Android：有关下拉菜单导航的学习
因为先前的学习都没想着记录自己的学习历程，所以该博客才那么迟才开始写。
内容： 下拉菜单导航
学习网站：android Spinner控件详解
Spinner提供了从一个数据集合中快速选择一项值的办法。默认情况下Spinner显示的是当前选择的值，点击Spinner会弹出一个包含所有可选值的dropdown菜单，从该菜单中可以为Spinner选择一个新值。
阶段一：最简单的Spinner
1、在布局文件中添加Spinner控件
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.dropdownlayout.MainActivity">
//AppBarLayout和Toolbar是对布局页面顶部的条进行操作
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
//该部分才是下拉菜单的本体
<Spinner
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/spinner"
android:entries="@array/places"></Spinner>//从这行可以看到资源都是从@array来的，因此需要一个这样的存放资源的xml文件
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main" />
</android.support.design.widget.CoordinatorLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="places">
<item>Beijing</item>
<item>Guangzhou</item>
<item>Shanghai</item>
</string-array>
</resources>
效果：
但是这个终究只是效果，若要对选择进行回应就需要更加复杂的步骤来完善。一般情况下我们是需要响应Spinner选择事件的,可以通过OnItemSelectedListener的回调方法实现
MainActivity:
package com.example.dropdownlayout;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener{
private Spinner spinner ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initUI();
}
private void initUI(){
spinner = (Spinner)findViewById(R.id.spinner);
spinner.setOnItemSelectedListener(this);
}
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
String[] places = getResources().getStringArray(R.array.places);
Toast.makeText(MainActivity.this,"你点击的是:"+places[i],Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
}
效果：
阶段二：学会设置Spinner的BaseAdapter
通过BaseAdapter可以自定义自己的菜单形式，但菜单的形式需要自己来设计
spinnerview:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/personName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="personName "
android:textSize="20dp"
android:textColor="@color/colorAccent"/>
<TextView
android:id="@+id/personAddress"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="personAddress"
android:textSize="20dp"
android:textColor="@color/colorAccent"/>
</LinearLayout>
main.xml中的spinner要把enteries这一项去掉。
Person.java
package com.example.dropdownlayout;
/**
* Created by Funny_One on 2017/8/18.
*/
public class Person {
public String personName,personAddress;
public Person(String personName,String personAddress){
this.personAddress = personAddress;
this.personName = personName;
}
public String getPersonAddress() {
return personAddress;
}
public String getPersonName() {
return personName;
}
}
Myadapter.java
package com.example.dropdownlayout;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.List;
/**
* Created by Funny_One on 2017/8/18.
*/
public class Myadapter extends BaseAdapter {
public List<Person> mList;
public Context context;
public View mView;
public Myadapter(Context context,List<Person> mList){
this.mList = mList;
this.context = context;
}
@Override
public int getCount() {
return mList.size();
}
@Override
public Object getItem(int i) {
return mList.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
LayoutInflater layoutInflater = LayoutInflater.from(context);
mView = layoutInflater.inflate(R.layout.spinnerview,null);
TextView personName = (TextView)mView.findViewById(R.id.personName);
TextView personAddress=(TextView)mView.findViewById(R.id.personAddress);
personAddress.setText(mList.get(i).getPersonAddress());
personName.setText(mList.get(i).getPersonName());
return mView;
}
}
MainActivity:
package com.example.dropdownlayout;
import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity {
private Spinner spinner ;
private List<Person> persons;
private Myadapter myadapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
spinner = (Spinner)findViewById(R.id.spinner);
persons = new ArrayList<Person>();
persons.add(new Person(" 袁逸灏 "," 广东 "));
persons.add(new Person(" 春旺 "," 云南 "));
persons.add(new Person(" 刘先润 "," 重庆 "));
persons.add(new Person(" 刘诚昊 "," 湖南 "));
myadapter = new Myadapter(this,persons);
spinner.setAdapter(myadapter);
}
}
效果：
