Try this...
Create 2 packages(activity, util), only for organization
In activity create the class MainActivity.java in util create the class AndroidWebServer.java
package awserverfatepi.com.activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiManager;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import awserverfatepi.com.R;
import awserverfatepi.com.util.AndroidWebServer;
public class MainActivity extends AppCompatActivity {
private static final int DEFAULT_PORT = 8080;
private AndroidWebServer androidWebServer;
private BroadcastReceiver broadcastReceiverNetworkState;
private static boolean isStarted = false;
private CoordinatorLayout coordinatorLayout;
private EditText editTextPort;
private FloatingActionButton floatingActionButtonOnOff;
private View textViewMessage;
private TextView textViewIpAccess;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initGui();
setIpAccess();
floatingActionButtonOnOff = (FloatingActionButton) findViewById(R.id.floatingActionButtonOnOff);
floatingActionButtonOnOff.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (isConnectedInWifi()) {
if (!isStarted && startAndroidWebServer()) {
isStarted = true;
textViewMessage.setVisibility(View.VISIBLE);
floatingActionButtonOnOff.setBackgroundTintList(ContextCompat.getColorStateList(MainActivity.this,
R.color.colorGreen));
editTextPort.setEnabled(false);
} else if (stopAndroidWebServer()) {
isStarted = false;
textViewMessage.setVisibility(View.INVISIBLE);
floatingActionButtonOnOff.setBackgroundTintList(ContextCompat.getColorStateList(MainActivity.this,
R.color.colorRed));
editTextPort.setEnabled(true);
}
} else {
Snackbar.make(coordinatorLayout, getString(R.string.wifi_message), Snackbar.LENGTH_LONG).show();
}
}
});
initBroadcastReceiverNetworkStateChanged();
}
private void initGui() {
coordinatorLayout = (CoordinatorLayout) findViewById(R.id.coordinatorLayout);
editTextPort = (EditText) findViewById(R.id.editTextPort);
textViewMessage = findViewById(R.id.textViewMessage);
textViewIpAccess = (TextView) findViewById(R.id.textViewIpAccess);
}
private boolean startAndroidWebServer() {
if (!isStarted) {
int port = getPortFromEditText();
try {
if (port == 0) {
throw new Exception();
}
androidWebServer = new AndroidWebServer(port);
androidWebServer.start();
return true;
} catch (Exception e) {
e.printStackTrace();
Snackbar.make(coordinatorLayout, "A porta " + port + " não está funcionando, por favor altere para outra no intervalo" +
" entre 1000 e 9999.", Snackbar.LENGTH_LONG).show();
}
}
return false;
}
private boolean stopAndroidWebServer() {
if (isStarted && androidWebServer != null) {
androidWebServer.stop();
return true;
}
return false;
}
private void setIpAccess() {
textViewIpAccess.setText(getIpAccess());
}
private void initBroadcastReceiverNetworkStateChanged() {
final IntentFilter filters = new IntentFilter();
filters.addAction("android.net.wifi.WIFI_STATE_CHANGED");
filters.addAction("android.net.wifi.STATE_CHANGE");
broadcastReceiverNetworkState = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
setIpAccess();
}
};
super.registerReceiver(broadcastReceiverNetworkState, filters);
}
private String getIpAccess() {
WifiManager wifiManager = (WifiManager) getSystemService(WIFI_SERVICE);
int ipAddress = wifiManager.getConnectionInfo().getIpAddress();
final String formatedIpAddress = String.format("%d.%d.%d.%d", (ipAddress & 0xff), (ipAddress >> 8 & 0xff),
(ipAddress >> 16 & 0xff), (ipAddress >> 24 & 0xff));
return "http://" + formatedIpAddress + ":";
}
private int getPortFromEditText() {
String valueEditText = editTextPort.getText().toString();
return (valueEditText.length() > 0) ? Integer.parseInt(valueEditText) : DEFAULT_PORT;
}
public boolean isConnectedInWifi() {
WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
NetworkInfo networkInfo = ((ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected()
&& wifiManager.isWifiEnabled() && networkInfo.getTypeName().equals("WIFI")) {
return true;
}
return false;
}
public boolean onKeyDown(int keyCode, KeyEvent evt) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if (isStarted) {
new AlertDialog.Builder(this)
.setTitle(R.string.warning)
.setMessage(R.string.dialog_exit_message)
.setPositiveButton(getResources().getString(android.R.string.ok), new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
}
})
.setNegativeButton(getResources().getString(android.R.string.cancel), null)
.show();
} else {
finish();
}
return true;
}
return false;
}
@Override
protected void onDestroy() {
super.onDestroy();
stopAndroidWebServer();
isStarted = false;
if (broadcastReceiverNetworkState != null) {
unregisterReceiver(broadcastReceiverNetworkState);
}
}
}
In the AndroidWebserver.java
package awserverfatepi.com.util;
import java.util.Map;
import fi.iki.elonen.NanoHTTPD;
public class AndroidWebServer extends NanoHTTPD {
public AndroidWebServer(int port) {
super(port);
}
public AndroidWebServer(String hostname, int port) {
super(hostname, port);
}
@Override
public Response serve(IHTTPSession session) {
String msg = "<html><body><h1>Hello World</h1>\n";
Map<String, String> parms = session.getParms();
if (parms.get("username") == null) {
msg += "<form action='?' method='get'>\n <p>Seu nome: <input type='text' name='username'></p>\n" + "</form>\n";
} else {
msg += "<p>Hello, " + parms.get("username") + "!</p>";
}
return newFixedLengthResponse( msg + "</body></html>\n" );
}
}
Don't forget Manifest.xml
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
And last
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/coordinatorLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:layout_width="match_parent"
android:layout_height="150dp"
android:scaleType="centerCrop"
android:src="@drawable/header" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="@color/colorPrimaryLight"
android:gravity="center"
android:orientation="vertical">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/textViewIpAccess"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="http://000.000.000.000:"
android:textColor="@android:color/white"
android:textSize="20sp"
android:textStyle="bold" />
<EditText
android:id="@+id/editTextPort"
android:layout_width="60dp"
android:layout_height="wrap_content"
android:gravity="center"
android:hint="8080"
android:inputType="numberDecimal"
android:maxLength="4"
android:text="8080"
android:textColor="@android:color/white"
android:textSize="20sp"
android:textStyle="bold" />
</LinearLayout>
<TextView
android:id="@+id/textViewMessage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="50dp"
android:layout_marginRight="50dp"
android:layout_marginTop="50dp"
android:gravity="center"
android:text="@string/message"
android:textColor="@android:color/white"
android:textSize="18sp"
android:visibility="invisible" />
</LinearLayout>
</LinearLayout>
<android.support.design.widget.FloatingActionButton
android:id="@+id/floatingActionButtonOnOff"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end|bottom"
android:layout_margin="16dp"
android:elevation="4dp"
android:src="@drawable/on_btn"
app:backgroundTint="@color/colorRed" />
</android.support.design.widget.CoordinatorLayout>