improved jdk8 optional support

alibaba · Mar 23, 2021 · 732c2a3 · 732c2a3
1 parent 3ec5aab
commit 732c2a3
Show file tree

Hide file tree

Showing 3 changed files with 40 additions and 1 deletion.
diff --git a/src/main/java/com/alibaba/fastjson/parser/DefaultJSONParser.java b/src/main/java/com/alibaba/fastjson/parser/DefaultJSONParser.java
@@ -676,7 +676,8 @@ public <T> T parseObject(Type type, Object fieldName) {
         int token = lexer.token();
         if (token == JSONToken.NULL) {
             lexer.nextToken();
-            return null;
+
+            return (T) TypeUtils.optionalEmpty(type);
         }
 
         if (token == JSONToken.LITERAL_STRING) {

diff --git a/src/main/java/com/alibaba/fastjson/util/TypeUtils.java b/src/main/java/com/alibaba/fastjson/util/TypeUtils.java
@@ -3327,4 +3327,32 @@ public static boolean isJacksonCreator(Method method) {
         }
         return class_JacksonCreator != null && method.isAnnotationPresent(class_JacksonCreator);
     }
+
+    private static Object OPTIONAL_EMPTY;
+    private static boolean OPTIONAL_ERROR = false;
+    public static Object optionalEmpty(Type type) {
+        if (OPTIONAL_ERROR) {
+            return null;
+        }
+
+        Class clazz = getClass(type);
+        if (clazz == null) {
+            return null;
+        }
+
+        String className = clazz.getName();
+
+        if ("java.util.Optional".equals(className)) {
+            if (OPTIONAL_EMPTY == null) {
+                try {
+                    Method empty = Class.forName(className).getMethod("empty");
+                    OPTIONAL_EMPTY = empty.invoke(null);
+                } catch (Throwable e) {
+                    OPTIONAL_ERROR = true;
+                }
+            }
+            return OPTIONAL_EMPTY;
+        }
+        return null;
+    }
 }
diff --git a/src/test/java/com/alibaba/json/bvt/jdk8/OptionalTest.java b/src/test/java/com/alibaba/json/bvt/jdk8/OptionalTest.java
@@ -74,4 +74,14 @@ public void test_optionalDouble() throws Exception {
         OptionalDouble val2 = JSON.parseObject(text, OptionalDouble.class);
         Assert.assertEquals(Double.toString(val.getAsDouble()), Double.toString(val2.getAsDouble()));
     }
+
+    public void test_optional_parseNull() throws Exception {
+        assertSame(Optional.empty()
+                , JSON.parseObject("null", Optional.class));
+    }
+
+    public void test_optional_parseNull_2() throws Exception {
+        assertSame(Optional.empty()
+                , JSON.parseObject("null", new TypeReference<Optional<Integer>>() {}));
+    }
 }