Android多个TAB选项卡切换效果

2019-12-12 06:34:03

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在前一期中，我们做了悬浮头部的两个tab切换和下拉刷新效果，后来项目中要求改成三个tab，当时就能估量了一下，如果从之前的改，也不是不可以，但是要互相记住的状态就太多了，很容易出现错误。就决定重新实现一下这个效果，为此先写了一个demo，这期间项目都已经又更新了两个版本了。demo还木有变成文章。

之前的版本中是采用了一个可以下拉刷新的listview，之后在listview中添加了两个头部，并且在该布局上的上面用了一个一模一样的切换tab，如果没有看过前面版本的，可以看看前一个版本，Listview多Tab上滑悬浮。

基于上述思路我们先来看看页面布局：main_activity

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:background="@color/color_gray_eaeaea" >  <android.support.v4.view.ViewPager    android:id="@+id/pager"    android:layout_width="match_parent"    android:layout_height="match_parent" />  <LinearLayout    android:id="@+id/header"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:background="@color/white"    android:orientation="vertical" >    <ImageView      android:id="@+id/show_event_detail_bg"      android:layout_width="fill_parent"      android:layout_height="135dip"      android:contentDescription="@string/empty"      android:scaleType="fitXY"      android:src="@drawable/header_default_bk" />    <TextView      android:id="@+id/show_event_detail_desc"      android:layout_width="wrap_content"      android:layout_height="104dip"      android:paddingBottom="24dip"      android:layout_marginLeft="15dip"      android:layout_marginRight="15dip"      android:paddingTop="25dip"      android:text="@string/head_title_desc"      android:textColor="@color/color_black_333333"      android:textSize="14sp" />    <View style="@style/horizontal_gray_divider" />    <View style="@style/horizontal_gray_divider" />    <com.example.refreashtabview.sliding.PagerSlidingTabStrip      android:id="@+id/show_tabs"      android:layout_width="match_parent"      android:layout_height="44dip"      android:background="@color/white" />  </LinearLayout></RelativeLayout>

页面采用了两层，后面一层为Viewpager，前面为悬浮头与tab切换，在这大家应该都想到了会怎么样实现，Viewpager中添加已经fragment，每个fragment里面加入一个可下拉刷新的Listview，根据ListView的滑动来控制前一帧页面的位置。

来看看页面代码吧，MainAcitivity.java

public class MainActivity extends ActionBarActivity implements OnPageChangeListener, ScrollTabHolder {  private PagerSlidingTabStrip tabs;  private ViewPager viewPager;  private SlidingPagerAdapter adapter;  private LinearLayout header;  private int headerHeight;  private int headerTranslationDis;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main_activity);    getHeaderHeight();    findViews();    setupPager();    setupTabs();  }  private void findViews() {    tabs = (PagerSlidingTabStrip) findViewById(R.id.show_tabs);    viewPager = (ViewPager) findViewById(R.id.pager);    header = (LinearLayout) findViewById(R.id.header);  }  private void getHeaderHeight() {    headerHeight = getResources().getDimensionPixelSize(R.dimen.max_header_height);    headerTranslationDis = -getResources().getDimensionPixelSize(R.dimen.header_offset_dis);  }  private void setupPager() {    adapter = new SlidingPagerAdapter(getSupportFragmentManager(), this, viewPager);    adapter.setTabHolderScrollingListener(this);//控制页面上滑    viewPager.setOffscreenPageLimit(adapter.getCacheCount());    viewPager.setAdapter(adapter);    viewPager.setOnPageChangeListener(this);  }  private void setupTabs() {    tabs.setShouldExpand(true);    tabs.setIndicatorColorResource(R.color.color_purple_bd6aff);    tabs.setUnderlineColorResource(R.color.color_purple_bd6aff);    tabs.setCheckedTextColorResource(R.color.color_purple_bd6aff);    tabs.setViewPager(viewPager);  }  @Override  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {    tabs.onPageScrolled(position, positionOffset, positionOffsetPixels);  }  @Override  public void onPageSelected(int position) {    tabs.onPageSelected(position);    reLocation = true;    SparseArrayCompat<ScrollTabHolder> scrollTabHolders = adapter.getScrollTabHolders();    ScrollTabHolder currentHolder = scrollTabHolders.valueAt(position);    if (NEED_RELAYOUT) {      currentHolder.adjustScroll((int) (header.getHeight() + headerTop));// 修正滚出去的偏移量    } else {      currentHolder.adjustScroll((int) (header.getHeight() + ViewHelper.getTranslationY(header)));// 修正滚出去的偏移量    }  }  @Override  public void onPageScrollStateChanged(int state) {    tabs.onPageScrollStateChanged(state);  }  @Override  public void adjustScroll(int scrollHeight) {  }  private boolean reLocation = false;  private int headerScrollSize = 0;  public static final boolean NEED_RELAYOUT = Integer.valueOf(Build.VERSION.SDK).intValue() < Build.VERSION_CODES.HONEYCOMB;  private int headerTop = 0;  // 刷新头部显示时，没有onScroll回调，只有当刷新时会有  @Override  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount,      int pagePosition) {    if (viewPager.getCurrentItem() != pagePosition) {      return;    }    if (headerScrollSize == 0 && reLocation) {      reLocation = false;      return;    }    reLocation = false;    int scrollY = Math.max(-getScrollY(view), headerTranslationDis);    if (NEED_RELAYOUT) {      headerTop = scrollY;      header.post(new Runnable() {        @Override        public void run() {          Log.e("Main", "scorry1="+ headerTop);          header.layout(0, headerTop, header.getWidth(), headerTop + header.getHeight());        }      });    } else {      ViewHelper.setTranslationY(header, scrollY);    }  }  /**   * 主要算这玩意，PullToRefreshListView插入了一个刷新头部，因此要根据不同的情况计算当前的偏移量</br>   *    * 当刷新时： 刷新头部显示，因此偏移量要加上刷新头的数值 未刷新时： 偏移量不计算头部。   *    * firstVisiblePosition >1时，listview中的项开始显示，姑且认为每一项等高来计算偏移量（其实只要显示一个项，向上偏移   * 量已经大于头部的最大偏移量，因此不准确也没有关系）   *    * @param view   * @return   */  public int getScrollY(AbsListView view) {    View c = view.getChildAt(0);    if (c == null) {      return 0;    }    int top = c.getTop();    int firstVisiblePosition = view.getFirstVisiblePosition();    if (firstVisiblePosition == 0) {      return -top + headerScrollSize;    } else if (firstVisiblePosition == 1) {      return -top;    } else {      return -top + (firstVisiblePosition - 2) * c.getHeight() + headerHeight;    }  }  // 与onHeadScroll互斥，不能同时执行  @Override  public void onHeaderScroll(boolean isRefreashing, int value, int pagePosition) {    if (viewPager.getCurrentItem() != pagePosition) {      return;    }    headerScrollSize = value;    if (NEED_RELAYOUT) {      header.post(new Runnable() {        @Override        public void run() {          Log.e("Main", "scorry="+ (-headerScrollSize));          header.layout(0, -headerScrollSize, header.getWidth(), -headerScrollSize + header.getHeight());        }      });    }else{      ViewHelper.setTranslationY(header, -value);    }  }}

解释一下上面的代码，界面中后一层为Viewpager，里面加入了多个fragment，每个fragment里面占用一个Listivew，Listview中添加一个与悬浮头高度完全一样的header，这样可显示区域就为能看到的区域，之后监听Listview的onScorll，根据当前显示的listview的item的高度来控制前一层的悬浮的位置，这个地方要注意的时，每次切换tab时，要将当前已经偏移的位置通知到当前切换的tab，比如tab1，向上滑动，影藏了悬浮头，当从tab1切换到tab2时，这是tab2的位置要向上修正，修正距离为悬浮头滑出去的距离。其他的部分代码页比较简单，看看就可以了，其次开源控件PullToRefreshListView中我修改了当在刷新时偏移的距离，当改距离通知到界面，这样在下拉刷新时，将整个头部向下偏移，

ps：上面的代码中也看到了，我们针对了不同的版本采用了不同的动画，这是由于在3.0以前，位移动画看起来移动了位置，可是实际上控件还在初始位置，为此要针对不同的版本处理不同的动画，否则tab上的点击事件在2.X版本上还是在初始位置。上面的动画采用了nineold控件，也可以自己写，这个部分动画还是比较简单的。

上面的Viewpager中添加了Fragment，我们来看看Tab1ListFragment.java

public class Tab1ListFragment extends ScrollTabHolderFragment {  private PullToRefreshListView listView;  private View placeHolderView;  private ArrayAdapter<String> adapter;  private ArrayList<String> listItems;  private Handler handler;  public Tab1ListFragment() {    this.setFragmentId(PageAdapterTab.PAGE_TAB1.fragmentId);  }  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);  }  @Override  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {    return inflater.inflate(R.layout.page_tab_fragment_layout, container, false);  }  @Override  public void onActivityCreated(Bundle savedInstanceState) {    super.onActivityCreated(savedInstanceState);    findViews();    initListView();  }  @SuppressLint("InflateParams")  private void findViews() {    handler = new Handler(Looper.getMainLooper());    listView = (PullToRefreshListView) getView().findViewById(R.id.page_tab_listview);  }  private void initListView() {    setListViewListener();    listViewAddHeader();    listViewLoadData();  }  private void setListViewListener() {    listView.setOnRefreshListener(new OnRefreshListener2<ListView>() {      @Override      public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {        loadNews();      }      @Override      public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {        loadOlds();      }    });    listView.setOnScrollListener(new OnScrollListener() {      @Override      public void onScrollStateChanged(AbsListView view, int scrollState) {      }      @Override      public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {        if (scrollTabHolder != null) {          scrollTabHolder.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount, getFragmentId());        }      }    });    listView.setOnHeaderScrollListener(new OnHeaderScrollListener() {      @Override      public void onHeaderScroll(boolean isRefreashing, boolean istop, int value) {        if (scrollTabHolder != null && istop) {          scrollTabHolder.onHeaderScroll(isRefreashing, value, getFragmentId());        }      }    });  }  private void listViewAddHeader() {    placeHolderView = new LinearLayout(getActivity());    AbsListView.LayoutParams params = new LayoutParams(AbsListView.LayoutParams.MATCH_PARENT, getResources()        .getDimensionPixelSize(R.dimen.max_header_height));    placeHolderView.setLayoutParams(params);    listView.getRefreshableView().addHeaderView(placeHolderView);  }  protected void listViewLoadData() {    listItems = new ArrayList<String>();    for (int i = 1; i <= 50; i++) {      listItems.add("currnet page: " + (getFragmentId() + 1) + " item --" + i);    }    adapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item, android.R.id.text1, listItems);    listView.setAdapter(adapter);    loadNews();  }  /**   * 下拉清空旧的数据   */  private void loadNews() {    handler.postDelayed(new Runnable() {// 模拟远程获取数据          @Override          public void run() {            stopRefresh();            // listItems.clear();            // for (int i = 1; i <= 50; i++) {            // listItems.add("currnet page: " + (getFragmentId() +            // 1) + " item --" + i);            // }            // notifyAdpterdataChanged();          }        }, 300);  }  private void notifyAdpterdataChanged() {    if (adapter != null) {      adapter.notifyDataSetChanged();    }  }  protected void loadOlds() {    handler.postDelayed(new Runnable() {// 模拟远程获取数据          @Override          public void run() {            stopRefresh();            int size = listItems.size() + 1;            for (int i = size; i < size + 50; ++i) {              listItems.add("currnet page: " + (getFragmentId() + 1) + " item --" + i);            }            notifyAdpterdataChanged();          }        }, 300);  }  // PullToRefreshListView 自动添加了一个头部  @Override  public void adjustScroll(int scrollHeight) {    if (scrollHeight == 0 && listView.getRefreshableView().getFirstVisiblePosition() >= 2) {      return;    }    //Log.d(getTag(), "scrollHeight:" + scrollHeight);    listView.getRefreshableView().setSelectionFromTop(2, scrollHeight);//   Log.d(getTag(), "getScrollY:" + getScrollY(listView.getRefreshableView()));//   handler.postDelayed(new Runnable() {//     //     @Override//     public void run() {//       Log.d(getTag(), "getScrollY:" + getScrollY(listView.getRefreshableView()));       //     }//   }, 5000);  }  public int getScrollY(AbsListView view) {    View c = view.getChildAt(0);    if (c == null) {      return 0;    }    int top = c.getTop();    int firstVisiblePosition = view.getFirstVisiblePosition();    if (firstVisiblePosition == 0) {      return -top;    } else if (firstVisiblePosition == 1) {      return top;    } else {      return -top + (firstVisiblePosition - 2) * c.getHeight() + 683;    }  }  protected void updateListView() {    if (adapter != null) {      adapter.notifyDataSetChanged();    }  }  protected void stopRefresh() {    listView.onRefreshComplete();  }}

上面代码中的界面就是xml中包含了一个PullToRefreshListView，比较简单这个地方就不贴出来了，我们看到在listViewAddHeader中，这个地方添加了一个与悬浮头等高的头部，这样就可以将内容区域给呈现出来，不会被悬浮头遮挡，其次在list的listener中我们将onScorll传到了主界面，这样Listview滚动，就可以将当前滚动的距离计算出来，修正悬浮头的距离。

我们再贴出上面剩下的代码ScrollTabHolderFragment.java与ScrollTabHolder.java

public abstract class ScrollTabHolderFragment extends Fragment implements ScrollTabHolder {  private int fragmentId;  protected ScrollTabHolder scrollTabHolder;  public void setScrollTabHolder(ScrollTabHolder scrollTabHolder) {    this.scrollTabHolder = scrollTabHolder;  }  @Override  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount,      int pagePosition) {    // nothing  }  @Override  public void onHeaderScroll(boolean isRefreashing, int value, int pagePosition) {  }  public int getFragmentId() {    return fragmentId;  }  public void setFragmentId(int fragmentId) {    this.fragmentId = fragmentId;  }}public interface ScrollTabHolder {  void adjustScroll(int scrollHeight);  void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount, int pagePosition);  void onHeaderScroll(boolean isRefreashing, int value, int pagePosition);}

最后我们来看看adaper

public class SlidingPagerAdapter extends FragmentPagerAdapter {  protected final ScrollTabHolderFragment[] fragments;  protected final Context context;  private SparseArrayCompat<ScrollTabHolder> mScrollTabHolders;  private ScrollTabHolder mListener;  public int getCacheCount() {    return PageAdapterTab.values().length;  }  public SlidingPagerAdapter(FragmentManager fm, Context context, ViewPager pager) {    super(fm);    fragments = new ScrollTabHolderFragment[PageAdapterTab.values().length];    this.context = context;    mScrollTabHolders = new SparseArrayCompat<ScrollTabHolder>();    init(fm);  }  private void init(FragmentManager fm) {    for (PageAdapterTab tab : PageAdapterTab.values()) {      try {        ScrollTabHolderFragment fragment = null;        List<Fragment> fs = fm.getFragments();        if (fs != null) {          for (Fragment f : fs) {            if (f.getClass() == tab.clazz) {              fragment = (ScrollTabHolderFragment) f;              break;            }          }        }        if (fragment == null) {          fragment = (ScrollTabHolderFragment) tab.clazz.newInstance();        }        fragments[tab.tabIndex] = fragment;      } catch (InstantiationException e) {        e.printStackTrace();      } catch (IllegalAccessException e) {        e.printStackTrace();      }    }  }  public void setTabHolderScrollingListener(ScrollTabHolder listener) {    mListener = listener;  }  @Override  public ScrollTabHolderFragment getItem(int pos) {    ScrollTabHolderFragment fragment = fragments[pos];    mScrollTabHolders.put(pos, fragment);    if (mListener != null) {      fragment.setScrollTabHolder(mListener);    }    return fragment;  }  public SparseArrayCompat<ScrollTabHolder> getScrollTabHolders() {    return mScrollTabHolders;  }  @Override  public int getCount() {    return PageAdapterTab.values().length;  }  @Override  public CharSequence getPageTitle(int position) {    PageAdapterTab tab = PageAdapterTab.fromTabIndex(position);    int resId = tab != null ? tab.resId : 0;    return resId != 0 ? context.getText(resId) : "";  }}

SlidingPagerAdapter 继承自FragmentPagerAdapter，从主界面传递了一个callback，将在callback传递给每个fragment，这样就将fragment与activity联系起来了。其实还有很多种方式，比如在fragment的attach中获取activity中的回调。上面代码中还有一个PageAdapterTab，它又是干什么的呐？来看看代码

public enum PageAdapterTab {  PAGE_TAB1(0, Tab1ListFragment.class, R.string.page_tab1),  PAGE_TAB2(1, Tab2ListFragment.class, R.string.page_tab2),  PAGE_TAB3(2, Tab3ListFragment.class, R.string.page_tab3),  ;  public final int tabIndex;  public final Class<? extends Fragment> clazz;  public final int resId;  public final int fragmentId;  private PageAdapterTab(int index, Class<? extends Fragment> clazz, int resId) {    this.tabIndex = index;    this.clazz = clazz;    this.resId = resId;    this.fragmentId = index;  }  public static final PageAdapterTab fromTabIndex(int tabIndex) {    for (PageAdapterTab value : PageAdapterTab.values()) {      if (value.tabIndex == tabIndex) {        return value;      }    }    return null;  }}

就是一个枚举类，配置了当前要显示的fragment，这样以后就要增加就可以只修改改枚举就ok了

到此整个工程就结束了，我们截几张图看看效果：