注意：要首先注册开启和关闭WiFi的权限，

　　MainActivity.java

package com.wyl.wifi;import android.content.Context;import android.database.sqlite.SQLiteOpenHelper;import android.net.wifi.WifiManager;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends ActionBarActivity {	Button btn;	Button btn2;	Button btn3;	TextView tv;	EditText et;	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		btn = (Button) findViewById(R.id.btn01);// 检查网卡		btn2 = (Button) findViewById(R.id.btn02);// 开启网卡		btn3 = (Button) findViewById(R.id.btn03);// 关闭网卡		et = (EditText)findViewById(R.id.editText2);		StartWifiListener start = new StartWifiListener();		CloseWifiListener close = new CloseWifiListener();		btn2.setOnClickListener(start);		btn3.setOnClickListener(close);	}		class StartWifiListener implements OnClickListener{		@Override		public void onClick(View v) {			//最重要的就是先获取到WifiManager			WifiManager wifiman = (WifiManager)MainActivity.this.getSystemService(Context.WIFI_SERVICE);			wifiman.setWifiEnabled(true);//开启WiFi			System.out.println("wifi state --->"+wifiman.getWifiState());			Toast.makeText(MainActivity.this, ""+wifiman.getWifiState(), Toast.LENGTH_LONG);		}			}	class CloseWifiListener implements OnClickListener{		@Override		public void onClick(View v) {			WifiManager wifiman = (WifiManager)MainActivity.this.getSystemService(Context.WIFI_SERVICE);			wifiman.setWifiEnabled(false);//关闭WiFi			System.out.println("wifi state --->"+wifiman.getWifiState());			Toast.makeText(MainActivity.this, ""+wifiman.getWifiState(), Toast.LENGTH_LONG);		}			}		}