Package groovy.json

Class JsonSlurper

java.lang.Object
groovy.json.JsonSlurper
public class JsonSlurper extends Object
This has the same interface as the original JsonSlurper written for version 1.8.0, but its implementation has completely changed. It is now up to 20x faster than before, and its speed competes and often substantially exceeds popular common JSON parsers circa Jan, 2014.

JSON slurper parses text or reader content into a data structure of lists and maps.

Example usage: 

 def slurper = new groovy.json.JsonSlurper()
 def result = slurper.parseText('{"person":{"name":"Guillaume","age":33,"pets":["dog","cat"]}}')

 assert result.person.name == "Guillaume"
 assert result.person.age == 33
 assert result.person.pets.size() == 2
 assert result.person.pets[0] == "dog"
 assert result.person.pets[1] == "cat"
JsonSlurper can use several types of JSON parsers. Please read the documentation for JsonParserType. There are relaxed mode parsers, large file parser, and index overlay parsers. Don't worry, it is all groovy. JsonSlurper will just work, but understanding the different parser types may allow you to drastically improve the performance of your JSON parsing.

Index overlay parsers (INDEX_OVERLAY and LAX) are the fastest JSON parsers. However they are not the default for a good reason. Index overlay parsers has pointers (indexes really) to original char buffer. Care must be used if putting parsed maps into a long term cache as members of map maybe index overlay objects pointing to original buffer. You can mitigate these risks by using chop and lazy chop properties.

Chop eagerly dices up the buffer so each Value element points to a small copy of the original buffer.

Lazy Chop dices up the buffer when a list get or map get is called so if an GPath expression or such is applied.

You do not need chop or lazy chop if you are NOT putting the map into a long term cache. You do not need chop or lazy chop if you are doing object de-serialization. Recommendation is to use INDEX_OVERLAY for JSON buffers under 2MB. The maxSizeForInMemory is set to 2MB and any file over 2MB will use a parser designed for large files, which is slower than the INDEX_OVERLAY, LAX, and CHAR_BUFFER parsers, but faster than most commonly used JSON parsers on the JVM for most use cases circa January 2014.

To enable the INDEX_OVERLAY parser do this: 

             parser = new JsonSlurper().setType(JsonParserType.INDEX_OVERLAY);

JsonSlurper reads the whole document into memory and does not bound total input size (only nesting depth, via setMaxNestingDepth(int)). For very large documents, bound the input size before parsing, or use a streaming / Jackson-based parser instead; Groovy interoperates cleanly with Jackson (the groovy-yaml/groovy-toml/groovy-csv slurpers are already Jackson-backed).

Since:
1.8.0
See Also:

  • Constructor Details

    • JsonSlurper

      public JsonSlurper()

  • Method Details

    • getMaxSizeForInMemory

      public int getMaxSizeForInMemory()
      The threshold (in characters) that selects which parser strategy the File-based parse methods use: documents smaller than this are parsed in memory, larger ones use a windowing buffer parser.

      This is a parser-strategy selector, not a size limit. It does not reject or cap input — an oversized document is still parsed in full (by the windowing parser). It is consulted only by the File-based parse methods; the parse(Reader), parse(InputStream) and parse(URL) entry points ignore it and buffer their entire input into memory regardless of this value. To bound untrusted input, limit its size yourself before parsing (and cap nesting via setMaxNestingDepth(int) or the groovy.json.maxNestingDepth system property).

      Returns:
      the in-memory vs windowing-parser selection threshold
      Since:
      2.3

    • setMaxSizeForInMemory

      public JsonSlurper setMaxSizeForInMemory(int maxSizeForInMemory)
      Sets the threshold that selects which parser strategy the File-based parse methods use (see getMaxSizeForInMemory()).

      This selects a parser strategy; it does not limit or reject input. Setting it gives no DoS protection: it is not consulted by parse(Reader), parse(InputStream) or parse(URL), and even the File-based methods still parse documents larger than the threshold. Bound untrusted input by its size before parsing, and cap nesting via setMaxNestingDepth(int) or groovy.json.maxNestingDepth.

      Parameters:
      maxSizeForInMemory - the in-memory vs windowing-parser selection threshold
      Returns:
      this JsonSlurper instance
      Since:
      2.3

    • getType

      public JsonParserType getType()
      Parser type.
      Returns:
      type
      Since:
      2.3
      See Also:

    • setType

      public JsonSlurper setType(JsonParserType type)
      Parser type.
      Returns:
      JsonSlurper
      Since:
      2.3
      See Also:

    • isChop

      public boolean isChop()
      Turns on buffer chopping for index overlay.
      Returns:
      chop on or off
      Since:
      2.3
      See Also:

    • setChop

      public JsonSlurper setChop(boolean chop)
      Turns on buffer chopping for index overlay.
      Returns:
      JsonSlurper
      Since:
      2.3
      See Also:

    • isLazyChop

      public boolean isLazyChop()
      Turns on buffer lazy chopping for index overlay.
      Returns:
      on or off
      Since:
      2.3
      See Also:

    • setLazyChop

      public JsonSlurper setLazyChop(boolean lazyChop)
      Turns on buffer lazy chopping for index overlay.
      Returns:
      JsonSlurper
      Since:
      2.3
      See Also:

    • isCheckDates

      @Deprecated public boolean isCheckDates()
      Deprecated.
      a boolean cannot say which type is wanted; use getDateHandling()
      Whether a string in a full ISO-8601 or JSON-date form is returned as a Date rather than as a String. On by default.

      This applies to JsonParserType.INDEX_OVERLAY and JsonParserType.LAX; the other two parser types return the string either way, so setting this has no effect on them. A date without a time, such as "2026-09-04", is left as a String by all four.

      Returns:
      whether date-like strings are converted
      Since:
      2.3

    • setCheckDates

      @Deprecated public JsonSlurper setCheckDates(boolean checkDates)
      Deprecated.
      a boolean cannot say which type is wanted; use setDateHandling(JsonDateHandling)
      Sets whether a string in a full ISO-8601 or JSON-date form is returned as a Date rather than as a String. On by default.

      This applies to JsonParserType.INDEX_OVERLAY and JsonParserType.LAX; the other two parser types return the string either way, so setting this has no effect on them. Note that a Date is an instant, so an offset in the source is not preserved by the conversion. Has no effect once setDateHandling(JsonDateHandling) has been called on this slurper, so that a choice made through the wider option is not undone by this one.

      Parameters:
      checkDates - whether date-like strings should be converted
      Returns:
      this slurper, for chaining
      Since:
      2.3

    • getDateHandling

      public JsonDateHandling getDateHandling()
      What a string in a full ISO-8601 or JSON-date form is turned into.
      Returns:
      the handling in effect
      Since:
      6.0.0

    • setDateHandling

      public JsonSlurper setDateHandling(JsonDateHandling dateHandling)
      Sets what a string in a full ISO-8601 or JSON-date form is turned into. Defaults to JsonDateHandling.UTIL_DATE, which is what a slurper has always produced.

      This applies to JsonParserType.INDEX_OVERLAY and JsonParserType.LAX; the other two parser types return the string whatever is set here. A date carrying no time, such as "2026-09-04", is left as a String by all four. Calling this also makes setCheckDates(boolean) a no-op on this slurper, whichever order the two are called in.

      Parameters:
      dateHandling - what a date-like string should become
      Returns:
      this slurper, for chaining
      Since:
      6.0.0

    • getMaxNestingDepth

      public int getMaxNestingDepth()
      The maximum nesting depth of arrays/objects the parser will accept before throwing a JsonException. This guards the recursive-descent parsers against a small but deeply-nested document driving a StackOverflowError. A value of 0 or less disables the check (restoring the previous, unbounded behaviour). Defaults to BaseJsonParser.DEFAULT_MAX_NESTING_DEPTH, and can be overridden globally with the groovy.json.maxNestingDepth system property.
      Returns:
      the maximum nesting depth
      Since:
      6.0.0

    • setMaxNestingDepth

      public JsonSlurper setMaxNestingDepth(int maxNestingDepth)
      Sets the maximum nesting depth of arrays/objects the parser will accept before throwing a JsonException. A value of 0 or less disables the check.
      Parameters:
      maxNestingDepth - maximum number of nested arrays/objects to allow
      Returns:
      this JsonSlurper
      Since:
      6.0.0

    • getMaxNumberLength

      public int getMaxNumberLength()
      The maximum length, in characters, of a single number token the parser will accept before throwing a JsonException. Converting a digit run past the long range builds a BigInteger or BigDecimal, and decimal conversion is superlinear in the digit count, so an uncapped token lets a small document cost quadratic CPU. A value of 0 or less disables the check (restoring the previous, unbounded behaviour). Defaults to BaseJsonParser.DEFAULT_MAX_NUMBER_LENGTH, and can be overridden globally with the groovy.json.maxNumberLength system property.
      Returns:
      the maximum number token length
      Since:
      6.0.0

    • setMaxNumberLength

      public JsonSlurper setMaxNumberLength(int maxNumberLength)
      Sets the maximum length, in characters, of a single number token the parser will accept before throwing a JsonException. A value of 0 or less disables the check.
      Parameters:
      maxNumberLength - maximum number of characters in a number token
      Returns:
      this JsonSlurper
      Since:
      6.0.0

    • parseText

      public Object parseText(String text)
      Parse a text representation of a JSON data structure
      Parameters:
      text - JSON text to parse
      Returns:
      a data structure of lists and maps

    • parse

      public Object parse(Reader reader)
      Parse a JSON data structure from content from a reader
      Parameters:
      reader - reader over a JSON content
      Returns:
      a data structure of lists and maps

    • parse

      public Object parse(InputStream inputStream)
      Parse a JSON data structure from content from an inputStream
      Parameters:
      inputStream - stream over a JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.3

    • parse

      public Object parse(InputStream inputStream, String charset)
      Parse a JSON data structure from content from an inputStream
      Parameters:
      inputStream - stream over a JSON content
      charset - charset
      Returns:
      a data structure of lists and maps
      Since:
      2.3

    • parse

      public Object parse(byte[] bytes, String charset)
      Parse a JSON data structure from content from a byte array.
      Parameters:
      bytes - buffer of JSON content
      charset - charset
      Returns:
      a data structure of lists and maps
      Since:
      2.3

    • parse

      public Object parse(byte[] bytes)
      Parse a JSON data structure from content from a byte array.
      Parameters:
      bytes - buffer of JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.3

    • parse

      public Object parse(char[] chars)
      Parse a JSON data structure from content from a char array.
      Parameters:
      chars - buffer of JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.3

    • parse

      public Object parse(Path path) throws IOException
      Parse a JSON data structure from content within a given Path.
      Parameters:
      path - Path containing JSON content
      Returns:
      a data structure of lists and maps
      Throws:
      IOException

    • parse

      public Object parse(Path path, String charset) throws IOException
      Parse a JSON data structure from content within a given Path.
      Parameters:
      path - Path containing JSON content
      charset - the charset for this File
      Returns:
      a data structure of lists and maps
      Throws:
      IOException

    • parse

      public Object parse(File file)
      Parse a JSON data structure from content within a given File.
      Parameters:
      file - File containing JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(File file, String charset)
      Parse a JSON data structure from content within a given File.
      Parameters:
      file - File containing JSON content
      charset - the charset for this File
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(URL url)
      Parse a JSON data structure from content at a given URL.
      Parameters:
      url - URL containing JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(URL url, Map params)
      Parse a JSON data structure from content at a given URL.
      Parameters:
      url - URL containing JSON content
      params - connection parameters
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(@NamedParam(value="connectTimeout",type=java.lang.Integer.class) @NamedParam(value="readTimeout",type=java.lang.Integer.class) @NamedParam(value="useCaches",type=java.lang.Boolean.class) @NamedParam(value="allowUserInteraction",type=java.lang.Boolean.class) @NamedParam(value="requestProperties",type=java.util.Map.class) Map<String,?> params, URL url)
      Parse a JSON data structure from content at a given URL. Convenience variant when using Groovy named parameters for the connection params.
      Parameters:
      params - connection parameters
      url - URL containing JSON content
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(URL url, String charset)
      Parse a JSON data structure from content at a given URL.
      Parameters:
      url - URL containing JSON content
      charset - the charset for this File
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(URL url, Map params, String charset)
      Parse a JSON data structure from content at a given URL.
      Parameters:
      url - URL containing JSON content
      params - connection parameters
      charset - the charset for this File
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0

    • parse

      public Object parse(Map params, URL url, String charset)
      Parse a JSON data structure from content at a given URL. Convenience variant when using Groovy named parameters for the connection params.
      Parameters:
      params - connection parameters
      url - URL containing JSON content
      charset - the charset for this File
      Returns:
      a data structure of lists and maps
      Since:
      2.2.0