com.fasterxml.jackson.core.format

## Class DataFormatDetector

- java.lang.Object
- - com.fasterxml.jackson.core.format.DataFormatDetector

-     public class DataFormatDetector
      extends Object

  Simple helper class that allows data format (content type) auto-detection, given an ordered set of `JsonFactory` instances to use for actual low-level detection.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected JsonFactory[]` | `_detectors` Ordered list of factories which both represent data formats to detect (in precedence order, starting with highest) and are used for actual detection.
    `protected int` | `_maxInputLookahead` Maximum number of leading bytes of the input that we can read to determine data format.
    `protected MatchStrength` | `_minimalMatch` Strength of minimal match we accept as the answer, unless better matches are found.
    `protected MatchStrength` | `_optimalMatch` Strength of match we consider to be good enough to be used without checking any other formats.
    `static int` | `DEFAULT_MAX_INPUT_LOOKAHEAD` By default we will look ahead at most 64 bytes; in most cases, much less (4 bytes or so) is needed, but we will allow bit more leniency to support data formats that need more complex heuristics.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `DataFormatDetector(Collection<JsonFactory> detectors)`
    `DataFormatDetector(JsonFactory... detectors)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `DataFormatMatcher` | `findFormat(byte[] fullInputData)` Method to call to find format that given content (full document) has, as per configuration of this detector instance.
    `DataFormatMatcher` | `findFormat(byte[] fullInputData, int offset, int len)` Method to call to find format that given content (full document) has, as per configuration of this detector instance.
    `DataFormatMatcher` | `findFormat(InputStream in)` Method to call to find format that content (accessible via given `InputStream`) given has, as per configuration of this detector instance.
    `String` | `toString()`
    `DataFormatDetector` | `withMaxInputLookahead(int lookaheadBytes)` Method that will return a detector instance that allows detectors to read up to specified number of bytes when determining format match strength.
    `DataFormatDetector` | `withMinimalMatch(MatchStrength minMatch)` Method that will return a detector instance that uses given minimal match level; match that may be returned unless a stronger match is found with other format detectors.
    `DataFormatDetector` | `withOptimalMatch(MatchStrength optMatch)` Method that will return a detector instance that uses given optimal match level (match that is considered sufficient to return, without trying to find stronger matches with other formats).

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### DEFAULT_MAX_INPUT_LOOKAHEAD

          public static final int DEFAULT_MAX_INPUT_LOOKAHEAD

      By default we will look ahead at most 64 bytes; in most cases, much less (4 bytes or so) is needed, but we will allow bit more leniency to support data formats that need more complex heuristics.
      See Also:
        Constant Field Values

    - #### _detectors

          protected final JsonFactory[] _detectors

      Ordered list of factories which both represent data formats to detect (in precedence order, starting with highest) and are used for actual detection.

    - #### _optimalMatch

          protected final MatchStrength _optimalMatch

      Strength of match we consider to be good enough to be used without checking any other formats. Default value is `MatchStrength.SOLID_MATCH`,

    - #### _minimalMatch

          protected final MatchStrength _minimalMatch

      Strength of minimal match we accept as the answer, unless better matches are found. Default value is `MatchStrength.WEAK_MATCH`,

    - #### _maxInputLookahead

          protected final int _maxInputLookahead

      Maximum number of leading bytes of the input that we can read to determine data format.

      Default value is `DEFAULT_MAX_INPUT_LOOKAHEAD`.

  - ### Constructor Detail

    - #### DataFormatDetector

          public DataFormatDetector(JsonFactory... detectors)

    - #### DataFormatDetector

          public DataFormatDetector(Collection<JsonFactory> detectors)

  - ### Method Detail

    - #### withOptimalMatch

          public DataFormatDetector withOptimalMatch(MatchStrength optMatch)

      Method that will return a detector instance that uses given optimal match level (match that is considered sufficient to return, without trying to find stronger matches with other formats).

    - #### withMinimalMatch

          public DataFormatDetector withMinimalMatch(MatchStrength minMatch)

      Method that will return a detector instance that uses given minimal match level; match that may be returned unless a stronger match is found with other format detectors.

    - #### withMaxInputLookahead

          public DataFormatDetector withMaxInputLookahead(int lookaheadBytes)

      Method that will return a detector instance that allows detectors to read up to specified number of bytes when determining format match strength.

    - #### findFormat

          public DataFormatMatcher findFormat(InputStream in)
                                       throws IOException

      Method to call to find format that content (accessible via given `InputStream`) given has, as per configuration of this detector instance.
      Returns:
        Matcher object which contains result; never null, even in cases where no match (with specified minimal match strength) is found.
      Throws:
        `IOException`

    - #### findFormat

          public DataFormatMatcher findFormat(byte[] fullInputData)
                                       throws IOException

      Method to call to find format that given content (full document) has, as per configuration of this detector instance.
      Returns:
        Matcher object which contains result; never null, even in cases where no match (with specified minimal match strength) is found.
      Throws:
        `IOException`

    - #### findFormat

          public DataFormatMatcher findFormat(byte[] fullInputData,
                                              int offset,
                                              int len)
                                       throws IOException

      Method to call to find format that given content (full document) has, as per configuration of this detector instance.
      Returns:
        Matcher object which contains result; never null, even in cases where no match (with specified minimal match strength) is found.
      Throws:
        `IOException`
      Since:
        2.1

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

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