Android实现底部切换标签

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <ImageView
    android:id="@+id/tab_image"
    android:layout_width="20dp"
    android:layout_height="20dp" />
  <TextView
    android:id="@+id/tab_label"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#666666"
    android:textSize="12sp" />
</merge>

public class TabView extends LinearLayout {
  private ImageView mTabImage;
  private TextView mTabLable;
  public TabView(Context context) {
    super(context);
    initView(context);
  }
  public TabView(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    initView(context);
  }
  public TabView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    initView(context);
  }
  private void initView(Context context) {
    setOrientation(VERTICAL);
    setGravity(Gravity.CENTER);
    LayoutInflater.from(context).inflate(R.layout.widget_tab_view, this, true);
    mTabImage = (ImageView) findViewById(R.id.tab_image);
    mTabLable = (TextView) findViewById(R.id.tab_label);
  }
  public void initData(TabItem tabItem) {
    mTabImage.setImageResource(tabItem.imageResId);
    mTabLable.setText(tabItem.lableResId);
  }
}

public class TabItem {
  public int imageResId;
  public int lableResId;
  public Class<? extends Fragment> tagFragmentClz;
  public TabItem(int imageResId, int lableResId) {
    this.imageResId = imageResId;
    this.lableResId = lableResId;
  }
  public TabItem(int imageResId, int lableResId, Class<? extends Fragment> tagFragmentClz) {
    this.imageResId = imageResId;
    this.lableResId = lableResId;
    this.tagFragmentClz = tagFragmentClz;
  }
}

public class BottomTabLayout extends LinearLayout implements View.OnClickListener {
  private ArrayList<TabItem> tabs;
  private OnTabClickListener listener;
  private int tabCount;
  private View selectedView;
  public BottomTabLayout(Context context) {
    super(context);
    initView();
  }
  public BottomTabLayout(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    initView();
  }
  public BottomTabLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    initView();
  }
  private void initView() {
    setOrientation(HORIZONTAL);
  }
  public void setCurrentTab(int i) {
    if (i < tabCount && i >= 0) {
      View view = getChildAt(i);
      onClick(view);
    }
  }
  public void initData(ArrayList<TabItem> tabs, OnTabClickListener listener) {
    this.tabs = tabs;
    this.listener = listener;
    LayoutParams params = new LayoutParams(0, ViewGroup.LayoutParams.MATCH_PARENT);
    params.weight = 1;
    params.gravity = Gravity.CENTER;
    if (tabs != null && tabs.size() > 0) {
      tabCount = tabs.size();
      TabView mTabView = null;
      for (int i = 0, len = tabs.size(); i < len; i++) {
        mTabView = new TabView(getContext());
        mTabView.setTag(tabs.get(i));
        mTabView.initData(tabs.get(i));
        mTabView.setOnClickListener(this);
        addView(mTabView, params);
      }
    } else {
      throw new IllegalArgumentException("tabs can not be empty");
    }
  }
  @Override
  public void onClick(View view) {
    if (selectedView != view) {
      listener.onTabClick((TabItem) view.getTag());
      view.setSelected(true);
      if (selectedView != null) {
        selectedView.setSelected(false);
      }
      selectedView = view;
    }
  }
  public interface OnTabClickListener {
    void onTabClick(TabItem tabItem);
  }
}

public class MainActivity extends AppCompatActivity implements BottomTabLayout.OnTabClickListener {
  private BottomTabLayout tab_layout;
  private ArrayList<TabItem> tabs;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    setTitle("底部切换标签");
    tab_layout = (BottomTabLayout) findViewById(R.id.tab_layout);
    initBottomTab();
    tab_layout.setCurrentTab(0);
  }
  private void initBottomTab() {
    tabs = new ArrayList<>();
    tabs.add(new TabItem(R.drawable.selector_tab_msg, R.string.wechat, OneFragment.class));
    tabs.add(new TabItem(R.drawable.selector_tab_contact, R.string.contacts, TwoFragment.class));
    tabs.add(new TabItem(R.drawable.selector_tab_moments, R.string.discover, ThreeFragment.class));
    tabs.add(new TabItem(R.drawable.selector_tab_profile, R.string.me, FourFragment.class));
    tab_layout.initData(tabs, this);
  }
  private Fragment lastFragment;
  @Override
  public void onTabClick(TabItem tabItem) {
    try {
      Fragment tmpFragment = getSupportFragmentManager().findFragmentByTag(tabItem.tagFragmentClz.getSimpleName());
      FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
      if (tmpFragment == null) {
        tmpFragment = tabItem.tagFragmentClz.newInstance();
        transaction.add(R.id.fl_container, tmpFragment, tabItem.tagFragmentClz.getSimpleName());
        if (lastFragment != null) {
          transaction.hide(lastFragment);
        }
        transaction.commitAllowingStateLoss();
      } else {
        transaction.show(tmpFragment);
        if (lastFragment != null) {
          transaction.hide(lastFragment);
        }
        transaction.commitAllowingStateLoss();
      }
      lastFragment = tmpFragment;
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  tools:context="com.sample.bottomtab.MainActivity">
  <FrameLayout
    android:id="@+id/fl_container"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:background="#ffffff" />
  <View
    android:layout_width="match_parent"
    android:layout_height="1dp"
    android:background="#dcdcdc" />
  <com.sample.bottomtab.widget.bottomtab.BottomTabLayout
    android:id="@+id/tab_layout"
    android:layout_width="match_parent"
    android:layout_height="48dp"
    android:background="#ffffff" />
</LinearLayout>