ParamTypeHelper.java

package io.ebeaninternal.util;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class ParamTypeHelper {

  public enum ManyType {
    LIST, SET, MAP, NONE
  }

  public static class TypeInfo {

    private final ManyType manyType;
    private final Class<?> beanType;

    private TypeInfo(ManyType manyType, Class<?> beanType) {
      this.manyType = manyType;
      this.beanType = beanType;
    }

    public boolean isManyType() {
      return !ManyType.NONE.equals(manyType);
    }

    public ManyType getManyType() {
      return manyType;
    }

    public Class<?> getBeanType() {
      return beanType;
    }

    @Override
    public String toString() {
      if (isManyType()) {
        return manyType + " " + beanType;
      } else {
        return beanType.toString();
      }
    }

  }

  public static TypeInfo getTypeInfo(Type genericType) {

    if (genericType instanceof ParameterizedType) {
      return getParamTypeInfo((ParameterizedType) genericType);
    }

    Class<?> entityType = getBeanType(genericType);
    if (entityType != null) {
      return new TypeInfo(ManyType.NONE, entityType);
    }
    return null;
  }

  /**
   * For Lists Sets and Maps of beans.
   */
  private static TypeInfo getParamTypeInfo(ParameterizedType paramType) {

    Type rawType = paramType.getRawType();

    ManyType manyType = getManyType(rawType);
    if (ManyType.NONE.equals(manyType)) {
      return null;
    }

    Type[] typeArguments = paramType.getActualTypeArguments();

    if (typeArguments.length == 1) {
      Type argType = typeArguments[0];
      Class<?> beanType = getBeanType(argType);
      if (beanType != null) {
        return new TypeInfo(manyType, beanType);
      }
    }

    return null;
  }

  private static Class<?> getBeanType(Type argType) {
    if (argType instanceof Class<?>) {
      return (Class<?>) argType;
    }
    return null;
  }

  private static ManyType getManyType(Type rawType) {
    if (List.class.equals(rawType)) {
      return ManyType.LIST;
    }
    if (Set.class.equals(rawType)) {
      return ManyType.SET;
    }
    if (Map.class.equals(rawType)) {
      return ManyType.MAP;
    }
    return ManyType.NONE;
  }
}