android -------- WIFI detailed explanation

Today, let’s briefly talk about Wifi in Android development. Some common basics are mainly divided into two parts:

  1: WiFi information  

  2: WiFi search and connection

 

Most apps nowadays need to obtain data from the network. So access to the Internet is inevitable. But before accessing the network, we should first judge the status of the network. In fact, before accessing the network, we need to make some status judgments, and deal with some status judgments, instead of directly using Http to access the network.

Many people often skip the network part and directly access the network during development. Once the network is disconnected, various experience effects will not be good. It does not mean that the app cannot be used, but the experience effect is poor. In addition, we may consider it for users, because now the general Internet connection is wifi and mobile phone traffic, and we all know that the latter charges are relatively high. If our app loads pictures or has a large data download operation, but the user's original intention is not to operate these very traffic-intensive operations if it is under traffic, so we must make some judgments about the connection status. Whether the network connection is good, the connected wifi is still traffic, what to do when the network is disconnected or the network changes, these are some details, but pay attention to handling.

 

 

Three classes and function descriptions of WIFI development:

class name	Function
WifiManager	WiFi unified management class, for various WiFi operations
WifiInfo	Describe the currently connected wifi hotspot information
WifiConfiguration	wifi network configuration information

WiFI information

Get information about connecting to WIFI

  WifiManager mWifiManager=(WifiManager) this.getSystemService(Context.WIFI_SERVICE);
  WifiInfo    mWifiInfo=mWifiManager.getConnectionInfo();

getBSSID() Get the BSSID, in the mobile phone WIFI, it is the MAC address

getSSID() Get SSID

getDetailedStateOf() gets the connectivity of the client

getHiddenSSID() Get whether the SSID is hidden

getIpAddress() to get the IP address

getLinkSpeed() gets the speed of the connection

getMacAddress() gets the Mac address

getRssi() Get the signal of the 802.11n network

getSupplicanState() returns information about the specific client state

As shown in the figure (simple test):

      

       

 

 

 

WiFi search and connection

Search for WiFi and display the WiFi list with the ListView list, click to enter the password to connect to WiFi,

Initially connected WiFi

       

 

After (the process can see the WiFI change in the status bar)

       

 

important code

 // 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<ScanResult> mWifiList;
    // 网络连接列表
    private List<WifiConfiguration> mWifiConfiguration;
    // 定义一个WifiLock
    WifiManager.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<WifiConfiguration> 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();
            }
        }*/

        mWifiManager.startScan();
        //得到扫描结果
        List<ScanResult> 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);
                }
            }
        }


    }

    // 得到网络列表
    public List<ScanResult> 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<WifiConfiguration> existingConfigs = mWifiManager.getConfiguredNetworks();
        for (WifiConfiguration existingConfig : existingConfigs)
        {
            if (existingConfig.SSID.equals("\""+SSID+"\""))
            {
                return existingConfig;
            }
        }
        return null;
    }

 

Other references 

Summary of WIFI system and system architecture: https://blog.csdn.net/liuhaomatou/article/details/40398753

Android Wifi framework process analysis: https://blog.csdn.net/King1425/article/details/68928558

 

 

Source address: https://github.com/DickyQie/android-wifi