判斷android設備wifi連接狀態

添加訪問權限（AndroidManifest.xml文件里）

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

    package com.example.androidtest;


import android.net.ConnectivityManager;  
import android.net.NetworkInfo.State;  
import android.os.Bundle;  
import android.app.Activity;  
import android.content.Context;  
import android.util.Log;  
import android.view.Menu;  

public class MainActivity extends Activity {  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  

        boolean bFlag = isWifiAvailable(this.getApplicationContext());  
        if (bFlag) {  
            Log.i("Wifi state - ", "connected");  
        } else {  
            Log.i("Wifi state - ", "not connected");  
        }  

    }  

    /** 
     * 判斷wifi連接狀態 
     *  
     * @param ctx 
     * @return 
     */  
    public boolean isWifiAvailable(Context ctx) {  
        ConnectivityManager conMan = (ConnectivityManager) ctx  
                .getSystemService(Context.CONNECTIVITY_SERVICE);  
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI)  
                .getState();  
        if (State.CONNECTED == wifi) {  
            return true;  
        } else {  
            return false;  
        }  
    }  

    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.activity_main, menu);  
        return true;  
    }  

}  </pre>