Jackson Core Source Code

Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Core Source Code files are provided in the source packge (jackson-core-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Core Source Code below:

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package com.fasterxml.jackson.core;

import java.io.OutputStream;
import java.io.Writer;
import java.math.BigDecimal;

import com.fasterxml.jackson.core.util.JacksonFeature;

 * Token writer (generator) features not-specific to any particular format backend.
 * Eventual replacement for non-JSON-specific {@link com.fasterxml.jackson.core.JsonGenerator.Feature}s.
 * @since 2.10
public enum StreamWriteFeature
    implements JacksonFeature // since 2.12
    // // Low-level I/O / content features

     * Feature that determines whether generator will automatically
     * close underlying output target that is NOT owned by the
     * generator.
     * If disabled, calling application has to separately
     * close the underlying {@link OutputStream} and {@link Writer}
     * instances used to create the generator. If enabled, generator
     * will handle closing, as long as generator itself gets closed:
     * this happens when end-of-input is encountered, or generator
     * is closed by a call to {@link JsonGenerator#close}.
     * Feature is enabled by default.

     * Feature that determines what happens when the generator is
     * closed while there are still unmatched
     * {@link JsonToken#START_ARRAY} or {@link JsonToken#START_OBJECT}
     * entries in output content. If enabled, such Array(s) and/or
     * Object(s) are automatically closed (that is, matching END_ token write
     * call is made for all open scopes); if disabled, no additional
     * write calls are made.
     * Feature is enabled by default.

     * Feature that specifies that calls to {@link JsonGenerator#flush} will cause
     * matching <code>flush()</code> to underlying {@link OutputStream}
     * or {@link Writer}; if disabled this will not be done.
     * Main reason to disable this feature is to prevent flushing at
     * generator level, if it is not possible to prevent method being
     * called by other code (like <code>ObjectMapper</code> or third
     * party libraries).
     * Feature is enabled by default.

    // // Datatype coercion features

     * Feature that determines whether {@link java.math.BigDecimal} entries are
     * serialized using {@link java.math.BigDecimal#toPlainString()} to prevent
     * values to be written using scientific notation.
     * NOTE: only affects generators that serialize {@link java.math.BigDecimal}s
     * using textual representation (textual formats but potentially some binary
     * formats).
     * Feature is disabled by default, so default output mode is used; this generally
     * depends on how {@link BigDecimal} has been created.

    // // Schema/Validity support features

     * Feature that determines whether {@link JsonGenerator} will explicitly
     * check that no duplicate JSON Object field names are written.
     * If enabled, generator will check all names within context and report
     * duplicates by throwing a {@link JsonGenerationException}; if disabled,
     * no such checking will be done. Assumption in latter case is
     * that caller takes care of not trying to write duplicate names.
     * Note that enabling this feature will incur performance overhead
     * due to having to store and check additional information.
     * Feature is disabled by default.
     * Feature that determines what to do if the underlying data format requires knowledge
     * of all properties to output, and if no definition is found for a property that
     * caller tries to write. If enabled, such properties will be quietly ignored;
     * if disabled, a {@link JsonProcessingException} will be thrown to indicate the
     * problem.
     * Typically most textual data formats do NOT require schema information (although
     * some do, such as CSV), whereas many binary data formats do require definitions
     * (such as Avro, protobuf), although not all (Smile, CBOR, BSON and MessagePack do not).
     * Note that support for this feature is implemented by individual data format
     * module, if (and only if) it makes sense for the format in question. For JSON,
     * for example, this feature has no effect as properties need not be pre-defined.
     * Feature is disabled by default, meaning that if the underlying data format
     * requires knowledge of all properties to output, attempts to write an unknown
     * property will result in a {@link JsonProcessingException}

    // // Misc other features

     * Feature that determines whether to use standard Java code to write floats/doubles
     * (default) or use the Schubfach algorithm which is faster.
     * The latter approach may lead to small differences in the precision of the
     * float/double that is written to the JSON output.
     * Feature is disabled by default, meaning that slower JDK default conversions are used.
     * @since 2.14

     * Whether feature is enabled or disabled by default.
    private final boolean _defaultState;

    private final int _mask;

     * For backwards compatibility we may need to map to one of existing {@link JsonParser.Feature}s;
     * if so, this is the feature to enable/disable.
    final private JsonGenerator.Feature _mappedFeature;

    private StreamWriteFeature(JsonGenerator.Feature mappedTo) {
        // only for 2.x, let's map everything to legacy feature:
        _mappedFeature = mappedTo;
        _mask = mappedTo.getMask();
        _defaultState = mappedTo.enabledByDefault();

     * Method that calculates bit set (flags) of all features that
     * are enabled by default.
     * @return Bit mask of all features that are enabled by default
    public static int collectDefaults()
        int flags = 0;
        for (StreamWriteFeature f : values()) {
            if (f.enabledByDefault()) {
                flags |= f.getMask();
        return flags;

    public boolean enabledByDefault() { return _defaultState; }
    public boolean enabledIn(int flags) { return (flags & _mask) != 0; }
    public int getMask() { return _mask; }

    public JsonGenerator.Feature mappedFeature() { return _mappedFeature; }



Or download all of them as a single archive file:

File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05


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