submenu – 蓝天白云

在Android中添加子菜单的方法很简单，只要在设计菜单的时候给菜单的item增加menu子节点就可以，菜单设计文件的xml代码如下：

<?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/get_image" android:title="添加照片" app:showAsAction="always">
        <menu>
            <item android:id="@+id/from_camera" android:title="拍摄"></item>
            <item android:id="@+id/from_album" android:title="相册">
                <menu>
                    <item android:title="本地" android:id="@+id/from_local"></item>
                    <item android:title="云盘" android:id="@+id/from_cloud"></item>
                </menu>
            </item>
        </menu>
    </item>
</menu>

<?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">

<menu>

<menu>

</menu>

</item>

</menu>

</item>

</menu>

在Activity中的响应代码和正常的菜单一样，如下：

package com.bcoder.study.androidanimation;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;

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) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.from_cloud){
            Toast.makeText(this, "从云盘获取图片...", Toast.LENGTH_LONG).show();
        }else if (item.getItemId() == R.id.from_local){
            Toast.makeText(this, "从本地获取图片...", Toast.LENGTH_LONG).show();
        }
        return super.onOptionsItemSelected(item);
    }
}

package com.bcoder.study.androidanimation;

import android.content.Intent;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.widget.Toast;

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) {

getMenuInflater().inflate(R.menu.main_menu, menu);

return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

if(item.getItemId() == R.id.from_cloud){

Toast.makeText(this, "从云盘获取图片...", Toast.LENGTH_LONG).show();

}else if (item.getItemId() == R.id.from_local){

Toast.makeText(this, "从本地获取图片...", Toast.LENGTH_LONG).show();

}

return super.onOptionsItemSelected(item);

}

这种下拉菜单的缺点就是子菜单的位置无法控制。