布局

package com.doit.huabeiwusheng;
 
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
 
/**
 * Created by wk on 2016/7/7.
 * Base Activity.
 */
public abstract class BaseAppCompatActivity extends AppCompatActivity {
    private static final String TAG = BaseAppCompatActivity.class.getSimpleName();
    private TextView mToolbarTitle;
    private TextView mToolbarSubTitle;
    private Toolbar mToolbar;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(getLayoutId());
 
        mToolbar = (Toolbar) findViewById(R.id.toolbar);
       /*
        toolbar.setLogo(R.mipmap.ic_launcher);
        toolbar.setTitle("Title");
        toolbar.setSubtitle("Sub Title");
        */
        mToolbarTitle = (TextView) findViewById(R.id.toolbar_title);
        mToolbarSubTitle = (TextView) findViewById(R.id.toolbar_subtitle);
        if (mToolbar != null) {
            //将Toolbar显示到界面
            setSupportActionBar(mToolbar);
        }
        if (mToolbarTitle != null) {
            //getTitle()的值是activity的android:lable属性值
            mToolbarTitle.setText(getTitle());
            //设置默认的标题不显示
            getSupportActionBar().setDisplayShowTitleEnabled(false);
        }
 
    }
 
    @Override
    protected void onStart() {
        super.onStart();
        /**
         * 判断是否有Toolbar,并默认显示返回按钮
         */
        if(null != getToolbar() && isShowBacking()){
             showBack();
        }
    }
 
    /**
     * 获取头部标题的TextView
     * @return
     */
    public TextView getToolbarTitle(){
            return mToolbarTitle;
    }
    /**
     * 获取头部标题的TextView
     * @return
     */
    public TextView getSubTitle(){
        return mToolbarSubTitle;
    }
 
    /**
     * 设置头部标题
     * @param title
     */
    public void setToolBarTitle(CharSequence title) {
        if(mToolbarTitle != null){
            mToolbarTitle.setText(title);
        }else{
            getToolbar().setTitle(title);
            setSupportActionBar(getToolbar());
        }
    }
 
    /**
     * this Activity of tool bar.
     * 获取头部.
     * @return support.v7.widget.Toolbar.
     */
    public Toolbar getToolbar() {
        return (Toolbar) findViewById(R.id.toolbar);
    }
 
    /**
     * 版本号小于21的后退按钮图片
     */
    private void showBack(){
        //setNavigationIcon必须在setSupportActionBar(toolbar);方法后面加入
        getToolbar().setNavigationIcon(R.drawable.ic_find);
        getToolbar().setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onBackPressed();
            }
        });
    }
 
    /**
     * 是否显示后退按钮,默认显示,可在子类重写该方法.
     * @return
     */
    protected boolean isShowBacking(){
        return true;
    }
 
    /**
     * this activity layout res
     * 设置layout布局,在子类重写该方法.
     * @return res layout xml id
     */
    protected abstract int getLayoutId();
 
    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.v(TAG, "onDestroy...");
 
 
    }
}

大师傅但是

package com.doit.huabeiwusheng;

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.RequiresApi;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.Toolbar;

public class MainActivity extends BaseAppCompatActivity{

    private TextView mTextMessage;

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.navigation_home:
                    mTextMessage.setText(R.string.title_home);
                    return true;
                case R.id.navigation_dashboard:
                    mTextMessage.setText(R.string.title_dashboard);
                    return true;
                case R.id.navigation_notifications:
                    mTextMessage.setText(R.string.title_notifications);
                    return true;
            }
            return false;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getToolbarTitle().setText("放心住");
       /* getSubTitle().setText("更多");*/
        mTextMessage = (TextView) findViewById(R.id.message);
        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
    }

    protected boolean isShowBacking() {
        return false;
    }

    @Override
    protected int getLayoutId() {
        return R.layout.activity_main;
    }
    /*public void login(View view) {
        Intent intent = new Intent(this, LoginActivity.class);
        startActivity(intent);
    }*/
     @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.navigation, menu);
            return false;
    }
            @Override
      public boolean onOptionsItemSelected(MenuItem item) {
                  switch(item.getItemId()){
                      case R.id.navigation_home:
                          Toast.makeText(MainActivity.this, ""+"关于", Toast.LENGTH_SHORT).show();
                          break;
                          case R.id.navigation_notifications:
                              Toast.makeText(MainActivity.this, ""+"设置", Toast.LENGTH_SHORT).show();
                              break;

                           default:
                               break;
                  }
                  return super.onOptionsItemSelected(item);
    }



}

大师傅但是

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <include layout="@layout/toolbar"/>
   <!-- <TextView
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:layout_marginStart="@dimen/activity_horizontal_margin"
        android:layout_marginTop="@dimen/activity_vertical_margin"
        android:text="@string/title_home"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />-->
    <TextView
        android:layout_marginTop="30px"
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="人口的JFK的咖啡店"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="0dp"
        android:layout_marginStart="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/navigation" />

</android.support.constraint.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimary"
    android:minHeight="?attr/actionBarSize">
    <!--自定义toolbar的title 和subtitle -->
    <TextView
        android:id="@+id/toolbar_subtitle"
        style="@style/TextAppearance.AppCompat.Widget.ActionBar.Subtitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:singleLine="true"
        android:textColor="#fffFff"
        android:text="subtitle"
        android:paddingRight="10dp"
        android:layout_gravity="right" />

    <TextView
        android:id="@+id/toolbar_title"
        style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:lines="1"
        android:ellipsize="end"
        android:text="title"
        android:scrollHorizontally="true"
        android:textColor="#ffffff"
        android:layout_gravity="center" />

</android.support.v7.widget.Toolbar>

的城市

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/navigation_home"
        android:icon="@drawable/ic_zhuye"
        android:title="首页" />

    <item
        android:id="@+id/navigation_dashboard"
        android:icon="@drawable/ic_find"
        android:title="发现" />

    <item
        android:id="@+id/navigation_notifications"
        android:icon="@drawable/ic_my"
        android:tint="#737373"
        android:title="我的" />

</menu>

sacs

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>