completed the device listener

app/src/main/java/com/example/lifeline_test2/MainActivity.java

@@ -14,6 +14,7 @@ import android.hardware.usb.UsbInterface;
 import android.hardware.usb.UsbManager;
 import android.os.Bundle;
 import android.util.Log;
+import android.view.View;
 import android.webkit.CookieManager;
 import android.webkit.JavascriptInterface;
 import android.webkit.WebSettings;
@@ -26,6 +27,9 @@ import androidx.appcompat.content.res.AppCompatResources;
 import java.nio.charset.Charset;
 import java.util.HashMap;
 import java.util.Iterator;
+import android.os.Process;
+import android.widget.Button;
+
 
 public class MainActivity extends AppCompatActivity {
 
@@ -40,19 +44,49 @@ public class MainActivity extends AppCompatActivity {
     private final BroadcastReceiver usbReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
-            if (ACTION_USB_PERMISSION.equals(intent.getAction())) {
+            String action = intent.getAction();
-                synchronized (this) {
+
+            if (ACTION_USB_PERMISSION.equals(action)) {
+                UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
+                boolean granted = intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false);
+                if (granted && device != null) {
+                    Log.d("USB", "Permission granted for: " + device);
+                    usbDevice = device;
+
+                    if (!setupPrinterConnection(device)) {
+                        Log.d("USB", "Permission ok, but no interface/endpoint found.");
+                    }
+                } else {
+                    Log.d("USB", "Permission denied for device: " + device);
+                }
+
+            } else if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
                 UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
-                    if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                 if (device != null) {
-                            setupPrinterConnection(device);
+                    Log.d("USB", "Device attached: " + device);
-                        }
+                    usbDevice = device;
+
+                    PendingIntent permissionIntent = PendingIntent.getBroadcast(
+                            context, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_IMMUTABLE
+                    );
+                    usbManager.requestPermission(device, permissionIntent);
                 }
+
+            } else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
+                UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
+                if (device != null && device.equals(usbDevice)) {
+                    Log.d("USB", "Device detached: " + device);
+                    usbDevice = null;
+                    usbInterface = null;
+                    usbEndpoint = null;
+                    usbDeviceConnection = null;
                 }
             }
         }
     };
 
+
+
 //    @Override
 //    protected void onCreate(Bundle savedInstanceState) {
 //        super.onCreate(savedInstanceState);
@@ -77,8 +111,11 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
         usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
-
+        IntentFilter filter = new IntentFilter();
-    registerReceiver(usbReceiver, new IntentFilter(ACTION_USB_PERMISSION), RECEIVER_NOT_EXPORTED);
+        filter.addAction(ACTION_USB_PERMISSION);
+        filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
+        filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
+        registerReceiver(usbReceiver, filter, RECEIVER_NOT_EXPORTED);
 
         WebView webView = new WebView(this);
         setContentView(webView);
@@ -91,81 +128,142 @@ protected void onCreate(Bundle savedInstanceState) {
         CookieManager.getInstance().setAcceptCookie(true);
         CookieManager.getInstance().setAcceptThirdPartyCookies(webView,true);
 
-    //webView.loadUrl("http://10.23.107.10:8000/kioskvideo");
+        webView.loadUrl("http://10.23.107.10:8000/kioskvideo");
 
-    webView.loadUrl("http://192.168.0.114:8000/kioskvideo");
+//    webView.loadUrl("http://192.168.0.114:8000/kioskvideo");
         //webView.loadUrl("file:///android_asset/index.html");
+
         findUsbPrinter();
     }
 
+
+
     private void findUsbPrinter() {
-        // Find the first connected USB device
         HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();
-        Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
+        for (UsbDevice device : deviceList.values()) {
-        while(deviceIterator.hasNext()){
+
-            UsbDevice device = deviceIterator.next();
+            boolean looksLikePrinter = false;
             for (int i = 0; i < device.getInterfaceCount(); i++) {
                 UsbInterface intf = device.getInterface(i);
-                Integer intfClass = intf.getInterfaceClass();
+                // Prefer PRINTER or VENDOR_SPEC, but accept any interface that has BULK OUT
-                if (intfClass == UsbConstants.USB_CLASS_PRINTER || intfClass == UsbConstants.USB_CLASS_VENDOR_SPEC) {
+                if (intf.getInterfaceClass() == UsbConstants.USB_CLASS_PRINTER
-                    usbInterface = intf;
+                        || intf.getInterfaceClass() == UsbConstants.USB_CLASS_VENDOR_SPEC) {
+                    looksLikePrinter = true;
+                    break;
+                }
+                for (int j = 0; j < intf.getEndpointCount(); j++) {
+                    UsbEndpoint ep = intf.getEndpoint(j);
+                    if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK
+                            && ep.getDirection() == UsbConstants.USB_DIR_OUT) {
+                        looksLikePrinter = true;
+                        break;
+                    }
+                }
+                if (looksLikePrinter) break;
+            }
+
+            if (looksLikePrinter) {
                 usbDevice = device;
                 PendingIntent permissionIntent = PendingIntent.getBroadcast(
                         this, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_IMMUTABLE
                 );
-                    if (!usbManager.hasPermission(usbDevice)) {
+                if (!usbManager.hasPermission(device)) {
-                        usbManager.requestPermission(usbDevice, permissionIntent);
+                    usbManager.requestPermission(device, permissionIntent);
                 } else {
-                        setupPrinterConnection(usbDevice);
+                    // We already have permission; now build interface+endpoint
+                    if (!setupPrinterConnection(device)) {
+                        Log.d("USB", "findUsbPrinter: permission ok but no interface/endpoint");
                     }
-                    break;
                 }
+                return; // stop after first suitable device
+            }
+        }
+
+        Log.d("USB", "findUsbPrinter: No suitable USB printer device found");
+    }
+
+
+    private boolean setupPrinterConnection(UsbDevice device) {
+        usbInterface = null;
+        usbEndpoint  = null;
+
+        if (device == null) {
+            Log.d("USB", "setupPrinterConnection: device is null");
+            return false;
+        }
+
+        // Pick the first interface that has a BULK OUT endpoint
+        for (int i = 0; i < device.getInterfaceCount(); i++) {
+            UsbInterface intf = device.getInterface(i);
+
+            for (int j = 0; j < intf.getEndpointCount(); j++) {
+                UsbEndpoint ep = intf.getEndpoint(j);
+                if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK
+                        && ep.getDirection() == UsbConstants.USB_DIR_OUT) {
+
+                    usbInterface = intf;
+                    usbEndpoint  = ep;
+
+                    Log.d("USB", "setupPrinterConnection: interface#" + i + ", OUT endpoint#" + j + " set");
+                    return true;
                 }
             }
         }
 
-    private void setupPrinterConnection(UsbDevice device){
+        Log.d("USB", "setupPrinterConnection: No printer interface or BULK OUT endpoint found");
-        for (int i = 0; i < usbInterface.getEndpointCount(); i++) {
+        return false;
-            UsbEndpoint ep = usbInterface.getEndpoint(i);
-            if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK &&
-                    ep.getDirection() == UsbConstants.USB_DIR_OUT) {
-                usbEndpoint = ep;
-                break;
-            }
-        }
     }
 
 
+
+
     private void print(String text) throws Exception {
-        if (usbInterface == null) {
+        if (usbDevice == null) {
-            System.out.println("No printer interface found.");
+            Log.d("USB", "print: usbDevice is null; trying discovery");
+            findUsbPrinter();
+            if (usbDevice == null) {
+                System.out.println("No USB device found.");
                 return;
             }
+        }
 
-        if (usbEndpoint == null) {
+        // Ensure we have a valid interface/endpoint for the current device
-            System.out.println("No bulk OUT endpoint found.");
+        if (usbInterface == null || usbEndpoint == null) {
+            if (!setupPrinterConnection(usbDevice)) {
+                System.out.println("No printer interface or BULK OUT endpoint found.");
                 return;
             }
+        }
 
         usbDeviceConnection = usbManager.openDevice(usbDevice);
         if (usbDeviceConnection == null) {
-            System.out.println("Unable to open connection.");
+            System.out.println("Unable to open connection. Requesting permission again...");
+            PendingIntent permissionIntent = PendingIntent.getBroadcast(
+                    this, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_IMMUTABLE
+            );
+            usbManager.requestPermission(usbDevice, permissionIntent);
             return;
         }
 
-        usbDeviceConnection.claimInterface(usbInterface, true);
+        boolean claimed = usbDeviceConnection.claimInterface(usbInterface, true);
-        if(usbDeviceConnection == null){
+        if (!claimed) {
+            System.out.println("Failed to claim interface.");
+            usbDeviceConnection.close();
             return;
         }
 
+        try {
             ESCPOS_Printer printer = new ESCPOS_Printer(usbDeviceConnection, usbEndpoint);
             printer.logo(AppCompatResources.getDrawable(this, R.drawable.updatedlogocropped));
             printer.printFormatted(text);
             printer.feed(5);
             printer.cut();
+        } finally {
             usbDeviceConnection.releaseInterface(usbInterface);
             usbDeviceConnection.close();
         }
+    }
+
 
 
     public class WebAppInterface {