Android基础：ActionBar

一.显示ActionBar
1.定义V7包下的ActionBar
android.support.v7.app.ActionBar actionBar;
2.获取ActionBar
actionBar = getSupportActionBar();
3.显示ActionBar动作栏
actionBar.show();

import android.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    Button action_show, action_hide; //定义显示与隐藏按钮
    android.support.v7.app.ActionBar actionBar; //定义V7包下的ActionBar

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        actionBar = getSupportActionBar(); //获取ActionBar动作栏
        action_show = (Button) findViewById(R.id.actionBar_show); //获取显示按钮
        action_hide = (Button) findViewById(R.id.actionBar_hide); //获取隐藏按钮
        action_show.setOnClickListener(l); //为显示按钮设置监听事件
        action_hide.setOnClickListener(l); //为隐藏按钮设置监听事件
    }

    View.OnClickListener l = new View.OnClickListener() { //创建一个新的监听事件l
        @Override
        public void onClick(View v) {
            switch (v.getId()) {  //根据选择按钮的id判断
                case R.id.actionBar_show:
                    actionBar.show(); //显示ActionBar动作栏
                    break;
                case R.id.actionBar_hide:
                    actionBar.hide(); //隐藏ActionBar动作栏
                    break;
            }
        }
    };
}

二.ActionItem
添加一个ActionItem需要以下步骤：
1.编写menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/search"
        android:icon="@drawable/search"
        android:title="@string/search"
        app:showAsAction="always"></item>
    <item
        android:id="@+id/bell"
        android:icon="@drawable/bell"
        android:title="@string/bell"
        app:showAsAction="always"></item>
    <item
        android:id="@+id/settings"
        android:title="@string/settings"
        app:showAsAction="ifRoom"></item>
    <item
        android:id="@+id/about"
        android:title="@string/about"
        app:showAsAction="never"></item>
</menu>

2.在onCreateOptionsMenu(Menu menu)方法内实例化一个MenuInflater对象并解析菜单文件

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;

public class MainActivity extends AppCompatActivity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater=getMenuInflater();  //实例化一个MenuInflater对象
        inflater.inflate(R.menu.menu,menu);       //解析菜单文件
        return super.onCreateOptionsMenu(menu);
    }
}

三.添加action_view
1.编写menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/search"
        android:title="@string/search"
        app:actionViewClass="android.support.v7.widget.SearchView"
        app:showAsAction="always"
        ></item>
    <item
        android:id="@+id/img1"
        android:title="@string/img1"
        app:actionLayout="@layout/img_message"
        app:showAsAction="always"></item>
    <item
        android:id="@+id/img2"
        android:title="@string/img2"
        app:actionLayout="@layout/img_add"
        app:showAsAction="always"></item>
</menu>

2.编写各个view
img_add.xml

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

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="14dp"
        android:src="@drawable/add" />
</LinearLayout>

3.在onCreateOptionsMenu(Menu menu)方法内实例化一个MenuInflater对象并解析菜单文件

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //隐藏ActionBar中显示的标题
        getSupportActionBar().setDisplayShowTitleEnabled(false);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater(); //实例化一个MenuInflater对象
        inflater.inflate(R.menu.menu, menu);      //解析菜单文件
        return super.onCreateOptionsMenu(menu);
    }
}

四.ActionBar中的tab
1.使用setTabListener（）方法添加并监听标签

 actionBar.addTab(actionBar.newTab().setText("词典").
                setTabListener(new MyTabListener(this, Fragment1.class)));

2.在MyTabListener方法中编写标签页变化代码

import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBar;

/**
 * Created by Administrator on 2016/5/16.
 */
public class MyTabListener implements ActionBar.TabListener {
    private Fragment fragment;  //定义Fragment
    private final Activity activity; //定义Activity
    private final Class aClass; //定义Class

    public MyTabListener(Activity activity, Class aClass) { //添加构造函数
        this.activity = activity;
        this.aClass = aClass;
    }
    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
        //判断碎片是否初始化
        if (fragment == null) { //如果没有初始化，将其初始化
            fragment = Fragment.instantiate(activity, aClass.getName());
            ft.add(android.R.id.content, fragment, null);
        }
        ft.attach(fragment); //显示新画面
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
        if (fragment != null) {
            ft.detach(fragment); //删除旧画面
        }
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {

    }
}

3.需要编写每一个标签的java和xml:

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

<ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="fitXY"
    android:src="@drawable/fragment_1"
    />
</LinearLayout>

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;
public class Fragment1 extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_1,null); //加载布局页面
    }
}

五.层级导航
1.编写两个Activity，其中子级Activity需要有返回符号

 if (NavUtils.getParentActivityName(FriendsActivity.this) != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);    //显示向左的箭头图标
        }

然后在AndroidManifest中将子级Activity注册父级Activity

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 <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />

Android基础：ActionBar

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