added a method for creating specific UsbSerialDevice objects

usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java

@@ -16,6 +16,12 @@ import android.hardware.usb.UsbRequest;
 
 public abstract class UsbSerialDevice implements UsbSerialInterface
 {
+    public static final String CDC = "cdc";
+    public static final String CH34x = "ch34x";
+    public static final String CP210x = "cp210x";
+    public static final String FTDI = "ftdi";
+    public static final String PL2303 = "pl2303";
+
     private static final String CLASS_ID = UsbSerialDevice.class.getSimpleName();
 
     private static boolean mr1Version;
@@ -88,6 +94,22 @@ public abstract class UsbSerialDevice implements UsbSerialInterface
             return null;
     }
 
+    public static UsbSerialDevice createUsbSerialDevice(String type, UsbDevice device, UsbDeviceConnection connection, int iface){
+        if(type.equals(FTDI)){
+            return new FTDISerialDevice(device, connection, iface);
+        }else if(type.equals(CP210x)){
+            return new CP2102SerialDevice(device, connection, iface);
+        }else if(type.equals(PL2303)){
+            return new PL2303SerialDevice(device, connection, iface);
+        }else if(type.equals(CH34x)){
+            return new CH34xSerialDevice(device, connection, iface);
+        }else if(type.equals(CDC)){
+            return new CDCSerialDevice(device, connection, iface);
+        }else{
+            throw new IllegalArgumentException("Invalid type argument. Must be:cdc, ch34x, cp210x, ftdi or pl2303");
+        }
+    }
+
     public static boolean isSupported(UsbDevice device)
     {
         int vid = device.getVendorId();