public class MainActivity extends Activity {WifiManager mWifiManager = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}public void onClick(View v) {switch (v.getId()) {case R.id.open_wifi:mWifiManager = (WifiManager)MainActivity.this.getSystemService(Context.WIFI_SERVICE);mWifiManager.setWifiEnabled(true);if(mWifiManager.getWifiState() == 2){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正在打开...", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 3){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正常使用", Toast.LENGTH_SHORT).show();}break;case R.id.close_wifi:mWifiManager = (WifiManager)MainActivity.this.getSystemService(Context.WIFI_SERVICE);mWifiManager.setWifiEnabled(false);if(mWifiManager.getWifiState() == 0){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正在关闭...", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 1){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI已关闭", Toast.LENGTH_SHORT).show();}break;case R.id.wifi_state:mWifiManager = (WifiManager)MainActivity.this.getSystemService(Context.WIFI_SERVICE);if(mWifiManager.getWifiState() == 0){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正在关闭...", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 1){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI已关闭", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 2){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正在打开...", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 3){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI正常使用", Toast.LENGTH_SHORT).show();}else if(mWifiManager.getWifiState() == 4){Toast.makeText(MainActivity.this, "当前网卡状态为：WIFI状态未知", Toast.LENGTH_SHORT).show();}break;default:break;}}@Overridepublic 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;}}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context=".MainActivity" ><Buttonandroid:id="@+id/open_wifi"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="打开WIFI"android:onClick="onClick" /><Buttonandroid:id="@+id/close_wifi"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="关闭WIFI" android:onClick="onClick"/><Buttonandroid:id="@+id/wifi_state"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="WIFI状态" android:onClick="onClick"/>
</LinearLayout>

<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" /><uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /><uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /><uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />CHANGE_NETWORK_STATE ：允许修改网络状态的权限。 CHANGE_WIFI_STATE ：允许修改 WIFI 状态的权限。 ACCESS_NETWORK_STATE ：允许访问网络状态的权限。 ACCESS_WIFI_STATE ：允许访问 WIFI 状态的权限。