如果你的设备知道Wifi配置(已经存储)，我们可以跳过火箭科学。只需循环配置，检查SSID是否匹配。如果是，连接并返回。

设置权限:

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

连接:

    try {
    String ssid = null;
    if (wifi == Wifi.PCAN_WIRELESS_GATEWAY) {
        ssid = AesPrefs.get(AesConst.PCAN_WIRELESS_SSID,
                context.getString(R.string.pcan_wireless_ssid_default));
    } else if (wifi == Wifi.KJ_WIFI) {
        ssid = context.getString(R.string.remote_wifi_ssid_default);
    }

    WifiManager wifiManager = (WifiManager) context.getApplicationContext()
            .getSystemService(Context.WIFI_SERVICE);

    List<WifiConfiguration> wifiConfigurations = wifiManager.getConfiguredNetworks();

    for (WifiConfiguration wifiConfiguration : wifiConfigurations) {
        if (wifiConfiguration.SSID.equals("\"" + ssid + "\"")) {
            wifiManager.enableNetwork(wifiConfiguration.networkId, true);
            Log.i(TAG, "connectToWifi: will enable " + wifiConfiguration.SSID);
            wifiManager.reconnect();
            return null; // return! (sometimes logcat showed me network-entries twice,
            // which may will end in bugs)
        }
    }
} catch (NullPointerException | IllegalStateException e) {
    Log.e(TAG, "connectToWifi: Missing network configuration.");
}
return null;

如果你的设备知道Wifi配置(已经存储)，我们可以跳过火箭科学。只需循环配置，检查SSID是否匹配。如果是，连接并返回。

设置权限:

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

连接:

    try {
    String ssid = null;
    if (wifi == Wifi.PCAN_WIRELESS_GATEWAY) {
        ssid = AesPrefs.get(AesConst.PCAN_WIRELESS_SSID,
                context.getString(R.string.pcan_wireless_ssid_default));
    } else if (wifi == Wifi.KJ_WIFI) {
        ssid = context.getString(R.string.remote_wifi_ssid_default);
    }

    WifiManager wifiManager = (WifiManager) context.getApplicationContext()
            .getSystemService(Context.WIFI_SERVICE);

    List<WifiConfiguration> wifiConfigurations = wifiManager.getConfiguredNetworks();

    for (WifiConfiguration wifiConfiguration : wifiConfigurations) {
        if (wifiConfiguration.SSID.equals("\"" + ssid + "\"")) {
            wifiManager.enableNetwork(wifiConfiguration.networkId, true);
            Log.i(TAG, "connectToWifi: will enable " + wifiConfiguration.SSID);
            wifiManager.reconnect();
            return null; // return! (sometimes logcat showed me network-entries twice,
            // which may will end in bugs)
        }
    }
} catch (NullPointerException | IllegalStateException e) {
    Log.e(TAG, "connectToWifi: Missing network configuration.");
}
return null;

试试这个方法。这很简单:

public static boolean setSsidAndPassword(Context context, String ssid, String ssidPassword) {
    try {
        WifiManager wifiManager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
        Method getConfigMethod = wifiManager.getClass().getMethod("getWifiApConfiguration");
        WifiConfiguration wifiConfig = (WifiConfiguration) getConfigMethod.invoke(wifiManager);

        wifiConfig.SSID = ssid;
        wifiConfig.preSharedKey = ssidPassword;

        Method setConfigMethod = wifiManager.getClass().getMethod("setWifiApConfiguration", WifiConfiguration.class);
        setConfigMethod.invoke(wifiManager, wifiConfig);

        return true;
    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
}

在API级别29中，WifiManager.enableNetwork()方法已弃用。根据Android API文档(点击这里查看):

请参阅WifiNetworkSpecifier.Builder#build()了解触发连接到Wi-Fi网络的新机制。 参见addnetworkrecommendations (java.util.List)， removenetworkrecommendations (java.util.List)获取添加Wi-Fi的新API 当自动连接到wifi时，考虑网络。兼容性 注意:对于以Build.VERSION_CODES为目标的应用程序。Q或以上，这个 API总是返回false。

从API级别29开始，要连接到WiFi网络，您将需要使用WifiNetworkSpecifier。您可以在https://developer.android.com/reference/android/net/wifi/WifiNetworkSpecifier.Builder.html#build(上找到示例代码)

前面的答案是可行的，但解决方案实际上可以更简单。循环通过配置的网络列表是不需要的，因为当你通过WifiManager添加网络时，你会得到网络id。

所以完整、简化的解决方案应该是这样的:

WifiConfiguration wifiConfig = new WifiConfiguration();
wifiConfig.SSID = String.format("\"%s\"", ssid);
wifiConfig.preSharedKey = String.format("\"%s\"", key);

WifiManager wifiManager = (WifiManager)getSystemService(WIFI_SERVICE);
//remember id
int netId = wifiManager.addNetwork(wifiConfig);
wifiManager.disconnect();
wifiManager.enableNetwork(netId, true);
wifiManager.reconnect();

这是一个你可以子类化的活动，以强制连接到特定的wifi: https://github.com/zoltanersek/android-wifi-activity/blob/master/app/src/main/java/com/zoltanersek/androidwifiactivity/WifiActivity.java

你需要子类化这个活动并实现它的方法:

public class SampleActivity extends WifiBaseActivity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  }

  @Override
  protected int getSecondsTimeout() {
      return 10;
  }

  @Override
  protected String getWifiSSID() {
      return "WifiNetwork";
  }

  @Override
  protected String getWifiPass() {
      return "123456";
  }
}