ListView用法详解

ListView作为一个经常被用来显示一组信息的控件，熟练掌握其用法显得尤为重要。这篇文章我们将从两个方面，介绍 ListView的用法。

ListView无非也就是多个控件的多次重复显示，ListView将Android中MVC模式很好的展示出来。MVC模式中最重要的就是控制器，Adapter很好的担任了这个角色。所以本片文章主要从Adapter的角度来讲解ListView的用法。本篇文章将从两个方面介绍Adapter，SimpleAdapter和自定义Adapter。

Ⅰ、SimpleAdapter。SimpleAdapter已经可以加载较为丰富的内容，知识内容形式比较单一罢了。

①、准备数据源。这里我随便列了一组数据

<span style="white-space:pre"></span>private String[] mtitle = {"姓名","性别","年龄","居住地","邮箱"};private String[] mdetailinfo = {"总有些草民想害朕","男","23","广东深圳","[e-mail]"};

我们还需要一个集合来存放这些数据

List<Map<String,Object>> mdata = new ArrayList<Map<String,Object>>();for(int i=0; i<mtitle.length; i++){Map<String,Object> map = new HashMap<String,Object>();map.put("titletv",mtitle[i]);map.put("detailtv", mdetailinfo[i]);mdata.add(map);}

②、准备总的一个布局，布局很简单就一个ListView

<LinearLayout 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:orientation="vertical" >    <ListView        android:id="@+id/listview"        android:layout_width="match_parent"        android:layout_height="wrap_content" >    </ListView></LinearLayout>

③、总的布局有了，要显示当然缺不了每个item的布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="horizontal" >    <ImageView        android:id="@+id/iconiv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@drawable/icon_img" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:background="#B3EC64"        android:orientation="vertical" >        <TextView            android:id="@+id/titletv"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:textColor="#E51A23"            android:textSize="18sp" />        <TextView            android:id="@+id/detailtv"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:textColor="#E51A23"            android:textSize="14sp" />    </LinearLayout></LinearLayout>

④、好了，准备工作做好了，我们只需要使用SimpleAdapter准备的数据关联起来即可。下面是SimpleAdapter

SimpleAdapter simpleAdapter = new SimpleAdapter(this,mdata,R.layout.list_item_layout, new String[]{"titletv","detailtv"}, new int[]{R.id.titletv,R.id.detailtv});listView.setAdapter(simpleAdapter);

大功告成，看看效果

嘿嘿，看着还不错，ListView的使用是不是很简单呢，当然不是的，在开发过程中，我们经常需要自定义Adapter来加载我们多需要的数据，让我们的界面什么的看起来更好一些，下面我们就来介绍一下自定义Adapter。

II、我选取的例子是用ListView加载搜索到的蓝牙设备，并将设备的名字与地址都展示出来。

这个小Demo主要用到了四个类。BluetoothDeviceDB.java,DeviceInfo.java,DeviceInfoAdaper.java以及MainActivity.java.下面我将一一介绍各个类的用途。

①、BluetoothDeviceDB.主要是数据库的创建，表格的创建，以及增删查改几个方法，目的是用来存放匹配的蓝牙设备信息。代码如下：

import java.util.ArrayList;import java.util.List;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;public class BluetoothDeviceDB extends SQLiteOpenHelper {public static final String DATABASE_NAME = "BluetoothDB";public static final String TABLE_NAME = "bluetoothrecord";public static final String TITLE = "title";public static final String ADDRESS = "address";public static final String STATUS = "statue";public static final int STATUE_CONNECTED = 1;public static final int STATUE_NOCONNECT = 0;public static String _id = "_id"; public static final String TABLE_CREATE = "create table " + TABLE_NAME+ "(" + _id + " INTEGER PRIMARY KEY AUTOINCREMENT," + TITLE+ " TEXT," + ADDRESS + " TEXT," + STATUS + " INTEGER" + ");";private static final String TAG = "BluetoothDeviceDB";private static final int DATABASE_VERSION = 2; public BluetoothDeviceDB(Context context){super(context,DATABASE_NAME,null,DATABASE_VERSION);}public BluetoothDeviceDB(Context context, String name,CursorFactory factory, int version) {super(context, name, factory, version);}//当数据库首次被创建时@Overridepublic void onCreate(SQLiteDatabase db) {db.execSQL(TABLE_CREATE);}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {String sql = "DROP TABLE IF EXISTS " + TABLE_NAME;db.execSQL(sql);}public long insert(SQLiteDatabase db, String title, String address, int statue){Log.d(TAG, "BluetoothDeviceDB-----insert()");if(checkIsExist(db,address)){Log.d(DATABASE_NAME, address+ " the device is exist");}ContentValues cv = new ContentValues();long row;cv.put(TITLE, title);cv.put(ADDRESS, address);cv.put(STATUS, statue);row = db.insert(TABLE_NAME, null, cv);return row;}public long update(SQLiteDatabase db, String title, String address, int statue, int position){ContentValues cv = new ContentValues();long row;cv.put(TITLE, title);cv.put(ADDRESS, address);cv.put(STATUS, statue);row = db.update(TABLE_NAME, cv, _id + "=" + position, null);return row;}//查询记录的总数public int getCount(SQLiteDatabase db){String sql = "select count(*) from " + TABLE_NAME;Cursor c = db.rawQuery(sql, null);c.moveToFirst();int length = c.getInt(0);c.close();return length;}private boolean checkIsExist(SQLiteDatabase db, String address) {ArrayList<CompanionData> list = selectAll(db);for(int i=0; i<list.size(); i++){if(list.get(i).compare(address)){return true;}}return false;}public CompanionData getCompanionData(SQLiteDatabase db,String address){ArrayList<CompanionData> list = selectAll(db);for(int i=0; i<list.size(); i++){if(list.get(i).compare(address)){return list.get(i);}}return null;}private ArrayList<CompanionData> selectAll(SQLiteDatabase db) {ArrayList<CompanionData> arrayList = new ArrayList<CompanionData>();Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null);if(cursor != null && cursor.getCount() > 0){cursor.moveToFirst();}for(cursor.moveToFirst(); !cursor.isAfterLast();cursor.moveToNext()){CompanionData data = new CompanionData();data.setmId(cursor.getInt(0));data.setmTitle(cursor.getString(1));data.setmAddress(cursor.getString(2));data.setmStatue(cursor.getInt(3));arrayList.add(data);}cursor.close();return arrayList;}public class CompanionData{private int mId;private String mAddress;private String mTitle;private int mStatue;public int getmId() {return mId;}public void setmId(int mId) {this.mId = mId;}public String getmAddress() {return mAddress;}public void setmAddress(String mAddress) {this.mAddress = mAddress;}public String getmTitle() {return mTitle;}public void setmTitle(String mTitle) {this.mTitle = mTitle;}public int getmStatue() {return mStatue;}public void setmStatue(int mStatue) {this.mStatue = mStatue;}public boolean compare(String address){if(mAddress.equals(address)){return true;}else{return false;}}}}

②、DeviceInfo.java顾名思义就是用来存放设备各种信息的分装类。代码如下：

public class DeviceInfo {private int imageId;private String deviceName;private String deviceAddress;public DeviceInfo(){imageId = R.drawable.ic_bluetooth;}public int getImageId() {return imageId;}public void setImageId(int imageId) {this.imageId = imageId;}public String getDeviceName() {return deviceName;}public void setDeviceName(String deviceName) {this.deviceName = deviceName;}public String getDeviceAddress() {return deviceAddress;}public void setDeviceAddress(String deviceAddress) {this.deviceAddress = deviceAddress;}}

③、好了，数据准备工作做好了，我们这篇文章的重头戏来了，DeviceInfoAdapter.java，他是用来把DeviceInfo加载到ListView中的。自定义Adapter，其实就是继承BaseAdapter，然后重写它其中的四个方法，getCount()，getItem()，getItemId()，和getView();各个方法具体是干什么的，代码中都有注释了，我就不在这里重复描述了。自定义Adapter的关键就在此，只要把这四个方法理顺了，你就可以定制任何自己想要的Adapter了。ok，让我们来观摩观摩代码：

package com.gajsh.bluetoothcommunication;import java.util.List;import com.gajsh.mybluetooth.R;import android.annotation.SuppressLint;import android.content.Context;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;@SuppressLint("ViewHolder")public class DeviceInfoAdapter extends BaseAdapter {private static final String TAG = "DeviceInfoAdapter";private Context context;List<DeviceInfo> devices;public DeviceInfoAdapter(Context context, List<DeviceInfo> mPairedList) {super();this.context = context;this.devices = mPairedList;}@Overridepublic int getCount() {// 获取数据长度Log.d(TAG,"size:"+devices.size());return devices.size();}@Overridepublic Object getItem(int position) {// 获取Item中的数据源组return devices.get(position);}@Overridepublic long getItemId(int position) {// 用于item的定位--系统内部调用return position;}@Overridepublic View getView(int position, View contentView, ViewGroup group) {if (devices != null)// 实例获取item控件// 为该控件管理布局并填充数据if (contentView == null) {LayoutInflater inflater = LayoutInflater.from(context);contentView = inflater.inflate(R.layout.list_item_layout, null);TextView devicename = (TextView) contentView.findViewById(R.id.titletv);TextView address = (TextView) contentView.findViewById(R.id.addresstv);devicename.setText(devices.get(position).getDeviceName());address.setText(devices.get(position).getDeviceAddress());}return contentView;}}

④、最后一个类当然是让我们写的这些东西组织起来，让我们能够达到最终的目的—ListView显示所有匹配蓝牙设备的信息。

有几个要强调的地方。

1、蓝牙核心类BlueAdapter，它是通过getDefaultAdapter()来得到，而不是New出来，通过它可以进行蓝牙的搜索、匹配等。

2、addSystemPairedDevicesToDB()，这个类是将匹配的设备添加到数据库中，其中涉及蓝牙设备是否存在于数据库的检查类ExistOnSystemDB();

3、将数据库中的设备信息取出来存放到List中，addPairedDeviceToList()

4、最终我们是在OnResume()这个生命周期的方法中完成数据的适配的。

下面是MainActivity.java的代码

import java.util.ArrayList;import java.util.List;import java.util.Set;import com.gajsh.mybluetooth.R;import android.annotation.SuppressLint;import android.app.Activity;import android.app.AlertDialog;import android.app.ProgressDialog;import android.bluetooth.BluetoothAdapter;import android.bluetooth.BluetoothDevice;import android.content.BroadcastReceiver;import android.content.Context;import android.content.DialogInterface;import android.content.Intent;import android.content.IntentFilter;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuInflater;import android.view.MenuItem;import android.widget.ListView;public class MainActivity extends Activity {private static final String TAG = "MainActivity";private BluetoothAdapter mBtAdapter;BluetoothDeviceDB dbhelper;DeviceInfoAdapter mPairedAdapter;SQLiteDatabase sql;Cursor cursor;List<DeviceInfo> mPairedList;ListView mPairedListView;Set<BluetoothDevice> pairedDevices;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mPairedList = new ArrayList<DeviceInfo>();mPairedListView = (ListView) findViewById(R.id.pairedlv);dbhelper = new BluetoothDeviceDB(this);sql = dbhelper.getWritableDatabase();mBtAdapter = BluetoothAdapter.getDefaultAdapter();// 向数据库中提交匹配的蓝牙设备addSystemPairedDevicesToDB();};@Overrideprotected void onResume() {super.onResume();Log.d(TAG, "-------------");addPairedDeviceToList();mPairedAdapter = new DeviceInfoAdapter(this, mPairedList);mPairedListView.setAdapter(mPairedAdapter);for (DeviceInfo device : mPairedList) {String devicename = device.getDeviceName();String address = device.getDeviceAddress();Log.d(TAG, "list的内容" + devicename + address);}}private void addPairedDeviceToList() {Cursor cursor = sql.rawQuery("select * from "+ BluetoothDeviceDB.TABLE_NAME + " order by "+ BluetoothDeviceDB._id, null);mPairedList.clear();if (cursor != null && cursor.moveToFirst()) {for (int i = 0; i < cursor.getCount(); i++) {Log.d(TAG, "这是添加第---" + i + "---个元素");DeviceInfo deviceInfo = new DeviceInfo();deviceInfo.setDeviceAddress(cursor.getString(cursor.getColumnIndex(BluetoothDeviceDB.ADDRESS)));deviceInfo.setDeviceName(cursor.getString(cursor.getColumnIndex(BluetoothDeviceDB.TITLE)));mPairedList.add(deviceInfo);cursor.moveToNext();}}if (cursor != null) {cursor.close();cursor = null;}Log.d(TAG, "---添加完成---");}private void addSystemPairedDevicesToDB() {pairedDevices = mBtAdapter.getBondedDevices();if (pairedDevices.size() > 0 && !ExistOnSystemDB(pairedDevices)) {for (BluetoothDevice device : pairedDevices) {String address = device.getAddress();String devicename = device.getName();if (address != null && devicename != null) {dbhelper.insert(sql, device.getName(), device.getAddress(),0);}}}Log.d(TAG, "数据库元素添加完成");}private boolean ExistOnSystemDB(Set<BluetoothDevice> pairedDevices) {Cursor cursor = sql.rawQuery("select address from "+ BluetoothDeviceDB.TABLE_NAME, null);if (cursor != null && cursor.moveToFirst()) {for (int j = 0; j < cursor.getCount(); j++) {String dbaddress = cursor.getString(cursor.getColumnIndex(BluetoothDeviceDB.ADDRESS));for (BluetoothDevice device : pairedDevices) {String pairedaddress = device.getAddress();if (pairedaddress.equalsIgnoreCase(dbaddress)) {return true;}}}}return false;}}

基本代码都有了，下面我把布局文件也列来，相当简单，首先是主布局

<LinearLayout 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:orientation="vertical" >    <TextView        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:background="@color/grey"        android:text="@string/bondeddevices" />    <ListView        android:id="@+id/pairedlv"        android:layout_width="fill_parent"        android:layout_height="wrap_content" /></LinearLayout>

由于布局相对简单，我就不给大家介绍布局的实现思路了，下面是list_item_layout

<LinearLayout 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:orientation="vertical" >    <TextView        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:background="@color/grey"        android:text="@string/bondeddevices" />    <ListView        android:id="@+id/pairedlv"        android:layout_width="fill_parent"        android:layout_height="wrap_content" /></LinearLayout>

由于我都是练习Demo，所以采用的都是线性布局，建议大家多用用相对布局，在开发中相对布局应用相对来说比较多些。

不知不觉，自定义Adapter也讲完了，其中也涉及到了SQLite数据库，有兴趣的朋友可以多研究一下。当然我加载的信息比较简单，大家有兴趣可以弄得复杂些，最后把效果图给大家看下：