<menu 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"
  tools:context="com.kongqw.myapplication.MainActivity">
  <item
    android:id="@+id/search_button"
    android:icon="@mipmap/navigation_icon_search"
    android:orderInCategory="100"
    android:title="搜索"
    app:showAsAction="ifRoom" />
  <item
    android:id="@+id/scan_button"
    android:icon="@mipmap/navigation_icon_sweep"
    android:orderInCategory="100"
    android:title="扫描"
    app:showAsAction="ifRoom" />

  <item
    android:id="@+id/setting_button"
    android:icon="@mipmap/titlebar_icon_settings_normal"
    android:orderInCategory="100"
    android:title="设置"
    app:showAsAction="ifRoom" />
</menu>

@Override
public boolean onPrepareOptionsMenu(Menu menu) {
  // 动态设置ToolBar状态
  switch (mViewPager.getCurrentItem()) {
    case 0:
      menu.findItem(R.id.search_button).setVisible(true);
      menu.findItem(R.id.scan_button).setVisible(true);
      menu.findItem(R.id.setting_button).setVisible(false);
      break;
    case 1:
      menu.findItem(R.id.search_button).setVisible(false);
      menu.findItem(R.id.scan_button).setVisible(false);
      menu.findItem(R.id.setting_button).setVisible(false);
      break;
    case 2:
      menu.findItem(R.id.search_button).setVisible(false);
      menu.findItem(R.id.scan_button).setVisible(false);
      menu.findItem(R.id.setting_button).setVisible(true);
      break;
  }
  return super.onPrepareOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
  int id = item.getItemId();
  if (id == R.id.search_button) {
    Toast.makeText(getApplicationContext(), "搜索", Toast.LENGTH_SHORT).show();
    return true;
  } else if (id == R.id.scan_button) {
    Toast.makeText(getApplicationContext(), "扫描", Toast.LENGTH_SHORT).show();
    return true;
  } else if (id == R.id.setting_button) {
    Toast.makeText(getApplicationContext(), "设置", Toast.LENGTH_SHORT).show();
    return true;
  }
  return super.onOptionsItemSelected(item);
}

mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

  }

  @Override
  public void onPageSelected(int position) {
    // getWindow().invalidatePanelMenu(Window.FEATURE_OPTIONS_PANEL);
    invalidateOptionsMenu();
  }

  @Override
  public void onPageScrollStateChanged(int state) {

  }
});

package com.kongqw.myapplication;

import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import android.view.Window;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

  private SectionsPagerAdapter mSectionsPagerAdapter;

  private ViewPager mViewPager;

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

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
      @Override
      public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

      }

      @Override
      public void onPageSelected(int position) {
        // getWindow().invalidatePanelMenu(Window.FEATURE_OPTIONS_PANEL);
        invalidateOptionsMenu();
      }

      @Override
      public void onPageScrollStateChanged(int state) {

      }
    });
  }


  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
  }

  @Override
  public boolean onPrepareOptionsMenu(Menu menu) {
    // 动态设置ToolBar状态
    switch (mViewPager.getCurrentItem()) {
      case 0:
        menu.findItem(R.id.search_button).setVisible(true);
        menu.findItem(R.id.scan_button).setVisible(true);
        menu.findItem(R.id.setting_button).setVisible(false);
        break;
      case 1:
        menu.findItem(R.id.search_button).setVisible(false);
        menu.findItem(R.id.scan_button).setVisible(false);
        menu.findItem(R.id.setting_button).setVisible(false);
        break;
      case 2:
        menu.findItem(R.id.search_button).setVisible(false);
        menu.findItem(R.id.scan_button).setVisible(false);
        menu.findItem(R.id.setting_button).setVisible(true);
        break;
    }
    return super.onPrepareOptionsMenu(menu);
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
    if (id == R.id.search_button) {
      Toast.makeText(getApplicationContext(), "搜索", Toast.LENGTH_SHORT).show();
      return true;
    } else if (id == R.id.scan_button) {
      Toast.makeText(getApplicationContext(), "扫描", Toast.LENGTH_SHORT).show();
      return true;
    } else if (id == R.id.setting_button) {
      Toast.makeText(getApplicationContext(), "设置", Toast.LENGTH_SHORT).show();
      return true;
    }
    return super.onOptionsItemSelected(item);
  }

  public static class PlaceholderFragment extends Fragment {
    private static final String ARG_SECTION_NUMBER = "section_number";

    public PlaceholderFragment() {
    }

    public static PlaceholderFragment newInstance(int sectionNumber) {
      PlaceholderFragment fragment = new PlaceholderFragment();
      Bundle args = new Bundle();
      args.putInt(ARG_SECTION_NUMBER, sectionNumber);
      fragment.setArguments(args);
      return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      View rootView = inflater.inflate(R.layout.fragment_main, container, false);
      TextView textView = (TextView) rootView.findViewById(R.id.section_label);
      textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
      return rootView;
    }
  }

  public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
      return PlaceholderFragment.newInstance(position + 1);
    }

    @Override
    public int getCount() {
      return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
      switch (position) {
        case 0:
          return "SECTION 1";
        case 1:
          return "SECTION 2";
        case 2:
          return "SECTION 3";
      }
      return null;
    }
  }
}