Android 修改TabLayout底部导航条Indicator的长短

关于Tablayout，使用的应该很频繁了，但是底部导航条长短是固定死的，需要自己来改动长短，找了半天没找着方法，看了下官方建议，可以通过映射来修改自己想要的长短，其实也就几行代码的问题，看代码：

  public static void setIndicator(Context context, TabLayout tabs, int leftDip, int rightDip) {

        Class<?> tabLayout = tabs.getClass();

        Field tabStrip = null;

        try {

            tabStrip = tabLayout.getDeclaredField("mTabStrip");

        } catch (NoSuchFieldException e) {

            e.printStackTrace();

        }

        tabStrip.setAccessible(true);

        LinearLayout ll_tab = null;

        try {

            ll_tab = (LinearLayout) tabStrip.get(tabs);

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        }

        int left = (int) (getDisplayMetrics(context).density * leftDip);

        int right = (int) (getDisplayMetrics(context).density * rightDip);

        for (int i = ; i < ll_tab.getChildCount(); i++) {

            View child = ll_tab.getChildAt(i);

            child.setPadding(, , , );

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(, LinearLayout.LayoutParams.MATCH_PARENT, );

            params.leftMargin = left;

            params.rightMargin = right;

            child.setLayoutParams(params);

            child.invalidate();

        }

    }

leftDip和rightDip是左右间距，根据自己的需要来设置，直接调用即可。

很多同学都遇到问题，这里附上源码，大家可以看看：

package com.example.donghe.myrefreshview;

import android.app.Activity;

import android.content.Context;

import android.support.design.widget.TabLayout;

import android.support.v4.app.Fragment;

import android.support.v4.app.FragmentManager;

import android.support.v4.app.FragmentStatePagerAdapter;

import android.support.v4.view.ViewPager;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.DisplayMetrics;

import android.util.TypedValue;

import android.view.View;

import android.widget.LinearLayout;

import android.widget.TableLayout;

import java.lang.reflect.Field;

public class MainActivity extends AppCompatActivity {

    private static int TAB_MARGIN_DIP = ;

    TabLayout tableLayout;

    ViewPager viewPager;

    RankingPagerAdapter adapter;

    String [] strings = {"皇帝","丞相","尚书","太监"};

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        tableLayout = (TabLayout) findViewById(R.id.tabs_ranking);

        viewPager = (ViewPager) findViewById(R.id.container_ranking);

        adapter = new RankingPagerAdapter(getSupportFragmentManager());

        viewPager.setAdapter(adapter);

        tableLayout.setupWithViewPager(viewPager);

        tableLayout.setTabTextColors(getResources().getColor(R.color.black), getResources().getColor(R.color.red_pre));

        tableLayout.setTabsFromPagerAdapter(adapter);

        setIndicator(this, tableLayout, TAB_MARGIN_DIP, TAB_MARGIN_DIP);

    }

    private class RankingPagerAdapter extends FragmentStatePagerAdapter {

        public RankingPagerAdapter(FragmentManager fm) {

            super(fm);

        }

        @Override

        public Fragment getItem(int position) {

            return new FuelFragment().newInstance(position, strings[position]);

        }

        @Override

        public int getCount() {

            return strings.length;

        }

        @Override

        public CharSequence getPageTitle(int position) {

            return strings[position];

        }

    }

    public static void setIndicator(Context context, TabLayout tabs, int leftDip, int rightDip) {

        Class<?> tabLayout = tabs.getClass();

        Field tabStrip = null;

        try {

            tabStrip = tabLayout.getDeclaredField("mTabStrip");

        } catch (NoSuchFieldException e) {

            e.printStackTrace();

        }

        tabStrip.setAccessible(true);

        LinearLayout ll_tab = null;

        try {

            ll_tab = (LinearLayout) tabStrip.get(tabs);

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        }

        int left = (int) (getDisplayMetrics(context).density * leftDip);

        int right = (int) (getDisplayMetrics(context).density * rightDip);

        for (int i = ; i < ll_tab.getChildCount(); i++) {

            View child = ll_tab.getChildAt(i);

            child.setPadding(, , , );

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(, LinearLayout.LayoutParams.MATCH_PARENT, );

            params.leftMargin = left;

            params.rightMargin = right;

            child.setLayoutParams(params);

            child.invalidate();

        }

    }

    public static DisplayMetrics getDisplayMetrics(Context context) {

        DisplayMetrics metric = new DisplayMetrics();

        ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);

        return metric;

    }

    public static float getPXfromDP(float value, Context context) {

        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, value,

                context.getResources().getDisplayMetrics());

    }

}

Fragment：

package com.example.donghe.myrefreshview;

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 dong.he on 2016/12/9.

 */

public class FuelFragment extends Fragment {

    public static String TAB_POSITION;

    public static String TAB_NAME;

    private String tabId;

    private int tabPosition;

    public FuelFragment() {

    }

    public static Fragment newInstance(int tabPosition, String tabName) {

        FuelFragment fragment = new FuelFragment();

        Bundle bundle = new Bundle();

        bundle.putInt(TAB_POSITION, tabPosition);

        bundle.putString(TAB_NAME, tabName);

        fragment.setArguments(bundle);

        return fragment;

    }

    @Nullable

    @Override

    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        return inflater.inflate(R.layout.layout, container, false);

    }

    @Override

    public void onActivityCreated(@Nullable Bundle savedInstanceState) {

        super.onActivityCreated(savedInstanceState);

        tabPosition = getArguments().getInt(TAB_POSITION, );

        tabId = getArguments().getString(TAB_NAME);

        ((TextView) getView().findViewById(R.id.text)).setText(tabId);

    }

}

布局：

<?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"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical">

    <android.support.design.widget.TabLayout

        android:id="@+id/tabs_ranking"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        app:tabGravity="fill"

        app:tabIndicatorColor="@color/red_pre"

        app:tabMode="scrollable" />

    <android.support.v4.view.ViewPager

        android:id="@+id/container_ranking"

        android:layout_width="match_parent"

        android:layout_height="match_parent" />

</LinearLayout>

有问题的欢迎垂询。