DataSupplier.java

/**
 * Copyright (C) 2013-2015 all@code-story.net
 *
 * Licensed 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 net.codestory.http.payload;

import java.io.*;

@FunctionalInterface
interface DataSupplier extends Serializable {
  byte[] get() throws IOException;

  static DataSupplier cache(DataSupplier supplier) {
    return new DataSupplier() {
      private byte[] data;

      @Override
      public byte[] get() throws IOException {
        if (data == null) {
          data = supplier.get();
        }
        return data;
      }
    };
  }
}