Android Wi-Fi basic operation

From the user's point of view, Android Wi-Fi module from bottom up can be viewed as Layer 5: Hardware driver, Wpa_suppplicant,jni,wifi api,wifisettings application.

1.wpa_supplicant is an open source library, which is the basis for the Android to implement Wi-Fi functionality, and it communicates with the hardware driver through the socket after receiving commands from the upper layer, operating the hardware to complete the required operations.

2.JNI (Java Native Interface) enables the interaction of Java code with other code, allowing Java code running in a Java virtual machine to interact with applications and libraries written in other languages, in Android, JNI allows Java programs to invoke C programs.

The 3.wi-fi API enables applications to use Wi-Fi functionality.

The 4.wi-fi Settings app is an app that comes with Android, choosing the phone's settings->wireless & Networks->wi-fi, allowing users to manually turn Wi-Fi on or off. When the user turns on the Wi-Fi feature, it automatically searches around the wireless network and displays it as a list for the user to select. The default is to connect to the wireless network for the user's last successful connection.

Some class management device Wi-Fi features are available in the Android.net.wifi package. Mainly includes Scanresult,wificonfiguration,wifiinfo,wifimanager.

1.ScanResult

Scanresult is primarily a scan of Wi-Fi hardware to get information about some of the surrounding Wi-Fi hotspots. The class consists of the following five domains:

return type	Domain name	Explain
Public String	BSSID	Access point Address
Public String	Ssid	Name of the network
Public String	Capabilities	Network performance, including authentication of intervention point support, Key management, encryption mechanism, etc.
public int	Frequency	Frequency of access in MHz
public int	Level	Signal strength in dbm

The class also provides a method, ToString (), that converts the result to a concise, easy-to-read string form.

2.wifiConfiguration class

This class allows you to obtain a network configuration for a Wi-Fi network, including security configuration. The class consists of six subclasses, as follows:

Sub-class	Explain
Wificonfiguration.authalgorthm	Get the encryption method for IEEE802.11
Wificonfiguration.groupcipher	Get Group Key
Wificonfiguration.keymgmt	Get password management mechanism
Wificonfiguration.pairwisecipher	Get a paired key for WPA mode
Wificonfiguration.protocol	Get a secret agreement
Wificonfiguration.status	Get Current network status

Each subclass gives the relevant configuration information in constant form, and some include fields and methods.

3.WifiInfo class

This class enables you to obtain status information for a Wi-Fi network that is already established or is active. This class provides many methods, some of which are commonly used as follows:

Method	Explain
Getbssis ()	Get the Bssid of the current access point
Getipaddress ()	Get IP Address
Getlinkspeed ()	Gets the speed of the current connection
Getmacaddress ()	Get MAC Address
Getrssi ()	Get signal strength indication for 802.11n networks
Getssid ()	Get Network SSID
Getsupplicanstate ()	Returns information about the status of the client

4.wifiManager class

This class is used to manage Wi-Fi connections, which defines 26 constants and 23 methods. Common methods are listed below:

Method	Explain
Addnetwork (wificonfiguration config)	Add a new network to a set up network
Calculatesignallevel (int rssi,int numlevels)	Calculate the level of the signal
Comparesignallevel (int rssia,int rssib)	Compare the strength of two signals
Createwifilock (int locktype,string tag)	Create a Wi-Fi lock to lock the current Wi-Fi connection
disablenetwork (int netId)	Make a network connection fail
Disconnect ()	Disconnect from current access point
enablenetwork (int netid,boolean disableothers)	Establish a connection to a previously provisioned network
Getconfigurednetworks ()	Client Gets network connection status
Getconnectioninfo ()	Get Current connection Information
Getdhcpinfo ()	Get DHCP information
Getscanresult ()	Get scan test Results
Getwifistate ()	Gets whether a Wi-Fi access point is valid
Iswifienabled ()	Determine if a Wi-Fi connection is valid
Pingsupplicant ()	See if the client daemon responds to requests
Ressociate ()	Reconnect to the access point, even if it is already connected
Reconnect ()	If there is no connection at this time, re-connect
removenetwork (int netId)	Move out of a particular network
Saveconfiguration ()	Keep a configuration message
Setwifienabled (Boolean enabled)	Make a connection valid or invalid
Startscan ()	Start scanning
Updatenetwork (wificonfiguration config)	Update a network connection information

It should be noted that the status of the Wi-Fi network card is represented by a series of integer constants.

The Wifi_state_disabled:wi-fi NIC is not available and is represented by an integer constant of 1.

The WIFI_STATE_DISABLING:WI-FI network adapter is shutting down and is represented by an integer constant of 0.

The Wifi_state_enabled:wi-fi network card is available, expressed as Integer constant 3.

The WIFI_STATE_ENABLING:WI-FI network card is open, it takes a while to start, and is represented by the integer constant 2.

Wifi_state_unknown: Unknown NIC status, denoted by integer constant 4.

In addition, Wifimanager also provides a subclass of the role of Wifimanagerlock.wifimanagerlock: In a normal state, if the state of Wi-Fi is idle, then the network will be temporarily interrupted, but if the current network status is locked, then Wi-Fi connectivity will be guaranteed Hold in a certain state, after the end of the lock, will return to normal.

Here's a brief description of how some methods are called

Private Wifiinfo Mwifiinfo;

Private Wifimanager Mwifimanager;

1. Get Wifimanager System Services

Mwifimanager= (Wifimanager) Context.getsystemservice (Context.wifi_service);

2. Regain connection information for current Wi-Fi

public void Againgetwifiinfo () {

Mwifiinfo=mwifimanager.getconnectioninfo ();

}

3. Determine if the user is turning on the Wi-Fi network

public Boolean isnetcardfriendly () {

return mwifimanager.iswifienabled ();

}

4. Determine whether Wi-Fi is currently connected

Private state State;

To create a connection manager

Private Connectivitymanager Connmanager;

public Boolean isconnectioning () {

State=connmanager.getnetworkinfo (Connectivitymanager.type_wifi). GetState ();

if (state.connecting==state) {

return true;

}else{

return false;

}

}

5. Get the current network connection status

Public State getcurrentstate () {

State=connmanager.getnetworkinfo (Connectivitymanager.type_wifi). GetState ();

return state;

}

6. Set the configured network (network with password and configure password), specify the

List of network connections

Private list<wificonfiguration> wificonfiglist=new arraylist<wificonfiguration> ();

Wi-Fi Configuration list

Private list<wificonfiguration> wificonfigedspecifiedlist=new arraylist<wificonfiguration> ();

public void Setwificonfigedspecifiedlist (String SSID) {

Wificonfigedspecifiedlist.clear ();

if (wificonfiglist!=null) {

for (Wificonfiguration item:wificonfiglist) {

If it is a specified network, join the list

if (item. Ssid.equalsignorecase ("\" "+ssid+" \ "") && Item.presharedkey!=null) {

Add to List

Wificonfigedspecifiedlist.add (item);

}

}

}

}

7. Return to the Wi-Fi settings list

Public list<wificonfiguration> getwificonfigedspecifiedlist () {

return wificonfigedspecifiedlist;

}

8. Turn on the Wi-Fi card

public void Opennetcard () {

if (!mwifimanager.iswifienabled ()) {

Mwifimanager.setwifienabled (TRUE);

}

}

9. Turn off the Wi-Fi connection

public void Closenetcard () {

if (mwifimanager.iswifienabled ()) {

Mwifimanager.setwifienabled (FALSE);

}

}

10. Check the current Wi-Fi card status

public void Checknetcardstate () {

if (Mwifimanager.getwifistate () ==0) {

LOG.I ("", "Nic is shutting down");

}else if (mwifimanager.getwifistate () ==1) {

LOG.I ("", "Nic has been turned off");

}else if (mwifimanager.getwifistate () ==2) {

LOG.I ("", "network card is open");

}else if (mwifimanager.getwifistate () ==3) {

LOG.I ("", "Nic has been turned on");

}else{

LOG.I ("", "not acquired to State");

}

}

11. Scan the perimeter network

Save a list of scan results

Public list<scanresult> listresult=new arraylist<scanresult> ();

public void Scan () {

Start scanning

Mwifimanager.startscan ();

Get scan Results

Listresult=mwifimanager.getscanresults ();

Scan Configuration List

Wificonfiglist=mwifimanager.getconfigurednetworks ();

if (listresult!=null) {

There is currently a wireless network

}else{

No wireless network in the current region

}

}

12. Return scan Results

Public list<scanresult> Getlistresult () {

return listresult;

}

13. Get scan Results

Store scan Results

Private StringBuffer mstringbuffer=new StringBuffer ();

Private Scanresult Mscanresult;

Public String Getscanresult () {

Clear the previous scan results before each click of the scan

if (mstringbuffer!=null) {

Mstringbuffer=new StringBuffer ();

}

method to begin scanning call 11

Scan ();

Listresult=mwifimanager.getscanresults ();

if (listresult!=null) {

for (int i=0;i<listresult.size (); i++) {

Mscanresult=listresult.get (i);

Connect the required properties to the string

Mstringbuffer.append ("NO."). Append (i+1). Append (":"). Append (Mscanresult.ssid). Append (". Append"). Mscanresult.bssid ("-"). Append (mscanresult.capabilities). Append (","). Append (mscanresult.frequency). Append ("-"). Append ( Mscanresult.level). Append ("-"). Append (Mscanresult.describecontents ()). Append ("\ n");

}

}

return mstringbuffer.tostring ();

}

14. Disconnect the currently connected network

public void Disconnectwifi () {

Get network ID

int Newid=getnetworkid ();

Setting up a network is not available

Mwifimanager.disablenetwork (NETID);

Disconnect Network

Mwifimanager.disconnect ();

Set Wi-Fi information to NULL

Mwifiinfo=null;

}

15. Check the current network status

Public Boolean checknetworkstate () {

if (mwifiinfo!=null) {

return true;

}else{

return false;

}

}

16. Get the ID of the connection

public int Getnetworkid () {

Return (mwifiinfo==null)? 0:mwifiinfo.getnetworkid ();

}

17. Get the IP address

public void getipaddress () {

Return (mwifiinfo==null)? 0:mwifiinfo.getipaddress ();

}

18. Lock Wifilock

Winfilock Mwifilock;

public void Acquirewifilock () {

Mwifilock.acquire ();

}

19. Unlocking the Wifilock

public void Releasewifilock () {

if (Mwifilock.isheld ()) {

Mwifilock.acquire ();

}

}

20. Create a Wifilock

public void Creatwifilock () {

Mwifilock=mwifimanager.createwifilock ("test");

}

21. Get the contents of the configured network wpa_supplicant.conf, regardless of the configuration password

Public list<wificonfiguration> GetConfiguration () {

return wificonfiglist;

}

22. Specify a configured network connection

Public Boolean connectconfiguration (int index) () {

is more than the configured network return

if (Index>=wificonfiglist.size ()) {

return false;

}

Return Mwifimanager.enablenetwork (Wificonfigedspecifiedlist.get (index). networkid,true);

}

23. Get Max Address

Public String getmacaddress () {

Return (Mwifiinfo=null)? ": Mwifiinfo.getmacaddress ();

}

24. Get access Point Bssid

Public String Getbssid () {

Return (mwifiinfo=null)? " NULL ": Mwifiinfo.getbssid ();

}

25. Get all the Wifiinfo information packets

Public String Getwifiinfo () {

Return (mwifiinfo=null)? " NULL ": mwifiinfo.tostring ();

}

26. Add a network and connect

public int addnetwork (Wificonfiguration g) {

Add Network

int Wcgid=mwifimanager.addnetwork (g);

Set up the added network available

Mwifimanager.enablenetwork (wcgid,true);

return wcgid;

}

Android Wi-Fi basic operation