From 45cc6b34343bc133a03c632d6c9dd4a2d895e2e9 Mon Sep 17 00:00:00 2001
From: "shaojin.wensj" <shaojin.wensj@alibaba-inc.com>
Date: Fri, 10 May 2024 20:37:05 +0800
Subject: [PATCH] fix toJSON date field error, for issue #2550

---
 .../fastjson2/writer/ObjectWriterAdapter.java |  6 +-
 .../alibaba/fastjson/v2issues/Issue2550.java  | 83 +++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 fastjson1-compatible/src/test/java/com/alibaba/fastjson/v2issues/Issue2550.java

diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterAdapter.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterAdapter.java
index b129d89674..01fc2ac427 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterAdapter.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterAdapter.java
@@ -616,7 +616,11 @@ public JSONObject toJSONObject(T object, long features) {
             Class fieldClass = fieldWriter.fieldClass;
             if (format != null) {
                 if (fieldClass == Date.class) {
-                    fieldValue = DateUtils.format((Date) fieldValue, format);
+                    if ("millis".equals(format)) {
+                        fieldValue = ((Date) fieldValue).getTime();
+                    } else {
+                        fieldValue = DateUtils.format((Date) fieldValue, format);
+                    }
                 } else if (fieldClass == LocalDate.class) {
                     fieldValue = DateUtils.format((LocalDate) fieldValue, format);
                 } else if (fieldClass == LocalDateTime.class) {
diff --git a/fastjson1-compatible/src/test/java/com/alibaba/fastjson/v2issues/Issue2550.java b/fastjson1-compatible/src/test/java/com/alibaba/fastjson/v2issues/Issue2550.java
new file mode 100644
index 0000000000..a8c20c283e
--- /dev/null
+++ b/fastjson1-compatible/src/test/java/com/alibaba/fastjson/v2issues/Issue2550.java
@@ -0,0 +1,83 @@
+package com.alibaba.fastjson.v2issues;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.annotation.JSONField;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue2550 {
+    @Test
+    public void mutatedTest1() {
+        Bean1 bean = new Bean1();
+        bean.date = new Date(1655097829796L);
+        String str = JSON.toJSON(bean).toString();
+        assertEquals("{\"date\":1655097829796}", str);
+
+        Bean1 bean1 = JSON.parseObject(str, Bean1.class);
+        assertEquals(bean.date.getTime(), bean1.date.getTime());
+        Bean1 bean2 = JSON.parseObject(str).toJavaObject(Bean1.class);
+        assertEquals(bean.date.getTime(), bean2.date.getTime());
+    }
+
+    public static class Bean1 {
+        @JSONField(format = "millis")
+        public Date date;
+    }
+
+    @Test
+    public void mutatedTest2() {
+        Bean2 bean = new Bean2();
+        bean.date = new Date(1655097829796L);
+        String str = JSON.toJSON(bean).toString();
+        assertEquals("{\"date\":1655097829796}", str);
+
+        Bean2 bean1 = JSON.parseObject(str, Bean2.class);
+        assertEquals(bean.date.getTime(), bean1.date.getTime());
+        Bean2 bean2 = JSON.parseObject(str).toJavaObject(Bean2.class);
+        assertEquals(bean.date.getTime(), bean2.date.getTime());
+    }
+
+    public static class Bean2 {
+        @JSONField(format = "millis")
+        public Date date;
+    }
+
+    @Test
+    public void mutatedTest1fj() {
+        Bean1fj bean = new Bean1fj();
+        bean.date = new Date(1655097829796L);
+        String str = com.alibaba.fastjson.JSON.toJSON(bean).toString();
+        assertEquals("{\"date\":1655097829796}", str);
+
+        Bean1fj bean1 = com.alibaba.fastjson.JSON.parseObject(str, Bean1fj.class);
+        assertEquals(bean.date.getTime(), bean1.date.getTime());
+        Bean1fj bean2 = com.alibaba.fastjson.JSON.parseObject(str).toJavaObject(Bean1fj.class);
+        assertEquals(bean.date.getTime(), bean2.date.getTime());
+    }
+
+    public static class Bean1fj {
+        @com.alibaba.fastjson.annotation.JSONField(format = "millis")
+        public Date date;
+    }
+
+    @Test
+    public void mutatedTest2fj() {
+        Bean2fj bean = new Bean2fj();
+        bean.date = new Date(1655097829796L);
+        String str = com.alibaba.fastjson.JSON.toJSON(bean).toString();
+        assertEquals("{\"date\":1655097829796}", str);
+
+        Bean2fj bean1 = com.alibaba.fastjson.JSON.parseObject(str, Bean2fj.class);
+        assertEquals(bean.date.getTime(), bean1.date.getTime());
+        Bean2fj bean2 = com.alibaba.fastjson.JSON.parseObject(str).toJavaObject(Bean2fj.class);
+        assertEquals(bean.date.getTime(), bean2.date.getTime());
+    }
+
+    public static class Bean2fj {
+        @com.alibaba.fastjson.annotation.JSONField(format = "millis")
+        public Date date;
+    }
+}