEdit = (EditText) findViewById(R.id.urlEdit);

        findViewById(R.id.goButton).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String url = mUrlEdit.getText().toString();
                if (!url.startsWith("http://") && !url.startsWith("https://")) {
                    url = "http://" + url;
                }
                mWebView.loadUrl(url);
            }
        });

        mToolBar = findViewById(R.id.toolBar);
        mScrollView = (MyScrollView)findViewById(R.id.scrollView);
        ScrollView scrollView = (ScrollView) mScrollView;

        findViewById(R.id.root).getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                mToolBarHeight = mToolBar.getHeight();
                mScrollViewHeight = mScrollView.getHeight();
                adjustScrollView();
            }
        });

        mGesture = new GestureDetector(this, new GestureListener());
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        mGesture.onTouchEvent(ev);
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public void afterDraw(WebView webView) {
        if (mWebView.getVScrollRange() < mScrollOffset) {
            mScrollOffset = mWebView.getVScrollRange();
            adjustScrollView();
        }
    }


    class GestureListener extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            Log.e("Temp", "onDoubleTap");
            return super.onDoubleTap(e);
        }

        @Override
        public boolean onDown(MotionEvent e) {
            Log.e("Temp", "onDown");
            return super.onDown(e);
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                               float velocityY) {
            Log.e("Temp", "onFling:velocityX = " + velocityX + " velocityY" + velocityY);

            int effectX = (int) velocityX;
            int effectY = (int) velocityY;

            if (effectOnScrollViewByScroll((velocityY < 0 ? 1 : -1) * 8000)) {
                effectY = 0;
            }
            mWebView.flingScroll(-effectX, -effectY);

            return super.onFling(e1, e2, velocityX, velocityY);
        }

        @Override
        public void onLongPress(MotionEvent e) {
            Log.e("Temp", "onLongPress");
            super.onLongPress(e);
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                                float distanceX, float distanceY) {
            Log.e("Temp", "onScroll:distanceX = " + distanceX + " distanceY = " + distanceY);

            int effectX = (int) distanceX;
            int effectY = (int) distanceY;
            if (effectOnScrollViewByScroll((int) distanceY)) {
                effectY  = 0;
            }
            mWebView.scrollBy(effectX, effectY);

            return super.onScroll(e1, e2, distanceX, distanceY);
        }

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            Log.e("Temp", "onSingleTapUp");
            return super.onSingleTapUp(e);
        }
    }

    private boolean effectOnScrollViewByScroll(int distanceY) {
        if (distanceY > 0) {
            // scroll up, the web will scroll down
            if (mScrollOffset >= mToolBarHeight || mScrollOffset >= mWebView.getVScrollRange()) {
                return false;
            }

            mScrollOffset += distanceY;
            if (mScrollOffset > mToolBarHeight) {
                mScrollOffset = mToolBarHeight;
            }
            if (mScrollOffset > mWebView.getVScrollRange()) {
                mScrollOffset = mWebView.getVScrollRange();
            }

        } else {
            if (mScrollOffset <= 0) {
                return false;
            }

            mScrollOffset += distanceY;
            if (mScrollOffset <= 0) {
                mScrollOffset = 0;
            }
        }

        adjustScrollView();
        return true;
    }

    private void adjustScrollView() {
        Log.e("Temp", "offset is " + mScrollOffset);
        ViewGroup.LayoutParams layoutParams = mWebView.getLayoutParams();
        int newHeight = (mScrollViewHeight - mToolBarHeight) + mScrollOffset;
        Log.e("Temp", "newHeight is " + newHeight + ", layoutParams.height" + layoutParams.height);
        if (newHeight != layoutParams.height) {
            layoutParams.height = newHeight;
            mWebView.setLayoutParams(layoutParams);

            new Handler(Looper.getMainLooper()).post(new Runnable() {
                @Override
                public void run() {
                    mScrollView.fullScroll(ScrollView.FOCUS_DOWN);
                }
            });
        }
    }
}