TypeConversionSupport.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.transport.amqp.client.util;

import java.util.Date;
import java.util.HashMap;

public final class TypeConversionSupport {

   static class ConversionKey {

      final Class<?> from;
      final Class<?> to;
      final int hashCode;

      ConversionKey(Class<?> from, Class<?> to) {
         this.from = from;
         this.to = to;
         this.hashCode = from.hashCode() ^ (to.hashCode() << 1);
      }

      @Override
      public boolean equals(Object o) {
         if (this == o) {
            return true;
         }

         if (o == null || o.getClass() != this.getClass()) {
            return false;
         }

         ConversionKey x = (ConversionKey) o;
         return x.from == from && x.to == to;
      }

      @Override
      public int hashCode() {
         return hashCode;
      }
   }

   interface Converter {

      Object convert(Object value);
   }

   private static final HashMap<ConversionKey, Converter> CONVERSION_MAP = new HashMap<>();

   static {
      Converter toStringConverter = new Converter() {
         @Override
         public Object convert(Object value) {
            return value.toString();
         }
      };
      CONVERSION_MAP.put(new ConversionKey(Boolean.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Byte.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Short.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Integer.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Long.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Float.class, String.class), toStringConverter);
      CONVERSION_MAP.put(new ConversionKey(Double.class, String.class), toStringConverter);

      CONVERSION_MAP.put(new ConversionKey(String.class, Boolean.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Boolean.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Byte.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Byte.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Short.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Short.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Integer.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Integer.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Long.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Long.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Float.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Float.valueOf((String) value);
         }
      });
      CONVERSION_MAP.put(new ConversionKey(String.class, Double.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Double.valueOf((String) value);
         }
      });

      Converter longConverter = new Converter() {
         @Override
         public Object convert(Object value) {
            return Long.valueOf(((Number) value).longValue());
         }
      };
      CONVERSION_MAP.put(new ConversionKey(Byte.class, Long.class), longConverter);
      CONVERSION_MAP.put(new ConversionKey(Short.class, Long.class), longConverter);
      CONVERSION_MAP.put(new ConversionKey(Integer.class, Long.class), longConverter);
      CONVERSION_MAP.put(new ConversionKey(Date.class, Long.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Long.valueOf(((Date) value).getTime());
         }
      });

      Converter intConverter = new Converter() {
         @Override
         public Object convert(Object value) {
            return Integer.valueOf(((Number) value).intValue());
         }
      };
      CONVERSION_MAP.put(new ConversionKey(Byte.class, Integer.class), intConverter);
      CONVERSION_MAP.put(new ConversionKey(Short.class, Integer.class), intConverter);

      CONVERSION_MAP.put(new ConversionKey(Byte.class, Short.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return Short.valueOf(((Number) value).shortValue());
         }
      });

      CONVERSION_MAP.put(new ConversionKey(Float.class, Double.class), new Converter() {
         @Override
         public Object convert(Object value) {
            return new Double(((Number) value).doubleValue());
         }
      });
   }

   public static Object convert(Object value, Class<?> toClass) {

      assert value != null && toClass != null;

      if (value.getClass() == toClass) {
         return value;
      }

      Class<?> fromClass = value.getClass();

      if (fromClass.isPrimitive()) {
         fromClass = convertPrimitiveTypeToWrapperType(fromClass);
      }

      if (toClass.isPrimitive()) {
         toClass = convertPrimitiveTypeToWrapperType(toClass);
      }

      Converter c = CONVERSION_MAP.get(new ConversionKey(fromClass, toClass));
      if (c == null) {
         return null;
      }

      return c.convert(value);
   }

   private static Class<?> convertPrimitiveTypeToWrapperType(Class<?> type) {
      Class<?> rc = type;
      if (type.isPrimitive()) {
         if (type == int.class) {
            rc = Integer.class;
         } else if (type == long.class) {
            rc = Long.class;
         } else if (type == double.class) {
            rc = Double.class;
         } else if (type == float.class) {
            rc = Float.class;
         } else if (type == short.class) {
            rc = Short.class;
         } else if (type == byte.class) {
            rc = Byte.class;
         } else if (type == boolean.class) {
            rc = Boolean.class;
         }
      }

      return rc;
   }

   private TypeConversionSupport() {
   }
}