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在上一篇文章《Android开发实践：WIFI扫描功能的封装》介绍了如何利用Andriod的API实现WIFI的扫描，本文则重点讲述一下如何连接WIFI吧，在此，也给出一个封装WIFI连接过程的类，提供简单的接口以供在各个代码工程中复用。
与WIFI扫描类似，WIFI的连接同样是一个耗时的过程，所以需要放到线程中执行，通过回调来通知调用者连接结果。该回调接口的定义如下：
public interface WifiConnectListener {
public void OnWifiConnectCompleted( boolean isConnected );
}从Android的WIFI Setting可以看出，一般添加一个新的WIFI连接，需要给出三个信息，一个是WIFI的SSID，一个是WIFI的密码，另一个是WIFI的加密类型，不同的加密方式，连接时程序中的配置是不同的，这里定义一个枚举，给出四种常见的加密类型：
public enum SecurityMode {
OPEN, WEP, WPA, WPA2
}Android的WIFI连接过程，总体上分为三步，第一步，添加网络配置，第二步，根据网络配置连接WIFI，第三步，监听系统的WIFI连接状态消息。下面就直接给出示例代码，关键的地方都在代码中注释了。
package com.example.testwifi;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.SupplicantState;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
public class WifiConnector {
private static final int WIFI_CONNECT_TIMEOUT = 20; //连接WIFI的超时时间
private Context mContext;
private WifiManager mWifiManager;
private Lock mLock;
private Condition mCondition;
private WiFiConncetReceiver mWifiConnectReceiver;
private WifiConnectListener mWifiConnectListener;
private boolean mIsConnnected = false;
private int mNetworkID = -1;
//网络加密模式
public enum SecurityMode {
OPEN, WEP, WPA, WPA2
}
//通知连接结果的监听接口
public interface WifiConnectListener {
public void OnWifiConnectCompleted( boolean isConnected );
}
public WifiConnector( Context context , WifiConnectListener listener ) {
mContext = context;
mLock = new ReentrantLock();
mCondition = mLock.newCondition();
mWifiManager=(WifiManager)mContext.getSystemService(Context.WIFI_SERVICE);
mWifiConnectReceiver = new WiFiConncetReceiver();
mWifiConnectListener = listener;
}
public void connect( final String ssid, final String password, final SecurityMode mode ) {
new Thread(new Runnable() {
@Override
public void run() {
//如果WIFI没有打开，则打开WIFI
if( !mWifiManager.isWifiEnabled() ) {
mWifiManager.setWifiEnabled(true);
}
//注册连接结果监听对象
mContext.registerReceiver(mWifiConnectReceiver, new IntentFilter(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION));
//连接指定SSID
if( !onConnect(ssid,password,mode) ) {
mWifiConnectListener.OnWifiConnectCompleted(false);
}
else {
mWifiConnectListener.OnWifiConnectCompleted(true);
}
//删除注册的监听类对象
mContext.unregisterReceiver(mWifiConnectReceiver);
}
}).start();
}
protected boolean onConnect( String ssid, String password, SecurityMode mode ) {
//添加新的网络配置
WifiConfiguration cfg = new WifiConfiguration();
cfg.SSID = "\"" + ssid + "\"";
if( password !=null && !"".equals(password) ) {
//这里比较关键，如果是WEP加密方式的网络，密码需要放到cfg.wepKeys[0]里面
if( mode == SecurityMode.WEP ) {
cfg.wepKeys[0] = "\"" + password + "\"";
cfg.wepTxKeyIndex = 0;
}
else {
cfg.preSharedKey = "\"" + password + "\"";
}
}
cfg.status = WifiConfiguration.Status.ENABLED;
//添加网络配置
mNetworkID = mWifiManager.addNetwork(cfg);
mLock.lock();
mIsConnnected = false;
//连接该网络
if( !mWifiManager.enableNetwork(mNetworkID , true) ) {
mLock.unlock();
return false;
}
try {
//等待连接结果
mCondition.await(WIFI_CONNECT_TIMEOUT, TimeUnit.SECONDS);
}
catch (InterruptedException e) {
e.printStackTrace();
}
mLock.unlock();
return mIsConnnected;
}
//监听系统的WIFI连接消息
protected class WiFiConncetReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if (!WifiManager.SUPPLICANT_STATE_CHANGED_ACTION.equals(intent.getAction())) {
return;
}
mLock.lock();
WifiInfo info = mWifiManager.getConnectionInfo();
if ( info.getNetworkId()==mNetworkID && info.getSupplicantState() == SupplicantState.COMPLETED ) {
mIsConnnected = true;
mCondition.signalAll();
}
mLock.unlock();
}
}
}与WIFI扫描的封装代码类似，这里也用到了Lock和Condition，就是为了阻塞地等待WIFI连接的结果，保证正确的registerReceiver和unregisterReceiver网络连接状态监听对象，同时，设置了WIFI连接超时，防止由于WIFI模块的问题导致界面收不到回调而长时间“卡死”。
另外，AndroidManifest.xml文件中记得添加权限支持哦：