UsbSerialProber: API cleanup; support multi-port devices.

acquire() is renamed and deprecated in favor of findFirstDevice().

findAllDevices() is added as new functionality.

Internally, probe() now returns a list, allow a (future) multi-port
device to return multiple drivers, one for each port (googlecode
issue #14).

UsbSerialExamples/src/com/hoho/android/usbserial/examples/DemoActivity.java

@@ -110,7 +110,7 @@ public class DemoActivity extends Activity {
     @Override
     protected void onResume() {
         super.onResume();
-        mSerialDevice = UsbSerialProber.acquire(mUsbManager);
+        mSerialDevice = UsbSerialProber.findFirstDevice(mUsbManager);
         Log.d(TAG, "Resumed, mSerialDevice=" + mSerialDevice);
         if (mSerialDevice == null) {
             mTitleTextView.setText("No serial device.");

UsbSerialLibrary/src/com/hoho/android/usbserial/driver/UsbSerialProber.java

@@ -20,15 +20,28 @@
 
 package com.hoho.android.usbserial.driver;
 
-import java.util.Map;
-
 import android.hardware.usb.UsbDevice;
 import android.hardware.usb.UsbDeviceConnection;
 import android.hardware.usb.UsbManager;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
 /**
- * Helper class to assist in detecting and building {@link UsbSerialDriver}
- * instances from available hardware.
+ * Helper class which finds compatible {@link UsbDevice}s and creates
+ * {@link UsbSerialDriver} instances.
+ *
+ * <p/>
+ * You don't need a Prober to use the rest of the library: it is perfectly
+ * acceptable to instantiate driver instances manually. The Prober simply
+ * provides convenience functions.
+ *
+ * <p/>
+ * For most drivers, the corresponding {@link #probe(UsbManager, UsbDevice)}
+ * method will either return an empty list (device unknown / unsupported) or a
+ * singleton list. However, multi-port drivers may return multiple instances.
  *
  * @author mike wakerly (opensource@hoho.com)
  */
@@ -43,102 +56,160 @@ public enum UsbSerialProber {
      */
     FTDI_SERIAL {
         @Override
-        public UsbSerialDriver getDevice(final UsbManager manager, final UsbDevice usbDevice) {
+        public List<UsbSerialDriver> probe(final UsbManager manager, final UsbDevice usbDevice) {
             if (!testIfSupported(usbDevice, FtdiSerialDriver.getSupportedDevices())) {
-                return null;
+                return Collections.emptyList();
             }
             final UsbDeviceConnection connection = manager.openDevice(usbDevice);
             if (connection == null) {
-                return null;
+                return Collections.emptyList();
             }
-            return new FtdiSerialDriver(usbDevice, connection);
+            final UsbSerialDriver driver = new FtdiSerialDriver(usbDevice, connection);
+            return Collections.singletonList(driver);
         }
     },
 
     CDC_ACM_SERIAL {
         @Override
-        public UsbSerialDriver getDevice(UsbManager manager, UsbDevice usbDevice) {
+        public List<UsbSerialDriver> probe(UsbManager manager, UsbDevice usbDevice) {
             if (!testIfSupported(usbDevice, CdcAcmSerialDriver.getSupportedDevices())) {
-               return null;
+               return Collections.emptyList();
             }
             final UsbDeviceConnection connection = manager.openDevice(usbDevice);
             if (connection == null) {
-                return null;
+                return Collections.emptyList();
             }
-            return new CdcAcmSerialDriver(usbDevice, connection);
+            final UsbSerialDriver driver = new CdcAcmSerialDriver(usbDevice, connection);
+            return Collections.singletonList(driver);
         }
     },
-    
+
     SILAB_SERIAL {
         @Override
-        public UsbSerialDriver getDevice(final UsbManager manager, final UsbDevice usbDevice) {
+        public List<UsbSerialDriver> probe(final UsbManager manager, final UsbDevice usbDevice) {
             if (!testIfSupported(usbDevice, Cp2102SerialDriver.getSupportedDevices())) {
-                return null;
+                return Collections.emptyList();
             }
             final UsbDeviceConnection connection = manager.openDevice(usbDevice);
             if (connection == null) {
-                return null;
+                return Collections.emptyList();
             }
-            return new Cp2102SerialDriver(usbDevice, connection);
+            final UsbSerialDriver driver = new Cp2102SerialDriver(usbDevice, connection);
+            return Collections.singletonList(driver);
         }
     };
 
     /**
-     * Builds a new {@link UsbSerialDriver} instance from the raw device, or
-     * returns <code>null</code> if it could not be built (for example, if the
-     * probe failed).
+     * Tests the supplied {@link UsbDevice} for compatibility with this enum
+     * member, returning one or more driver instances if compatible.
      *
      * @param manager the {@link UsbManager} to use
      * @param usbDevice the raw {@link UsbDevice} to use
-     * @return the first available {@link UsbSerialDriver}, or {@code null} if
-     *         no devices could be acquired
+     * @return zero or more {@link UsbSerialDriver}, depending on compatibility
+     *         (never {@code null}).
      */
-    public abstract UsbSerialDriver getDevice(final UsbManager manager, final UsbDevice usbDevice);
+    protected abstract List<UsbSerialDriver> probe(final UsbManager manager, final UsbDevice usbDevice);
 
     /**
-     * Acquires and returns the first available serial device among all
-     * available {@link UsbDevice}s, or returns {@code null} if no device could
-     * be acquired.
+     * Creates and returns a new {@link UsbSerialDriver} instance for the first
+     * compatible {@link UsbDevice} found on the bus.  If none are found,
+     * returns {@code null}.
      *
-     * @param usbManager the {@link UsbManager} to use
+     * <p/>
+     * The order of devices is undefined, therefore if there are multiple
+     * devices on the bus, the chosen device may not be predictable (clients
+     * should use {@link #findAllDevices(UsbManager)} instead).
+     *
+     * @param usbManager the {@link UsbManager} to use.
      * @return the first available {@link UsbSerialDriver}, or {@code null} if
-     *         no devices could be acquired
+     *         none are available.
      */
-    public static UsbSerialDriver acquire(final UsbManager usbManager) {
+    public static UsbSerialDriver findFirstDevice(final UsbManager usbManager) {
         for (final UsbDevice usbDevice : usbManager.getDeviceList().values()) {
-            final UsbSerialDriver probedDevice = acquire(usbManager, usbDevice);
-            if (probedDevice != null) {
-                return probedDevice;
+            for (final UsbSerialProber prober : values()) {
+                final List<UsbSerialDriver> probedDevices = prober.probe(usbManager, usbDevice);
+                if (!probedDevices.isEmpty()) {
+                    return probedDevices.get(0);
+                }
             }
         }
         return null;
     }
 
     /**
-     * Builds and returns a new {@link UsbSerialDriver} from the given
-     * {@link UsbDevice}, or returns {@code null} if no drivers supported this
-     * device.
+     * Creates a new {@link UsbSerialDriver} instance for all compatible
+     * {@link UsbDevice}s found on the bus. If no compatible devices are found,
+     * the list will be empty.
      *
-     * @param usbManager the {@link UsbManager} to use
-     * @param usbDevice the {@link UsbDevice} to use
-     * @return a new {@link UsbSerialDriver}, or {@code null} if no devices
-     *         could be acquired
+     * @param usbManager
+     * @return
      */
-    public static UsbSerialDriver acquire(final UsbManager usbManager, final UsbDevice usbDevice) {
+    public static List<UsbSerialDriver> findAllDevices(final UsbManager usbManager) {
+        final List<UsbSerialDriver> result = new ArrayList<UsbSerialDriver>();
+
+        // For each UsbDevice, call probe() for each prober.
+        for (final UsbDevice usbDevice : usbManager.getDeviceList().values()) {
+            result.addAll(probeSingleDevice(usbManager, usbDevice));
+        }
+        return result;
+    }
+
+    /**
+     * Special method for testing a specific device for driver support,
+     * returning any compatible driver(s).
+     *
+     * <p/>
+     * Clients should ordinarily use {@link #findAllDevices(UsbManager)}, which
+     * operates against the entire bus of devices. This method is useful when
+     * testing against only a single target is desired.
+     *
+     * @param usbManager the {@link UsbManager} to use.
+     * @param usbDevice the device to test against.
+     * @return a list containing zero or more {@link UsbSerialDriver} instances.
+     */
+    public static List<UsbSerialDriver> probeSingleDevice(final UsbManager usbManager,
+            UsbDevice usbDevice) {
+        final List<UsbSerialDriver> result = new ArrayList<UsbSerialDriver>();
         for (final UsbSerialProber prober : values()) {
-            final UsbSerialDriver probedDevice = prober.getDevice(usbManager, usbDevice);
-            if (probedDevice != null) {
-                return probedDevice;
-            }
+            final List<UsbSerialDriver> probedDevices = prober.probe(usbManager, usbDevice);
+            result.addAll(probedDevices);
+        }
+        return result;
+    }
+
+    /**
+     * Deprecated; Use {@link #findFirstDevice(UsbManager)}.
+     *
+     * @param usbManager
+     * @return
+     */
+    @Deprecated
+    public static UsbSerialDriver acquire(final UsbManager usbManager) {
+        return findFirstDevice(usbManager);
+    }
+
+    /**
+     * Deprecated; use {@link #probeSingleDevice(UsbManager, UsbDevice)}.
+     *
+     * @param usbManager
+     * @param usbDevice
+     * @return
+     */
+    @Deprecated
+    public static UsbSerialDriver acquire(final UsbManager usbManager, final UsbDevice usbDevice) {
+        final List<UsbSerialDriver> probedDevices = probeSingleDevice(usbManager, usbDevice);
+        if (!probedDevices.isEmpty()) {
+            return probedDevices.get(0);
         }
         return null;
     }
 
     /**
-     * Returns {@code true} if the given device is found in the vendor/product map.
+     * Returns {@code true} if the given device is found in the driver's
+     * vendor/product map.
      *
      * @param usbDevice the device to test
-     * @param supportedDevices map of vendor ids to product id(s)
+     * @param supportedDevices map of vendor IDs to product ID(s)
      * @return {@code true} if supported
      */
     private static boolean testIfSupported(final UsbDevice usbDevice,