src/test/java/com/fasterxml/jackson/databind/jsontype/TestCustomTypeIdResolver.java

package com.fasterxml.jackson.databind.jsontype;

import java.util.*;

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;

import com.fasterxml.jackson.databind.BaseMapTest;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver;
import com.fasterxml.jackson.databind.jsontype.TypeIdResolver;
import com.fasterxml.jackson.databind.type.TypeFactory;

public class TestCustomTypeIdResolver extends BaseMapTest
{
    @JsonTypeInfo(use=Id.CUSTOM, include=As.WRAPPER_OBJECT)
    @JsonTypeIdResolver(CustomResolver.class)
    static abstract class CustomBean { }

    static class CustomBeanImpl extends CustomBean {
        public int x;
        
        public CustomBeanImpl() { }
        public CustomBeanImpl(int x) { this.x = x; }
    }

    static class CustomBeanWrapper {
//        @JsonTypeInfo(use=Id.NONE, include=As.EXTERNAL_PROPERTY, property="type")
        @JsonTypeInfo(use=Id.CUSTOM, include=As.PROPERTY, property="type")
        public CustomBean value;
    }
    
    static class CustomResolver implements TypeIdResolver
    {
        static List<JavaType> initTypes;

        public CustomResolver() { }

        @Override
        public Id getMechanism() {
            return Id.CUSTOM;
        }

        @Override
        public String idFromValue(Object value)
        {
            if (value instanceof CustomBean) {
                return "*";
            }
            return "unknown";
        }

        @Override
        public String idFromValueAndType(Object value, Class<?> type) {
            return idFromValue(value);
        }

        @Override
        public void init(JavaType baseType) {
            if (initTypes != null) {
                initTypes.add(baseType);
            }
        }

        @Override
        public JavaType typeFromId(String id)
        {
            if ("*".equals(id)) {
                return TypeFactory.defaultInstance().constructType(CustomBeanImpl.class);
            }
            return null;
        }

        @Override
        public String idFromBaseType() {
            return "xxx";
        }
    }
    
    /*
    /**********************************************************
    /* Unit tests
    /**********************************************************
     */

    private final ObjectMapper MAPPER = objectMapper();
    
    // for [JACKSON-359]
    public void testCustomTypeIdResolver() throws Exception
    {
        List<JavaType> types = new ArrayList<JavaType>();
        CustomResolver.initTypes = types;
        String json = MAPPER.writeValueAsString(new CustomBean[] { new CustomBeanImpl(28) });
        assertEquals("[{\"*\":{\"x\":28}}]", json);
        assertEquals(1, types.size());
        assertEquals(CustomBean.class, types.get(0).getRawClass());

        types = new ArrayList<JavaType>();
        CustomResolver.initTypes = types;
        CustomBean[] result = MAPPER.readValue(json, CustomBean[].class);
        assertNotNull(result);
        assertEquals(1, result.length);
        assertEquals(28, ((CustomBeanImpl) result[0]).x);
        assertEquals(1, types.size());
        assertEquals(CustomBean.class, types.get(0).getRawClass());
    }

    public void testCustomWithExternal() throws Exception
    {
        CustomBeanWrapper w = new CustomBeanWrapper();
        w.value = new CustomBeanImpl(12);

        String json = MAPPER.writeValueAsString(w);

System.out.println("JSON = "+json);
        
        CustomBeanWrapper out = MAPPER.readValue(json, CustomBeanWrapper.class);
        assertNotNull(out);
        
        assertEquals(12, ((CustomBeanImpl) out.value).x);
    }
}