add method

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

@@ -332,6 +332,18 @@ public final class JSONUtil {
 	}
 
 	/**
+	 * 转为JSON字符串，并写出到write
+	 *
+	 * @param json JSON
+	 * @since 5.3.3
+	 */
+	public static void toJsonStr(JSON json, Writer writer) {
+		if (null != json) {
+			json.write(writer);
+		}
+	}
+
+	/**
 	 * 转为JSON字符串
 	 *
 	 * @param json JSON
@@ -354,13 +366,26 @@ public final class JSONUtil {
 		if (null == obj) {
 			return null;
 		}
-		if (obj instanceof String) {
-			return (String) obj;
+		if (obj instanceof CharSequence) {
+			return StrUtil.str((CharSequence) obj);
 		}
 		return toJsonStr(parse(obj));
 	}
 
 	/**
+	 * 转换为JSON字符串并写出到writer
+	 *
+	 * @param obj 被转为JSON的对象
+	 * @param writer Writer
+	 * @since 5.3.3
+	 */
+	public static void toJsonStr(Object obj, Writer writer) {
+		if (null != obj) {
+			toJsonStr(parse(obj), writer);
+		}
+	}
+
+	/**
 	 * 转换为格式化后的JSON字符串
 	 *
 	 * @param obj Bean对象