fix improve feature of NullAsDefaultValue, for issue #3518

core/src/main/java/com/alibaba/fastjson2/JSONWriter.java

@@ -1147,6 +1147,18 @@ public abstract class JSONWriter
 
     public abstract void writeNull();
 
+    public void writeObjectNull(Class<?> fieldClass) {
+        if ((this.context.features & (MASK_NULL_AS_DEFAULT_VALUE)) != 0) {
+            if (fieldClass == Character.class) {
+                writeString("\u0000");
+            } else {
+                writeRaw('{', '}');
+            }
+        } else {
+            writeNull();
+        }
+    }
+
     public void writeStringNull() {
         String raw;
         long features = this.context.features;
@@ -1176,6 +1188,16 @@ public abstract class JSONWriter
         }
     }
 
+    public final void writeDecimalNull() {
+        if ((this.context.features & MASK_NULL_AS_DEFAULT_VALUE) != 0) {
+            writeDouble(0.0);
+        } else if ((this.context.features & MASK_WRITE_NULL_NUMBER_AS_ZERO) != 0) {
+            writeInt32(0);
+        } else {
+            writeNull();
+        }
+    }
+
     public final void writeInt64Null() {
         if ((this.context.features & (MASK_NULL_AS_DEFAULT_VALUE | MASK_WRITE_NULL_NUMBER_AS_ZERO)) != 0) {
             writeInt64(0);

core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF16.java

@@ -1045,7 +1045,7 @@ class JSONWriterUTF16
 
     public final void writeDecimal(BigDecimal value, long features, DecimalFormat format) {
         if (value == null) {
-            writeNumberNull();
+            writeDecimalNull();
             return;
         }
 

core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java

@@ -2371,7 +2371,7 @@ final class JSONWriterUTF8
     @Override
     public final void writeDecimal(BigDecimal value, long features, DecimalFormat format) {
         if (value == null) {
-            writeNumberNull();
+            writeDecimalNull();
             return;
         }
 

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterBigDecimalField.java

@@ -23,7 +23,7 @@ final class FieldWriterBigDecimalField<T>
         BigDecimal value = (BigDecimal) getFieldValue(object);
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
         }

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterBigDecimalFunc.java

@@ -50,7 +50,7 @@ final class FieldWriterBigDecimalFunc<T>
 
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
         }

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterBigDecimalMethod.java

@@ -51,7 +51,7 @@ final class FieldWriterBigDecimalMethod<T>
 
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
         }

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterBigIntField.java

@@ -23,7 +23,7 @@ final class FieldWriterBigIntField<T>
         BigInteger value = (BigInteger) getFieldValue(object);
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
         }

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterBigIntFunc.java

@@ -41,7 +41,7 @@ final class FieldWriterBigIntFunc<T>
         BigInteger value = function.apply(o);
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
         }

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterDoubleFunc.java

@@ -58,11 +58,12 @@ final class FieldWriterDoubleFunc<T>
 
         if (value == null) {
             long features = jsonWriter.getFeatures(this.features);
-            if ((features & JSONWriter.Feature.WriteNulls.mask) != 0
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
-                    && (features & JSONWriter.Feature.NotWriteDefaultValue.mask) == 0
+                return false;
-            ) {
+            }
+            if ((features & JSONWriter.Feature.NotWriteDefaultValue.mask) == 0) {
                 writeFieldName(jsonWriter);
-                jsonWriter.writeNumberNull();
+                jsonWriter.writeDecimalNull();
                 return true;
             }
             return false;

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterFloatFunc.java

@@ -58,11 +58,12 @@ final class FieldWriterFloatFunc<T>
 
         if (value == null) {
             long features = jsonWriter.getFeatures(this.features);
-            if ((features & JSONWriter.Feature.WriteNulls.mask) != 0
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
-                    && (features & JSONWriter.Feature.NotWriteDefaultValue.mask) == 0
+                return false;
-            ) {
+            }
+            if ((features & JSONWriter.Feature.NotWriteDefaultValue.mask) == 0) {
                 writeFieldName(jsonWriter);
-                jsonWriter.writeNumberNull();
+                jsonWriter.writeDecimalNull();
                 return true;
             }
             return false;

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterInt16.java

@@ -46,7 +46,7 @@ abstract class FieldWriterInt16<T>
 
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
             writeFieldName(jsonWriter);

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterInt8.java

@@ -45,7 +45,7 @@ abstract class FieldWriterInt8<T>
 
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
                 return false;
             }
             writeFieldName(jsonWriter);

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterObject.java

@@ -272,7 +272,10 @@ public class FieldWriterObject<T>
 
         // (features & JSONWriter.Feature.WriteNullNumberAsZero.mask) != 0
         if (value == null) {
-            if ((features & WriteNulls.mask) != 0 && (features & NotWriteDefaultValue.mask) == 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
+                return false;
+            }
+            if ((features & NotWriteDefaultValue.mask) == 0) {
                 writeFieldName(jsonWriter);
                 if (array) {
                     jsonWriter.writeArrayNull();
@@ -283,7 +286,7 @@ public class FieldWriterObject<T>
                         || fieldClass == StringBuilder.class) {
                     jsonWriter.writeStringNull();
                 } else {
-                    jsonWriter.writeNull();
+                    jsonWriter.writeObjectNull(fieldClass);
                 }
                 return true;
             } else {

core/src/main/java/com/alibaba/fastjson2/writer/FieldWriterObjectFinal.java

@@ -59,20 +59,18 @@ abstract class FieldWriterObjectFinal<T>
 
         if (value == null) {
             long features = this.features | jsonWriter.getFeatures();
-            if ((features & JSONWriter.Feature.WriteNulls.mask) != 0) {
+            if ((features & (JSONWriter.Feature.WriteNulls.mask | JSONWriter.Feature.NullAsDefaultValue.mask)) == 0) {
-                writeFieldName(jsonWriter);
-
-                if (fieldClass.isArray()) {
-                    jsonWriter.writeArrayNull();
-                } else if (fieldClass == StringBuffer.class || fieldClass == StringBuilder.class) {
-                    jsonWriter.writeStringNull();
-                } else {
-                    jsonWriter.writeNull();
-                }
-                return true;
-            } else {
                 return false;
             }
+            writeFieldName(jsonWriter);
+            if (fieldClass.isArray()) {
+                jsonWriter.writeArrayNull();
+            } else if (fieldClass == StringBuffer.class || fieldClass == StringBuilder.class) {
+                jsonWriter.writeStringNull();
+            } else {
+                jsonWriter.writeObjectNull(fieldClass);
+            }
+            return true;
         }
 
         ObjectWriter valueWriter = getObjectWriter(jsonWriter, fieldClass);

core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java

@@ -2526,7 +2526,7 @@ public class ObjectWriterCreatorASM
         // writeFieldName(w);
         gwFieldName(mwc, fieldWriter, i);
 
-        // jw.writeNulll
+        // jw.writeNull
         mw.aload(JSON_WRITER);
         mw.invokevirtual(TYPE_JSON_WRITER, "writeNull", "()V");
 
@@ -2813,6 +2813,8 @@ public class ObjectWriterCreatorASM
             } else if (fieldClass == String.class) {
                 nullFeatures |= WriteNullStringAsEmpty.mask;
                 nullFeatures |= NullAsDefaultValue.mask;
+            } else {
+                nullFeatures |= NullAsDefaultValue.mask;
             }
             mwc.genIsEnabled(nullFeatures, notNull_);
 //            mw.iload(mwc.var(WRITE_NULLS));
@@ -2822,13 +2824,19 @@ public class ObjectWriterCreatorASM
         // writeFieldName(w);
         gwFieldName(mwc, fieldWriter, i);
 
-        // jw.writeNulll
+        // jw.writeNull
+        mw.aload(JSON_WRITER);
         String WRITE_NULL_METHOD;
+        String WRITE_NULL_DESC = "()V";
         if (fieldClass == AtomicLongArray.class
                 || fieldClass == AtomicIntegerArray.class
                 || Collection.class.isAssignableFrom(fieldClass)
                 || fieldClass.isArray()) {
             WRITE_NULL_METHOD = "writeArrayNull";
+        } else if (fieldClass == Float.class
+                || fieldClass == Double.class
+                || fieldClass == BigDecimal.class) {
+            WRITE_NULL_METHOD = "writeDecimalNull";
         } else if (Number.class.isAssignableFrom(fieldClass)) {
             WRITE_NULL_METHOD = "writeNumberNull";
         } else if (fieldClass == Boolean.class) {
@@ -2839,10 +2847,11 @@ public class ObjectWriterCreatorASM
                 || fieldClass == StringBuilder.class) {
             WRITE_NULL_METHOD = "writeStringNull";
         } else {
-            WRITE_NULL_METHOD = "writeNull";
+            WRITE_NULL_METHOD = "writeObjectNull";
+            WRITE_NULL_DESC = "(Ljava/lang/Class;)V";
+            mwc.loadFieldClass(i, fieldClass);
         }
-        mw.aload(JSON_WRITER);
+        mw.invokevirtual(TYPE_JSON_WRITER, WRITE_NULL_METHOD, WRITE_NULL_DESC);
-        mw.invokevirtual(TYPE_JSON_WRITER, WRITE_NULL_METHOD, "()V");
 
         mw.visitLabel(notNull_);
     }
@@ -3005,7 +3014,7 @@ public class ObjectWriterCreatorASM
         // writeFieldName(w);
         gwFieldName(mwc, fieldWriter, i);
 
-        // jw.writeNulll
+        // jw.writeNull
         mw.aload(JSON_WRITER);
         mw.invokevirtual(TYPE_JSON_WRITER, "writeArrayNull", "()V");
 
@@ -3239,7 +3248,7 @@ public class ObjectWriterCreatorASM
         gwFieldName(mwc, fieldWriter, i);
 
         mw.aload(JSON_WRITER);
-        mw.invokevirtual(TYPE_JSON_WRITER, "writeNumberNull", "()V");
+        mw.invokevirtual(TYPE_JSON_WRITER, "writeDecimalNull", "()V");
 
         mw.goto_(endIfNull_);
 
@@ -3300,7 +3309,7 @@ public class ObjectWriterCreatorASM
         gwFieldName(mwc, fieldWriter, i);
 
         mw.aload(JSON_WRITER);
-        mw.invokevirtual(TYPE_JSON_WRITER, "writeNumberNull", "()V");
+        mw.invokevirtual(TYPE_JSON_WRITER, "writeDecimalNull", "()V");
 
         mw.goto_(endIfNull_);
 
@@ -3484,7 +3493,7 @@ public class ObjectWriterCreatorASM
         mw.visitLabel(writeNull_);
         gwFieldName(mwc, fieldWriter, i);
 
-        // jw.writeNulll
+        // jw.writeNull
         mw.aload(JSON_WRITER);
         mw.invokevirtual(TYPE_JSON_WRITER, "writeNull", "()V");
 
@@ -4190,7 +4199,7 @@ public class ObjectWriterCreatorASM
         mw.invokevirtual(TYPE_JSON_WRITER, "writeString", "(Ljava/lang/String;)V");
         mw.goto_(endIfNull_);
 
-        // jw.writeNulll
+        // jw.writeNull
         mw.visitLabel(writeNullValue_);
         mw.aload(JSON_WRITER);
         mw.invokevirtual(TYPE_JSON_WRITER, "writeStringNull", "()V");

core/src/test/java/com/alibaba/fastjson2/issues/Issue364.java

@@ -11,7 +11,7 @@ public class Issue364 {
     @Test
     public void test() {
         TestBean bean = new TestBean();
-        assertEquals("{\"msg\":\"\"}", JSON.toJSONString(bean, JSONWriter.Feature.NullAsDefaultValue));
+        assertEquals("{\"bean\":{},\"msg\":\"\"}", JSON.toJSONString(bean, JSONWriter.Feature.NullAsDefaultValue));
     }
 
     @Data

core/src/test/java/com/alibaba/fastjson2/issues_3500/Issue3515.java

@@ -0,0 +1,56 @@
+package com.alibaba.fastjson2.issues_3500;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONWriter;
+import lombok.Getter;
+import lombok.Setter;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+public class Issue3515 {
+    @Test
+    public void test() throws Exception {
+        String jsonString = JSON.toJSONString(new Bean(), JSONWriter.Feature.NullAsDefaultValue);
+        Bean bean = JSON.parseObject(jsonString, Bean.class);
+        assertFalse(bean.getBoolVal());
+        assertEquals((byte) 0, bean.getByteVal());
+        assertEquals('\u0000', bean.getCharVal());
+        assertEquals((short) 0, bean.getShortVal());
+        assertEquals(0, bean.getIntVal());
+        assertEquals(0L, bean.getLongVal());
+        assertEquals(0.0F, bean.getFloatVal());
+        assertEquals(0.0D, bean.getDoubleVal());
+        assertEquals("", bean.getStringVal());
+        assertEquals("{}", bean.getMapVal().toString());
+        assertEquals("[]", bean.getListVal().toString());
+        assertEquals(BigInteger.ZERO, bean.getIntegerVal());
+        assertEquals(new BigDecimal("0.0"), bean.getDecimalVal());
+        assertEquals("{}", bean.getObjectVal().toString());
+    }
+
+    @Getter
+    @Setter
+    static class Bean {
+        private Boolean boolVal;
+        private Byte byteVal;
+        private Character charVal;
+        private Short shortVal;
+        private Integer intVal;
+        private Long longVal;
+        private Float floatVal;
+        private Double doubleVal;
+        private String stringVal;
+        private Map<?, ?> mapVal;
+        private List<?> listVal;
+        private BigDecimal decimalVal;
+        private BigInteger integerVal;
+        private Object objectVal;
+    }
+}

core/src/test/java/com/alibaba/fastjson2/v1issues/issue_3400/Issue_20201016_01.java

@@ -19,7 +19,7 @@ public class Issue_20201016_01 {
 
         String s = JSON.toJSONString(config, JSONWriter.Feature.WriteNulls, JSONWriter.Feature.NullAsDefaultValue);
 
-        assertEquals("{\"agent\":null,\"creator\":{\"account\":\"account\",\"name\":\"name\",\"workid\":\"\"},\"owner\":{\"account\":\"account\",\"name\":\"name\",\"workid\":\"\"}}", s);
+        assertEquals("{\"agent\":{},\"creator\":{\"account\":\"account\",\"name\":\"name\",\"workid\":\"\"},\"owner\":{\"account\":\"account\",\"name\":\"name\",\"workid\":\"\"}}", s);
     }
 
     @Test