cn.vlabs.clb.server.storage.mongo.extend.MyGridFSDBFile.java Source code

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Here is the source code for cn.vlabs.clb.server.storage.mongo.extend.MyGridFSDBFile.java

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/*
 * Copyright (c) 2008-2016 Computer Network Information Center (CNIC), Chinese Academy of Sciences.
 * 
 * This file is part of Duckling project.
 *
 * 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 cn.vlabs.clb.server.storage.mongo.extend;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import com.mongodb.BasicDBObject;
import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.DBObject;
import com.mongodb.MongoException;

public class MyGridFSDBFile extends MyGridFSFile {

    public InputStream getInputStream() {
        return new MyInputStream();
    }

    public long writeTo(String filename) throws IOException {
        return writeTo(new File(filename));
    }

    public long writeTo(File f) throws IOException {
        FileOutputStream out = null;
        try {
            out = new FileOutputStream(f);
            return writeTo(out);
        } finally {
            if (out != null)
                out.close();
        }
    }

    public long writeTo(OutputStream out) throws IOException {
        final int nc = numChunks();
        for (int i = 0; i < nc; i++) {
            out.write(getChunk(i));
        }
        return _length;
    }

    byte[] getChunk(int i) {
        if (_fs == null) {
            throw new RuntimeException("no gridfs!");
        }

        DBObject chunk = _fs._chunkCollection
                .findOne(BasicDBObjectBuilder.start("files_id", _id).add("n", i).get());
        if (chunk == null)
            throw new MongoException("can't find a chunk!  file id: " + _id + " chunk: " + i);

        return (byte[]) chunk.get("data");
    }

    class MyInputStream extends InputStream {

        MyInputStream() {
            _numChunks = numChunks();
        }

        public int available() {
            if (_data == null)
                return 0;
            return _data.length - _offset;
        }

        public void close() {
        }

        public void mark(int readlimit) {
            throw new RuntimeException("mark not supported");
        }

        public void reset() {
            throw new RuntimeException("mark not supported");
        }

        public boolean markSupported() {
            return false;
        }

        public int read() {
            byte b[] = new byte[1];
            int res = read(b);
            if (res < 0)
                return -1;
            return b[0] & 0xFF;
        }

        public int read(byte[] b) {
            return read(b, 0, b.length);
        }

        public int read(byte[] b, int off, int len) {

            if (_data == null || _offset >= _data.length) {
                if (_currentChunkIdx + 1 >= _numChunks)
                    return -1;

                _data = getChunk(++_currentChunkIdx);
                _offset = 0;
            }

            int r = Math.min(len, _data.length - _offset);
            System.arraycopy(_data, _offset, b, off, r);
            _offset += r;
            return r;
        }

        /**
         * Will smartly skips over chunks without fetching them if possible.
         */
        public long skip(long numBytesToSkip) throws IOException {
            if (numBytesToSkip <= 0)
                return 0;

            if (_currentChunkIdx == _numChunks)
                // We're actually skipping over the back end of the file,
                // short-circuit here
                // Don't count those extra bytes to skip in with the return
                // value
                return 0;

            // offset in the whole file
            long offsetInFile = 0;
            if (_currentChunkIdx >= 0)
                offsetInFile = _currentChunkIdx * _chunkSize + _offset;
            if (numBytesToSkip + offsetInFile >= _length) {
                _currentChunkIdx = _numChunks;
                _data = null;
                return _length - offsetInFile;
            }

            int temp = _currentChunkIdx;
            _currentChunkIdx = (int) ((numBytesToSkip + offsetInFile) / _chunkSize);
            if (temp != _currentChunkIdx)
                _data = getChunk(_currentChunkIdx);
            _offset = (int) ((numBytesToSkip + offsetInFile) % _chunkSize);

            return numBytesToSkip;
        }

        final int _numChunks;

        int _currentChunkIdx = -1;
        int _offset = 0;
        byte[] _data = null;
    }

    void remove() {
        _fs._filesCollection.remove(new BasicDBObject("_id", _id));
        _fs._chunkCollection.remove(new BasicDBObject("files_id", _id));
    }
}