仿网易选项卡的实现

Google在2015的IO大会上，给我们带来了更加详细的Material Design设计规范，同时，也给我们带来了全新的Android Design Support Library，在这个support库里面，Google给我们提供了更加规范的MD设计风格的控件。最重要的是，Android Design Support Library的兼容性更广，直接可以向下兼容到Android 2.2。

app/build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.hd.tabviewtest"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.2.0'
    compile 'com.android.support:support-annotations:23.2.0'
    compile 'com.android.support:design:23.2.0'
}

需要添加compile ‘com.android.support:design:23.2.0’包。

layout/activity_main.xml

<?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.hd.tabviewtest.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabIndicatorColor="#ADBE107E"
            app:tabMode="scrollable"></android.support.design.widget.TabLayout>

        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/white"
            ></android.support.v4.view.ViewPager>

    </android.support.design.widget.AppBarLayout>


</LinearLayout>

这里需要注意控件所属的包别用错了，android.widget.TabLayout也有一个TabLayout，我们需要使用design.support包中的控件。

com.hd.tabviewtest.MainActivity

package com.hd.tabviewtest;

import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private ViewPager viewPager;
    private TabLayout mTablayout;

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

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        initViewger();
    }

    private void initViewger() {
        mTablayout = (android.support.design.widget.TabLayout) findViewById(R.id.tabs);
        List<String> titles = new ArrayList<>();
        titles.add("精选");
        titles.add("体育");
        titles.add("巴萨");
        titles.add("明星");
        titles.add("视频");
        titles.add("健康");
        titles.add("励志");
        titles.add("图文");
        titles.add("本地");
        titles.add("动漫");
        titles.add("搞笑");
        titles.add("精选");
        for (int i=0;i<titles.size();i++) {
            mTablayout.addTab(mTablayout.newTab().setText(titles.get(i)));
        }
        List<Fragment> fragmentList = new ArrayList<>();
        for (int i =0;i<titles.size();i++) {
            ListFragment fragment = new ListFragment();
            Bundle bundle = new Bundle();
            bundle.putString("title",titles.get(i));
            fragment.setArguments(bundle);
            fragmentList.add(fragment);
        }
        FragmentAdapter adapter = new FragmentAdapter(getSupportFragmentManager(), fragmentList, titles);
        viewPager.setAdapter(adapter);
        mTablayout.setupWithViewPager(viewPager);
    }
}

这里主要说下mTablayout.setupWithViewPager(viewPager)这个方法。这个方法会把TabLayout和ViewPager进行关联，无论哪一个控件改变，另外一个控件都会对应做出改变。当然，这是因为适配器的功能，当进行页面切换时，viewpger会回调适配器中的getItem方法去加载对应Frament，而TabLayout也会回调适配器中的getPageTitle方法。

layout/fragment_1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent">


    <TextView  android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:text="fragment1"/>
</LinearLayout>

package com.hd.tabviewtest;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/** * Created by hd on 2016/3/5. */
public class ListFragment extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        String title = getArguments().getString("title");
        View view = inflater.inflate(R.layout.fragment_1, container, false);
        TextView mTextView = (TextView) view.findViewById(R.id.textView);
        mTextView.setText(title);
        return view;
    }
}

com.hd.tabviewtest.FragmentAdapter

package com.hd.tabviewtest;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;

import java.util.List;

/** * Created by hd on 2016/3/5. */
public class FragmentAdapter extends FragmentStatePagerAdapter {

    private List<Fragment> mFragmentList;
    private List<String> mTitleList;

    public FragmentAdapter(FragmentManager fm, List<Fragment> fragmentsList, List<String> TitleList) {
        super(fm);
        mFragmentList = fragmentsList;
        mTitleList = TitleList;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mTitleList.get(position);
    }
}