java - 如何转到Android中的下一个 Activity

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How to start new activity on button click
                                
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我不知道为什么订购下一个活动时我的应用程序崩溃，尽管它在其他应用程序中也能正常工作。

基本上，我希望用户连接到特定的wifi（我在WIFIConfiguration中提到过）

如果已连接，则他应进入主要活动，否则他将无法访问其他活动。有什么问题，如果用户连接到wifi，还有什么更好的身份验证方法？

wifi.java类

public class WiFiConfiguration extends Activity {

Button btnnext;

public String networkSSID = null;
public String networkPass = null;

public Button ConnectButton;

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

    btnnext = (Button) findViewById(R.id.btnnext);
    ConnectButton = (Button)findViewById(R.id.connButton);


    /*btnnext.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent i = new Intent(WiFiConfiguration,this secondActivity.class);

            startActivity(i);
        }
    });*/



    ConnectButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            networkSSID = "myssid";
            networkPass = "mypass";

            WifiConfiguration conf = new WifiConfiguration();
            conf.SSID = "\"" + networkSSID + "\"";   // Please note the quotes. String should contain ssid in quotes

            /* for wep*/
            //conf.wepKeys[0] = "\"" + networkPass + "\"";
            //conf.wepTxKeyIndex = 0;
            //conf.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
            //conf.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40);

            /* for wpa*/
            conf.preSharedKey = "\""+ networkPass +"\"";

            /* for open network*/
            //conf.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);

            Context context = getApplicationContext();
            WifiManager wifiManager = (WifiManager)context.getSystemService(Context.WIFI_SERVICE);

            wifiManager.setWifiEnabled(true);

            wifiManager.addNetwork(conf);

            List<WifiConfiguration> list = wifiManager.getConfiguredNetworks();
            for( WifiConfiguration i : list )
                if (i.SSID != null && i.SSID.equals("\"" + networkSSID + "\"")) {
                    wifiManager.disconnect();
                    wifiManager.enableNetwork(i.networkId, true);
                    wifiManager.reconnect();

                    WifiInfo wifiInfo = wifiManager.getConnectionInfo();
                    while (wifiInfo.getSSID() == null) {
                        Log.i("WifiStatus", "Here I am");
                        try {
                            Thread.sleep(Time.SECOND);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                        wifiInfo = wifiManager.getConnectionInfo();
                    }

                    System.out.println("Connection established");
                    Toast.makeText(context, "Connection established", 1000).show();


                    Intent i = new Intent(WiFiConfiguration,this secondActivity.class);

                    startActivity(i);


                    break;


                }
        }
    });



}

}

最佳答案

我认为WifiManager#reconnect()是异步调用。因此，我们应该使用WifiManager#WIFI_STATE_CHANGED_ACTION操作注册广播接收器。请参考以下片段：

  private BroadcastReceiver mWifiStateChangeReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent != null) {
            String action = intent.getAction();
            if (!TextUtils.isEmpty(action)) {
                if (action.equalsIgnoreCase(WifiManager.WIFI_STATE_CHANGED_ACTION)) {
                    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
                    if (connectivityManager != null) {
                        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
                        if (networkInfo != null) {
                            // just to be more sure, you can also check whether the connected APN as same as the required one
                            // by comparing APN names
                            if (networkInfo.getDetailedState() == NetworkInfo.DetailedState.CONNECTED) {
                                Intent i = new Intent(context, secondActivity.class);
                                startActivity(i);
                            }
                        }
                    }
                }
            }
        }
    }
};

确保像这样注册和注销接收者：

 @Override
protected void onStart() {
    super.onStart();
    IntentFilter intentFilter = new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION);
    this.registerReceiver(mWifiStateChangeReceiver, intentFilter);
}

@Override
protected void onStop() {
    super.onStop();
    this.unregisterReceiver(mWifiStateChangeReceiver);
}

当我们执行此操作时，我们应该使用ConnectivityManager.getActiveNetworkInfo()来获取NetworkInfo，它又具有内部枚举NetworkInfo.State#CONNECTED。

我们可以使用该枚举来检查WifiManager#reconnect()调用是否已完成，并且我们已经连接到APN，并且检查之后，我们可以在此处开始新的活动。