微信出現之後，它的底部導航（bottom navigation）引領了潮流，後來，很多軟件都進行模仿，紛紛加入了bottom navigation。那麼，我也來模仿模仿，雖然與微信的底部效果有點區別，但是，畢竟是個學習的過程，就記錄了下來，也給大家參考參考。
先給大家看一下效果：
下面介紹一下實現過程：
ItemView的設計
BottomNavigation有四個ItemView，對應四個TabItemView，TabItemView佈局也很簡單，如下（tab_item_view.xml）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:id="@+id/tab_icon"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_gravity="center_horizontal"
/>
<TextView
android:id="@+id/tab_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:textSize="12sp" />
</LinearLayout>TabItemView繼承了LinearLayout，
public class TabItemView extends LinearLayout{
private ColorStateList colorStateList;
private ImageView mTabIcon;
private TextView mTabText;
public TabItemView(Context context) {
this(context, null);
}
public TabItemView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public TabItemView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context);
}
public void setDefaultTextColor(ColorStateList colorStateList) {
this.colorStateList = colorStateList;
}
private void initView(Context context) {
setOrientation(VERTICAL);
setGravity(Gravity.CENTER);
LayoutInflater.from(context).inflate(R.layout.tab_item_view, this, true);
mTabIcon = (ImageView) findViewById(R.id.tab_icon);
mTabText = (TextView) findViewById(R.id.tab_text);
}
public void initData(TabItem tabItem) {
if (mTabIcon != null && mTabText!= null && colorStateList != null){
mTabIcon.setImageResource(tabItem.getImageResId());
mTabText.setTextColor(colorStateList);
mTabText.setText(tabItem.getTextResId());
}
}
}以上介紹的是BottomNavigation中每個ItemView的創建，接下來定義一個Layout，把這些ItemView放置到其中：
TabLayout的創建：
創建TabLayout繼承自LinearLayout，並實現View.OnClickListener接口：
public class TabLayout extends LinearLayout implements View.OnClickListener {
private List<TabItem> tabs;
private View selectedView;
private int tabCount;
private ColorStateList colorStateList;
private ViewPager mViewPager;
public TabLayout(Context context) {
this(context, null);
}
public TabLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public TabLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context, attrs);
}
private void initView(Context context, AttributeSet attrs) {
setOrientation(HORIZONTAL);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TabLayout);
for (int i = 0; i < a.getIndexCount(); i++) {
int attr = a.getIndex(i);
if (attr == R.styleable.TabLayout_textColorSelector) {
colorStateList = a.getColorStateList(attr);
}
}
a.recycle();
}
@Override
public void onClick(View v) {
tabClickListener.onTabClick((TabItem) v.getTag());
}
public void intData(List<TabItem> tabItems, OnTabClickListener listener) {
this.tabClickListener = listener;
this.tabs = tabItems;
LayoutParams params = new LayoutParams(0, ViewGroup.LayoutParams.MATCH_PARENT);
params.weight = 1;
params.setMargins(12,9,12,10);
TabItemView itemView = null;
if (tabs != null && tabs.size() > 0) {
tabCount = tabs.size();
for (int index = 0; index < tabs.size(); index++) {
itemView = new TabItemView(getContext());
itemView.setDefaultTextColor(colorStateList);
itemView.setTag(tabs.get(index));
itemView.initData(tabs.get(index));
itemView.setOnClickListener(this);
addView(itemView, params);
}
} else {
throw new IllegalArgumentException("tabs can not be empty");
}
}
public void setCurrentTab(int position) {
if (position >= 0 && position < tabCount) {
View view = getChildAt(position);
if (selectedView != view) {
view.setSelected(true);
if (selectedView != null) {
selectedView.setSelected(false);
}
selectedView = view;
}
}
}
public void setTextColorSelected(ColorStateList colorStateList){
this.colorStateList = colorStateList;
}
public interface OnTabClickListener {
void onTabClick(TabItem tabItem);
}
OnTabClickListener tabClickListener;
}<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="TabLayout">
<attr name="textColorSelector" format="reference"/>
</declare-styleable>
</resources> for (int index = 0; index < tabs.size(); index++) {
itemView = new TabItemView(getContext());
itemView.setDefaultTextColor(colorStateList); //設置默認的colorStateList
itemView.setTag(tabs.get(index)); //設置每個itemView的Tag，便於點擊時，利用getTag方法來獲取點擊的ItemView
itemView.initData(tabs.get(index)); //調用TabItemView中的initData方法來初始化每個ItemView
itemView.setOnClickListener(this); //初始化監聽
addView(itemView, params); //添加View
}定義一個接口OnTabClickListener，返回被點擊的TabItemView
到此，一個BottomNavigation已經完成一半了，接下來就是，怎麼配合ViewPager來進行頁面切換了。
不知道大家有沒有遇到這種情況：
如果使用官方提供的ViewPager，噹噹前頁面是第1個頁面，然後點擊切換到第3個頁面的時候，第2個頁面還是會被快速顯示出來，然後在切換第3個頁面。只要所點擊的頁面和當前頁面之間還有其他頁面，在點擊切換時，都是把中間的所有頁面快速切換而過。我不知道我這樣描述大家有沒有看懂，如果不懂，那我也只能抱歉了。接下來解決這個問題。
自定義ViewPager
解決的思路：當用戶滑動頁面進行頁面切換時，允許ViewPager滑動。如果用戶是通過點擊底部的Tab來進行頁面切換時，禁止ViewPager滑動，直接切換到點擊所指的頁面。
創建一個IndexViewPager繼承自ViewPager
public class IndexViewPager extends ViewPager {
private boolean isCanScroll = true;
public IndexViewPager(Context context) {
super(context);
}
public IndexViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setScanScroll(boolean isCanScroll) {
this.isCanScroll = isCanScroll;
}
@Override
public void scrollTo(int x, int y) {
super.scrollTo(x, y);
}
@Override
public boolean onTouchEvent(MotionEvent arg0) {
// TODO Auto-generated method stub
if (isCanScroll) {
return super.onTouchEvent(arg0);
} else {
return false;
}
}
@Override
public void setCurrentItem(int item) {
// TODO Auto-generated method stub
super.setCurrentItem(item, false);
}
@Override
public void setCurrentItem(int item, boolean smoothScroll) {
// TODO Auto-generated method stub
super.setCurrentItem(item, smoothScroll);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent arg0) {
// TODO Auto-generated method stub
if (isCanScroll) {
return super.onInterceptTouchEvent(arg0);
} else {
return false;
}
}
}實現BottomNavigation：
這裏先定義一個Model的來保存每個TabItemView的數據，
在Activity中使用：
public class TabItem {
/**
* icon
*/
private int imageResId;
/**
* the text
*/
private int textResId;
private Class<? extends Fragment> tagFramgentClz;
public TabItem(int imageResId, int lableResId) {
this.imageResId = imageResId;
this.textResId = lableResId;
}
public TabItem(int imageResId, int lableResId, Class<? extends Fragment> tagFramgentClz) {
this.imageResId = imageResId;
this.textResId = lableResId;
this.tagFramgentClz = tagFramgentClz;
}
public int getImageResId() {
return imageResId;
}
public void setImageResId(int imageResId) {
this.imageResId = imageResId;
}
public int getTextResId() {
return textResId;
}
public void setTextResId(int textResId) {
this.textResId = textResId;
}
public Class<? extends Fragment> getTagFramgentClz() {
return tagFramgentClz;
}
public void setTagFramgentClz(Class<? extends Fragment> tagFramgentClz) {
this.tagFramgentClz = tagFramgentClz;
}
}在Activity的佈局文件中添加IndexViewPager和TabLayout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
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"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation='vertical'
tools:context="com.wujs.bottomnavigationtest.MainActivity">
<com.wujs.bottomnavigation.IndexViewPager
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/tab_layout"
/>
<com.wujs.bottomnavigation.TabLayout
android:id="@+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="56dp"
android:background="@color/white"
android:layout_alignParentBottom="true"
app:textColorSelector="@drawable/selector_tab_text"
/>
</RelativeLayout><?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:color="@color/colorPrimary" android:state_selected="true" />
<item android:color="@color/darker_gray" android:state_selected="false" />
</selector>public class MainActivity extends AppCompatActivity implements TabLayout.OnTabClickListener {
@BindView(R.id.tab_layout)
TabLayout tabLayout;
@BindView(R.id.viewPager)
IndexViewPager mViewPager;
private List<TabItem> tabs;
private int selectedPosition;
private boolean isPermsGranted = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
initData();
}
private void initData() {
tabs = new ArrayList<>();
tabs.add(BottomTabPosConstant.HOME_TAB_POS, new TabItem(R.drawable.selector_tab_home_icon,
R.string.tabactivity_tab_home_text, PaxFragment.class));
tabs.add(BottomTabPosConstant.CONCERN_TAB_POS, new TabItem(R.drawable.selector_tab_concern_icon,
R.string.tabactivity_tab_concern_text, ConcernFragment.class));
tabs.add(BottomTabPosConstant.NEARBY_TAB_POS, new TabItem(R.drawable.selector_tab_nearby_icon,
R.string.tabactivty_tab_nearby_text, NearbyFragment.class));
tabs.add(BottomTabPosConstant.ME_TAB_POS, new TabItem(R.drawable.selector_tab_me_icon,
R.string.tabactivity_tab_me_text, MeFragment.class));
tabLayout.intData(tabs, this);
tabLayout.setCurrentTab(0);
FragAdapter adapter = new FragAdapter(getSupportFragmentManager());
mViewPager.setAdapter(adapter);
mViewPager.setOffscreenPageLimit(2); //設置限定預加載的ViewPager頁面個數
//Change the selected tag, when the viewpager changes page.
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
mViewPager.setScanScroll(true); //enable scroll of viewpager
tabLayout.setCurrentTab(position);
selectedPosition = position;
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
@Override
public void onTabClick(TabItem tabItem) {
int position = tabs.indexOf(tabItem);
if (position != selectedPosition) {
mViewPager.setScanScroll(false); //disable scroll of viewpager
selectedPosition = position;
mViewPager.setCurrentItem(tabs.indexOf(tabItem)); // Here change the selected tag by setting current item of ViewPager.
}
}
private class FragAdapter extends FragmentPagerAdapter {
FragAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int arg0) {
try {
return tabs.get(arg0).getTagFramgentClz().newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
return null;
} catch (IllegalAccessException e) {
e.printStackTrace();
return null;
}
}
@Override
public int getCount() {
return tabs.size();
}
}
}
到此，一個模仿微信的BottomNavigation就完成了，歡迎大家來吐槽。
代碼已經上傳到CSDN上：點擊下載BottomNavigationTest
也可以到github上去下載：github