2025-02-15

<1>什麼是Wi-Fi?
Wi-Fi是一種可以將個人電腦、手持設備(如PDA、手機)等終端以無線方式互相連接的技術。Wi-Fi是一個無線網路通信技術的品牌,由Wi-Fi聯盟(Wi-FiAlliance)所持有。
Wi-Fi 原先是無線保真的縮寫,Wi-Fi 的英文全稱為wireless fidelity,在無線局域網的范疇是指“無線相容性認證”,實質上是一種商業認證,同時也是一種無線聯網的技術,以前通過網線連接電腦,而現在則是通過無線電波來連網;常見的就是一個無線路由器,那麼在這個無線路由器的電波覆蓋的有效范圍都可以采用WIFI連接方式進行聯網,如果無線路由器連接瞭一條ADSL線路或者別的上網線路,則又被稱為“熱點”。
<2>獲取WI-FI網卡的狀態(常量)
public    static    final    int    WIFI_STATE_DISABLED
Wi-Fi is disabled.      WI-FI網卡不可用
Constant Value(常量值):        1         (0x00000001)                  
 
 public    static    final   int     WIFI_STATE_DISABLING  
Wi-Fi is currently being disabled.   WI-FI網卡正在關閉
The state will change to WIFI_STATE_DISABLED if it finishes successfully.
 最終狀態會變成WI-FI網卡不可用
Constant Value(常量值):         0          (0x00000000)                   
 
 public   static    final      int     WIFI_STATE_ENABLED  
Wi-Fi is enabled.  WI-FI網卡可用
Constant Value(常量值):        3         (0x00000003)                  
 
 public   static    final    int      WIFI_STATE_ENABLING  
Wi-Fi is currently being enabled.   WI-FI網卡正在打開
The state will change to WIFI_STATE_ENABLED if it finishes successfully.
最終狀態會變成WI-FI網卡可用
Constant Value(常量值):         2         (0x00000002)                  
 
 public    static    final    int       WIFI_STATE_UNKNOWN  
Wi-Fi is in an unknown state.  未知 網卡狀態
This state will occur when an error happens while enabling or disabling.
Constant Value(常量值):         4          (0x00000004)                  
 
<3>操作WI-FI的所需的權限
可以在幫助文檔裡找到詳細的權限,這裡隻列出一部分。
Manifest.permission(權限)
public         static         final         String        CHANGE_WIFI_MULTICAST_STATE  
Allows applications to enter Wi-Fi Multicast mode
Constant Value:                             "android.permission.CHANGE_WIFI_MULTICAST_STATE"                  
 
public         static         final         String        CHANGE_WIFI_STATE  
Allows applications to change Wi-Fi connectivity state
Constant Value:                             "android.permission.CHANGE_WIFI_STATE"                  
 
public         static         final         String        CHANGE_NETWORK_STATE  
Allows applications to change network connectivity state
Constant Value:                             "android.permission.CHANGE_NETWORK_STATE
 
<4>改變WI-FI網卡的狀態
對WI-FI網卡進行操作需要通過WifiManager對象進行
WifiManager  wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);
打開WI-FI網卡
wifiManager.setWifiEnabled(true);  
關閉WI-FI網卡
wifiManager.setWifiEnabled(false);  
獲取網卡當前狀態
wifiManager..getWifiState()
 
package mars.wifi; 
 
import android.app.Activity; 
import android.content.Context; 
import android.net.wifi.WifiManager; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.Toast; 
 
public class WifiActivity extends Activity { 
    /** Called when the activity is first created. */ 
    private Button startButton = null; 
    private Button stopButton = null; 
    private Button checkButton = null; 
    private WifiManager wifiManager = null; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
        startButton = (Button)findViewById(R.id.startWifi); 
        stopButton = (Button)findViewById(R.id.stopWifi); 
        checkButton = (Button)findViewById(R.id.checkWifi); 
        startButton.setOnClickListener(new StartWifiListener()); 
        stopButton.setOnClickListener(new StopWifiListener()); 
        checkButton.setOnClickListener(new CheckWifiListener()); 
    } 
    class StartWifiListener implements OnClickListener{ 
 
        public void onClick(View v) { 
            wifiManager = (WifiManager)WifiActivity.this.getSystemService(Context.WIFI_SERVICE); 
            wifiManager.setWifiEnabled(true); 
            System.out.println("wifi state —>" + wifiManager.getWifiState()); 
            Toast.makeText(WifiActivity.this, "當前Wifi網卡狀態為" + wifiManager.getWifiState(), Toast.LENGTH_SHORT).show(); 
        } 
    } 
    class StopWifiListener implements OnClickListener{ 
 
        public void onClick(View arg0) { 
            // TODO Auto-generated method stub 
            wifiManager = (WifiManager)WifiActivity.this.getSystemService(Context.WIFI_SERVICE); 
            wifiManager.setWifiEnabled(false); 
            switch (wifiManager.getWifiState())  
            {  
                case WifiManager.WIFI_STATE_DISABLED:  
                    System.out.println("wifi state —>" + "WIFI已關閉"); 
                    break;  
 
                case WifiManager.WIFI_STATE_DISABLING:  
                    System.out.println("wifi state —>" + "WIFI正在關閉中");  
                    break;  
                case WifiManager.WIFI_STATE_ENABLED:  
                    System.out.println("wifi state —>" + "WIFI已啟用");  
                    break;  
                case WifiManager.WIFI_STATE_ENABLING:  
                    System.out.println("wifi state —>" + "WIFI正在啟動中");  
                    break;  
                case WifiManager.WIFI_STATE_UNKNOWN:  
                    System.out.println("wifi state —>" + "未知WIFI狀態");  
                    break;  
            }  
            Toast.makeText(WifiActivity.this, "當前Wifi網卡狀態為" + wifiManager.getWifiState(), Toast.LENGTH_SHORT).show(); 
        } 
     
    } 
     
    class CheckWifiListener implements OnClickListener{ 
 
        public void onClick(View v) { 
            wifiManager = (WifiManager)WifiActivity.this.getSystemService(Context.WIFI_SERVICE); 
            System.out.println("wifi state —>" + wifiManager.getWifiState()); 
            Toast.makeText(WifiActivity.this, "當前Wifi網卡狀態為" + wifiManager.getWifiState(), Toast.LENGTH_SHORT).show(); 
        } 
         
    } 

 
 
 
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="https://schemas.android.com/apk/res/android" 
    package="mars.wifi" android:versionCode="1" android:versionName="1.0"> 
    <application android:icon="@drawable/icon" android:label="@string/app_name"> 
        <activity android:name=".WifiActivity" android:label="@string/app_name"> 
            <intent-filter> 
                <action android:name="android.intent.action.MAIN" /> 
                <category android:name="android.intent.category.LAUNCHER" /> 
            </intent-filter> 
        </activity> 
 
    </application> 
    <uses-sdk android:minSdkVersion="4" /> 
    <!– 以下是使用wifi訪問網絡所需要的權限 www.aiwalls.com –> 
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"></uses-permission> 
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission> 
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission> 
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission> 
</manifest>    

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