[maimai2] Add dx support

src/main/java/icu/samnyan/aqua/sega/maimai2/util/IntegerListConverter.java

@@ -0,0 +1,47 @@
+package icu.samnyan.aqua.sega.maimai2.util;
+
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+
+import javax.persistence.AttributeConverter;
+import javax.persistence.Converter;
+
+import static java.util.Collections.*;
+
+import java.util.ArrayList;
+
+@Converter
+public class IntegerListConverter implements AttributeConverter<List<Integer>, String> {
+    private static final String SPLIT_CHAR = ";";
+    
+    @Override
+    public String convertToDatabaseColumn(List<Integer> integerList) {
+        if (integerList != null && !integerList.isEmpty()) {
+            StringBuilder str  = new StringBuilder();
+            Iterator<Integer> iter = integerList.iterator();
+            while(iter.hasNext()) {
+                str.append(iter.next());
+                if(iter.hasNext()){
+                str.append(SPLIT_CHAR);
+                }
+            }
+            return str.toString();
+        } else {
+            return "";
+        }
+    }
+
+    @Override
+    public List<Integer> convertToEntityAttribute(String string) {
+        if (string != null && !string.isEmpty()) {
+            List<Integer> iList = new ArrayList<Integer>();
+            for (String s : string.split(SPLIT_CHAR)) {
+                iList.add(Integer.parseInt(s));
+            }
+            return iList;
+        } else {
+            return emptyList();
+        }
+    }
+}