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/Base64Variants.java

/* Jackson JSON-processor.
 *
 * Copyright (c) 2007- Tatu Saloranta, tatu.saloranta@iki.fi
 */
package com.fasterxml.jackson.core;

/**
 * Container for commonly used Base64 variants:
 *<ul>
 * <li> {@link #MIME}
 * <li> {@link #MIME_NO_LINEFEEDS}
 * <li> {@link #PEM}
 * <li> {@link #MODIFIED_FOR_URL}
 * </ul>
 * See entries for full description of differences.
 *<p>
 * Note that for default {@link Base64Variant} instances listed above, configuration
 * is such that if padding is written on output, it will also be required on
 * reading. This behavior may be changed by using methods:
 *<ul>
 * <li>{@link Base64Variant#withPaddingAllowed()}
 *  </li>
 * <li>{@link Base64Variant#withPaddingForbidden()}
 *  </li>
 * <li>{@link Base64Variant#withPaddingRequired()}
 *  </li>
 * <li>{@link Base64Variant#withWritePadding(boolean)}
 *  </li>
 *</ul>
 *
 * @author Tatu Saloranta
 */
public final class Base64Variants
{
    final static String STD_BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    /**
     * This variant is what most people would think of "the standard"
     * Base64 encoding.
     *<p>
     * See <a href="http://en.wikipedia.org/wiki/Base64">wikipedia Base64 entry</a> for details.
     *<p>
     * Note that although this can be thought of as the standard variant,
     * it is <b>not</b> the default for Jackson: no-linefeeds alternative
     * is instead used because of JSON requirement of escaping all linefeeds.
     *<p>
     * Writes padding on output; requires padding when reading (may change later with a call to {@link Base64Variant#withWritePadding})
     */
    public final static Base64Variant MIME;
    static {
        MIME = new Base64Variant("MIME", STD_BASE64_ALPHABET, true, '=', 76);
    }

    /**
     * Slightly non-standard modification of {@link #MIME} which does not
     * use linefeeds (max line length set to infinite). Useful when linefeeds
     * wouldn't work well (possibly in attributes), or for minor space savings
     * (save 1 linefeed per 76 data chars, ie. ~1.4% savings).
     *<p>
     * Writes padding on output; requires padding when reading (may change later with a call to {@link Base64Variant#withWritePadding})
     */
    public final static Base64Variant MIME_NO_LINEFEEDS;
    static {
        MIME_NO_LINEFEEDS = new Base64Variant(MIME, "MIME-NO-LINEFEEDS", Integer.MAX_VALUE);
    }

    /**
     * This variant is the one that predates {@link #MIME}: it is otherwise
     * identical, except that it mandates shorter line length.
     *<p>
     * Writes padding on output; requires padding when reading (may change later with a call to {@link Base64Variant#withWritePadding})
     */
    public final static Base64Variant PEM = new Base64Variant(MIME, "PEM", true, '=', 64);

    /**
     * This non-standard variant is usually used when encoded data needs to be
     * passed via URLs (such as part of GET request). It differs from the
     * base {@link #MIME} variant in multiple ways.
     * First, no padding is used: this also means that it generally can not
     * be written in multiple separate but adjacent chunks (which would not
     * be the usual use case in any case). Also, no linefeeds are used (max
     * line length set to infinite). And finally, two characters (plus and
     * slash) that would need quoting in URLs are replaced with more
     * optimal alternatives (hyphen and underscore, respectively).
     *<p>
     * Does not write padding on output; does not accept padding when reading (may change later with a call to {@link Base64Variant#withWritePadding})
     */
    public final static Base64Variant MODIFIED_FOR_URL;
    static {
        StringBuilder sb = new StringBuilder(STD_BASE64_ALPHABET);
        // Replace plus with hyphen, slash with underscore (and no padding)
        sb.setCharAt(sb.indexOf("+"), '-');
        sb.setCharAt(sb.indexOf("/"), '_');
        // And finally, let's not split lines either, wouldn't work too well with URLs
        MODIFIED_FOR_URL = new Base64Variant("MODIFIED-FOR-URL", sb.toString(), false, Base64Variant.PADDING_CHAR_NONE, Integer.MAX_VALUE);
    }

    /**
     * Method used to get the default variant -- {@link #MIME_NO_LINEFEEDS} -- for cases
     * where caller does not explicitly specify the variant.
     * We will prefer no-linefeed version because linefeeds in JSON values
     * must be escaped, making linefeed-containing variants sub-optimal.
     *
     * @return Default variant ({@code MIME_NO_LINEFEEDS})
     */
    public static Base64Variant getDefaultVariant() {
        return MIME_NO_LINEFEEDS;
    }

    /**
     * Lookup method for finding one of standard variants by name.
     * If name does not match any of standard variant names,
     * a {@link IllegalArgumentException} is thrown.
     *
     * @param name Name of base64 variant to return
     *
     * @return Standard base64 variant that matches given {@code name}
     *
     * @throws IllegalArgumentException if no standard variant with given name exists
     */
    public static Base64Variant valueOf(String name) throws IllegalArgumentException
    {
        if (MIME._name.equals(name)) {
            return MIME;
        }
        if (MIME_NO_LINEFEEDS._name.equals(name)) {
            return MIME_NO_LINEFEEDS;
        }
        if (PEM._name.equals(name)) {
            return PEM;
        }
        if (MODIFIED_FOR_URL._name.equals(name)) {
            return MODIFIED_FOR_URL;
        }
        if (name == null) {
            name = "<null>";
        } else {
            name = "'"+name+"'";
        }
        throw new IllegalArgumentException("No Base64Variant with name "+name);
    }
}

⏎ com/fasterxml/jackson/core/Base64Variants.java

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