org.apache.flink.runtime.util.SerializableHashMap Maven / Gradle / Ivy
/*
* 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.flink.runtime.util;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.apache.flink.core.io.IOReadableWritable;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.util.StringUtils;
/**
* This class extends a standard {@link java.util.HashMap} by implementing the
* {@link org.apache.flink.core.io.IOReadableWritable} interface.
*
* @param
* the type of the key used in this hash map
* @param
* the type of the value used in this hash map
*/
public class SerializableHashMap extends HashMap
implements IOReadableWritable {
/**
* The generated serial version UID.
*/
private static final long serialVersionUID = 6693468726881121924L;
@Override
public void write(final DataOutputView out) throws IOException {
out.writeInt(size());
for (Map.Entry entry : entrySet()) {
final K key = entry.getKey();
final V value = entry.getValue();
StringUtils.writeNullableString(key.getClass().getName(), out);
key.write(out);
StringUtils.writeNullableString(value.getClass().getName(), out);
value.write(out);
}
}
@SuppressWarnings("unchecked")
@Override
public void read(final DataInputView in) throws IOException {
final int numberOfMapEntries = in.readInt();
for (int i = 0; i < numberOfMapEntries; i++) {
final String keyType = StringUtils.readNullableString(in);
Class keyClass;
try {
keyClass = (Class) Class.forName(keyType);
} catch (ClassNotFoundException e) {
throw new IOException(e);
}
K key = null;
try {
key = keyClass.newInstance();
} catch (Exception e) {
throw new IOException(e);
}
key.read(in);
final String valueType = StringUtils.readNullableString(in);
Class valueClass;
try {
valueClass = (Class) Class.forName(valueType);
} catch (ClassNotFoundException e) {
throw new IOException(e);
}
V value;
try {
value = valueClass.newInstance();
} catch (Exception e) {
throw new IOException(e);
}
value.read(in);
put(key, value);
}
}
}