Android 使用TabLayout制作下划线能滑动的Tab标签页-design

原文地址: https://blog.csdn.net/zhuwentao2150/article/details/52279133

google提供的Design开发包里，有很多实用好看的新控件，这里介绍下使用TabLayout+ViewPager实现下划线能滑动的Tab标签页

效果图 
 
不使用google的design包，我们也可以自己制作这样的效果，详看我的这篇博客：http://blog.csdn.net/zhuwentao2150/article/details/51407661

要使用Design包，在项目的build.gradle中添加下依赖就好（记得更新SDK到最新版本）

dependencies {
     compile 'com.android.support:design:23.4.0'
}

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先来看布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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">

    <android.support.design.widget.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        app:tabSelectedTextColor="#ffffff"
        app:tabIndicatorColor="#ff00ff"
        app:tabTextColor="#000000"
        app:tabIndicatorHeight="5dp"
        app:tabMode="fixed"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/vp_tab_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

常用属性 
tabSelectedTextColor：当Tab标签被选中时的文字颜色 
tabTextColor：Tab标签中文字的默认颜色 
tabIndicatorColor：下划线颜色 
tabIndicatorHeight：下划线的高度 
tabBackground：设置Tab标签的背景 
tabMode：Tab标签的行为模式

MODE_FIXED: Fixed tabs display all tabs concurrently and are best used with content that benefits from quick pivots between tabs. 
MODE_SCROLLABLE: Scrollable tabs display a subset of tabs at any given moment, and can contain longer tab labels and a larger number of tabs. They are best used for browsing contexts in touch interfaces when users don’t need to directly compare the tab labels. This mode is commonly used with a ViewPager.

两种模式的差异： 
tabMode=”scrollable” 
滚动模式，TabLayout可以滚动 
标签多时，TabLayout支持滑动查看 
 
标签少时，，这些Tab会挤在一侧，且各个Tab不是等量分布的，有的占地多有的占地少 

tabMode=”fixed” 
填充模式，TabLayout不可滚动，所有的Tab都被限制在一定区域内 
标签多时，Tab会受到挤压 

Tab少时，各个Tab等量空间分布 

Fragment页面

/**
 * ViewPager页面
 * Created by zhuwentao on 2016-08-22.
 */
public class ViewPagerFragment extends Fragment{

    private String mPageNo;

    private TextView mPageNoTv;

    /** 状态类型常量 */
    public static final String STATUS_TYPE = "pagerType";

    public static final String STATUS_ONE = "One";

    public static final String STATUS_TWO = "Two";

    public static final String STATUS_THREE = "Three";

    /**
     * 取得Fragment实例
     */
    public static ViewPagerFragment newInstance(Bundle args) {
        ViewPagerFragment fragment = new ViewPagerFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPageNo = getArguments().getString(STATUS_TYPE);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_tab, container, false);
        mPageNoTv = (TextView) v.findViewById(R.id.tv_page_text);
        mPageNoTv.setText(mPageNo);
        return v;
    }

}

Activity界面

public class TabLayoutActivity extends AppCompatActivity {

    private ViewPager mPageVp;

    private TabLayout mLayoutTab;

    /**
     * 选项卡总数
     */
    private static final int TAB_COUNT = 3;

    private static final int TAB_0 = 0;

    private static final int TAB_1 = 1;

    private static final int TAB_2 = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tab_layout);
        initUI();
    }

    /**
     * 初始化UI
     */
    private void initUI() {
        mPageVp = (ViewPager) findViewById(R.id.vp_tab_pager);
        mLayoutTab = (TabLayout) findViewById(R.id.tab_layout);

        mPageVp.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
        // 把TabLayout和ViewPager关联起来
        mLayoutTab.setupWithViewPager(mPageVp);
    }

    /**
     * ViewPager适配器
     */
    public class MyPagerAdapter extends FragmentPagerAdapter {

        // 定义Tab标题
        private String[] tabTitles = new String[]{
                "One","Two","Three"
        };

        public MyPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            Bundle args = new Bundle();
            boolean flag = true;
            switch (position) {
                case TAB_0:
                    args.putString(ViewPagerFragment.STATUS_TYPE, ViewPagerFragment.STATUS_ONE);
                    break;
                case TAB_1:
                    args.putString(ViewPagerFragment.STATUS_TYPE, ViewPagerFragment.STATUS_TWO);
                    break;
                case TAB_2:
                    args.putString(ViewPagerFragment.STATUS_TYPE, ViewPagerFragment.STATUS_THREE);
                    break;
                default:
                    flag = false;
                    break;
            }
            if (flag) {
                // 返回对应的Fragment页面
                return ViewPagerFragment.newInstance(args);
            }
            return null;
        }

        @Override
        public int getCount() {
            return TAB_COUNT;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            // 设置Page对应的Tab标题
            return tabTitles[position];
        }
    }

}

调用setupWithViewPager()方法传入一个ViewPager对象，请确保该ViewPager对象已经通过setAdapter设置好了Adapter适配器 
从源码可以看出

public void setupWithViewPager(@Nullable final ViewPager viewPager) {
    if (mViewPager != null && mPageChangeListener != null) {
        // If we've already been setup with a ViewPager, remove us from it
        mViewPager .removeOnPageChangeListener( mPageChangeListener);
    }

    if (viewPager != null ) {
        final PagerAdapter adapter = viewPager.getAdapter();
        if (adapter == null) {
            throw new IllegalArgumentException( "ViewPager does not have a PagerAdapter set");
        }
    // ......

如果ViewPager的Adapter为空，则会抛出IllegalArgumentException异常 
把 TabLayout和 ViewPager 关联起来，该方法相当于帮我们封装好了 addOnPageChangeListener 和setOnTabSelectedListener ，帮我们节省了大量的代码。