Example usage for java.io RandomAccessFile readFully

List of usage examples for java.io RandomAccessFile readFully

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Introduction

In this page you can find the example usage for java.io RandomAccessFile readFully.

Prototype

public final void readFully(byte b[], int off, int len) throws IOException

Source Link

Document

Reads exactly len bytes from this file into the byte array, starting at the current file pointer.

Usage

From source file:Main.java

public static void main(String[] args) {
    try {//from  www .j  a  va2  s .c om
        String s = "Hello world from java2s.com";

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");

        // write something in the file
        raf.writeUTF(s);

        // set the file pointer at 0 position
        raf.seek(0);

        // create an array equal to the length of raf
        byte[] arr = new byte[10];

        // read the file
        raf.readFully(arr, 3, 7);

        // create a new string based on arr
        String s2 = new String(arr);

        // print it
        System.out.println(s2);
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

From source file:Main.java

public static void main(String args[]) throws Exception {
    RandomAccessFile fh1 = new RandomAccessFile("a.txt", "r");
    RandomAccessFile fh2 = new RandomAccessFile("b.txt", "r");
    long filesize1 = fh1.length();
    long filesize2 = fh2.length();
    // allocate two buffers large enough to hold entire files
    int bufsize = (int) Math.min(filesize1, filesize2);
    byte[] buffer1 = new byte[bufsize];
    byte[] buffer2 = new byte[bufsize];

    fh1.readFully(buffer1, 0, bufsize);
    fh2.readFully(buffer2, 0, bufsize);// w w w.j  a v a  2  s .co  m

    for (int i = 0; i < bufsize; i++) {
        if (buffer1[i] != buffer2[i]) {
            System.out.println("Files differ at offset " + i);
            break;
        }
    }
    fh1.close();
    fh2.close();
}

From source file:Diff.java

public static void main(String args[]) {
    RandomAccessFile fh1 = null;
    RandomAccessFile fh2 = null;//from  w  w  w. j a  va2 s  . c om
    int bufsize; // size of smallest file
    long filesize1 = -1;
    long filesize2 = -1;
    byte buffer1[]; // the two file caches
    byte buffer2[];
    // check what you get as command-line arguments
    if (args.length == 0 || args[0].equals("?")) {
        System.err.println("USAGE: java Diff <file1> <file2> | ?");
        System.exit(0);
    }
    // open file ONE for reading
    try {
        fh1 = new RandomAccessFile(args[0], "r");
        filesize1 = fh1.length();
    } catch (IOException ioErr) {
        System.err.println("Could not find " + args[0]);
        System.err.println(ioErr);
        System.exit(100);
    }
    // open file TWO for reading
    try {
        fh2 = new RandomAccessFile(args[1], "r");
        filesize2 = fh2.length();
    } catch (IOException ioErr) {
        System.err.println("Could not find " + args[1]);
        System.err.println(ioErr);
        System.exit(100);
    }
    if (filesize1 != filesize2) {
        System.out.println("Files differ in size !");
        System.out.println("'" + args[0] + "' is " + filesize1 + " bytes");
        System.out.println("'" + args[1] + "' is " + filesize2 + " bytes");
    }
    // allocate two buffers large enough to hold entire files
    bufsize = (int) Math.min(filesize1, filesize2);
    buffer1 = new byte[bufsize];
    buffer2 = new byte[bufsize];
    try {
        fh1.readFully(buffer1, 0, bufsize);
        fh2.readFully(buffer2, 0, bufsize);

        for (int i = 0; i < bufsize; i++) {
            if (buffer1[i] != buffer2[i]) {
                System.out.println("Files differ at offset " + i);
                break;
            }
        }
    } catch (IOException ioErr) {
        System.err.println("ERROR: An exception occurred while processing the files");
        System.err.println(ioErr);
    } finally {
        try {
            fh1.close();
            fh2.close();
        } catch (IOException ignored) {
        }
    }
}

From source file:org.apache.hadoop.hdfs.server.datanode.BlockMetadataHeader.java

/**
 * Read the header at the beginning of the given block meta file.
 * The current file position will be altered by this method.
 * If an error occurs, the file is <em>not</em> closed.
 *///from w w w  . ja  v  a  2s.c o m
public static BlockMetadataHeader readHeader(RandomAccessFile raf) throws IOException {
    byte[] buf = new byte[getHeaderSize()];
    raf.seek(0);
    raf.readFully(buf, 0, buf.length);
    return readHeader(new DataInputStream(new ByteArrayInputStream(buf)));
}

From source file:org.apache.sling.commons.log.logback.internal.Tailer.java

/**
 * Returns the starting position of UNIX "tail -n".
 *//*  w w w  . j  a  v a2  s .c  o  m*/
private long getTailStartPos(RandomAccessFile file, int n) throws IOException {
    int newlineCount = 0;
    long length = file.length();
    long pos = length - BUFFER_SIZE;
    int buffLength = BUFFER_SIZE;

    if (pos < 0) {
        pos = 0;
        buffLength = (int) length;
    }

    while (true) {
        file.seek(pos);
        file.readFully(buffer, 0, buffLength);

        for (int i = buffLength - 1; i >= 0; i--) {
            if ((char) buffer[i] == '\n') {
                newlineCount++;

                if (newlineCount >= n) {
                    pos += (i + 1);
                    return pos;
                }
            }
        }

        if (pos == 0) {
            break;
        }

        if (pos - BUFFER_SIZE < 0) {
            buffLength = (int) pos;
            pos = 0;
        } else {
            pos -= BUFFER_SIZE;
        }
    }

    return pos;
}

From source file:org.openengsb.connector.promreport.internal.ProcessFileStore.java

private long findLastProcess(RandomAccessFile raf) throws IOException {
    final String proc = "</Process>";
    final byte[] bproc = proc.getBytes();
    final int len = proc.length();
    for (long i = raf.length() - "</Process></WorkflowLog>".length(); i >= 0; i--) {
        byte[] buf = new byte[len];
        raf.seek(i);//from   w  ww  . j  av a2  s. c  o m
        raf.readFully(buf, 0, len);
        int b;
        for (b = 0; b < len; b++) {
            if (buf[b] != bproc[b]) {
                break;
            }
        }
        if (b == len) {
            return i;
        }
    }
    return -1;
}

From source file:com.limegroup.gnutella.metadata.MP3DataEditor.java

/**
 * Actually writes the ID3 tags out to the ID3V1 section of mp3 file.
 *///  ww w.  jav a  2s  .  com
private int writeID3V1DataToDisk(RandomAccessFile file) {
    byte[] buffer = new byte[30];//max buffer length...drop/pickup vehicle

    //see if there are ID3 Tags in the file
    String tag = "";
    try {
        file.readFully(buffer, 0, 3);
        tag = new String(buffer, 0, 3);
    } catch (EOFException e) {
        return LimeXMLReplyCollection.RW_ERROR;
    } catch (IOException e) {
        return LimeXMLReplyCollection.RW_ERROR;
    }
    //We are sure this is an MP3 file.Otherwise this method would never
    //be called.
    if (!tag.equals("TAG")) {
        //Write the TAG
        try {
            byte[] tagBytes = "TAG".getBytes();//has to be len 3
            file.seek(file.length() - 128);//reset the file-pointer
            file.write(tagBytes, 0, 3);//write these three bytes into the File
        } catch (IOException ioe) {
            return LimeXMLReplyCollection.BAD_ID3;
        }
    }
    LOG.debug("about to start writing to file");
    boolean b;
    b = toFile(title_, 30, file, buffer);
    if (!b)
        return LimeXMLReplyCollection.FAILED_TITLE;
    b = toFile(artist_, 30, file, buffer);
    if (!b)
        return LimeXMLReplyCollection.FAILED_ARTIST;
    b = toFile(album_, 30, file, buffer);
    if (!b)
        return LimeXMLReplyCollection.FAILED_ALBUM;
    b = toFile(year_, 4, file, buffer);
    if (!b)
        return LimeXMLReplyCollection.FAILED_YEAR;
    //comment and track (a little bit tricky)
    b = toFile(comment_, 28, file, buffer);//28 bytes for comment
    if (!b)
        return LimeXMLReplyCollection.FAILED_COMMENT;

    byte trackByte = (byte) -1;//initialize
    try {
        if (track_ == null || track_.equals(""))
            trackByte = (byte) 0;
        else
            trackByte = Byte.parseByte(track_);
    } catch (NumberFormatException nfe) {
        return LimeXMLReplyCollection.FAILED_TRACK;
    }

    try {
        file.write(0);//separator b/w comment and track(track is optional)
        file.write(trackByte);
    } catch (IOException e) {
        return LimeXMLReplyCollection.FAILED_TRACK;
    }

    //genre
    byte genreByte = getGenreByte();
    try {
        file.write(genreByte);
    } catch (IOException e) {
        return LimeXMLReplyCollection.FAILED_GENRE;
    }
    //come this far means we are OK.
    return LimeXMLReplyCollection.NORMAL;

}

From source file:org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.java

static private void truncateBlock(File blockFile, File metaFile, long oldlen, long newlen) throws IOException {
    LOG.info("truncateBlock: blockFile=" + blockFile + ", metaFile=" + metaFile + ", oldlen=" + oldlen
            + ", newlen=" + newlen);

    if (newlen == oldlen) {
        return;/*from w  w  w. ja v a 2  s .c  o m*/
    }
    if (newlen > oldlen) {
        throw new IOException(
                "Cannot truncate block to from oldlen (=" + oldlen + ") to newlen (=" + newlen + ")");
    }

    DataChecksum dcs = BlockMetadataHeader.readHeader(metaFile).getChecksum();
    int checksumsize = dcs.getChecksumSize();
    int bpc = dcs.getBytesPerChecksum();
    long n = (newlen - 1) / bpc + 1;
    long newmetalen = BlockMetadataHeader.getHeaderSize() + n * checksumsize;
    long lastchunkoffset = (n - 1) * bpc;
    int lastchunksize = (int) (newlen - lastchunkoffset);
    byte[] b = new byte[Math.max(lastchunksize, checksumsize)];

    RandomAccessFile blockRAF = new RandomAccessFile(blockFile, "rw");
    try {
        //truncate blockFile 
        blockRAF.setLength(newlen);

        //read last chunk
        blockRAF.seek(lastchunkoffset);
        blockRAF.readFully(b, 0, lastchunksize);
    } finally {
        blockRAF.close();
    }

    //compute checksum
    dcs.update(b, 0, lastchunksize);
    dcs.writeValue(b, 0, false);

    //update metaFile 
    RandomAccessFile metaRAF = new RandomAccessFile(metaFile, "rw");
    try {
        metaRAF.setLength(newmetalen);
        metaRAF.seek(newmetalen - checksumsize);
        metaRAF.write(b, 0, checksumsize);
    } finally {
        metaRAF.close();
    }
}

From source file:org.commoncrawl.service.listcrawler.CrawlList.java

void resetSubDomainCounts() throws IOException {

    LOG.info("*** LIST:" + getListId() + " Reset SubDomain Queued Counts.");

    if (_subDomainMetadataFile.exists()) {

        LOG.info("*** LIST:" + getListId() + " FILE EXISTS .");

        RandomAccessFile file = new RandomAccessFile(_subDomainMetadataFile, "rw");
        DataInputBuffer inputBuffer = new DataInputBuffer();
        DataOutputBuffer outputBuffer = new DataOutputBuffer(CrawlListMetadata.Constants.FixedDataSize);

        try {/*from w  ww  . j a  v a  2s .  c o  m*/
            // skip version 
            file.read();
            // read item count 
            int itemCount = file.readInt();

            LOG.info("*** LIST:" + getListId() + " SUBDOMAIN ITEM COUNT:" + itemCount);

            CrawlListMetadata newMetadata = new CrawlListMetadata();

            for (int i = 0; i < itemCount; ++i) {

                long orignalPos = file.getFilePointer();
                file.readFully(outputBuffer.getData(), 0, CrawlListMetadata.Constants.FixedDataSize);
                inputBuffer.reset(outputBuffer.getData(), CrawlListMetadata.Constants.FixedDataSize);
                try {
                    newMetadata.deserialize(inputBuffer, new BinaryProtocol());
                } catch (Exception e) {
                    LOG.error("-----Failed to Deserialize Metadata at Index:" + i + " Exception:"
                            + CCStringUtils.stringifyException(e));
                }
                // ok reset everything except hashes and first/last url pointers 
                int urlCount = newMetadata.getUrlCount();
                long firstRecordOffset = newMetadata.getFirstRecordOffset();
                long lastRecordOffset = newMetadata.getLastRecordOffset();
                String domainName = newMetadata.getDomainName();
                long domainHash = newMetadata.getDomainHash();

                // reset 
                newMetadata.clear();
                // restore 
                newMetadata.setUrlCount(urlCount);
                newMetadata.setFirstRecordOffset(firstRecordOffset);
                newMetadata.setLastRecordOffset(lastRecordOffset);
                newMetadata.setDomainName(domainName);
                newMetadata.setDomainHash(domainHash);

                // serialize it ... 
                outputBuffer.reset();
                newMetadata.serialize(outputBuffer, new BinaryProtocol());
                // write it back to disk 
                file.seek(orignalPos);
                // and rewrite it ... 
                file.write(outputBuffer.getData(), 0, CrawlListMetadata.Constants.FixedDataSize);
            }
        } finally {
            file.close();
        }
        LOG.info("*** LIST:" + getListId() + " DONE RESETTIGN SUBDOMAIN METADATA QUEUE COUNTS");
    }
}

From source file:org.commoncrawl.service.listcrawler.CrawlList.java

void loadSubDomainMetadataFromDisk() throws IOException {
    LOG.info("*** LIST:" + getListId() + " LOAD SUBDOMAIN METADATA FROM DISK ...  ");
    if (_subDomainMetadataFile.exists()) {

        LOG.info("*** LIST:" + getListId() + " FILE EXISTS LOADING SUBDOMAIN DATA FROM DISK.");

        RandomAccessFile file = new RandomAccessFile(_subDomainMetadataFile, "rw");
        DataInputBuffer inputBuffer = new DataInputBuffer();
        byte fixedDataBlock[] = new byte[CrawlListMetadata.Constants.FixedDataSize];

        try {//from  w w w  . jav  a 2  s .c o m
            // skip version 
            file.read();
            // read item count 
            int itemCount = file.readInt();

            LOG.info("*** LIST:" + getListId() + " SUBDOMAIN ITEM COUNT:" + itemCount);

            CrawlListMetadata newMetadata = new CrawlListMetadata();

            TreeMap<Long, Integer> idToOffsetMap = new TreeMap<Long, Integer>();
            for (int i = 0; i < itemCount; ++i) {

                long orignalPos = file.getFilePointer();
                file.readFully(fixedDataBlock, 0, fixedDataBlock.length);
                inputBuffer.reset(fixedDataBlock, fixedDataBlock.length);
                try {
                    newMetadata.deserialize(inputBuffer, new BinaryProtocol());
                } catch (Exception e) {
                    LOG.error("-----Failed to Deserialize Metadata at Index:" + i + " Exception:"
                            + CCStringUtils.stringifyException(e));
                }
                idToOffsetMap.put(newMetadata.getDomainHash(), (int) orignalPos);
            }

            // write lookup table 
            _offsetLookupTable = new DataOutputBuffer(idToOffsetMap.size() * OFFSET_TABLE_ENTRY_SIZE);
            for (Map.Entry<Long, Integer> entry : idToOffsetMap.entrySet()) {
                _offsetLookupTable.writeLong(entry.getKey());
                _offsetLookupTable.writeInt(entry.getValue());
            }
        } finally {
            file.close();
        }
        LOG.info("*** LIST:" + getListId() + " DONE LOADING SUBDOMAIN DATA FROM DISK");
    } else {

        LOG.info("*** LIST:" + getListId() + " SUBDOMAIN METADATA DOES NOT EXIST! LOADING FROM SCRATCH");

        RandomAccessFile fixedDataReader = new RandomAccessFile(_fixedDataFile, "rw");
        RandomAccessFile stringDataReader = new RandomAccessFile(_variableDataFile, "rw");

        try {

            //ok rebuild top level metadata as well 
            _metadata.clear();

            OnDiskCrawlHistoryItem item = new OnDiskCrawlHistoryItem();

            int processedCount = 0;
            while (fixedDataReader.getFilePointer() != fixedDataReader.length()) {

                long position = fixedDataReader.getFilePointer();

                // store offset in item 
                item._fileOffset = position;
                // load from disk 
                item.deserialize(fixedDataReader);
                try {
                    // seek to string data 
                    stringDataReader.seek(item._stringsOffset);
                    // and skip buffer length 
                    WritableUtils.readVInt(stringDataReader);
                    // and read primary string 
                    String url = stringDataReader.readUTF();

                    // get metadata object for subdomain 
                    CrawlListMetadata subDomainMetadata = getTransientSubDomainMetadata(url);

                    // increment url count 
                    subDomainMetadata.setUrlCount(subDomainMetadata.getUrlCount() + 1);

                    // increment top level metadata count 
                    _metadata.setUrlCount(_metadata.getUrlCount() + 1);

                    // update top level metadata ..
                    updateMetadata(item, _metadata, 0);

                    // update sub-domain metadata object  from item data
                    updateMetadata(item, subDomainMetadata, 0);

                    ++processedCount;
                } catch (IOException e) {
                    LOG.error("Exception Reading String Data For Item:" + (processedCount + 1));
                    LOG.error("Exception:" + CCStringUtils.stringifyException(e));
                    LOG.error("File Position:" + fixedDataReader.getFilePointer() + " StringsPointer:"
                            + stringDataReader.getFilePointer());
                }

                if (processedCount % 10000 == 0) {
                    LOG.info("*** LIST:" + getListId() + " Processed:" + processedCount + " Items");
                }
            }

            // ok commit top level metadata to disk as well 
            writeMetadataToDisk();

        } catch (IOException e) {
            LOG.error("Encountered Exception Queueing Items for List:" + _listId + " Exception:"
                    + CCStringUtils.stringifyException(e));
            LOG.error("File Position:" + fixedDataReader.getFilePointer() + " StringsPointer:"
                    + stringDataReader.getFilePointer());
            _queueState = QueueState.QUEUED;
        } finally {
            fixedDataReader.close();
            stringDataReader.close();
        }
        LOG.info("*** LIST:" + getListId() + " SUBDOMAIN METADATA REBUILT FROM LIST DATA . WRITING TO DISK");

        // write metadat to disk 
        writeInitialSubDomainMetadataToDisk();

        LOG.info("*** LIST:" + getListId() + " SUBDOMAIN METADATA REBUILT FROM LIST DATA . WRITE COMPLETE");
    }
}