Client can work with different charsets

src/main/java/org/fintrace/core/drivers/tspl/connection/AbstractConnectionClient.java

@@ -19,11 +19,14 @@
 import org.fintrace.core.drivers.tspl.listeners.ClientListener;
 import org.fintrace.core.drivers.tspl.listeners.DataListener;
 
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
+import static java.nio.charset.StandardCharsets.US_ASCII;
+
 /**
  * Generic client connection implementation for TSPL2 device
  * <p>
@@ -43,6 +46,8 @@ public abstract class AbstractConnectionClient implements TSPLConnectionClient {
     protected boolean isConnected = Boolean.FALSE;
     protected boolean alive = Boolean.FALSE;
 
+    private Charset charset = US_ASCII;
+
     /**
      * {@inheritDoc}
      */
@@ -176,4 +181,21 @@ protected void notifyDisconnected() {
                 clientListener.connectionLost(AbstractConnectionClient.this)
         ));
     }
+
+    public void send(String message) {
+        send(message.getBytes(charset));
+    }
+
+    protected abstract void send(byte[] message);
+
+    /** Sets the charset for transmitting Strings as bytes.
+     * Does not add the corresponding CODEPAGE command. */
+    public void setCharset(Charset charset) {
+        this.charset = charset;
+    }
+
+    public Charset getCharset() {
+        return charset;
+    }
+
 }

src/main/java/org/fintrace/core/drivers/tspl/connection/EthernetConnectionClient.java

@@ -176,18 +176,10 @@ public void send(TSPLLabel label) {
         send(label.getTsplCode());
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public void send(String tsplMessage) {
-        send(tsplMessage.getBytes(US_ASCII));
-    }
-
     /**
      * @param message
      */
-    private void send(byte[] message) {
+    protected void send(byte[] message) {
         if (!isConnected) {
             throw new PrinterException("Printer is not connected");
         }

src/main/java/org/fintrace/core/drivers/tspl/connection/TSPLConnectionClient.java

@@ -20,6 +20,8 @@
 import org.fintrace.core.drivers.tspl.listeners.ClientListener;
 import org.fintrace.core.drivers.tspl.listeners.DataListener;
 
+import java.nio.charset.Charset;
+
 /**
  * This interface define the Connection level contract with the
  * TSPL system. Implementation can be done
@@ -114,4 +116,9 @@ public interface TSPLConnectionClient {
      * If the specified listener doesn't exist, the method will not do anything.
      */
     void removeDataListener(DataListener listener);
+
+    /** Sets the charset for transmitting Strings as bytes.
+     * Does not add the corresponding CODEPAGE command. */
+    void setCharset(Charset charset);
+    Charset getCharset();
 }

src/main/java/org/fintrace/core/drivers/tspl/connection/USBConnectionClient.java

@@ -155,22 +155,11 @@ public void send(TSPLLabel label) {
         send(label.getTsplCode());
     }
 
-    /**
-     * Note that submissions (except interrupt and bulk in-direction) will not block indefinitely,
-     * they will complete or fail within a finite amount of time.
-     * <p>
-     * {@inheritDoc}
-     */
-    @Override
-    public void send(String tsplMessage) {
-        send(tsplMessage.getBytes(US_ASCII));
-    }
-
     /**
      * @param message
      */
 
-    private void send(byte[] message) {
+    protected void send(byte[] message) {
         if (!isConnected) {
             throw new PrinterException("Printer is not connected");
         }

src/test/java/org/fintrace/core/drivers/tspl/test/connection/AbstractConnectionClientTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2017 fintrace (https://fintrace.org/)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.fintrace.core.drivers.tspl.test.connection;
+
+import lombok.extern.slf4j.Slf4j;
+import org.fintrace.core.drivers.tspl.connection.TSPLConnectionClient;
+import org.fintrace.core.drivers.tspl.connection.USBConnectionClient;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import static java.nio.charset.StandardCharsets.US_ASCII;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+@Slf4j public class AbstractConnectionClientTest {
+    short vendorId;
+    byte[] bytes;
+
+    TSPLConnectionClient client = new USBConnectionClient(vendorId) {
+        @Override protected void send(byte[] bs) { bytes = bs; }
+    };
+
+    @Test public void checkCharset(){
+        Assertions.assertEquals(US_ASCII, client.getCharset());
+        client.setCharset(UTF_8);
+        Assertions.assertEquals(UTF_8, client.getCharset());
+        client.send("ë");
+        Assertions.assertArrayEquals(bytes, new byte[]{(byte) 0xC3, (byte) 0xAB});
+        String recover = new String(bytes, UTF_8);
+        Assertions.assertEquals(recover, "ë");
+    }
+
+}