思路要求
ScrollView 嵌套 地址栏 和 WebView
手指滑屏向下滚动（网页向上），如果网页有滚动条，首先把 地址栏 滚动到消失，然后 WebView 才开始滚动；
手指滑屏向上滚动（网页向下），如果地址栏隐藏，那么 地址栏 首先慢慢显示，然后 WebView 才开始滚动。
实现方案
- 根据 View 的 onInterceptTouchEvent 和 onTouchEvent 原理。把 ScrollView 设置为 WebView 的一个变量，在 WebView的 onInterceptTouchEvent 方法里检测到 MotionEvent.ACTION_DOWN 事件后中断事件，在 WebView 的 onTouchEvent 事件中根据具体情况决定是把 MotionEvent.ACTION_MOVE 事件传送给 ScrollView 还是留给自己
- 由于MotionEvent.ACTION_MOVE 事件传送给 ScrollView 后无法在一次 Touch 事件中再接收，所以会导致如果有地址栏，向下滑动第一次只能滑动到 ScrollView 消失
- Hack网页，加入JS脚本，前行让网页顶部空出来一段空白，空白处覆盖地址栏
- 优点是WebView大小不变化，容易控制
- 缺点是比较复杂要处理各种网页元素,各种 position 情况，实现复杂，效率低
- 由手势接管所有触发操作，再由它分发给需要滚动的控件
本文方法
资源
SrollView下面包含节点地址栏,WebView控件
代码语言：javascript复制<?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继承自 ScrollView
代码语言：javascript复制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继承自 WebView
onTouchEvent 中阻止 MotionEvent.ACTION_MOVE 事件
onDrawListner
计算竖直滚动范围
代码语言：javascript复制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;
}
}主窗口
GlobalLayoutListener 获取地址栏和滚动视图高度
GestureDetector 逻辑分发 – 决定是滑动webview还是改变webview高度从而改变ScrollView滚动范围（ScrollView总是滚动到最底）
WebView 重画之后检测当前地址栏偏移
代码语言：javascript复制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);
}
});
}
}
}总结
以上所述是小编给大家介绍的Android 类似UC浏览器的效果：向上滑动地址栏隐藏功能，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对ZaLou.Cn网站的支持！
