org.codehaus.jackson
Class JsonParser

java.lang.Object
  org.codehaus.jackson.JsonParser

Direct Known Subclasses:

JsonParserBase

public abstract class JsonParser
extends java.lang.Object

Base class that defines public API for reading JSON content. Instances are created using factory methods of a JsonFactory instance.

Author:

Tatu Saloranta

Nested Class Summary

static class	JsonParser.Feature Enumeration that defines all togglable features for parsers.
static class	JsonParser.NumberType Enumeration of possible "native" (optimal) types that can be used for numbers.

Field Summary

protected JsonToken	_currToken Last token retrieved via nextToken(), if any.
protected int	_features Bit flag composed of bits that indicate which JsonParser.Features are enabled.
protected JsonToken	_lastClearedToken Last cleared token, if any: that is, value that was in effect when clearCurrentToken() was called.

Constructor Summary

protected

JsonParser()

Method Summary

void	clearCurrentToken() Method called to "consume" the current token by effectively removing it so that hasCurrentToken() returns false, and getCurrentToken() null).
abstract void	close() Closes the parser so that no further iteration or data access can be made.
void	disableFeature(JsonParser.Feature f) Method for disabling specified feature (check JsonParser.Feature for list of features)
void	enableFeature(JsonParser.Feature f) Method for enabling specified parser feature (check JsonParser.Feature for list of features)
abstract java.math.BigInteger	getBigIntegerValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can not be used as a Java long primitive type due to its magnitude.
byte[]	getBinaryValue() Convenience alternative to getBinaryValue(Base64Variant) that defaults to using Base64Variants.getDefaultVariant() as the default encoding.
abstract byte[]	getBinaryValue(Base64Variant b64variant) Method that can be used to read (and consume -- results may not be accessible using other methods after the call) base64-encoded binary data included in the current textual json value.
abstract byte	getByteValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java byte primitive type.
abstract JsonLocation	getCurrentLocation() Method that returns location of the last processed character; usually for error reporting purposes.
abstract java.lang.String	getCurrentName() Method that can be called to get the name associated with the current event: for JsonToken.FIELD_NAMEs it will be the same as what getText() returns; for field values it will be preceding field name; and for others (array values, root-level values) null.
JsonToken	getCurrentToken()
abstract java.math.BigDecimal	getDecimalValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT or JsonToken.VALUE_NUMBER_INT.
abstract double	getDoubleValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT and it can be expressed as a Java double primitive type.
abstract float	getFloatValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT and it can be expressed as a Java float primitive type.
abstract int	getIntValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java int primitive type.
JsonToken	getLastClearedToken() Method that can be called to get the last token that was cleared using clearCurrentToken().
abstract long	getLongValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a Java long primitive type.
abstract JsonParser.NumberType	getNumberType() If current event is of type JsonToken.VALUE_NUMBER_INT or JsonToken.VALUE_NUMBER_FLOAT, returns one of JsonParser.NumberType constants; otherwise returns null.
abstract java.lang.Number	getNumberValue() Generic number value accessor method that will work for all kinds of numeric values.
abstract JsonStreamContext	getParsingContext() Method that can be used to access current parsing context reader is in.
abstract short	getShortValue() Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java short primitive type.
abstract java.lang.String	getText() Method for accessing textual representation of the current event; if no current event (before first call to nextToken(), or after encountering end-of-input), returns null.
abstract char[]	getTextCharacters() Method similar to getText(), but that will return underlying (unmodifiable) character array that contains textual value, instead of constructing a String object to contain this information.
abstract int	getTextLength()
abstract int	getTextOffset()
abstract JsonLocation	getTokenLocation() Method that return the starting location of the current token; that is, position of the first character from input that starts the current token.
boolean	hasCurrentToken()
abstract boolean	isClosed() Method that can be called to determine whether this parser is closed or not.
boolean	isFeatureEnabled(JsonParser.Feature f) Method for checking whether specified JsonParser.Feature is enabled.
abstract JsonToken	nextToken() Main iteration method, which will advance stream enough to determine type of the next token, if any.
abstract JsonToken	nextValue() Iteration method that will advance stream enough to determine type of the next token that is a value type (including Json Array and Object start/end markers).
abstract <T> T	readValueAs(java.lang.Class<T> valueType) Method to deserialize Json content into a non-container type (it can be an array type, however): typically a bean, array or a wrapper type (like Boolean).
abstract <T> T	readValueAs(TypeReference<?> valueTypeRef) Method to deserialize Json content into a Java type, reference to which is passed as argument.
abstract JsonNode	readValueAsTree() Method to deserialize Json content into equivalent "tree model", represented by root JsonNode of resulting model.
void	setFeature(JsonParser.Feature f, boolean state) Method for enabled or disabling specified feature (check JsonParser.Feature for list of features)
abstract void	skipChildren() Method that will skip all child tokens of an array or object token that the parser currently points to, iff stream points to JsonToken.START_OBJECT or JsonToken.START_ARRAY.

Methods inherited from class java.lang.Object

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

Field Detail

_features

protected int _features

Bit flag composed of bits that indicate which JsonParser.Features are enabled.

_currToken

protected JsonToken _currToken

Last token retrieved via nextToken(), if any. Null before the first call to nextToken(), as well as if token has been explicitly cleared (by call to clearCurrentToken())

_lastClearedToken

protected JsonToken _lastClearedToken

Last cleared token, if any: that is, value that was in effect when clearCurrentToken() was called.

Constructor Detail

JsonParser

protected JsonParser()

Method Detail

enableFeature

public void enableFeature(JsonParser.Feature f)

Method for enabling specified parser feature (check JsonParser.Feature for list of features)

disableFeature

public void disableFeature(JsonParser.Feature f)

Method for disabling specified feature (check JsonParser.Feature for list of features)

setFeature

public void setFeature(JsonParser.Feature f,
                       boolean state)

Method for enabled or disabling specified feature (check JsonParser.Feature for list of features)

isFeatureEnabled

public final boolean isFeatureEnabled(JsonParser.Feature f)

Method for checking whether specified JsonParser.Feature is enabled.

nextToken

public abstract JsonToken nextToken()
                             throws java.io.IOException,
                                    JsonParseException

Main iteration method, which will advance stream enough to determine type of the next token, if any. If none remaining (stream has no content other than possible white space before ending), null will be returned.

Returns:

Next token from the stream, if any found, or null to indicate end-of-input

Throws:

java.io.IOException

JsonParseException

nextValue

public abstract JsonToken nextValue()
                             throws java.io.IOException,
                                    JsonParseException

Iteration method that will advance stream enough to determine type of the next token that is a value type (including Json Array and Object start/end markers). Or put another way, nextToken() will be called once, and if JsonToken.FIELD_NAME is returned, another time to get the value for the field. Method is most useful for iterating over value entries of Json objects; field name will still be available by calling getCurrentName() when parser points to the value.

Returns:

Next non-field-name token from the stream, if any found, or null to indicate end-of-input (or, for non-blocking parsers, JsonToken.NOT_AVAILABLE if no tokens were available yet)

Throws:

java.io.IOException

JsonParseException

Since:

0.9.7

skipChildren

public abstract void skipChildren()
                           throws java.io.IOException,
                                  JsonParseException

Method that will skip all child tokens of an array or object token that the parser currently points to, iff stream points to JsonToken.START_OBJECT or JsonToken.START_ARRAY. If not, it will do nothing. After skipping, stream will point to matching JsonToken.END_OBJECT or JsonToken.END_ARRAY (possibly skipping nested pairs of START/END OBJECT/ARRAY tokens as well as value tokens). The idea is that after calling this method, application will call nextToken() to point to the next available token, if any.

Throws:

java.io.IOException

JsonParseException

close

public abstract void close()
                    throws java.io.IOException

Closes the parser so that no further iteration or data access can be made.

Method will also close the underlying input source, if parser either owns the input source, or feature JsonParser.Feature.AUTO_CLOSE_SOURCE is enabled. Whether parser owns the input source depends on factory method that was used to construct instance (so check JsonFactory for details, but the general idea is that if caller passes in closable resource (such as InputStream or Reader) parser does NOT own the source; but if it passes a reference (such as File or URL and creates stream or reader it does own them.

Throws:

java.io.IOException

isClosed

public abstract boolean isClosed()

Method that can be called to determine whether this parser is closed or not. If it is closed, no new events can be retrieved by calling nextToken() (and the underlying stream may be closed). Closing may be due to an explicit call to close() or because parser has encountered end of input.

Since:

0.9.9-3

getCurrentToken

public final JsonToken getCurrentToken()

Returns:

Type of the token this parser currently points to, if any: null before any tokens have been read, and after end-of-input has been encountered, as well as if the current token has been explicitly cleared.

hasCurrentToken

public final boolean hasCurrentToken()

Returns:

True if the parser just returned a valid token via nextToken(); false otherwise (parser was just constructed, encountered end-of-input and returned null from nextToken(), or the event has been consumed)

clearCurrentToken

public final void clearCurrentToken()

Method called to "consume" the current token by effectively removing it so that hasCurrentToken() returns false, and getCurrentToken() null). Cleared token value can still be accessed by calling getLastClearedToken() (if absolutely needed), but usually isn't.

Method was added to be used by the optional data binder, since it has to be able to consume last token used for binding (so that it will not be used again).

Since:

0.9.9-3

getCurrentName

public abstract java.lang.String getCurrentName()
                                         throws java.io.IOException,
                                                JsonParseException

Method that can be called to get the name associated with the current event: for JsonToken.FIELD_NAMEs it will be the same as what getText() returns; for field values it will be preceding field name; and for others (array values, root-level values) null.

Throws:

java.io.IOException

JsonParseException

getParsingContext

public abstract JsonStreamContext getParsingContext()

Method that can be used to access current parsing context reader is in. There are 3 different types: root, array and object contexts, with slightly different available information. Contexts are hierarchically nested, and can be used for example for figuring out part of the input document that correspond to specific array or object (for highlighting purposes, or error reporting). Contexts can also be used for simple xpath-like matching of input, if so desired.

getTokenLocation

public abstract JsonLocation getTokenLocation()

Method that return the starting location of the current token; that is, position of the first character from input that starts the current token.

getCurrentLocation

public abstract JsonLocation getCurrentLocation()

Method that returns location of the last processed character; usually for error reporting purposes.

getLastClearedToken

public JsonToken getLastClearedToken()

Method that can be called to get the last token that was cleared using clearCurrentToken(). This is not necessarily the latest token read. Will return null if no tokens have been cleared, or if parser has been closed.

getText

public abstract java.lang.String getText()
                                  throws java.io.IOException,
                                         JsonParseException

Method for accessing textual representation of the current event; if no current event (before first call to nextToken(), or after encountering end-of-input), returns null. Method can be called for any event.

Throws:

java.io.IOException

JsonParseException

getTextCharacters

public abstract char[] getTextCharacters()
                                  throws java.io.IOException,
                                         JsonParseException

Method similar to getText(), but that will return underlying (unmodifiable) character array that contains textual value, instead of constructing a String object to contain this information. Note, however, that:

• Textual contents are not guaranteed to start at index 0 (rather, call getTextOffset()) to know the actual offset
• Length of textual contents may be less than the length of returned buffer: call getTextLength() for actual length of returned content.

Note that caller MUST NOT modify the returned character array in any way -- doing so may corrupt current parser state and render parser instance useless.

The only reason to call this method (over getText()) is to avoid construction of a String object (which will make a copy of contents).

Throws:

java.io.IOException

JsonParseException

getTextLength

public abstract int getTextLength()
                           throws java.io.IOException,
                                  JsonParseException

Returns:

Number of characters within buffer returned by getTextCharacters() that are part of textual content of the current token.

Throws:

java.io.IOException

JsonParseException

getTextOffset

public abstract int getTextOffset()
                           throws java.io.IOException,
                                  JsonParseException

Returns:

Offset of the first character within buffer returned by getTextCharacters() that is part of textual content of the current token.

Throws:

java.io.IOException

JsonParseException

getNumberValue

public abstract java.lang.Number getNumberValue()
                                         throws java.io.IOException,
                                                JsonParseException

Generic number value accessor method that will work for all kinds of numeric values. It will return the optimal (simplest/smallest possibl) wrapper object that can express the numeric value just parsed.

Throws:

java.io.IOException

JsonParseException

getNumberType

public abstract JsonParser.NumberType getNumberType()
                                             throws java.io.IOException,
                                                    JsonParseException

If current event is of type JsonToken.VALUE_NUMBER_INT or JsonToken.VALUE_NUMBER_FLOAT, returns one of JsonParser.NumberType constants; otherwise returns null.

Throws:

java.io.IOException

JsonParseException

getByteValue

public abstract byte getByteValue()
                           throws java.io.IOException,
                                  JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java byte primitive type. It can also be called for JsonToken.VALUE_NUMBER_FLOAT; if so, it is equivalent to calling getDoubleValue() and then casting; except for possible overflow/underflow exception.

Note: if the resulting integer value falls outside range of Java byte, a JsonParseException will be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getShortValue

public abstract short getShortValue()
                             throws java.io.IOException,
                                    JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java short primitive type. It can also be called for JsonToken.VALUE_NUMBER_FLOAT; if so, it is equivalent to calling getDoubleValue() and then casting; except for possible overflow/underflow exception.

Note: if the resulting integer value falls outside range of Java short, a JsonParseException will be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getIntValue

public abstract int getIntValue()
                         throws java.io.IOException,
                                JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a value of Java int primitive type. It can also be called for JsonToken.VALUE_NUMBER_FLOAT; if so, it is equivalent to calling getDoubleValue() and then casting; except for possible overflow/underflow exception.

Note: if the resulting integer value falls outside range of Java int, a JsonParseException may be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getLongValue

public abstract long getLongValue()
                           throws java.io.IOException,
                                  JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can be expressed as a Java long primitive type. It can also be called for JsonToken.VALUE_NUMBER_FLOAT; if so, it is equivalent to calling getDoubleValue() and then casting to int; except for possible overflow/underflow exception.

Note: if the token is an integer, but its value falls outside of range of Java long, a JsonParseException may be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getBigIntegerValue

public abstract java.math.BigInteger getBigIntegerValue()
                                                 throws java.io.IOException,
                                                        JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_INT and it can not be used as a Java long primitive type due to its magnitude. It can also be called for JsonToken.VALUE_NUMBER_FLOAT; if so, it is equivalent to calling getDecimalValue() and then constructing a BigInteger from that value.

Throws:

java.io.IOException

JsonParseException

getFloatValue

public abstract float getFloatValue()
                             throws java.io.IOException,
                                    JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT and it can be expressed as a Java float primitive type. It can also be called for JsonToken.VALUE_NUMBER_INT; if so, it is equivalent to calling getLongValue() and then casting; except for possible overflow/underflow exception.

Note: if the value falls outside of range of Java float, a JsonParseException will be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getDoubleValue

public abstract double getDoubleValue()
                               throws java.io.IOException,
                                      JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT and it can be expressed as a Java double primitive type. It can also be called for JsonToken.VALUE_NUMBER_INT; if so, it is equivalent to calling getLongValue() and then casting; except for possible overflow/underflow exception.

Note: if the value falls outside of range of Java double, a JsonParseException will be thrown to indicate numeric overflow/underflow.

Throws:

java.io.IOException

JsonParseException

getDecimalValue

public abstract java.math.BigDecimal getDecimalValue()
                                              throws java.io.IOException,
                                                     JsonParseException

Numeric accessor that can be called when the current token is of type JsonToken.VALUE_NUMBER_FLOAT or JsonToken.VALUE_NUMBER_INT. No under/overflow exceptions are ever thrown.

Throws:

java.io.IOException

JsonParseException

getBinaryValue

public abstract byte[] getBinaryValue(Base64Variant b64variant)
                               throws java.io.IOException,
                                      JsonParseException

Method that can be used to read (and consume -- results may not be accessible using other methods after the call) base64-encoded binary data included in the current textual json value. It works similar to getting String value via getText() and decoding result (except for decoding part), but should be significantly more performant.

Note that non-decoded textual contents of the current event are not guaranteed to be accessible after this method is called. Current implementation, for example, clears up textual content during decoding. Decoded binary content, however, will be retained until parser is advanced to the next event.

Parameters:

b64variant - Expected variant of base64 encoded content (see Base64Variants for definitions of "standard" variants).

Returns:

Decoded binary data

Throws:

java.io.IOException

JsonParseException

getBinaryValue

public byte[] getBinaryValue()
                      throws java.io.IOException,
                             JsonParseException

Convenience alternative to getBinaryValue(Base64Variant) that defaults to using Base64Variants.getDefaultVariant() as the default encoding.

Throws:

java.io.IOException

JsonParseException

readValueAs

public abstract <T> T readValueAs(java.lang.Class<T> valueType)
                       throws java.io.IOException,
                              JsonProcessingException

Method to deserialize Json content into a non-container type (it can be an array type, however): typically a bean, array or a wrapper type (like Boolean). Note: method can only be called if the parser has an object codec assigned; this is true for parsers constructed by MappingJsonFactory but not for JsonFactory (unless its setCodec method has been explicitly called).

This method may advance the evens stream, for structured types the current event will be the closing end marker (END_ARRAY, END_OBJECT) of the bound structure. For non-structured Json types stream is not advanced.

Note: this method should NOT be used if the result type is a container (Collection or Map. The reason is that due to type erasure, key and value types can not be introspected when using this method.

Throws:

java.io.IOException

JsonProcessingException

readValueAs

public abstract <T> T readValueAs(TypeReference<?> valueTypeRef)
                       throws java.io.IOException,
                              JsonProcessingException

Method to deserialize Json content into a Java type, reference to which is passed as argument. Type is passed using so-called "super type token" and specifically needs to be used if the root type is a parameterized (generic) container type. Note: method can only be called if the parser has an object codec assigned; this is true for parsers constructed by MappingJsonFactory but not for JsonFactory (unless its setCodec method has been explicitly called).

This method may advance the event stream, for structured types the current event will be the closing end marker (END_ARRAY, END_OBJECT) of the bound structure. For non-structured Json types stream is not advanced.

Throws:

java.io.IOException

JsonProcessingException

readValueAsTree

public abstract JsonNode readValueAsTree()
                                  throws java.io.IOException,
                                         JsonProcessingException

Method to deserialize Json content into equivalent "tree model", represented by root JsonNode of resulting model. For Json Arrays it will an array node (with child nodes), for objects object node (with child nodes), and for other types matching leaf node type

Throws:

java.io.IOException

JsonProcessingException