| /** |
| * 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.hadoop.streaming.io; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.streaming.PipeMapRed; |
| |
| /** |
| * Abstract base for classes that read the client's output. |
| */ |
| public abstract class OutputReader<K, V> { |
| |
| /** |
| * Initializes the OutputReader. This method has to be called before |
| * calling any of the other methods. |
| */ |
| public void initialize(PipeMapRed pipeMapRed) throws IOException { |
| // nothing here yet, but that might change in the future |
| } |
| |
| /** |
| * Read the next key/value pair outputted by the client. |
| * @return true iff a key/value pair was read |
| */ |
| public abstract boolean readKeyValue() throws IOException; |
| |
| /** |
| * Returns the current key. |
| */ |
| public abstract K getCurrentKey() throws IOException; |
| |
| /** |
| * Returns the current value. |
| */ |
| public abstract V getCurrentValue() throws IOException; |
| |
| /** |
| * Returns the last output from the client as a String. |
| */ |
| public abstract String getLastOutput(); |
| |
| } |