Add support for new JsonTypeInfo.Id.SIMPLE_NAME polymorphic type id option

src/main/java/com/fasterxml/jackson/databind/jsontype/impl/SimpleNameIdResolver.java

@@ -0,0 +1,205 @@
+package com.fasterxml.jackson.databind.jsontype.impl;
+
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.databind.BeanDescription;
+import com.fasterxml.jackson.databind.DatabindContext;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.cfg.MapperConfig;
+import com.fasterxml.jackson.databind.jsontype.NamedType;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * {@link com.fasterxml.jackson.databind.jsontype.TypeIdResolver} implementation
+ * that converts between (JSON) Strings and simple Java class names.
+ * 
+ * @since 2.16
+ */
+public class SimpleNameIdResolver
+    extends TypeIdResolverBase
+{
+    protected final MapperConfig<?> _config;
+
+    /**
+     * Mappings from class name to type id, used for serialization.
+     *<p>
+     * Since lazily constructed will require synchronization (either internal
+     * by type, or external)
+     */
+    protected final ConcurrentHashMap<String, String> _typeToId;
+
+    /**
+     * Mappings from type id to JavaType, used for deserialization.
+     *<p>
+     * Eagerly constructed, not modified, can use regular unsynchronized {@link Map}.
+     */
+    protected final Map<String, JavaType> _idToType;
+
+    protected final boolean _caseInsensitive;
+
+    protected SimpleNameIdResolver(MapperConfig<?> config, JavaType baseType,
+            ConcurrentHashMap<String, String> typeToId,
+            HashMap<String, JavaType> idToType)
+    {
+        super(baseType, config.getTypeFactory());
+        _config = config;
+        _typeToId = typeToId;
+        _idToType = idToType;
+        _caseInsensitive = config.isEnabled(MapperFeature.ACCEPT_CASE_INSENSITIVE_VALUES);
+    }
+
+    public static SimpleNameIdResolver construct(MapperConfig<?> config, JavaType baseType,
+            Collection<NamedType> subtypes, boolean forSer, boolean forDeser)
+    {
+        // sanity check
+        if (forSer == forDeser) throw new IllegalArgumentException();
+
+        final ConcurrentHashMap<String, String> typeToId;
+        final HashMap<String, JavaType> idToType;
+
+        if (forSer) {
+            // Only need Class-to-id for serialization; but synchronized since may be
+            // lazily built (if adding type-id-mappings dynamically)
+            typeToId = new ConcurrentHashMap<>();
+            idToType = null;
+        } else {
+            idToType = new HashMap<>();
+            // 14-Apr-2016, tatu: Apparently needed for special case of `defaultImpl`;
+            //    see [databind#1198] for details: but essentially we only need room
+            //    for a single value.
+            typeToId = new ConcurrentHashMap<>(4);
+        }
+        final boolean caseInsensitive = config.isEnabled(MapperFeature.ACCEPT_CASE_INSENSITIVE_VALUES);
+
+        if (subtypes != null) {
+            for (NamedType t : subtypes) {
+                // no name? Need to figure out default; for now, let's just
+                // use non-qualified class name
+                Class<?> cls = t.getType();
+                String id = t.hasName() ? t.getName() : _defaultTypeId(cls);
+                if (forSer) {
+                    typeToId.put(cls.getName(), id);
+                }
+                if (forDeser) {
+                    // [databind#1983]: for case-insensitive lookups must canonicalize:
+                    if (caseInsensitive) {
+                        id = id.toLowerCase();
+                    }
+                    // One more problem; sometimes we have same name for multiple types;
+                    // if so, use most specific
+                    JavaType prev = idToType.get(id); // lgtm [java/dereferenced-value-may-be-null]
+                    if (prev != null) { // Can only override if more specific
+                        if (cls.isAssignableFrom(prev.getRawClass())) { // nope, more generic (or same)
+                            continue;
+                        }
+                    }
+                    idToType.put(id, config.constructType(cls));
+                }
+            }
+        }
+        return new SimpleNameIdResolver(config, baseType, typeToId, idToType);
+    }
+
+    @Override
+    public JsonTypeInfo.Id getMechanism() { return JsonTypeInfo.Id.SIMPLE_NAME; }
+
+    @Override
+    public String idFromValue(Object value) {
+        return idFromClass(value.getClass());
+    }
+
+    protected String idFromClass(Class<?> clazz)
+    {
+        if (clazz == null) {
+            return null;
+        }
+        // NOTE: although we may need to let `TypeModifier` change actual type to use
+        // for id, we can use original type as key for more efficient lookup:
+        final String key = clazz.getName();
+        String name = _typeToId.get(key);
+
+        if (name == null) {
+            // 29-Nov-2019, tatu: As per test in `TestTypeModifierNameResolution` somehow
+            //    we need to do this odd piece here which seems unnecessary but isn't.
+            Class<?> cls = _typeFactory.constructType(clazz).getRawClass();
+            // 24-Feb-2011, tatu: As per [JACKSON-498], may need to dynamically look up name
+            // can either throw an exception, or use default name...
+            if (_config.isAnnotationProcessingEnabled()) {
+                BeanDescription beanDesc = _config.introspectClassAnnotations(cls);
+                name = _config.getAnnotationIntrospector().findTypeName(beanDesc.getClassInfo());
+            }
+            if (name == null) {
+                // And if still not found, let's choose default?
+                name = _defaultTypeId(cls);
+            }
+            _typeToId.put(key, name);
+        }
+        return name;
+    }
+
+    @Override
+    public String idFromValueAndType(Object value, Class<?> type) {
+        // 18-Jan-2013, tatu: We may be called with null value occasionally
+        //   it seems; nothing much we can figure out that way.
+        if (value == null) {
+            return idFromClass(type);
+        }
+        return idFromValue(value);
+    }
+
+    @Override
+    public JavaType typeFromId(DatabindContext context, String id) {
+        return _typeFromId(id);
+    }
+
+    protected JavaType _typeFromId(String id) {
+        // [databind#1983]: for case-insensitive lookups must canonicalize:
+        if (_caseInsensitive) {
+            id = id.toLowerCase();
+        }
+        // Now: if no type is found, should we try to locate it by
+        // some other means? (specifically, if in same package as base type,
+        // could just try Class.forName)
+        // For now let's not add any such workarounds; can add if need be
+        return _idToType.get(id);
+    }
+
+    @Override
+    public String getDescForKnownTypeIds() {
+        // 05-May-2020, tatu: As per [databind#1919], only include ids for
+        //    non-abstract types
+        final TreeSet<String> ids = new TreeSet<>();
+        for (Map.Entry<String, JavaType> entry : _idToType.entrySet()) {
+            if (entry.getValue().isConcrete()) {
+                ids.add(entry.getKey());
+            }
+        }
+        return ids.toString();
+    }
+
+    @Override
+    public String toString() {
+        return String.format("[%s; id-to-type=%s]", getClass().getName(), _idToType);
+    }
+
+    /*
+    /*********************************************************
+    /* Helper methods
+    /*********************************************************
+     */
+
+    /**
+     * If no name was explicitly given for a class, we will just
+     * use simple class name
+     */
+    protected static String _defaultTypeId(Class<?> cls)
+    {
+        String n = cls.getName();
+        int ix = Math.max(n.lastIndexOf('.'), n.lastIndexOf('$'));
+        return (ix < 0) ? n : n.substring(ix+1);
+    }
+}

src/main/java/com/fasterxml/jackson/databind/jsontype/impl/StdTypeResolverBuilder.java

@@ -368,6 +368,8 @@ protected TypeIdResolver idResolver(MapperConfig<?> config,
             return ClassNameIdResolver.construct(baseType, config, subtypeValidator);
         case MINIMAL_CLASS:
             return MinimalClassNameIdResolver.construct(baseType, config, subtypeValidator);
+        case SIMPLE_NAME:
+            return SimpleNameIdResolver.construct(config, baseType, subtypes, forSer, forDeser);
         case NAME:
             return TypeNameIdResolver.construct(config, baseType, subtypes, forSer, forDeser);
         case NONE: // hmmh. should never get this far with 'none'