hadoop TwoDArrayWritable 源码
haddop TwoDArrayWritable 代码
文件路径:/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/TwoDArrayWritable.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.hadoop.io;
import java.io.*;
import java.lang.reflect.Array;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/** A Writable for 2D arrays containing a matrix of instances of a class. */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class TwoDArrayWritable implements Writable {
private Class valueClass;
private Writable[][] values;
public TwoDArrayWritable(Class valueClass) {
this.valueClass = valueClass;
}
public TwoDArrayWritable(Class valueClass, Writable[][] values) {
this(valueClass);
this.values = values;
}
public Object toArray() {
int dimensions[] = {values.length, 0};
Object result = Array.newInstance(valueClass, dimensions);
for (int i = 0; i < values.length; i++) {
Object resultRow = Array.newInstance(valueClass, values[i].length);
Array.set(result, i, resultRow);
for (int j = 0; j < values[i].length; j++) {
Array.set(resultRow, j, values[i][j]);
}
}
return result;
}
public void set(Writable[][] values) { this.values = values; }
public Writable[][] get() { return values; }
@Override
public void readFields(DataInput in) throws IOException {
// construct matrix
values = new Writable[in.readInt()][];
for (int i = 0; i < values.length; i++) {
values[i] = new Writable[in.readInt()];
}
// construct values
for (int i = 0; i < values.length; i++) {
for (int j = 0; j < values[i].length; j++) {
Writable value; // construct value
try {
value = (Writable)valueClass.newInstance();
} catch (InstantiationException e) {
throw new RuntimeException(e.toString());
} catch (IllegalAccessException e) {
throw new RuntimeException(e.toString());
}
value.readFields(in); // read a value
values[i][j] = value; // store it in values
}
}
}
@Override
public void write(DataOutput out) throws IOException {
out.writeInt(values.length); // write values
for (int i = 0; i < values.length; i++) {
out.writeInt(values[i].length);
}
for (int i = 0; i < values.length; i++) {
for (int j = 0; j < values[i].length; j++) {
values[i][j].write(out);
}
}
}
}
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