Package com.alibaba.fastjson2

Class OffsetJSONReader

  • All Implemented Interfaces:
    java.io.Closeable , java.lang.AutoCloseable 
    
public class OffsetJSONReader
extends JSONReaderUTF8

    A JSONReader that extends JSONReaderUTF8 to track the exact byte offset where a parsed JSON object ends. Designed for non-greedy parsing: when the input contains trailing non-JSON content after a valid object, this reader captures the precise boundary.

    This class lives in the com.alibaba.fastjson2 package because JSONReaderUTF8 is package-private. It does not modify any existing source files.

    Supported features (passed through to the underlying reader):

    • AllowUnQuotedFieldNames — unquoted keys like {key:"val"}
    • IgnoreCheckClose — no-op on the readObject() path; trailing content is naturally ignored
    • NonStringKeyAsString — numeric keys are handled as unquoted names when AllowUnQuotedFieldNames is set
    
OffsetResult r = OffsetJSONReader.parseObject(
    "{\"test\":\"111\"} trailing garbage",
    Feature.AllowUnQuotedFieldNames,
    Feature.IgnoreCheckClose,
    Feature.NonStringKeyAsString
);
Map<String, Object> map = r.object;  // {"test":"111"}
int endOffset = r.endOffset;         // byte position right after '
    '
}

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      public class OffsetJSONReader.OffsetResult

      Holds the result of a non-greedy JSON object parse.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      public int jsonEndOffset
      public final boolean jsonb
      public final boolean utf8

    • Constructor Summary

      Constructors 
      Constructor Description
      OffsetJSONReader(JSONReader.Context ctx, Array<byte> bytes, int offset, int length) Constructs an OffsetJSONReader over a byte range.

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      int getJsonEndOffset() Returns the byte offset immediately after the closing '}' of the most recently parsed top-level JSON object, or -1 if no object has been parsed yet.
      void next() Intercepts next to capture the byte offset at the exact moment a JSON object's closing '}' is detected.
      static OffsetJSONReader.OffsetResult parseObject(Array<byte> utf8Bytes, Array<JSONReader.Feature> features) Non-greedy JSON object parse over the full byte array.
      static OffsetJSONReader.OffsetResult parseObject(Array<byte> utf8Bytes, int off, int len, Array<JSONReader.Feature> features) Non-greedy JSON object parse over a byte range.
      static OffsetJSONReader.OffsetResult parseObject(String json, Array<JSONReader.Feature> features) Non-greedy JSON object parse from a String.

      • Methods inherited from class com.alibaba.fastjson2.JSONReaderUTF8

        close, getFieldName, getNameHashCodeLCase, getRawInt, getRawLong, getString, getStringLength, info, isNull, isReference, next, nextIfArrayEnd, nextIfArrayStart, nextIfComma, nextIfInfinity, nextIfMatch, nextIfMatchIdent, nextIfName4Match10, nextIfName4Match11, nextIfName4Match12, nextIfName4Match13, nextIfName4Match14, nextIfName4Match15, nextIfName4Match16, nextIfName4Match17, nextIfName4Match18, nextIfName4Match19, nextIfName4Match2, nextIfName4Match20, nextIfName4Match21, nextIfName4Match22, nextIfName4Match23, nextIfName4Match24, nextIfName4Match25, nextIfName4Match26, nextIfName4Match27, nextIfName4Match28, nextIfName4Match29, nextIfName4Match3, nextIfName4Match30, nextIfName4Match31, nextIfName4Match32, nextIfName4Match33, nextIfName4Match34, nextIfName4Match35, nextIfName4Match36, nextIfName4Match37, nextIfName4Match38, nextIfName4Match39, nextIfName4Match4, nextIfName4Match40, nextIfName4Match41, nextIfName4Match42, nextIfName4Match43, nextIfName4Match5, nextIfName4Match6, nextIfName4Match7, nextIfName4Match8, nextIfName4Match9, nextIfName8Match0, nextIfName8Match1, nextIfName8Match2, nextIfNull, nextIfNullOrEmptyString, nextIfObjectEnd, nextIfObjectStart, nextIfSet, nextIfValue4Match10, nextIfValue4Match11, nextIfValue4Match2, nextIfValue4Match3, nextIfValue4Match4, nextIfValue4Match5, nextIfValue4Match6, nextIfValue4Match7, nextIfValue4Match8, nextIfValue4Match9, nextWithoutComment, of, readBase64, readBigDecimal, readBoolValue, readDoubleValue, readFieldName, readFieldNameHashCode, readFieldNameHashCodeE, readFieldNameHashCodeUnquote, readFloatValue, readHex, readIfNull, readInt32, readInt32Value, readInt64, readInt64Value, readLocalDate, readLocalDate10, readLocalDate8, readLocalDate9, readMillis19, readNaN, readNull, readNullOrNewDate, readNumber, readNumber0, readOffsetDateTime, readOffsetTime, readPattern, readReference, readString, readString, readUUID, readValueHashCode, skipComment, skipName, skipValue

      • Methods inherited from class com.alibaba.fastjson2.JSONReader

        addResolveTask, autoTypeFilter, checkAutoType, current, endArray, errorOnNoneSerializable, features, getBigDecimal, getBigInteger, getContext, getDoubleValue, getFloatValue, getInt32Value, getInt64Value, getLocale, getNumber, getObjectReader, getObjectReaderAutoType, getOffset, getType, getZoneId, handleResolveTasks, hasAutoTypeBeforeHandler, hasComma, isArray, isBinary, isBool, isDate, isEnabled, isEnd, isIgnoreNoneSerializable, isInitStringFieldAsEmpty, isInt, isJSONB, isNumber, isObject, isString, isSupportAutoType, isSupportAutoTypeOrHandler, isSupportBeanArray, isSupportSmartMatch, isTypeRedirect, mark, nextIfMatchTypedAny, of, ofJSONB, read, read, readAny, readArray, readArray, readArray, readBigInteger, readBinary, readBool, readCalendar, readCharValue, readCharacter, readDate, readDouble, readFieldNameUnquote, readFloat, readInstant, readInt16, readInt16Value, readInt32ValueArray, readInt64ValueArray, readInt8, readInt8Value, readJSONArray, readJSONObject, readList, readLocalDateTime, readLocalTime, readMillisFromString, readNumber, readObject, readObject, readReference, readStringArray, readTypeHashCode, readZonedDateTime, reset, setTypeRedirect, startArray, wasNull

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • OffsetJSONReader

        OffsetJSONReader(JSONReader.Context ctx, Array<byte> bytes, int offset, int length)
        Constructs an OffsetJSONReader over a byte range.
        Parameters:
        ctx - the reader context (features, provider, etc.
        bytes - the UTF-8 encoded input
        offset - start offset in the array
        length - number of bytes to read

    • Method Detail

      • getJsonEndOffset

         int getJsonEndOffset()

        Returns the byte offset immediately after the closing '}' of the most recently parsed top-level JSON object, or -1 if no object has been parsed yet.

      • next

         void next()

        Intercepts next to capture the byte offset at the exact moment a JSON object's closing '}' is detected.

        The core insight: in JSONReader.readObject() (line 3719), when ch == ''} the reader calls next() to advance past the brace. At that instant this.offset points to the byte immediately following '}' — the precise JSON end boundary. We save this value before super.next() overwrites it with the lookahead position.

      • parseObject

         static OffsetJSONReader.OffsetResult parseObject(Array<byte> utf8Bytes, Array<JSONReader.Feature> features)

        Non-greedy JSON object parse over the full byte array.

        Parameters:
        utf8Bytes - UTF-8 encoded JSON text (trailing content allowed)
        features - optional reader features
        Returns:

        the parsed map and the byte offset where JSON ended

      • parseObject

         static OffsetJSONReader.OffsetResult parseObject(Array<byte> utf8Bytes, int off, int len, Array<JSONReader.Feature> features)

        Non-greedy JSON object parse over a byte range.

        Parameters:
        utf8Bytes - UTF-8 encoded JSON text (trailing content allowed)
        off - start offset
        len - number of bytes to read
        features - optional reader features
        Returns:

        the parsed map and the byte offset where JSON ended

      • parseObject

         static OffsetJSONReader.OffsetResult parseObject(String json, Array<JSONReader.Feature> features)

        Non-greedy JSON object parse from a String. The string is converted to UTF-8 bytes internally; the returned endOffset is a byte offset within that UTF-8 representation.

        Parameters:
        json - the JSON string (trailing content allowed)
        features - optional reader features
        Returns:

        the parsed map and the byte offset where JSON ended