Android WiFi开发 （一）扫描、连接、信息
在平常开发中经常会涉及到wifi相关的内容，在此将之前所用到的整理一下，以免忘记。
操作wifi的相关类，主要放在android.net.wifi包下面。使用wifi相关方法需要申请一些权限：
ACCESS_WIFI_STATE 获取WiFi状态。
CHANGE_WIFI_STATE 改变WiFi状态。
CHANGE_WIFI_MULTICAST_STATE 改变WiFi多播状态
申请权限方式：在AndroidManifest.xml文件中填写
wifi相关操作所需要用到的类。
先说一下wifi的基本使用情况。
import java.util.List;
import android.content.Context;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.net.wifi.WifiManager.WifiLock;
import android.widget.Toast;
public class WifiAdmin {
// 定义WifiManager对象
private WifiManager mWifiManager;
// 定义WifiInfo对象
private WifiInfo mWifiInfo;
// 扫描出的网络连接列表
private List mWifiList;
// 网络连接列表
private List mWifiConfiguration;
// 定义一个WifiLock
WifiLock mWifiLock;
// 构造器
public WifiAdmin(Context context) {
// 取得WifiManager对象
mWifiManager = (WifiManager) context
.getSystemService(Context.WIFI_SERVICE);
// 取得WifiInfo对象
mWifiInfo = mWifiManager.getConnectionInfo();
}
// 打开WIFI
public void openWifi(Context context) {
if (!mWifiManager.isWifiEnabled()) {
mWifiManager.setWifiEnabled(true);
}else if (mWifiManager.getWifiState() == 2) {
Toast.makeText(context,"亲，Wifi正在开启，不用再开了", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"亲，Wifi已经开启,不用再开了", Toast.LENGTH_SHORT).show();
}
}
// 关闭WIFI
public void closeWifi(Context context) {
if (mWifiManager.isWifiEnabled()) {
mWifiManager.setWifiEnabled(false);
}else if(mWifiManager.getWifiState() == 1){
Toast.makeText(context,"亲，Wifi已经关闭，不用再关了", Toast.LENGTH_SHORT).show();
}else if (mWifiManager.getWifiState() == 0) {
Toast.makeText(context,"亲，Wifi正在关闭，不用再关了", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"请重新关闭", Toast.LENGTH_SHORT).show();
}
}
// 检查当前WIFI状态
public void checkState(Context context) {
if (mWifiManager.getWifiState() == 0) {
Toast.makeText(context,"Wifi正在关闭", Toast.LENGTH_SHORT).show();
} else if (mWifiManager.getWifiState() == 1) {
Toast.makeText(context,"Wifi已经关闭", Toast.LENGTH_SHORT).show();
} else if (mWifiManager.getWifiState() == 2) {
Toast.makeText(context,"Wifi正在开启", Toast.LENGTH_SHORT).show();
} else if (mWifiManager.getWifiState() == 3) {
Toast.makeText(context,"Wifi已经开启", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(context,"没有获取到WiFi状态", Toast.LENGTH_SHORT).show();
}
}
// 锁定WifiLock
public void acquireWifiLock() {
mWifiLock.acquire();
}
// 解锁WifiLock
public void releaseWifiLock() {
// 判断时候锁定
if (mWifiLock.isHeld()) {
mWifiLock.acquire();
}
}
// 创建一个WifiLock
public void creatWifiLock() {
mWifiLock = mWifiManager.createWifiLock("Test");
}
// 得到配置好的网络
public List getConfiguration() {
return mWifiConfiguration;
}
// 指定配置好的网络进行连接
public void connectConfiguration(int index) {
// 索引大于配置好的网络索引返回
if (index > mWifiConfiguration.size()) {
return;
}
// 连接配置好的指定ID的网络
mWifiManager.enableNetwork(mWifiConfiguration.get(index).networkId,
true);
}
public void startScan(Context context) {
mWifiManager.startScan();
// 得到扫描结果
mWifiList = mWifiManager.getScanResults();
// 得到配置好的网络连接
mWifiConfiguration = mWifiManager.getConfiguredNetworks();
if (mWifiList == null) {
if(mWifiManager.getWifiState()==3){
Toast.makeText(context,"当前区域没有无线网络", Toast.LENGTH_SHORT).show();
}else if(mWifiManager.getWifiState()==2){
Toast.makeText(context,"WiFi正在开启，请稍后重新点击扫描", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"WiFi没有开启，无法扫描", Toast.LENGTH_SHORT).show();
}
}
}
// 得到网络列表
public List getWifiList() {
return mWifiList;
}
// 查看扫描结果
public StringBuilder lookUpScan() {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < mWifiList.size(); i++) {
stringBuilder
.append("Index_" + new Integer(i + 1).toString() + ":");
// 将ScanResult信息转换成一个字符串包
// 其中把包括：BSSID、SSID、capabilities、frequency、level
stringBuilder.append((mWifiList.get(i)).toString());
stringBuilder.append("/n");
}
return stringBuilder;
}
// 得到MAC地址
public String getMacAddress() {
return (mWifiInfo == null) ? "NULL" : mWifiInfo.getMacAddress();
}
// 得到接入点的BSSID
public String getBSSID() {
return (mWifiInfo == null) ? "NULL" : mWifiInfo.getBSSID();
}
// 得到IP地址
public int getIPAddress() {
return (mWifiInfo == null) ? 0 : mWifiInfo.getIpAddress();
}
// 得到连接的ID
public int getNetworkId() {
return (mWifiInfo == null) ? 0 : mWifiInfo.getNetworkId();
}
// 得到WifiInfo的所有信息包
public String getWifiInfo() {
return (mWifiInfo == null) ? "NULL" : mWifiInfo.toString();
}
// 添加一个网络并连接
public void addNetwork(WifiConfiguration wcg) {
int wcgID = mWifiManager.addNetwork(wcg);
boolean b = mWifiManager.enableNetwork(wcgID, true);
System.out.println("a--" + wcgID);
System.out.println("b--" + b);
}
// 断开指定ID的网络
public void disconnectWifi(int netId) {
mWifiManager.disableNetwork(netId);
mWifiManager.disconnect();
}
public void removeWifi(int netId) {
disconnectWifi(netId);
mWifiManager.removeNetwork(netId);
}
//然后是一个实际应用方法，只验证过没有密码的情况：
public WifiConfiguration CreateWifiInfo(String SSID, String Password, int Type)
{
WifiConfiguration config = new WifiConfiguration();
config.allowedAuthAlgorithms.clear();
config.allowedGroupCiphers.clear();
config.allowedKeyManagement.clear();
config.allowedPairwiseCiphers.clear();
config.allowedProtocols.clear();
config.SSID = "\"" + SSID + "\"";
WifiConfiguration tempConfig = this.IsExsits(SSID);
if(tempConfig != null) {
mWifiManager.removeNetwork(tempConfig.networkId);
}
if(Type == 1) //WIFICIPHER_NOPASS
{
config.wepKeys[0] = "";
config.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
config.wepTxKeyIndex = 0;
}
if(Type == 2) //WIFICIPHER_WEP
{
config.hiddenSSID = true;
config.wepKeys[0]= "\""+Password+"\"";
config.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.SHARED);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP104);
config.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
config.wepTxKeyIndex = 0;
}
if(Type == 3) //WIFICIPHER_WPA
{
config.preSharedKey = "\""+Password+"\"";
config.hiddenSSID = true;
config.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP);
config.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK);
config.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
//config.allowedProtocols.set(WifiConfiguration.Protocol.WPA);
config.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP);
config.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
config.status = WifiConfiguration.Status.ENABLED;
}
return config;
}
private WifiConfiguration IsExsits(String SSID)
{
List existingConfigs = mWifiManager.getConfiguredNetworks();
for (WifiConfiguration existingConfig : existingConfigs)
{
if (existingConfig.SSID.equals("\""+SSID+"\""))
{
return existingConfig;
}
}
return null;
}
} 
俩bug
这些代码看起来没有什么问题，但是通过不同环境的测试，发现了一些问题。
1 测试到的wifi热点，有的ssid为”“，也就是ssid ！＝ null,获取不到said。
2 wifi列表中有许多同名的wifi热点，也就是扫描的结果中有重合部分，并不是有多个同名的wifi热点。
第一个问题ssid为“”，这个看设置中并没有多余wifi，但这个热点点其它信息可以获取到，说明这个热点是存在的，应该是该热点隐藏了，所以获取不到。这也就是手机设置中为什么会有添加网路的按钮了。
第二个问题，当附近wifi热点比较少时不会出现此问题，当附近wifi网络比较多时会出现此问题。这就需要将同名的热点进行删除，但是如果真有两个ssid名相同的wifi，那就可以通过capabilities去区分吧，如果capabilities也相同就没办法了，系统设置里面也不显示同名的。
修改上面的方法 startScan（）。
public void startScan(Context context) {
mWifiManager.startScan();
//得到扫描结果
List results = mWifiManager.getScanResults();
// 得到配置好的网络连接
mWifiConfiguration = mWifiManager.getConfiguredNetworks();
if (results == null) {
if(mWifiManager.getWifiState()==3){
Toast.makeText(context,"当前区域没有无线网络",Toast.LENGTH_SHORT).show();
}else if(mWifiManager.getWifiState()==2){
Toast.makeText(context,"wifi正在开启，请稍后扫描", Toast.LENGTH_SHORT).show();
}else{Toast.makeText(context,"WiFi没有开启", Toast.LENGTH_SHORT).show();
}
} else {
mWifiList = new ArrayList();
for(ScanResult result : results){
if (result.SSID == null || result.SSID.length() == 0 || result.capabilities.contains("[IBSS]")) {
continue;
}
boolean found = false;
for(ScanResult item:mWifiList){
if(item.SSID.equals(result.SSID)&&item.capabilities.equals(result.capabilities)){
found = true;break;
}
}
if(!found){
mWifiList.add(result);
}
}
}
} 
代码
public class MainActivity extends Activity implements OnClickListener {
public static final String TAG = "MainActivity";
private Button check_wifi,open_wifi,close_wifi,scan_wifi;
private ListView mlistView;
protected WifiAdmin mWifiAdmin;
private List mWifiList;
public int level;
protected String ssid;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mWifiAdmin = new WifiAdmin(MainActivity.this);
initViews();
IntentFilter filter = new IntentFilter(
WifiManager.NETWORK_STATE_CHANGED_ACTION);
//="android.net.wifi.STATE_CHANGE" 监听wifi状态的变化
registerReceiver(mReceiver, filter);
mlistView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView parent, View view,
int position, long id) {
AlertDialog.Builder alert=new AlertDialog.Builder(MainActivity.this);
ssid=mWifiList.get(position).SSID;
alert.setTitle(ssid);
alert.setMessage("输入密码");
final EditText et_password=new EditText(MainActivity.this);
final SharedPreferences preferences=getSharedPreferences("wifi_password",Context.MODE_PRIVATE);
et_password.setText(preferences.getString(ssid, ""));
alert.setView(et_password);
//alert.setView(view1);
alert.setPositiveButton("连接", new DialogInterface.OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
String pw = et_password.getText().toString();
if(null == pw || pw.length() < 8){
Toast.makeText(MainActivity.this, "密码至少8位", Toast.LENGTH_SHORT).show();
return;
}
Editor editor=preferences.edit();
editor.putString(ssid, pw); //保存密码
editor.commit();
mWifiAdmin.addNetwork(mWifiAdmin.CreateWifiInfo(ssid, et_password.getText().toString(), 3));
}
});
alert.setNegativeButton("取消", new DialogInterface.OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
//
//mWifiAdmin.removeWifi(mWifiAdmin.getNetworkId());
}
});
alert.create();
alert.show();
}
});
}
/*
* 控件初始化
* */
private void initViews() {
check_wifi=(Button) findViewById(R.id.check_wifi);
open_wifi=(Button) findViewById(R.id.open_wifi);
close_wifi=(Button) findViewById(R.id.close_wifi);
scan_wifi=(Button) findViewById(R.id.scan_wifi);
mlistView=(ListView) findViewById(R.id.wifi_list);
check_wifi.setOnClickListener(MainActivity.this);
open_wifi.setOnClickListener(MainActivity.this);
close_wifi.setOnClickListener(MainActivity.this);
scan_wifi.setOnClickListener(MainActivity.this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.check_wifi:
mWifiAdmin.checkState(MainActivity.this);
break;
case R.id.open_wifi:
mWifiAdmin.openWifi(MainActivity.this);
break;
case R.id.close_wifi:
mWifiAdmin.closeWifi(MainActivity.this);
break;
case R.id.scan_wifi:
mWifiAdmin.startScan(MainActivity.this);
mWifiList=mWifiAdmin.getWifiList();
if(mWifiList!=null){
mlistView.setAdapter(new MyAdapter(this,mWifiList));
new Utility().setListViewHeightBasedOnChildren(mlistView);
}
break;
default:
break;
}
}
public class MyAdapter extends BaseAdapter{
LayoutInflater inflater;
List list;
public MyAdapter(Context context, List list){
this.inflater=LayoutInflater.from(context);
this.list=list;
}
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@SuppressLint({ "ViewHolder", "InflateParams" })
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view=null;
view=inflater.inflate(R.layout.wifi_listitem, null);
ScanResult scanResult = list.get(position);
TextView wifi_ssid=(TextView) view.findViewById(R.id.ssid);
ImageView wifi_level=(ImageView) view.findViewById(R.id.wifi_level);
wifi_ssid.setText(scanResult.SSID);
Log.i(TAG, "scanResult.SSID="+scanResult);
level=WifiManager.calculateSignalLevel(scanResult.level,5);
if(scanResult.capabilities.contains("WEP")||scanResult.capabilities.contains("PSK")||
scanResult.capabilities.contains("EAP")){
wifi_level.setImageResource(R.drawable.wifi_signal_lock);
}else{
wifi_level.setImageResource(R.drawable.wifi_signal_open);
}
wifi_level.setImageLevel(level);
//判断信号强度，显示对应的指示图标
return view;
}
}
/*设置listview的高度*/
public class Utility {
public void setListViewHeightBasedOnChildren(ListView listView) {
ListAdapter listAdapter = listView.getAdapter();
if (listAdapter == null) {
return;
}
int totalHeight = 0;
for (int i = 0; i < listAdapter.getCount(); i++) {
View listItem = listAdapter.getView(i, null, listView);
listItem.measure(0, 0);
totalHeight += listItem.getMeasuredHeight();
}
ViewGroup.LayoutParams params = listView.getLayoutParams();
params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1));
listView.setLayoutParams(params);
}
}
//监听wifi状态
private BroadcastReceiver mReceiver = new BroadcastReceiver (){
@Override
public void onReceive(Context context, Intent intent) {
ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo wifiInfo = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
if(wifiInfo.isConnected()){
WifiManager wifiManager = (WifiManager) context
.getSystemService(Context.WIFI_SERVICE);
String wifiSSID = wifiManager.getConnectionInfo()
.getSSID();
Toast.makeText(context, wifiSSID+"连接成功", 1).show();
}
}
};
}
ScanResult类
这个类主要是通过Wifi硬件的扫描来获取一些周边的wifi热点（access point）的信息。该类主要有5个域，
| 返回类型 | 域名 | 解释 |
| public String | BSSID | 接入点的地址 |
| public String | SSID | 网络的名字 |
| public String | capabilities | 网络性能，包括接入点支持的认证、密钥管理、加密机制等 |
| public int | frequency | 以MHz为单位的接入频率 |
| public int | level | 以dBm为单位的信号强度。 |
打印信息如下所示：
WifiConfiguration类
通过该类获取一个wifi网络的网络配置，包括安全配置等。它包含6个子类，如下所示：
| 子类 | 解释 |
| WifiConfiguration.AuthAlgorthm | 获取IEEE 802.11的加密方法 |
| WifiConfiguration.GroupCipher |
获取组密钥 |
| WifiConfiguration.KeyMgmt |
获取密码管理体制 |
| WifiConfiguration.PairwiseCipher |
获取WPA方式的成对密钥 |
| WifiConfiguration.Protocol |
获取加密协议 |
| WifiConfiguration.Status |
获取当前网络状态 |
WifiInfo类
该类可以获得已经建立的或处于活动状态的wifi网络的状态信息。常用方法如下：
代码：
mWifiManager = (WifiManager)getSystemService(Context.WIFI_SERVICE);
mWifiInfo = mWifiManager.getConnectionInfo();
if(null != mWifiInfo && null != mWifiInfo.getSSID()){
String info = "getSSID()="+mWifiInfo.getSSID()+"\n"
+"getBSSID()="+mWifiInfo.getBSSID()+"\n"
+"getHiddenSSID()="+mWifiInfo.getHiddenSSID()+"\n"
+"getLinkSpeed()="+mWifiInfo.getLinkSpeed()+"\n"
+"getMacAddress()="+mWifiInfo.getMacAddress()+"\n"
+"getNetworkId()="+mWifiInfo.getNetworkId()+"\n"
+"getRssi()="+mWifiInfo.getRssi()+"\n"
+"getSupplicantState()="+mWifiInfo.getSupplicantState()+"\n"
+"getDetailedStateOf()="+mWifiInfo.getDetailedStateOf(mWifiInfo.getSupplicantState());
mTVWifiInfo.setText(info);
}else {
mTVWifiInfo.setText("没有连接到wifi");
}WifiManager类
该类用于管理Wifi连接，定义了许多常量和方法，这里就不一一说了。
常用方法。
需要指出的是getWifiState()方法是反悔wifi的状态，有整型常量表示，
demo下载地址