feat: add UTF-8 with BOM support for CSV exported files

pom.xml

@@ -4,7 +4,7 @@
 
 	<groupId>org.vaadin.addons.flowingcode</groupId>
 	<artifactId>grid-exporter-addon</artifactId>
-	<version>2.2.2-SNAPSHOT</version>
+	<version>2.3.0-SNAPSHOT</version>
 	<name>Grid Exporter Add-on</name>
 	<description>Grid Exporter Add-on for Vaadin Flow</description>
 

src/main/java/com/flowingcode/vaadin/addons/gridexporter/CsvInputStreamFactory.java

@@ -28,6 +28,7 @@
 import java.io.OutputStreamWriter;
 import java.io.PipedInputStream;
 import java.io.PipedOutputStream;
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.stream.Collectors;
 import org.apache.commons.io.IOUtils;
@@ -72,7 +73,14 @@ public InputStream createInputStream() {
       PipedOutputStream out = new PipedOutputStream(in);
       new Thread(
               () -> {
-                try (CSVWriter writer = new CSVWriter(new OutputStreamWriter(out))) {
+                try (
+                  OutputStreamWriter os = new OutputStreamWriter(out, exporter.getCsvCharset());
+                  CSVWriter writer = new CSVWriter(os)) {
+                  if (StandardCharsets.UTF_8.equals(exporter.getCsvCharset())) {
+                    // write BOM
+                    os.write(0xfeff);
+                  }
+
                   writer.writeNext(headers);
                   writer.writeAll(data);
                   if (footers.length > 0) {

src/main/java/com/flowingcode/vaadin/addons/gridexporter/GridExporter.java

@@ -39,6 +39,7 @@
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
+import java.nio.charset.Charset;
 import java.text.DateFormat;
 import java.text.DecimalFormat;
 import java.util.Comparator;
@@ -102,6 +103,8 @@ public class GridExporter<T> implements Serializable {
 
   private List<FooterToolbarItem> footerToolbarItems;
 
+  private SerializableSupplier<Charset> csvCharset;
+
   private GridExporter(Grid<T> grid) {
     this.grid = grid;
   }
@@ -554,4 +557,17 @@ public void setFooterToolbarItems(List<FooterToolbarItem> footerToolbarItems) {
     this.footerToolbarItems = footerToolbarItems;
   }
 
+  /**
+   * Charset to use when exporting the CSV file.
+   * 
+   * @return CSV file charset or default one.
+   */
+  public Charset getCsvCharset() {
+    return csvCharset == null ? Charset.defaultCharset() : csvCharset.get();
+  }
+
+  public void setCsvCharset(SerializableSupplier<Charset> charset) {
+    this.csvCharset = charset;
+  }
+
 }

src/test/java/com/flowingcode/vaadin/addons/gridexporter/GridExporterDemo.java

@@ -35,6 +35,7 @@
 import com.vaadin.flow.router.Route;
 import java.io.IOException;
 import java.math.BigDecimal;
+import java.nio.charset.StandardCharsets;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.List;
@@ -81,6 +82,7 @@ public GridExporterDemo() throws EncryptedDocumentException, IOException {
     exporter.setTitle("People information");
     exporter.setFileName(
         "GridExport" + new SimpleDateFormat("yyyyddMM").format(Calendar.getInstance().getTime()));
+    exporter.setCsvCharset(() -> StandardCharsets.UTF_8);
 
     TextField filterField = new TextField();
     filterField.setPlaceholder("Filter by");

src/test/java/com/flowingcode/vaadin/addons/gridexporter/test/SerializationTest.java

@@ -26,6 +26,7 @@
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
+import java.nio.charset.StandardCharsets;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -46,7 +47,9 @@ private void testSerializationOf(Object obj) throws IOException, ClassNotFoundEx
   public void testSerialization() throws ClassNotFoundException, IOException {
     try {
       Grid<String> grid = new Grid<>();
-      testSerializationOf(GridExporter.createFor(grid));
+      GridExporter<String> exporter = GridExporter.createFor(grid);
+      exporter.setCsvCharset(() -> StandardCharsets.ISO_8859_1);
+      testSerializationOf(exporter);
     } catch (Exception e) {
       Assert.fail("Problem while testing serialization: " + e.getMessage());
     }