This is the incorrect way to perform polymorphic JSON deserialization using Jackson's ObjectMapper. The correct way can be seen here: https://gist.github.com/sscovil/8788339. This gist was created for the following StackOverflow question: http://stackoverflow.com/questions/21485923/java-jackson-polymorphic-json-deserialization-of-an-object-with-…

PolymorphicDeserialization.java

import org.codehaus.jackson.annotate.JsonSubTypes;
import org.codehaus.jackson.annotate.JsonTypeInfo;
import org.codehaus.jackson.annotate.JsonTypeName;
import org.codehaus.jackson.map.ObjectMapper;

import org.testng.Assert;
import org.testng.annotations.Test;

import java.io.IOException;

public class IntegrationTests {

    @Test
    public void deserializeJsonSucceeds() {
        Asset asset = deserializeJson("{ \"type\": \"document\", \"properties\": { \"source\": \"foo\", \"proxy\": \"bar\" } }");
        Assert.assertTrue(asset.getProperties() instanceof DocumentAssetProperties);
    }

    public Asset deserializeJson(String json) {
        ObjectMapper mapper = new ObjectMapper();
        try {
            return mapper.readValue(json, Asset.class);
        }
        catch(IOException e) {
            Assert.fail("Could not deserialize JSON.", e);
        }
        return null;
    }

    public class Asset {
        private String type;
        private AssetProperties properties;

        public String getType() { return type; }
        public void setType(String type) { this.type = type; }

        public AssetProperties getProperties() { return properties; }
        public void setProperties(AssetProperties properties) { this.properties = properties; }
    }

    @JsonTypeInfo(
            use = JsonTypeInfo.Id.NAME,
            include = JsonTypeInfo.As.PROPERTY,
            property = "type"
    )
    @JsonSubTypes({
            @JsonSubTypes.Type(value = ImageAssetProperties.class, name = "image"),
            @JsonSubTypes.Type(value = DocumentAssetProperties.class, name = "document")
    })
    public interface AssetProperties {
        String getSource();
        AssetProperties setSource(String source);
        String getProxy();
        AssetProperties setProxy(String proxy);
    }

    @JsonTypeName("document")
    public class DocumentAssetProperties implements AssetProperties {
        private String source;
        private String proxy;

        public String getSource() { return source; }
        public DocumentAssetProperties setSource(String source) {
            this.source = source;
            return this;
        }

        public String getProxy() { return proxy; }
        public DocumentAssetProperties setProxy(String proxy) {
            this.proxy = proxy;
            return this;
        }
    }    
}