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

Jackson Annotations Source Code files are provided in the source packge (jackson-annotations-2.12.4-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Annotations Source Code below:

⏎ com/fasterxml/jackson/databind/ser/impl/UnknownSerializer.java

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

import java.io.IOException;
import java.lang.reflect.Type;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.type.WritableTypeId;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;

@SuppressWarnings("serial")
public class UnknownSerializer
    extends StdSerializer<Object>
{
    public UnknownSerializer() {
        super(Object.class);
    }

    /**
     * @since 2.6
     */
    public UnknownSerializer(Class<?> cls) {
        super(cls, false);
    }
    
    @Override
    public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException
    {
        // 27-Nov-2009, tatu: As per [JACKSON-201] may or may not fail...
        if (provider.isEnabled(SerializationFeature.FAIL_ON_EMPTY_BEANS)) {
            failForEmpty(provider, value);
        }
        // But if it's fine, we'll just output empty JSON Object:
        gen.writeStartObject(value, 0);
        gen.writeEndObject();
    }

    @Override
    public final void serializeWithType(Object value, JsonGenerator gen, SerializerProvider provider,
            TypeSerializer typeSer) throws IOException
    {
        if (provider.isEnabled(SerializationFeature.FAIL_ON_EMPTY_BEANS)) {
            failForEmpty(provider, value);
        }
        WritableTypeId typeIdDef = typeSer.writeTypePrefix(gen,
                typeSer.typeId(value, JsonToken.START_OBJECT));
        typeSer.writeTypeSuffix(gen, typeIdDef);
    }

    @Override
    public boolean isEmpty(SerializerProvider provider, Object value) {
        return true;
    }

    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) throws JsonMappingException {
        return null;
    }
    
    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint)
        throws JsonMappingException
    { 
        visitor.expectAnyFormat(typeHint);
    }

    protected void failForEmpty(SerializerProvider prov, Object value)
            throws JsonMappingException {
        prov.reportBadDefinition(handledType(), String.format(
                "No serializer found for class %s and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS)",
                value.getClass().getName()));
    }
}

⏎ com/fasterxml/jackson/databind/ser/impl/UnknownSerializer.java

 

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⇑⇑ Jackson - Java JSON library