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:

⏎ com/fasterxml/jackson/core/json/JsonGeneratorImpl.java

package com.fasterxml.jackson.core.json;

import java.io.IOException;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.base.GeneratorBase;
import com.fasterxml.jackson.core.io.CharTypes;
import com.fasterxml.jackson.core.io.CharacterEscapes;
import com.fasterxml.jackson.core.io.IOContext;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.core.util.JacksonFeatureSet;
import com.fasterxml.jackson.core.util.VersionUtil;

/**
 * Intermediate base class shared by JSON-backed generators
 * like {@link UTF8JsonGenerator} and {@link WriterBasedJsonGenerator}.
 * 
 * @since 2.1
 */
public abstract class JsonGeneratorImpl extends GeneratorBase
{
    /*
    /**********************************************************
    /* Constants
    /**********************************************************
     */

    /**
     * This is the default set of escape codes, over 7-bit ASCII range
     * (first 128 character codes), used for single-byte UTF-8 characters.
     */
    protected final static int[] sOutputEscapes = CharTypes.get7BitOutputEscapes();

    /**
     * Default capabilities for JSON generator implementations which do not
     * different from "general textual" defaults
     *
     * @since 2.12
     */
    protected final static JacksonFeatureSet<StreamWriteCapability> JSON_WRITE_CAPABILITIES
        = DEFAULT_TEXTUAL_WRITE_CAPABILITIES;

    /*
    /**********************************************************
    /* Configuration, basic I/O
    /**********************************************************
     */

    protected final IOContext _ioContext;

    /*
    /**********************************************************
    /* Configuration, output escaping
    /**********************************************************
     */

    /**
     * Currently active set of output escape code definitions (whether
     * and how to escape or not) for 7-bit ASCII range (first 128
     * character codes). Defined separately to make potentially
     * customizable
     */
    protected int[] _outputEscapes = sOutputEscapes;

    /**
     * Value between 128 (0x80) and 65535 (0xFFFF) that indicates highest
     * Unicode code point that will not need escaping; or 0 to indicate
     * that all characters can be represented without escaping.
     * Typically used to force escaping of some portion of character set;
     * for example to always escape non-ASCII characters (if value was 127).
     *<p>
     * NOTE: not all sub-classes make use of this setting.
     */
    protected int _maximumNonEscapedChar;

    /**
     * Definition of custom character escapes to use for generators created
     * by this factory, if any. If null, standard data format specific
     * escapes are used.
     */
    protected CharacterEscapes _characterEscapes;
    
    /*
    /**********************************************************
    /* Configuration, other
    /**********************************************************
     */

    /**
     * Separator to use, if any, between root-level values.
     * 
     * @since 2.1
     */
    protected SerializableString _rootValueSeparator
        = DefaultPrettyPrinter.DEFAULT_ROOT_VALUE_SEPARATOR;

    /**
     * Flag that is set if quoting is not to be added around
     * JSON Object property names.
     *
     * @since 2.7
     */
    protected boolean _cfgUnqNames;


    /**
     * Write Hex values with uppercase letters
     *
     * @since 2.14
     */
    protected boolean _cfgWriteHexUppercase;

    /*
    /**********************************************************
    /* Life-cycle
    /**********************************************************
     */

    @SuppressWarnings("deprecation")
    public JsonGeneratorImpl(IOContext ctxt, int features, ObjectCodec codec)
    {
        super(features, codec);
        _ioContext = ctxt;
        if (Feature.ESCAPE_NON_ASCII.enabledIn(features)) {
            // inlined `setHighestNonEscapedChar()`
            _maximumNonEscapedChar = 127;
        }
        _cfgWriteHexUppercase = Feature.WRITE_HEX_UPPER_CASE.enabledIn(features);
        _cfgUnqNames = !Feature.QUOTE_FIELD_NAMES.enabledIn(features);
    }

    /*
    /**********************************************************
    /* Versioned
    /**********************************************************
     */

    @Override
    public Version version() {
        return VersionUtil.versionFor(getClass());
    }

    /*
    /**********************************************************
    /* Overridden configuration methods
    /**********************************************************
     */

    @SuppressWarnings("deprecation")
    @Override
    public JsonGenerator enable(Feature f) {
        super.enable(f);
        if (f == Feature.QUOTE_FIELD_NAMES) {
            _cfgUnqNames = false;
        } else if ( f == Feature.WRITE_HEX_UPPER_CASE) {
            _cfgWriteHexUppercase = true;
        }
        return this;
    }

    @SuppressWarnings("deprecation")
    @Override
    public JsonGenerator disable(Feature f) {
        super.disable(f);
        if (f == Feature.QUOTE_FIELD_NAMES) {
            _cfgUnqNames = true;
        } else if ( f == Feature.WRITE_HEX_UPPER_CASE) {
            _cfgWriteHexUppercase = false;
        }
        return this;
    }

    @SuppressWarnings("deprecation")
    @Override
    protected void _checkStdFeatureChanges(int newFeatureFlags, int changedFeatures) {
        super._checkStdFeatureChanges(newFeatureFlags, changedFeatures);
        _cfgUnqNames = !Feature.QUOTE_FIELD_NAMES.enabledIn(newFeatureFlags);
        _cfgWriteHexUppercase = Feature.WRITE_HEX_UPPER_CASE.enabledIn(newFeatureFlags);
    }

    @Override
    public JsonGenerator setHighestNonEscapedChar(int charCode) {
        _maximumNonEscapedChar = (charCode < 0) ? 0 : charCode;
        return this;
    }

    @Override
    public int getHighestEscapedChar() {
        return _maximumNonEscapedChar;
    }

    @Override
    public JsonGenerator setCharacterEscapes(CharacterEscapes esc)
    {
        _characterEscapes = esc;
        if (esc == null) { // revert to standard escapes
            _outputEscapes = sOutputEscapes;
        } else {
            _outputEscapes = esc.getEscapeCodesForAscii();
        }
        return this;
    }

    /**
     * Method for accessing custom escapes factory uses for {@link JsonGenerator}s
     * it creates.
     */
    @Override
    public CharacterEscapes getCharacterEscapes() {
        return _characterEscapes;
    }
    
    @Override
    public JsonGenerator setRootValueSeparator(SerializableString sep) {
        _rootValueSeparator = sep;
        return this;
    }

    @Override
    public JacksonFeatureSet<StreamWriteCapability> getWriteCapabilities() {
        return JSON_WRITE_CAPABILITIES;
    }

    /*
    /**********************************************************
    /* Shared helper methods
    /**********************************************************
     */

    protected void _verifyPrettyValueWrite(String typeMsg, int status) throws IOException
    {
        // If we have a pretty printer, it knows what to do:
        switch (status) {
        case JsonWriteContext.STATUS_OK_AFTER_COMMA: // array
            _cfgPrettyPrinter.writeArrayValueSeparator(this);
            break;
        case JsonWriteContext.STATUS_OK_AFTER_COLON:
            _cfgPrettyPrinter.writeObjectFieldValueSeparator(this);
            break;
        case JsonWriteContext.STATUS_OK_AFTER_SPACE:
            _cfgPrettyPrinter.writeRootValueSeparator(this);
            break;
        case JsonWriteContext.STATUS_OK_AS_IS:
            // First entry, but of which context?
            if (_writeContext.inArray()) {
                _cfgPrettyPrinter.beforeArrayValues(this);
            } else if (_writeContext.inObject()) {
                _cfgPrettyPrinter.beforeObjectEntries(this);
            }
            break;
        case JsonWriteContext.STATUS_EXPECT_NAME:
            _reportCantWriteValueExpectName(typeMsg);
            break;
        default:
            _throwInternal();
            break;
        }
    }

    protected void _reportCantWriteValueExpectName(String typeMsg) throws IOException
    {
        _reportError(String.format("Can not %s, expecting field name (context: %s)",
                typeMsg, _writeContext.typeDesc()));
    }
}

⏎ com/fasterxml/jackson/core/json/JsonGeneratorImpl.java

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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