Widgets之Spinner

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Spinner相当于下拉列表，在Android开发文档中的关于Spinner的介绍：

android.widget
类 Spinner

java.lang.Object
  android.view.View
      android.view.ViewGroup
          android.widget.AdapterView<SpinnerAdapter>
              android.widget.AbsSpinner
                  android.widget.Spinner

所有已实现的接口：

DialogInterface.OnClickListener,Drawable.Callback,KeyEvent.Callback, ViewManager, ViewParent

A view that displays one child at a time and lets the user pick among them.

The items in the Spinner come from the Adapter associated with this view.

从官方文档中我们可以看出，要想使用spinner必须要一个Adapter，它是这个Spinner的数据源。

那我们先建立一个数据源：数据源有两种形式，1.直接新建一个数组2.在strings.xml中声明。

我们先在strings.xml中声明一个数组：

<string-array name="cities">
    <item>北京</item>
    <item>上海</item>
</string-array>

String []cities = String []items = getResources().getStringArray(R.array.cities); 
Adapter <String>myAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,cities);
aadapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
sp_spinner01.setAdapter(aadapter);

sp_spinner01.setOnItemSelectedListener(new OnItemSelectedListener() {
			@Override
			public void onItemSelected(AdapterView<?> arg0, View arg1,
					int arg2, long arg3) {
				// TODO Auto-generated method stub
				Log.i("abc", "arg1="+arg2+"text="+arg0.getItemAtPosition(arg2).toString());
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
				// TODO Auto-generated method stub
				Log.i("abc","你什么都没选择");
			}
		});

按照惯例，我们一般不会使用系统提供的Spinner，一般都是使用自定义的Spinner，从上面的例子我们可以看出来如果要使用自定义的Spinner，需要有一个Adapter，还有一个layout用于承载每一个Item。Android系统提供的样式不太好看，我希望每一个Item都有一个图片还有相应的文字，这样的话我们可以自己来定义一下：

在layout目录下新建一个Items.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="horizontal" >

<ImageView 
    android:id="@+id/iv_icon"
    android:layout_width="0dp"
    android:layout_weight="5"
    android:layout_height="match_parent"/>

<TextView 
    android:id="@+id/tv_content"
    android:layout_width="0dp"
    android:layout_weight="5"
    android:layout_height="match_parent"
    android:gravity="center"/>
</LinearLayout>

最重要的就是我们的Adapter，要从BaseAdapter继承。

package com.example.widgetstest;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MyOwnAdapter extends BaseAdapter {
	
	private List<Items>myList;
	private Context myContext;
	
	public MyOwnAdapter(List<Items>myList,Context context) {
		// TODO Auto-generated constructor stub
		this.myList = myList;
		this.myContext = context;
	}
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return myList.size();
	}

	@Override
	public Object getItem(int arg0) {
		// TODO Auto-generated method stub
		return myList.get(arg0);
	}

	@Override
	public long getItemId(int arg0) {
		// TODO Auto-generated method stub
		return arg0;
	}

	@Override
	public View getView(int arg0, View arg1, ViewGroup arg2) {
		// TODO Auto-generated method stub
		LayoutInflater _myInflater = LayoutInflater.from(myContext);
		arg1 = _myInflater.inflate(R.layout.spinner_item, null);
		
		if(arg1 != null){
			TextView content = (TextView)arg1.findViewById(R.id.tv_content);
			content.setText(myList.get(arg0).getItem());
			int imageIcon = R.drawable.ic_launcher;
			switch(arg0){
			    case 0: imageIcon = R.drawable.broadcasting_system_monitor;
			    break;
			    case 1: imageIcon = R.drawable.parking_monitor;
			    break;
			    case 2 : imageIcon = R.drawable.device_alarming;
			    break;
			}
			ImageView icon = (ImageView)arg1.findViewById(R.id.iv_icon);
			icon.setImageResource(imageIcon);
		}
		return arg1;
	}

}

新建一个Items类内容为：

package com.example.widgetstest;

public class Items {
	Items(){}
	
	Items(String items){
		this.item = items;
	}
	private String item;

	public String getItem() {
		return item;
	}

	public void setItem(String item) {
		this.item = item;
	}
	
}

然后就是在Activity中的调用：

Spinner mySpinner = (Spinner)findViewById(R.id.my_spinner);
		List <Items>_items = new ArrayList<Items>(); 
		_items.add(new Items("报警"));
		_items.add(new Items("停车"));
		_items.add(new Items("广播"));
		MyOwnAdapter _myAdapter = new MyOwnAdapter(_items,this);
		mySpinner.setAdapter(_myAdapter);
		
		mySpinner.setOnItemSelectedListener(new OnItemSelectedListener() {

			@Override
			public void onItemSelected(AdapterView<?> arg0, View arg1,
					int arg2, long arg3) {
				Items t =  (Items) arg0.getItemAtPosition(arg2);	
				Log.i("abc",t.getItem().toString());
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
				// TODO Auto-generated method stub				
			}
		});

 public Object getItemAtPosition(int position) {
           T adapter = getAdapter();
           return (adapter == null || position < 0) ? null : adapter.getItem(position);
      }

public Object getItem(int arg0) {
		return myList.get(arg0);
	}

List <Items>_items = new ArrayList<Items>(); 

Items t =  (Items) arg0.getItemAtPosition(arg2);

运行结果如下：

Widgets之Spinner

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原文地址：http://blog.csdn.net/zhaoxiaoyao1987/article/details/51252183