RAMDirectoryUtil.java
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上传日期:2018-01-08
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- /**
- * 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.contrib.index.lucene;
- import java.io.DataInput;
- import java.io.DataOutput;
- import java.io.IOException;
- import org.apache.hadoop.io.Text;
- import org.apache.lucene.store.IndexInput;
- import org.apache.lucene.store.IndexOutput;
- import org.apache.lucene.store.RAMDirectory;
- /**
- * A utility class which writes an index in a ram dir into a DataOutput and
- * read from a DataInput an index into a ram dir.
- */
- public class RAMDirectoryUtil {
- private static final int BUFFER_SIZE = 1024; // RAMOutputStream.BUFFER_SIZE;
- /**
- * Write a number of files from a ram directory to a data output.
- * @param out the data output
- * @param dir the ram directory
- * @param names the names of the files to write
- * @throws IOException
- */
- public static void writeRAMFiles(DataOutput out, RAMDirectory dir,
- String[] names) throws IOException {
- out.writeInt(names.length);
- for (int i = 0; i < names.length; i++) {
- Text.writeString(out, names[i]);
- long length = dir.fileLength(names[i]);
- out.writeLong(length);
- if (length > 0) {
- // can we avoid the extra copy?
- IndexInput input = null;
- try {
- input = dir.openInput(names[i], BUFFER_SIZE);
- int position = 0;
- byte[] buffer = new byte[BUFFER_SIZE];
- while (position < length) {
- int len =
- position + BUFFER_SIZE <= length ? BUFFER_SIZE
- : (int) (length - position);
- input.readBytes(buffer, 0, len);
- out.write(buffer, 0, len);
- position += len;
- }
- } finally {
- if (input != null) {
- input.close();
- }
- }
- }
- }
- }
- /**
- * Read a number of files from a data input to a ram directory.
- * @param in the data input
- * @param dir the ram directory
- * @throws IOException
- */
- public static void readRAMFiles(DataInput in, RAMDirectory dir)
- throws IOException {
- int numFiles = in.readInt();
- for (int i = 0; i < numFiles; i++) {
- String name = Text.readString(in);
- long length = in.readLong();
- if (length > 0) {
- // can we avoid the extra copy?
- IndexOutput output = null;
- try {
- output = dir.createOutput(name);
- int position = 0;
- byte[] buffer = new byte[BUFFER_SIZE];
- while (position < length) {
- int len =
- position + BUFFER_SIZE <= length ? BUFFER_SIZE
- : (int) (length - position);
- in.readFully(buffer, 0, len);
- output.writeBytes(buffer, 0, len);
- position += len;
- }
- } finally {
- if (output != null) {
- output.close();
- }
- }
- }
- }
- }
- }