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/ser/std/StdSerializer.java

package com.fasterxml.jackson.databind.ser.std;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.IdentityHashMap;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.JsonParser.NumberType;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
import com.fasterxml.jackson.databind.jsonFormatVisitors.*;
import com.fasterxml.jackson.databind.jsonschema.SchemaAware;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.ser.FilterProvider;
import com.fasterxml.jackson.databind.ser.PropertyFilter;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.Converter;

/**
 * Base class used by all standard serializers, and can also
 * be used for custom serializers (in fact, this is the recommended
 * base class to use).
 * Provides convenience methods for implementing {@link SchemaAware}
 */
public abstract class StdSerializer<T>
    extends JsonSerializer<T>
    implements JsonFormatVisitable, SchemaAware, java.io.Serializable
{
    private static final long serialVersionUID = 1L;

    /**
     * Key used for storing a lock object to prevent infinite recursion when
     * constructing converting serializers.
     *
     * @since 2.9
     */
    private final static Object KEY_CONTENT_CONVERTER_LOCK = new Object();
    
    /**
     * Nominal type supported, usually declared type of
     * property for which serializer is used.
     */
    protected final Class<T> _handledType;

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

    protected StdSerializer(Class<T> t) {
        _handledType = t;
    }

    @SuppressWarnings("unchecked")
    protected StdSerializer(JavaType type) {
        _handledType = (Class<T>) type.getRawClass();
    }

    /**
     * Alternate constructor that is (alas!) needed to work
     * around kinks of generic type handling
     */
    @SuppressWarnings("unchecked")
    protected StdSerializer(Class<?> t, boolean dummy) {
        _handledType = (Class<T>) t;
    }

    /**
     * @since 2.6
     */
    @SuppressWarnings("unchecked")
    protected StdSerializer(StdSerializer<?> src) {
        _handledType = (Class<T>) src._handledType;
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    @Override
    public Class<T> handledType() { return _handledType; }

    /*
    /**********************************************************
    /* Serialization
    /**********************************************************
     */

    @Override
    public abstract void serialize(T value, JsonGenerator gen, SerializerProvider provider)
        throws IOException;

    /*
    /**********************************************************
    /* Type introspection API, partial/default implementation
    /**********************************************************
     */

    /**
     * Default implementation specifies no format. This behavior is usually
     * overriden by custom serializers.
     */
    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint)
        throws JsonMappingException
    {
        visitor.expectAnyFormat(typeHint);
    }

    /**
     * Default implementation simply claims type is "string"; usually
     * overriden by custom serializers.
     */
    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) throws JsonMappingException
    {
        return createSchemaNode("string");
    }
    
    /**
     * Default implementation simply claims type is "string"; usually
     * overriden by custom serializers.
     */
    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint, boolean isOptional)
        throws JsonMappingException
    {
        ObjectNode schema = (ObjectNode) getSchema(provider, typeHint);
        if (!isOptional) {
            schema.put("required", !isOptional);
        }
        return schema;
    }

    /*
    /**********************************************************
    /* Helper methods for JSON Schema generation
    /**********************************************************
     */

    protected ObjectNode createSchemaNode(String type)
    {
        ObjectNode schema = JsonNodeFactory.instance.objectNode();
        schema.put("type", type);
        return schema;
    }
    
    protected ObjectNode createSchemaNode(String type, boolean isOptional)
    {
        ObjectNode schema = createSchemaNode(type);
        if (!isOptional) {
            schema.put("required", !isOptional);
        }
        return schema;
    }

    /**
     * Helper method that calls necessary visit method(s) to indicate that the
     * underlying JSON type is JSON String.
     *
     * @since 2.7
     */
    protected void visitStringFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint)
            throws JsonMappingException {
        /*JsonStringFormatVisitor v2 =*/ visitor.expectStringFormat(typeHint);
    }

    /**
     * Helper method that calls necessary visit method(s) to indicate that the
     * underlying JSON type is JSON String, but that there is a more refined
     * logical type
     *
     * @since 2.7
     */
    protected void visitStringFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            JsonValueFormat format)
        throws JsonMappingException
    {
        JsonStringFormatVisitor v2 = visitor.expectStringFormat(typeHint);
        if (v2 != null) {
            v2.format(format);
        }
    }

    /**
     * Helper method that calls necessary visit method(s) to indicate that the
     * underlying JSON type is JSON Integer number.
     *
     * @since 2.7
     */
    protected void visitIntFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            NumberType numberType)
        throws JsonMappingException
    {
        JsonIntegerFormatVisitor v2 = visitor.expectIntegerFormat(typeHint);
        if (_neitherNull(v2, numberType)) {
            v2.numberType(numberType);
        }
    }

    /**
     * Helper method that calls necessary visit method(s) to indicate that the
     * underlying JSON type is JSON Integer number, but that there is also a further
     * format restriction involved.
     *
     * @since 2.7
     */
    protected void visitIntFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            NumberType numberType, JsonValueFormat format)
        throws JsonMappingException
    {
        JsonIntegerFormatVisitor v2 = visitor.expectIntegerFormat(typeHint);
        if (v2 != null) {
            if (numberType != null) {
                v2.numberType(numberType);
            }
            if (format != null) {
                v2.format(format);
            }
        }
    }
    
    /**
     * Helper method that calls necessary visit method(s) to indicate that the
     * underlying JSON type is a floating-point JSON number.
     *
     * @since 2.7
     */
    protected void visitFloatFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            NumberType numberType)
        throws JsonMappingException
    {
        JsonNumberFormatVisitor v2 = visitor.expectNumberFormat(typeHint);
        if (v2 != null) {
            v2.numberType(numberType);
        }
    }

    /**
     * @since 2.7
     */
    protected void visitArrayFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            JsonSerializer<?> itemSerializer, JavaType itemType)
        throws JsonMappingException
    {
        JsonArrayFormatVisitor v2 = visitor.expectArrayFormat(typeHint);
        if (_neitherNull(v2, itemSerializer)) {
            v2.itemsFormat(itemSerializer, itemType);
        }
    }

    /**
     * @since 2.7
     */
    protected void visitArrayFormat(JsonFormatVisitorWrapper visitor, JavaType typeHint,
            JsonFormatTypes itemType)
        throws JsonMappingException
    {
        JsonArrayFormatVisitor v2 = visitor.expectArrayFormat(typeHint);
        if (v2 != null) {
            v2.itemsFormat(itemType);
        }
    }

    /*
    /**********************************************************
    /* Helper methods for exception handling
    /**********************************************************
     */
    
    /**
     * Method that will modify caught exception (passed in as argument)
     * as necessary to include reference information, and to ensure it
     * is a subtype of {@link IOException}, or an unchecked exception.
     *<p>
     * Rules for wrapping and unwrapping are bit complicated; essentially:
     *<ul>
     * <li>Errors are to be passed as is (if uncovered via unwrapping)
     * <li>"Plain" IOExceptions (ones that are not of type
     *   {@link JsonMappingException} are to be passed as is
     *</ul>
     */
    public void wrapAndThrow(SerializerProvider provider,
            Throwable t, Object bean, String fieldName)
        throws IOException
    {
        /* 05-Mar-2009, tatu: But one nasty edge is when we get
         *   StackOverflow: usually due to infinite loop. But that
         *   usually gets hidden within an InvocationTargetException...
         */
        while (t instanceof InvocationTargetException && t.getCause() != null) {
            t = t.getCause();
        }
        // Errors and "plain" to be passed as is
        ClassUtil.throwIfError(t);
        // Ditto for IOExceptions... except for mapping exceptions!
        boolean wrap = (provider == null) || provider.isEnabled(SerializationFeature.WRAP_EXCEPTIONS);
        if (t instanceof IOException) {
            if (!wrap || !(t instanceof JacksonException)) {
                throw (IOException) t;
            }
        } else if (!wrap) {
            ClassUtil.throwIfRTE(t);
        }
        // Need to add reference information
        throw JsonMappingException.wrapWithPath(t, bean, fieldName);
    }

    public void wrapAndThrow(SerializerProvider provider,
            Throwable t, Object bean, int index)
        throws IOException
    {
        while (t instanceof InvocationTargetException && t.getCause() != null) {
            t = t.getCause();
        }
        // Errors are to be passed as is
        ClassUtil.throwIfError(t);
        // Ditto for IOExceptions... except for mapping exceptions!
        boolean wrap = (provider == null) || provider.isEnabled(SerializationFeature.WRAP_EXCEPTIONS);
        if (t instanceof IOException) {
            if (!wrap || !(t instanceof JacksonException)) {
                throw (IOException) t;
            }
        } else if (!wrap) {
            ClassUtil.throwIfRTE(t);
        }
        // Need to add reference information
        throw JsonMappingException.wrapWithPath(t, bean, index);
    }

    /*
    /**********************************************************
    /* Helper methods, accessing annotation-based configuration
    /**********************************************************
     */

    /**
     * Helper method that can be used to see if specified property has annotation
     * indicating that a converter is to be used for contained values (contents
     * of structured types; array/List/Map values)
     * 
     * @param existingSerializer (optional) configured content
     *    serializer if one already exists.
     * 
     * @since 2.9
     */
    protected JsonSerializer<?> findContextualConvertingSerializer(SerializerProvider provider,
            BeanProperty property, JsonSerializer<?> existingSerializer)
        throws JsonMappingException
    {
        // 08-Dec-2016, tatu: to fix [databind#357], need to prevent recursive calls for
        //     same property
        @SuppressWarnings("unchecked")
        Map<Object,Object> conversions = (Map<Object,Object>) provider.getAttribute(KEY_CONTENT_CONVERTER_LOCK);
        if (conversions != null) {
            Object lock = conversions.get(property);
            if (lock != null) {
                return existingSerializer;
            }
        } else {
            conversions = new IdentityHashMap<>();
            provider.setAttribute(KEY_CONTENT_CONVERTER_LOCK, conversions);
        }
        conversions.put(property, Boolean.TRUE);
        try {
            JsonSerializer<?> ser = findConvertingContentSerializer(provider, property, existingSerializer);
            if (ser != null) {
                return provider.handleSecondaryContextualization(ser, property);
            }
        } finally {
            conversions.remove(property);
        }
        return existingSerializer;
    }

    /**
     * @deprecated Since 2.9 use {link {@link #findContextualConvertingSerializer} instead
     */
    @Deprecated
    protected JsonSerializer<?> findConvertingContentSerializer(SerializerProvider provider,
            BeanProperty prop, JsonSerializer<?> existingSerializer)
        throws JsonMappingException
    {
        final AnnotationIntrospector intr = provider.getAnnotationIntrospector();
        if (_neitherNull(intr, prop)) {
            AnnotatedMember m = prop.getMember();
            if (m != null) {
                Object convDef = intr.findSerializationContentConverter(m);
                if (convDef != null) {
                    Converter<Object,Object> conv = provider.converterInstance(prop.getMember(), convDef);
                    JavaType delegateType = conv.getOutputType(provider.getTypeFactory());
                    // [databind#731]: Should skip if nominally java.lang.Object
                    if ((existingSerializer == null) && !delegateType.isJavaLangObject()) {
                        existingSerializer = provider.findValueSerializer(delegateType);
                    }
                    return new StdDelegatingSerializer(conv, delegateType, existingSerializer);
                }
            }
        }
        return existingSerializer;
    }

    /**
     * Helper method used to locate filter that is needed, based on filter id
     * this serializer was constructed with.
     * 
     * @since 2.3
     */
    protected PropertyFilter findPropertyFilter(SerializerProvider provider,
            Object filterId, Object valueToFilter)
        throws JsonMappingException
    {
        FilterProvider filters = provider.getFilterProvider();
        // Not ok to miss the provider, if a filter is declared to be needed.
        if (filters == null) {
            return provider.reportBadDefinition(handledType(),
                    "Cannot resolve PropertyFilter with id '"+filterId+"'; no FilterProvider configured");
        }
        // But whether unknown ids are ok just depends on filter provider; if we get null that's fine
        return filters.findPropertyFilter(filterId, valueToFilter);
    }

    /**
     * Helper method that may be used to find if this deserializer has specific
     * {@link JsonFormat} settings, either via property, or through type-specific
     * defaulting.
     *
     * @param typeForDefaults Type (erased) used for finding default format settings, if any
     *
     * @since 2.7
     */
    protected JsonFormat.Value findFormatOverrides(SerializerProvider provider,
            BeanProperty prop, Class<?> typeForDefaults)
    {
        if (prop != null) {
            return prop.findPropertyFormat(provider.getConfig(), typeForDefaults);
        }
        // even without property or AnnotationIntrospector, may have type-specific defaults
        return provider.getDefaultPropertyFormat(typeForDefaults);
    }

    /**
     * Convenience method that uses {@link #findFormatOverrides} to find possible
     * defaults and/of overrides, and then calls <code>JsonFormat.Value.getFeature(...)</code>
     * to find whether that feature has been specifically marked as enabled or disabled.
     * 
     * @param typeForDefaults Type (erased) used for finding default format settings, if any
     *
     * @since 2.7
     */
    protected Boolean findFormatFeature(SerializerProvider provider,
            BeanProperty prop, Class<?> typeForDefaults, JsonFormat.Feature feat)
    {
        JsonFormat.Value format = findFormatOverrides(provider, prop, typeForDefaults);
        if (format != null) {
            return format.getFeature(feat);
        }
        return null;
    }

    /**
     * @since 2.8
     */
    protected JsonInclude.Value findIncludeOverrides(SerializerProvider provider,
            BeanProperty prop, Class<?> typeForDefaults)
    {
        if (prop != null) {
            return prop.findPropertyInclusion(provider.getConfig(), typeForDefaults);
        }
        // even without property or AnnotationIntrospector, may have type-specific defaults
        return provider.getDefaultPropertyInclusion(typeForDefaults);
    }
    
    /**
     * Convenience method for finding out possibly configured content value serializer.
     *
     * @since 2.7.4
     */
    protected JsonSerializer<?> findAnnotatedContentSerializer(SerializerProvider serializers,
            BeanProperty property)
        throws JsonMappingException
    {
        if (property != null) {
            // First: if we have a property, may have property-annotation overrides
            AnnotatedMember m = property.getMember();
            final AnnotationIntrospector intr = serializers.getAnnotationIntrospector();
            if (m != null) {
                Object serDef = intr.findContentSerializer(m);
                if (serDef != null) {
                    return serializers.serializerInstance(m, serDef);
                }
            }
        }
        return null;
    }

    /*
    /**********************************************************
    /* Helper methods, other
    /**********************************************************
     */
    
    /**
     * Method that can be called to determine if given serializer is the default
     * serializer Jackson uses; as opposed to a custom serializer installed by
     * a module or calling application. Determination is done using
     * {@link JacksonStdImpl} annotation on serializer class.
     */
    protected boolean isDefaultSerializer(JsonSerializer<?> serializer) {
        return ClassUtil.isJacksonStdImpl(serializer);
    }

    /**
     * @since 2.9
     */
    protected final static boolean _neitherNull(Object a, Object b) {
        return (a != null) && (b != null);
    }

    /**
     * @since 2.9
     */
    protected final static boolean _nonEmpty(Collection<?> c) {
        return (c != null) && !c.isEmpty();
    }
}

⏎ com/fasterxml/jackson/databind/ser/std/StdSerializer.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 

⇒ Jackson Annotations Source Code

⇐ Download and Install Jackson Binary Package

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library