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

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

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/jsontype/impl/TypeIdResolverBase.java

package com.fasterxml.jackson.databind.jsontype.impl;

import java.io.IOException;

import com.fasterxml.jackson.databind.DatabindContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.jsontype.TypeIdResolver;
import com.fasterxml.jackson.databind.type.TypeFactory;

/**
 * Partial base implementation of {@link TypeIdResolver}: all custom implementations
 * are <b>strongly</b> recommended to extend this class, instead of directly
 * implementing {@link TypeIdResolver}.
 * Note that ALL sub-class need to re-implement
 * {@link #typeFromId(DatabindContext, String)} method; otherwise implementation
 * will not work.
 *<p>
 * Note that instances created to be constructed from annotations
 * ({@link com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver})
 * are always created using no-arguments constructor; protected constructor
 * is only used sub-classes.
 */
public abstract class TypeIdResolverBase
    implements TypeIdResolver
{
    protected final TypeFactory _typeFactory;

    /**
     * Common base type for all polymorphic instances handled.
     */
    protected final JavaType _baseType;

    protected TypeIdResolverBase() {
        this(null, null);
    }
    
    protected TypeIdResolverBase(JavaType baseType, TypeFactory typeFactory) {
        _baseType = baseType;
        _typeFactory = typeFactory;
    }

    // Standard type id resolvers do not need this: only useful for custom ones.
    @Override
    public void init(JavaType bt) { }

    @Override
    public String idFromBaseType() {
        /* By default we will just defer to regular handling, handing out the
         * base type; and since there is no value, must just pass null here
         * assuming that implementations can deal with it.
         * Alternative would be to pass a bogus Object, but that does not seem right.
         */
        return idFromValueAndType(null, _baseType.getRawClass());
    }

    @Override
    public JavaType typeFromId(DatabindContext context, String id)  throws IOException {
        // 22-Dec-2015, tatu: Must be overridden by sub-classes, so let's throw
        //    an exception if not
        throw new IllegalStateException("Sub-class "+getClass().getName()+" MUST implement "
                +"`typeFromId(DatabindContext,String)");
    }

    /**
     * Helper method used to get a simple description of all known type ids,
     * for use in error messages.
     */
    @Override
    public String getDescForKnownTypeIds() {
        return null;
    }
}

⏎ com/fasterxml/jackson/databind/jsontype/impl/TypeIdResolverBase.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
Download 

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