Android-Spinner的使用以及两种适配器

Spinner是安卓提供的下拉列表的类。 
首先它也和ListView大致差不多，三个步骤： 
1.准备数据源 
2.构造适配器 
3.加载适配器 
有安卓自带的布局，也有自定义的布局。然后就是监听事件。

ArrayAdapter第一种方式 
布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:tools="http://schemas.android.com/tools"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingBottom="@dimen/activity_vertical_margin"
                android:paddingLeft="@dimen/activity_horizontal_margin"
                android:paddingRight="@dimen/activity_horizontal_margin"
                android:paddingTop="@dimen/activity_vertical_margin"
                tools:context=".MainActivity"
    >

    <TextView
        android:id="@+id/id_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world"
        android:textColor="@android:color/holo_red_dark"
        android:textSize="18dp"
        />

    <Spinner
        android:id="@+id/id_spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_text"
        >


    </Spinner>

</RelativeLayout>

主活动： 
监听事件实现AdapterView.OnItemSelectedListener接口

package com.xieth.as.spinnerdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    private TextView tv = null;

    private Spinner spinner = null;

    // 数据源
    private String[] city = {"北京", "上海", "广州", "深圳", "长沙", "南京", "杭州"};

    private List<String> list = null;

    private ArrayAdapter adapter = null;

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

        initViews();
        setData();

        adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, list);

        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        spinner.setAdapter(adapter);

        spinner.setOnItemSelectedListener(this);
    }

    private void setData() {
        for (int i = 0; i < city.length; i++) {
            list.add(city[i]);
        }
    }

    private void initViews() {
        list = new ArrayList<>();
        tv = (TextView) findViewById(R.id.id_text);
        spinner = (Spinner) findViewById(R.id.id_spinner);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        String cityName = (String) adapter.getItem(position);
        tv.setText(cityName);
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

运行效果： 

SimpleAdapter自定义布局 
其实感觉和ListView差不多，万变不离其踪。 

item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_margin="10dp"
    >

    <ImageView
        android:id="@+id/id_image"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:src="@mipmap/chat_tool_audio"
        />


    <TextView
        android:id="@+id/id_text1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginLeft="20dp"
        android:layout_toRightOf="@id/id_image"
        android:text="123"
        android:textColor="@android:color/background_dark"
        android:textSize="15sp"
        />

</RelativeLayout>

主活动：

package com.xieth.as.spinnerdemo;

import android.annotation.TargetApi;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    private TextView tv = null;

    private Spinner spinner = null;

    // 数据源
    private String[] city = {"北京", "上海", "广州", "深圳", "长沙", "南京"};
    private int[] picId = {R.mipmap.chat_tool_audio, R.mipmap.chat_tool_camera, R.mipmap.chat_tool_location
            ,R.mipmap.chat_tool_photo, R.mipmap.chat_tool_send_file, R.mipmap.chat_tool_video};
    private List<Map<String, Object>> dataList = null;

    private List<String> list = null;

    private ArrayAdapter adapter = null;

    private SimpleAdapter simpleAdapter = null;

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initViews();
        setData();

        adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, list);

        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        simpleAdapter = new SimpleAdapter(this, getData(), R.layout.item,
                    new String[] {"pic", "text"}, new int[]{R.id.id_image, R.id.id_text1});


        spinner.setAdapter(simpleAdapter);

        spinner.setOnItemSelectedListener(this);

        spinner.setDropDownVerticalOffset(30);

    }

    private List<Map<String, Object>> getData() {

        for (int i = 0; i < city.length; i++) {
            Map<String, Object> map = new HashMap<>();
            map.put("pic", picId[i]);
            map.put("text", city[i]);
            dataList.add(map);
        }

        return dataList;
    }


    private void setData() {
        for (int i = 0; i < city.length; i++) {
            list.add(city[i]);
        }
    }

    private void initViews() {
        dataList = new ArrayList<>();
        list = new ArrayList<>();
        tv = (TextView) findViewById(R.id.id_text);
        spinner = (Spinner) findViewById(R.id.id_spinner);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        String cityName = (String) adapter.getItem(position);
        tv.setText(cityName);
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }

运行效果： 
 
几乎和ListView差不多。 
对于Spinner这里有更加详细的描述