Allows users to pass a custom DateTimeFormatter for the ZonedDateTime…

src/main/java/com/fasterxml/jackson/datatype/jsr310/ser/ZonedDateTimeSerializer.java

@@ -14,13 +14,17 @@ public class ZonedDateTimeSerializer extends InstantSerializerBase<ZonedDateTime
     public static final ZonedDateTimeSerializer INSTANCE = new ZonedDateTimeSerializer();
 
     protected ZonedDateTimeSerializer() {
+        // ISO_ZONED_DATE_TIME is not the ISO format, it is an extension of it
+        this(DateTimeFormatter.ISO_OFFSET_DATE_TIME);
+    }
+
+    public ZonedDateTimeSerializer(DateTimeFormatter formatter) {
         super(ZonedDateTime.class, dt -> dt.toInstant().toEpochMilli(),
-                ZonedDateTime::toEpochSecond, ZonedDateTime::getNano,
-                // ISO_ZONED_DATE_TIME is not the ISO format, it is an extension of it
-                DateTimeFormatter.ISO_OFFSET_DATE_TIME);
+              ZonedDateTime::toEpochSecond, ZonedDateTime::getNano,
+              formatter);
     }
 
-    protected ZonedDateTimeSerializer(ZonedDateTimeSerializer base,
+    private ZonedDateTimeSerializer(ZonedDateTimeSerializer base,
             Boolean useTimestamp, DateTimeFormatter formatter) {
         super(base, useTimestamp, formatter);
     }

src/test/java/com/fasterxml/jackson/datatype/jsr310/TestZonedDateTimeSerializationWithCustomFormatter.java

@@ -0,0 +1,50 @@
+package com.fasterxml.jackson.datatype.jsr310;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.datatype.jsr310.ser.ZonedDateTimeSerializer;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.Collection;
+
+import static org.junit.Assert.assertThat;
+import static org.junit.internal.matchers.StringContains.containsString;
+
+@RunWith(Parameterized.class)
+public class TestZonedDateTimeSerializationWithCustomFormatter {
+    private final DateTimeFormatter formatter;
+
+    public TestZonedDateTimeSerializationWithCustomFormatter(DateTimeFormatter formatter) {
+        this.formatter = formatter;
+    }
+
+    @Test
+    public void testSerialization() throws Exception {
+        ZonedDateTime zonedDateTime = ZonedDateTime.now();
+        assertThat(serializeWith(zonedDateTime, formatter), containsString(zonedDateTime.format(formatter)));
+    }
+
+    private String serializeWith(ZonedDateTime zonedDateTime, DateTimeFormatter formatter) throws Exception {
+        ObjectMapper mapper = new ObjectMapper().registerModule(new SimpleModule().addSerializer(
+                new ZonedDateTimeSerializer(formatter)));
+        mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
+        return mapper.writeValueAsString(zonedDateTime);
+    }
+
+    @Parameters
+    public static Collection<Object[]> customFormatters() {
+        Collection<Object[]> formatters = new ArrayList<>();
+        formatters.add(new Object[]{DateTimeFormatter.ISO_ZONED_DATE_TIME});
+        formatters.add(new Object[]{DateTimeFormatter.ISO_OFFSET_DATE_TIME});
+        formatters.add(new Object[]{DateTimeFormatter.ISO_LOCAL_DATE_TIME});
+        formatters.add(new Object[]{DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ")});
+        return formatters;
+    }
+}