fix code

hutool-core/src/main/java/cn/hutool/core/reflect/NullType.java

@@ -0,0 +1,23 @@
+package cn.hutool.core.reflect;
+
+import java.lang.reflect.Type;
+
+/**
+ * 空类型表示
+ *
+ * @author looly
+ * @since 6.0.0
+ */
+public class NullType implements Type {
+	/**
+	 * 单例对象
+	 */
+	public static NullType INSTANCE = new NullType();
+
+	private NullType(){}
+
+	@Override
+	public String toString() {
+		return "Type of null";
+	}
+}

hutool-json/src/main/java/cn/hutool/json/InternalJSONUtil.java

@@ -9,25 +9,26 @@ import cn.hutool.core.map.CaseInsensitiveLinkedMap;
 import cn.hutool.core.map.CaseInsensitiveTreeMap;
 import cn.hutool.core.math.NumberUtil;
 import cn.hutool.core.reflect.ClassUtil;
+import cn.hutool.core.reflect.ConstructorUtil;
+import cn.hutool.core.reflect.TypeUtil;
 import cn.hutool.core.text.StrUtil;
 import cn.hutool.core.util.ArrayUtil;
 import cn.hutool.core.util.CharUtil;
 import cn.hutool.core.util.ObjUtil;
+import cn.hutool.json.serialize.GlobalSerializeMapping;
+import cn.hutool.json.serialize.JSONDeserializer;
 import cn.hutool.json.serialize.JSONString;
+import cn.hutool.json.writer.GlobalValueWriterMapping;
+import cn.hutool.json.writer.JSONValueWriter;
 
 import java.io.IOException;
 import java.io.StringWriter;
 import java.io.Writer;
+import java.lang.reflect.Type;
 import java.math.BigDecimal;
 import java.sql.SQLException;
 import java.time.temporal.TemporalAccessor;
-import java.util.Calendar;
+import java.util.*;
-import java.util.Collection;
-import java.util.Comparator;
-import java.util.Date;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.TreeMap;
 import java.util.function.Predicate;
 
 /**
@@ -56,9 +57,11 @@ public final class InternalJSONUtil {
 	 * @return 包装后的值，null表示此值需被忽略
 	 */
 	static Object wrap(final Object object, final JSONConfig jsonConfig) {
-		if (object == null) {
+		// null和自定义对象原样存储
-			return null;
+		if (null == object || null != InternalJSONUtil.getValueWriter(object)) {
+			return object;
 		}
+
 		if (object instanceof JSON //
 				|| object instanceof JSONString //
 				|| object instanceof CharSequence //
@@ -369,7 +372,44 @@ public final class InternalJSONUtil {
 		return rawHashMap;
 	}
 
+	/**
+	 * 根据值类型获取{@link JSONValueWriter}，首先判断对象是否实现了{@link JSONValueWriter}接口<br>
+	 * 如果未实现从{@link GlobalValueWriterMapping}中查找全局的writer，否则返回null。
+	 *
+	 * @param value 值
+	 * @param <T>   值类型
+	 * @return {@link JSONValueWriter}
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T> JSONValueWriter<T> getValueWriter(final T value) {
+		if (value instanceof JSONValueWriter) {
+			return (JSONValueWriter<T>) value;
+		}
+		// 全局自定义序列化，支持null的自定义写出
+		return (JSONValueWriter<T>) GlobalValueWriterMapping.get(null == value ? null : value.getClass());
+	}
+
+	/**
+	 * 根据目标类型，获取对应的{@link JSONDeserializer}，首先判断是否实现了{@link JSONDeserializer}接口<br>
+	 * 如果未实现从{@link GlobalSerializeMapping}中查找全局的{@link JSONDeserializer}，否则返回null
+	 *
+	 * @param targetType 目标类型
+	 * @param <T> 目标类型
+	 * @return {@link JSONDeserializer}
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T> JSONDeserializer<T> getDeserializer(final Type targetType) {
+		final Class<T> rawType = (Class<T>) TypeUtil.getClass(targetType);
+		if (null != rawType && JSONDeserializer.class.isAssignableFrom(rawType)) {
+			return (JSONDeserializer<T>) ConstructorUtil.newInstanceIfPossible(rawType);
+		}
+
+		// 全局自定义反序列化（优先级低于实现JSONDeserializer接口）
+		return (JSONDeserializer<T>) GlobalSerializeMapping.getDeserializer(targetType);
+	}
+
 	// --------------------------------------------------------------------------------------------- Private method start
+
 	/**
 	 * 对所有双引号做转义处理（使用双反斜杠做转义）<br>
 	 * 为了能在HTML中较好的显示，会将&lt;/转义为&lt;\/<br>

hutool-json/src/main/java/cn/hutool/json/JSONConfig.java

@@ -1,19 +1,11 @@
 package cn.hutool.json;
 
 import cn.hutool.core.comparator.CompareUtil;
-import cn.hutool.core.convert.Convert;
 import cn.hutool.core.convert.Converter;
-import cn.hutool.core.convert.impl.DateConverter;
-import cn.hutool.core.convert.impl.TemporalAccessorConverter;
-import cn.hutool.core.reflect.TypeUtil;
-import cn.hutool.core.text.StrUtil;
 import cn.hutool.json.convert.JSONConverter;
-import cn.hutool.json.serialize.JSONString;
 
 import java.io.Serializable;
-import java.time.temporal.TemporalAccessor;
 import java.util.Comparator;
-import java.util.Date;
 
 /**
  * JSON配置项
@@ -59,35 +51,7 @@ public class JSONConfig implements Serializable {
 	/**
 	 * 自定义的类型转换器，用于在getXXX操作中自动转换类型
 	 */
-	private Converter converter = (type, value)->{
+	private Converter converter = JSONConverter.of(this);
-		if(null == value){
-			return null;
-		}
-		if(value instanceof JSONString){
-			// 被JSONString包装的对象，获取其原始类型
-			value = ((JSONString) value).getRaw();
-		}
-
-		final Class<?> rawType = TypeUtil.getClass(type);
-		if(null == rawType){
-			return value;
-		}
-		if(JSON.class.isAssignableFrom(rawType)){
-			return JSONConverter.INSTANCE.toJSON(value);
-		}
-		if(Date.class.isAssignableFrom(rawType) || TemporalAccessor.class.isAssignableFrom(rawType)){
-			// 日期转换，支持自定义日期格式
-			final String format = getDateFormat();
-			if (StrUtil.isNotBlank(format)) {
-				if (Date.class.isAssignableFrom(rawType)) {
-					return new DateConverter(format).convert(type, value);
-				} else {
-					return new TemporalAccessorConverter(format).convert(type, value);
-				}
-			}
-		}
-		return Convert.convertWithCheck(type, value, null, isIgnoreError());
-	};
 
 	/**
 	 * 创建默认的配置项

hutool-json/src/main/java/cn/hutool/json/JSONParser.java

@@ -2,6 +2,7 @@ package cn.hutool.json;
 
 import cn.hutool.core.lang.mutable.Mutable;
 import cn.hutool.core.lang.mutable.MutableEntry;
+import cn.hutool.core.util.CharUtil;
 
 import java.util.function.Predicate;
 
@@ -80,7 +81,7 @@ public class JSONParser {
 
 			switch (tokener.nextClean()) {
 				case ';':
-				case ',':
+				case CharUtil.COMMA:
 					if (tokener.nextClean() == '}') {
 						// issue#2380
 						// 尾后逗号（Trailing Commas），JSON中虽然不支持，但是ECMAScript 2017支持，此处做兼容。
@@ -111,7 +112,7 @@ public class JSONParser {
 		if (x.nextClean() != ']') {
 			x.back();
 			for (; ; ) {
-				if (x.nextClean() == ',') {
+				if (x.nextClean() == CharUtil.COMMA) {
 					x.back();
 					jsonArray.addRaw(null, predicate);
 				} else {
@@ -119,7 +120,7 @@ public class JSONParser {
 					jsonArray.addRaw(x.nextValue(), predicate);
 				}
 				switch (x.nextClean()) {
-					case ',':
+					case CharUtil.COMMA:
 						if (x.nextClean() == ']') {
 							return;
 						}

hutool-json/src/main/java/cn/hutool/json/JSONTokener.java

@@ -71,6 +71,7 @@ public class JSONTokener {
 	 *
 	 * @param inputStream InputStream
 	 * @param config      JSON配置
+	 * @throws JSONException JSON异常，包装IO异常
 	 */
 	public JSONTokener(final InputStream inputStream, final JSONConfig config) throws JSONException {
 		this(IoUtil.getUtf8Reader(inputStream), config);
@@ -89,6 +90,8 @@ public class JSONTokener {
 
 	/**
 	 * 将标记回退到第一个字符，重新开始解析新的JSON
+	 *
+	 * @throws JSONException JSON异常，包装IO异常
 	 */
 	public void back() throws JSONException {
 		if (this.usePrevious || this.index <= 0) {
@@ -111,6 +114,7 @@ public class JSONTokener {
 	 * 源字符串是否有更多的字符
 	 *
 	 * @return 如果未达到结尾返回true，否则false
+	 * @throws JSONException JSON异常，包装IO异常
 	 */
 	public boolean more() throws JSONException {
 		this.next();
@@ -272,11 +276,11 @@ public class JSONTokener {
 	}
 
 	/**
-	 * Get the text up but not including the specified character or the end of line, whichever comes first. <br>
 	 * 获得从当前位置直到分隔符（不包括分隔符）或行尾的的所有字符。
 	 *
 	 * @param delimiter 分隔符
 	 * @return 字符串
+	 * @throws JSONException JSON异常，包装IO异常
 	 */
 	public String nextTo(final char delimiter) throws JSONException {
 		final StringBuilder sb = new StringBuilder();
@@ -297,6 +301,7 @@ public class JSONTokener {
 	 *
 	 * @param delimiters A set of delimiter characters.
 	 * @return A string, trimmed.
+	 * @throws JSONException JSON异常，包装IO异常
 	 */
 	public String nextTo(final String delimiters) throws JSONException {
 		char c;
@@ -314,9 +319,9 @@ public class JSONTokener {
 	}
 
 	/**
-	 * 获得下一个值，值类型可以是Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the JSONObject.NULL
+	 * 获得下一个值，值类型可以是Boolean, Double, Integer, JSONArray, JSONObject, Long, or String
 	 *
-	 * @return Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the JSONObject.NULL
+	 * @return Boolean, Double, Integer, JSONArray, JSONObject, Long, or String
 	 * @throws JSONException 语法错误
 	 */
 	public Object nextValue() throws JSONException {
@@ -360,6 +365,7 @@ public class JSONTokener {
 	 *
 	 * @param to 需要定位的字符
 	 * @return 定位的字符，如果字符未找到返回0
+	 * @throws JSONException IO异常
 	 */
 	public char skipTo(final char to) throws JSONException {
 		char c;
@@ -378,8 +384,8 @@ public class JSONTokener {
 					return c;
 				}
 			} while (c != to);
-		} catch (final IOException exception) {
+		} catch (final IOException e) {
-			throw new JSONException(exception);
+			throw new JSONException(e);
 		}
 		this.back();
 		return c;
@@ -396,43 +402,6 @@ public class JSONTokener {
 		return new JSONException(message + this);
 	}
 
-	/**
-	 * 转为 {@link JSONArray}
-	 *
-	 * @return {@link JSONArray}
-	 */
-	public JSONArray toJSONArray() {
-		final JSONArray jsonArray = new JSONArray(this.config);
-		if (this.nextClean() != '[') {
-			throw this.syntaxError("A JSONArray text must start with '['");
-		}
-		if (this.nextClean() != ']') {
-			this.back();
-			while (true) {
-				if (this.nextClean() == ',') {
-					this.back();
-					jsonArray.add(null);
-				} else {
-					this.back();
-					jsonArray.add(this.nextValue());
-				}
-				switch (this.nextClean()) {
-					case ',':
-						if (this.nextClean() == ']') {
-							return jsonArray;
-						}
-						this.back();
-						break;
-					case ']':
-						return jsonArray;
-					default:
-						throw this.syntaxError("Expected a ',' or ']'");
-				}
-			}
-		}
-		return jsonArray;
-	}
-
 	/**
 	 * Make a printable string of this JSONTokener.
 	 *

hutool-json/src/main/java/cn/hutool/json/JSONUtil.java

@@ -10,12 +10,11 @@ import cn.hutool.json.serialize.GlobalSerializeMapping;
 import cn.hutool.json.serialize.JSONArraySerializer;
 import cn.hutool.json.serialize.JSONDeserializer;
 import cn.hutool.json.serialize.JSONObjectSerializer;
+import cn.hutool.json.writer.JSONValueWriter;
+import cn.hutool.json.writer.JSONWriter;
 import cn.hutool.json.xml.JSONXMLUtil;
 
-import java.io.File;
+import java.io.*;
-import java.io.IOException;
-import java.io.Reader;
-import java.io.Writer;
 import java.lang.reflect.Type;
 import java.nio.charset.Charset;
 import java.util.List;
@@ -296,7 +295,18 @@ public class JSONUtil {
 	 * @return JSON字符串
 	 * @since 5.7.12
 	 */
+	@SuppressWarnings({"unchecked", "rawtypes"})
 	public static String toJsonStr(final Object obj, final JSONConfig jsonConfig) {
+		// 自定义规则，优先级高于全局规则
+		final JSONValueWriter valueWriter = InternalJSONUtil.getValueWriter(obj);
+		if(null != valueWriter){
+			final StringWriter stringWriter = new StringWriter();
+			final JSONWriter jsonWriter = JSONWriter.of(stringWriter, 0, 0, null);
+			// 用户对象自定义实现了JSONValueWriter接口，理解为需要自定义输出
+			valueWriter.write(jsonWriter, obj);
+			return stringWriter.toString();
+		}
+
 		if (null == obj) {
 			return null;
 		}

hutool-json/src/main/java/cn/hutool/json/convert/JSONConverter.java

@@ -2,39 +2,33 @@ package cn.hutool.json.convert;
 
 import cn.hutool.core.bean.BeanUtil;
 import cn.hutool.core.bean.copier.BeanCopier;
+import cn.hutool.core.convert.Convert;
 import cn.hutool.core.convert.ConvertException;
 import cn.hutool.core.convert.Converter;
 import cn.hutool.core.convert.RegisterConverter;
-import cn.hutool.core.convert.impl.ArrayConverter;
+import cn.hutool.core.convert.impl.*;
-import cn.hutool.core.convert.impl.CollectionConverter;
-import cn.hutool.core.convert.impl.MapConverter;
 import cn.hutool.core.map.MapWrapper;
 import cn.hutool.core.reflect.ConstructorUtil;
 import cn.hutool.core.reflect.TypeReference;
 import cn.hutool.core.reflect.TypeUtil;
 import cn.hutool.core.text.StrUtil;
 import cn.hutool.core.util.ArrayUtil;
-import cn.hutool.json.InternalJSONUtil;
+import cn.hutool.json.*;
-import cn.hutool.json.JSON;
-import cn.hutool.json.JSONArray;
-import cn.hutool.json.JSONConfig;
-import cn.hutool.json.JSONException;
-import cn.hutool.json.JSONObject;
-import cn.hutool.json.JSONUtil;
-import cn.hutool.json.serialize.GlobalSerializeMapping;
 import cn.hutool.json.serialize.JSONDeserializer;
+import cn.hutool.json.serialize.JSONString;
 
 import java.lang.reflect.Type;
+import java.time.temporal.TemporalAccessor;
 import java.util.Collection;
+import java.util.Date;
 import java.util.Iterator;
 import java.util.Map;
 
 /**
  * JSON转换器，实现Object对象转换为{@link JSON}，支持的对象：
  * <ul>
- *     <li>String: 转换为相应的对象</li>
+ *     <li>任意支持的对象，转换为JSON</li>
- *     <li>Array、Iterable、Iterator：转换为JSONArray</li>
+ *     <li>JSOn转换为指定对象Bean</li>
- *     <li>Bean对象：转为JSONObject</li>
  * </ul>
  *
  * @author looly
@@ -73,27 +67,40 @@ public class JSONConverter implements Converter {
 	}
 
 	@Override
-	public Object convert(Type targetType, final Object obj) throws ConvertException {
+	public Object convert(Type targetType, Object value) throws ConvertException {
-		if (null == obj) {
+		if (null == value) {
 			return null;
 		}
-
+		if (value instanceof JSONString) {
-		// 对象转JSON
+			// 被JSONString包装的对象，获取其原始类型
-		if (targetType instanceof JSON) {
+			value = ((JSONString) value).getRaw();
-			return toJSON(obj);
 		}
 
 		// JSON转对象
-		if (obj instanceof JSON) {
+		if (value instanceof JSON) {
 			if (targetType instanceof TypeReference) {
+				// 还原原始类型
 				targetType = ((TypeReference<?>) targetType).getType();
 			}
-			return toBean(targetType, (JSON) obj);
+			return toBean(targetType, (JSON) value);
 		}
 
-		// 无法转换
+		// 对象转JSON
-		throw new JSONException("Can not convert from {}: [{}] to [{}]",
+		final Class<?> targetClass = TypeUtil.getClass(targetType);
-				obj.getClass().getName(), obj, targetType.getTypeName());
+		if(null != targetClass){
+			if (JSON.class.isAssignableFrom(targetClass)) {
+				return toJSON(value);
+			}
+			// 自定义日期格式
+			if(Date.class.isAssignableFrom(targetClass) || TemporalAccessor.class.isAssignableFrom(targetClass)){
+				final Object date = toDateWithFormat(targetClass, value);
+				if(null != date){
+					return date;
+				}
+			}
+		}
+
+		return Convert.convertWithCheck(targetType, value, null, config.isIgnoreError());
 	}
 
 	/**
@@ -127,22 +134,30 @@ public class JSONConverter implements Converter {
 		return json;
 	}
 
+	// ----------------------------------------------------------- Private method start
+
+	/**
+	 * JSON转Bean
+	 *
+	 * @param <T>        目标类型
+	 * @param targetType 目标类型，
+	 * @param json       JSON
+	 * @return bean
+	 */
 	@SuppressWarnings("unchecked")
 	private <T> T toBean(final Type targetType, final JSON json) {
-		final Class<T> rawType = (Class<T>) TypeUtil.getClass(targetType);
-		if(null != rawType && JSONDeserializer.class.isAssignableFrom(rawType)){
-			return (T) JSONDeserializerConverter.INSTANCE.convert(targetType, json);
-		}
 
-		// 全局自定义反序列化（优先级低于实现JSONDeserializer接口）
+		// 自定义对象反序列化
-		final JSONDeserializer<?> deserializer = GlobalSerializeMapping.getDeserializer(targetType);
+		final JSONDeserializer<Object> deserializer = InternalJSONUtil.getDeserializer(targetType);
 		if (null != deserializer) {
 			return (T) deserializer.deserialize(json);
 		}
 
-		// 其他转换不支持非Class的泛型类型
+		final Class<T> rawType = (Class<T>) TypeUtil.getClass(targetType);
 		if (null == rawType) {
-			throw new JSONException("Can not get class from type: {}", targetType);
+			// 当目标类型不确定时，返回原JSON
+			return (T) json;
+			//throw new JSONException("Can not get class from type: {}", targetType);
 		}
 		// 特殊类型转换，包括Collection、Map、强转、Array等
 		final T result = toSpecial(targetType, rawType, json);
@@ -173,8 +188,6 @@ public class JSONConverter implements Converter {
 				json.getClass().getName(), json, targetType.getTypeName());
 	}
 
-	// ----------------------------------------------------------- Private method start
-
 	/**
 	 * 特殊类型转换<br>
 	 * 包括：
@@ -220,5 +233,18 @@ public class JSONConverter implements Converter {
 		// 表示非需要特殊转换的对象
 		return null;
 	}
+
+	private Object toDateWithFormat(final Class<?> targetClass, final Object value){
+		// 日期转换，支持自定义日期格式
+		final String format = config.getDateFormat();
+		if (StrUtil.isNotBlank(format)) {
+			if (Date.class.isAssignableFrom(targetClass)) {
+				return new DateConverter(format).convert(targetClass, value);
+			} else {
+				return new TemporalAccessorConverter(format).convert(targetClass, value);
+			}
+		}
+		return null;
+	}
 	// ----------------------------------------------------------- Private method end
 }

hutool-json/src/main/java/cn/hutool/json/convert/JSONDeserializerConverter.java

@@ -1,36 +0,0 @@
-package cn.hutool.json.convert;
-
-import cn.hutool.core.convert.AbstractConverter;
-import cn.hutool.core.convert.ConvertException;
-import cn.hutool.core.reflect.ConstructorUtil;
-import cn.hutool.json.JSON;
-import cn.hutool.json.serialize.JSONDeserializer;
-
-/**
- * 实现了{@link JSONDeserializer}接口的Bean对象转换器，用于将指定JSON转换为JSONDeserializer子对象。
- *
- * @author looly
- * @since 6.0.0
- */
-public class JSONDeserializerConverter extends AbstractConverter {
-	private static final long serialVersionUID = 1L;
-
-	/**
-	 * 单例
-	 */
-	public static final JSONDeserializerConverter INSTANCE = new JSONDeserializerConverter();
-
-	@Override
-	protected Object convertInternal(final Class<?> targetClass, final Object value) {
-		// 自定义反序列化
-		if (value instanceof JSON) {
-			final JSONDeserializer<?> target = (JSONDeserializer<?>) ConstructorUtil.newInstanceIfPossible(targetClass);
-			if (null == target) {
-				throw new ConvertException("Can not instance target: [{}]", targetClass);
-			}
-			return target.deserialize((JSON) value);
-		}
-
-		throw new ConvertException("JSONDeserializer bean must be convert from JSON!");
-	}
-}

hutool-json/src/main/java/cn/hutool/json/serialize/GlobalSerializeMapping.java

@@ -1,6 +1,8 @@
 package cn.hutool.json.serialize;
 
 import cn.hutool.core.map.SafeConcurrentHashMap;
+import cn.hutool.core.reflect.NullType;
+import cn.hutool.core.util.ObjUtil;
 import cn.hutool.json.JSON;
 
 import java.lang.reflect.Type;
@@ -59,19 +61,6 @@ public class GlobalSerializeMapping {
 		putInternal(type, serializer);
 	}
 
-	/**
-	 * 加入自定义的序列化器
-	 *
-	 * @param type       对象类型
-	 * @param serializer 序列化器实现
-	 */
-	synchronized private static void putInternal(final Type type, final JSONSerializer<? extends JSON, ?> serializer) {
-		if (null == serializerMap) {
-			serializerMap = new ConcurrentHashMap<>();
-		}
-		serializerMap.put(type, serializer);
-	}
-
 	/**
 	 * 加入自定义的反序列化器
 	 *
@@ -82,7 +71,7 @@ public class GlobalSerializeMapping {
 		if (null == deserializerMap) {
 			deserializerMap = new ConcurrentHashMap<>();
 		}
-		deserializerMap.put(type, deserializer);
+		deserializerMap.put(ObjUtil.defaultIfNull(type, NullType.INSTANCE), deserializer);
 	}
 
 	/**
@@ -95,7 +84,7 @@ public class GlobalSerializeMapping {
 		if (null == serializerMap) {
 			return null;
 		}
-		return serializerMap.get(type);
+		return serializerMap.get(ObjUtil.defaultIfNull(type, NullType.INSTANCE));
 	}
 
 	/**
@@ -108,6 +97,19 @@ public class GlobalSerializeMapping {
 		if (null == deserializerMap) {
 			return null;
 		}
-		return deserializerMap.get(type);
+		return deserializerMap.get(ObjUtil.defaultIfNull(type, NullType.INSTANCE));
+	}
+
+	/**
+	 * 加入自定义的序列化器
+	 *
+	 * @param type       对象类型
+	 * @param serializer 序列化器实现
+	 */
+	synchronized private static void putInternal(final Type type, final JSONSerializer<? extends JSON, ?> serializer) {
+		if (null == serializerMap) {
+			serializerMap = new ConcurrentHashMap<>();
+		}
+		serializerMap.put(ObjUtil.defaultIfNull(type, NullType.INSTANCE), serializer);
 	}
 }

hutool-json/src/main/java/cn/hutool/json/serialize/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * JSON序列化和反序列化，提供对象和JSON之间的转换
+ */
+package cn.hutool.json.serialize;

hutool-json/src/main/java/cn/hutool/json/writer/GlobalValueWriterMapping.java

@@ -0,0 +1,44 @@
+package cn.hutool.json.writer;
+
+import cn.hutool.core.map.SafeConcurrentHashMap;
+import cn.hutool.core.reflect.NullType;
+import cn.hutool.core.util.ObjUtil;
+
+import java.lang.reflect.Type;
+import java.util.Map;
+
+/**
+ * 全局自定义对象写出<br>
+ * 用户通过此全局定义，可针对某些特殊对象
+ *
+ * @author looly
+ * @since 6.0.0
+ */
+public class GlobalValueWriterMapping {
+
+	private static final Map<Type, JSONValueWriter<?>> writerMap;
+
+	static {
+		writerMap = new SafeConcurrentHashMap<>();
+	}
+
+	/**
+	 * 加入自定义的对象值写出规则
+	 *
+	 * @param type   对象类型
+	 * @param writer 自定义对象写出实现
+	 */
+	public static void put(final Type type, final JSONValueWriter<?> writer) {
+		writerMap.put(ObjUtil.defaultIfNull(type, NullType.INSTANCE), writer);
+	}
+
+	/**
+	 * 获取自定义对象值写出规则
+	 *
+	 * @param type 对象类型
+	 * @return 自定义的 {@link JSONValueWriter}
+	 */
+	public static JSONValueWriter<?> get(final Type type) {
+		return writerMap.get(ObjUtil.defaultIfNull(type, NullType.INSTANCE));
+	}
+}

hutool-json/src/main/java/cn/hutool/json/writer/JSONValueWriter.java

@@ -1,5 +1,7 @@
 package cn.hutool.json.writer;
 
+import java.io.IOException;
+
 /**
  * JSON的值自定义写出
  *
@@ -14,6 +16,7 @@ public interface JSONValueWriter<T> {
 	 *
 	 * @param writer {@link JSONWriter}
 	 * @param value  被写出的值
+	 * @throws IOException IO异常
 	 */
 	void write(JSONWriter writer, T value);
 }

hutool-json/src/main/java/cn/hutool/json/writer/JSONWriter.java

@@ -4,6 +4,7 @@ import cn.hutool.core.io.IORuntimeException;
 import cn.hutool.core.lang.mutable.MutableEntry;
 import cn.hutool.core.text.StrUtil;
 import cn.hutool.core.util.CharUtil;
+import cn.hutool.core.util.ObjUtil;
 import cn.hutool.json.InternalJSONUtil;
 import cn.hutool.json.JSON;
 import cn.hutool.json.JSONConfig;
@@ -76,7 +77,7 @@ public class JSONWriter extends Writer {
 		this.writer = writer;
 		this.indentFactor = indentFactor;
 		this.indent = indent;
-		this.config = config;
+		this.config = ObjUtil.defaultIfNull(config, JSONConfig.of());
 	}
 
 	/**
@@ -298,8 +299,17 @@ public class JSONWriter extends Writer {
 	 * @param predicate 过滤修改器
 	 * @return this
 	 */
+	@SuppressWarnings({"unchecked", "rawtypes"})
 	private JSONWriter writeObjValue(final Object value, final Predicate<MutableEntry<Object, Object>> predicate) {
 		final int indent = indentFactor + this.indent;
+
+		// 自定义规则
+		final JSONValueWriter valueWriter = InternalJSONUtil.getValueWriter(value);
+		if(null != valueWriter){
+			valueWriter.write(this, value);
+			return this;
+		}
+
 		if (value == null) {
 			//noinspection resource
 			writeRaw(StrUtil.NULL);

hutool-json/src/test/java/cn/hutool/json/writer/GlobalValueWriterMappingTest.java

@@ -0,0 +1,67 @@
+package cn.hutool.json.writer;
+
+import cn.hutool.core.convert.Converter;
+import cn.hutool.json.JSONConfig;
+import cn.hutool.json.JSONUtil;
+import lombok.Data;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class GlobalValueWriterMappingTest {
+
+	@Before
+	public void init(){
+		GlobalValueWriterMapping.put(CustomSubBean.class, (JSONValueWriter<CustomSubBean>) (writer, value) -> {
+			writer.writeRaw(String.valueOf(value.getId()));
+		});
+	}
+
+	@Test
+	public void customWriteTest(){
+		final CustomSubBean customBean = new CustomSubBean();
+		customBean.setId(12);
+		customBean.setName("aaa");
+		final String s = JSONUtil.toJsonStr(customBean);
+		Assert.assertEquals("12", s);
+	}
+
+	@Test
+	public void customWriteSubTest(){
+		final CustomSubBean customSubBean = new CustomSubBean();
+		customSubBean.setId(12);
+		customSubBean.setName("aaa");
+		final CustomBean customBean = new CustomBean();
+		customBean.setId(1);
+		customBean.setSub(customSubBean);
+
+		final String s = JSONUtil.toJsonStr(customBean);
+		Assert.assertEquals("{\"id\":1,\"sub\":12}", s);
+
+		// 自定义转换
+		final JSONConfig jsonConfig = JSONConfig.of();
+		final Converter converter = jsonConfig.getConverter();
+		jsonConfig.setConverter((targetType, value) -> {
+			if(targetType == CustomSubBean.class){
+				final CustomSubBean subBean = new CustomSubBean();
+				subBean.setId((Integer) value);
+				return subBean;
+			}
+			return converter.convert(targetType, value);
+		});
+		final CustomBean customBean1 = JSONUtil.parseObj(s, jsonConfig).toBean(CustomBean.class);
+		Assert.assertEquals(12, customBean1.getSub().getId());
+	}
+
+	@Data
+	static class CustomSubBean {
+		private int id;
+		private String name;
+	}
+
+	@Data
+	static class CustomBean{
+		private int id;
+		private CustomSubBean sub;
+	}
+}