Android 锚点定位 Android tabLayout+recyclerView实现锚点定位的示例

private LinearLayoutManager manager;
private String[] tabTxt = {"客厅", "卧室", "餐厅", "书房", "阳台", "儿童房"};
//判读是否是recyclerView主动引起的滑动，true- 是，false- 否，由tablayout引起的
private boolean isRecyclerScroll;
//记录上一次位置，防止在同一内容块里滑动 重复定位到tablayout
private int lastPos;
//用于recyclerView滑动到指定的位置
private boolean canScroll;
private int scrollToPosition;

//tablayout设置标签
for (int i = 0; i < tabTxt.length; i++) {
  tabLayout.addTab(tabLayout.newTab().setText(tabTxt[i]));
}

//计算内容块所在的高度，全屏高度-状态栏高度-tablayout的高度(这里固定高度50dp)，用于recyclerView的最后一个item view填充高度
int screenH = getScreenHeight();
int statusBarH = getStatusBarHeight(this);
int tabH = 50 * 3;
int lastH = screenH - statusBarH - tabH;
manager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(manager);
recyclerView.setAdapter(new MyAdapter(this, tabTxt, lastH));


@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
  holder.anchorView.setContentTxt(tabTxt[position]);
  holder.anchorView.setAnchorTxt(tabTxt[position]);
  //判断最后一个view
  if (position == tabTxt.length - 1) {
    if (holder.anchorView.getHeight() < lastH) {
      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
      params.height = lastH;
      holder.anchorView.setLayoutParams(params);
    }
  }
}

recyclerView.setOnTouchListener(new View.OnTouchListener() {
  @Override
  public boolean onTouch(View v, MotionEvent event) {
    //当滑动由recyclerView触发时，isRecyclerScroll 置true
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
      isRecyclerScroll = true;
    }
    return false;
  }
});

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
  @Override
  public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);
    if (isRecyclerScroll) {
      //第一个可见的view的位置，即tablayou需定位的位置
      int position = manager.findFirstVisibleItemPosition();
      if (lastPos != position) {
        tabLayout.setScrollPosition(position, 0, true);
      }
      lastPos = position;
    }
  }
});

tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
  @Override
  public void onTabSelected(TabLayout.Tab tab) {
    //点击标签，使recyclerView滑动，isRecyclerScroll置false
    int pos = tab.getPosition();
    isRecyclerScroll = false;
    moveToPosition(manager, recyclerView, pos);
  }

  @Override
  public void onTabUnselected(TabLayout.Tab tab) {

  }

  @Override
  public void onTabReselected(TabLayout.Tab tab) {

  }
});


public void moveToPosition(LinearLayoutManager manager, RecyclerView mRecyclerView, int position) {
  // 第一个可见的view的位置
  int firstItem = manager.findFirstVisibleItemPosition();
  // 最后一个可见的view的位置
  int lastItem = manager.findLastVisibleItemPosition();
  if (position <= firstItem) {
    // 如果跳转位置firstItem 之前(滑出屏幕的情况)，就smoothScrollToPosition可以直接跳转，
    mRecyclerView.smoothScrollToPosition(position);
  } else if (position <= lastItem) {
    // 跳转位置在firstItem 之后，lastItem 之间（显示在当前屏幕），smoothScrollBy来滑动到指定位置
    int top = mRecyclerView.getChildAt(position - firstItem).getTop();
    mRecyclerView.smoothScrollBy(0, top);
  } else {
    // 如果要跳转的位置在lastItem 之后，则先调用smoothScrollToPosition将要跳转的位置滚动到可见位置
    // 再通过onScrollStateChanged控制再次调用当前moveToPosition方法，执行上一个判断中的方法
    mRecyclerView.smoothScrollToPosition(position);
    scrollToPosition = position;
    canScroll = true;
  }
}

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
  @Override
  public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
    super.onScrollStateChanged(recyclerView, newState);
    if (canScroll) {
      canScroll = false;
      moveToPosition(manager, recyclerView, scrollToPosition);
    }
  }
});