Allow setting String[] and int[] properties (#2291)

Nice! Thanks.

Author: joejensen

src/main/java/com/zaxxer/hikari/util/PropertyElf.java

@@ -31,6 +31,8 @@
  */
 public final class PropertyElf
 {
+   private static final char ESCAPE_CHAR = '\\';
+   private static final char SEPARATOR_CHAR = ',';
    private static final Pattern DURATION_PATTERN = Pattern.compile("^(?<number>\\d+)(?<unit>ms|s|m|h|d)$");
 
    private PropertyElf() {
@@ -160,6 +162,12 @@ else if (paramClass == boolean.class || paramClass == Boolean.class) {
          else if (paramClass.isArray() && char.class.isAssignableFrom(paramClass.getComponentType())) {
             writeMethod.invoke(target, value.toCharArray());
          }
+         else if (paramClass.isArray() && int.class.isAssignableFrom(paramClass.getComponentType())) {
+            writeMethod.invoke(target, parseIntArray(value));
+         }
+         else if (paramClass.isArray() && String.class.isAssignableFrom(paramClass.getComponentType())) {
+            writeMethod.invoke(target, new Object[]{parseStringArray(value)});
+         }
          else if (paramClass == String.class) {
             writeMethod.invoke(target, value);
          }
@@ -186,6 +194,54 @@ private static String capitalizedPropertyName(String propertyName)
       return propertyName.substring(0, 1).toUpperCase(Locale.ENGLISH) + propertyName.substring(1);
    }
 
+   private static int[] parseIntArray(String value)
+   {
+      if (value == null || value.isEmpty() ) {
+         return new int[0];
+      }
+
+      var split = value.split(",");
+      var intArray = new int[split.length];
+      for (int i = 0; i < split.length; i++) {
+         intArray[i] = Integer.parseInt(split[i]);
+      }
+      return intArray;
+   }
+
+   private static String[] parseStringArray(String value)
+   {
+      if (value == null || value.isEmpty()) {
+         return new String[0];
+      }
+
+      var resultList = new ArrayList<String>();
+      var inEscape = false;
+      var currentField = new StringBuilder();
+      for (var c : value.toCharArray())
+      {
+         if (inEscape) {
+            currentField.append(c);
+            inEscape = false;
+         }
+         else if (c == ESCAPE_CHAR) {
+            inEscape = true;
+         } else if (c == SEPARATOR_CHAR) {
+            resultList.add(currentField.toString());
+            currentField.setLength(0);
+         }
+         else {
+            currentField.append(c);
+         }
+      }
+
+      if (inEscape) {
+         throw new IllegalArgumentException(String.format("Unterminated escape sequence in property value: %s", value));
+      }
+
+      resultList.add(currentField.toString());
+      return resultList.toArray(new String[0]);
+   }
+
    private static Optional<Duration> parseDuration(String value)
    {
       var matcher = DURATION_PATTERN.matcher(value);

src/test/java/com/zaxxer/hikari/mocks/TestObject.java

@@ -6,6 +6,8 @@ public class TestObject
    private String string;
    private short shortRaw;
    private char[] charArray;
+   private String[] stringArray;
+   private int[] intArray;
 
    public void setTestObject(TestObject testObject)
    {
@@ -44,4 +46,24 @@ public char[] getCharArray()
    {
       return charArray;
    }
+
+   public void setStringArray(String[] stringArray)
+   {
+      this.stringArray = stringArray;
+   }
+
+   public String[] getStringArray()
+   {
+      return stringArray;
+   }
+
+   public void setIntArray(int[] intArray)
+   {
+      this.intArray = intArray;
+   }
+
+   public int[] getIntArray()
+   {
+      return intArray;
+   }
 }

src/test/java/com/zaxxer/hikari/util/PropertyElfTest.java

@@ -5,10 +5,7 @@
 
 import java.util.Properties;
 
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotSame;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 public class PropertyElfTest
 {
@@ -44,4 +41,49 @@ public void setTargetFromPropertiesNotAClass() throws Exception
          assertEquals("argument type mismatch", e.getCause().getMessage());
       }
    }
+
+   @Test
+   public void setStringArray()
+   {
+      Properties properties = new Properties();
+      TestObject testObject = new TestObject();
+
+      properties.setProperty("stringArray", "abc,123");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new String[] {"abc", "123"}, testObject.getStringArray());
+
+      properties.setProperty("stringArray", "abc\\,123");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new String[] {"abc,123"}, testObject.getStringArray());
+
+      properties.setProperty("stringArray", "abc\\\\,123");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new String[] {"abc\\","123"}, testObject.getStringArray());
+
+      properties.setProperty("stringArray", "");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new String[] {}, testObject.getStringArray());
+
+      properties.setProperty("stringArray", "abc,12\\3");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new String[] {"abc","123"}, testObject.getStringArray());
+
+      properties.setProperty("stringArray", "abc,123\\");
+      assertThrows(RuntimeException.class, () -> PropertyElf.setTargetFromProperties(testObject, properties));
+   }
+
+   @Test
+   public void setIntArray()
+   {
+      Properties properties = new Properties();
+      TestObject testObject = new TestObject();
+
+      properties.setProperty("intArray", "1,2,3");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new int[] {1,2,3}, testObject.getIntArray());
+
+      properties.setProperty("intArray", "");
+      PropertyElf.setTargetFromProperties(testObject, properties);
+      assertArrayEquals(new int[] {}, testObject.getIntArray());
+   }
 }