Example usage for java.io RandomAccessFile length

Introduction

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

Prototype

public native long length() throws IOException;

Source Link

Document

Returns the length of this file.

Usage

From source file:com.piaoyou.util.FileUtil.java

public static String[] getLastLines(File file, int linesToReturn) throws IOException, FileNotFoundException {

    final int AVERAGE_CHARS_PER_LINE = 250;
    final int BYTES_PER_CHAR = 2;

    RandomAccessFile randomAccessFile = null;
    StringBuffer buffer = new StringBuffer(linesToReturn * AVERAGE_CHARS_PER_LINE);
    int lineTotal = 0;
    try {// w  ww .  ja v  a  2 s  . c o  m
        randomAccessFile = new RandomAccessFile(file, "r");
        long byteTotal = randomAccessFile.length();
        long byteEstimateToRead = linesToReturn * AVERAGE_CHARS_PER_LINE * BYTES_PER_CHAR;

        long offset = byteTotal - byteEstimateToRead;
        if (offset < 0) {
            offset = 0;
        }

        randomAccessFile.seek(offset);
        //log.debug("SKIP IS ::" + offset);

        String line = null;
        String lineUTF8 = null;
        while ((line = randomAccessFile.readLine()) != null) {
            lineUTF8 = new String(line.getBytes("ISO8859_1"), "UTF-8");
            lineTotal++;
            buffer.append(lineUTF8).append('\n');
        }
    } finally {
        if (randomAccessFile != null) {
            try {
                randomAccessFile.close();
            } catch (IOException ex) {
            }
        }
    }

    String[] resultLines = new String[linesToReturn];
    BufferedReader in = null;
    try {
        in = new BufferedReader(new StringReader(buffer.toString()));

        int start = lineTotal /* + 2 */ - linesToReturn; // Ex : 55 - 10 = 45 ~ offset
        if (start < 0)
            start = 0; // not start line
        for (int i = 0; i < start; i++) {
            in.readLine(); // loop until the offset. Ex: loop 0, 1 ~~ 2 lines
        }

        int i = 0;
        String line = null;
        while ((line = in.readLine()) != null) {
            resultLines[i] = line;
            i++;
        }
    } catch (IOException ie) {
        log.error("Error" + ie);
        throw ie;
    } finally {
        if (in != null) {
            try {
                in.close();
            } catch (IOException ex) {
            }
        }
    }
    return resultLines;
}

---

From source file:org.apache.jackrabbit.oak.segment.file.TarReader.java

/**
 * Tries to read an existing index from the given tar file. The index is
 * returned if it is found and looks valid (correct checksum, passes
 * sanity checks).//from  ww  w  .j a v a  2  s. co m
 *
 * @param file tar file
 * @param name name of the tar file, for logging purposes
 * @return tar index, or {@code null} if not found or not valid
 * @throws IOException if the tar file could not be read
 */
private static ByteBuffer loadAndValidateIndex(RandomAccessFile file, String name) throws IOException {
    long length = file.length();
    if (length % BLOCK_SIZE != 0 || length < 6 * BLOCK_SIZE || length > Integer.MAX_VALUE) {
        log.warn("Unexpected size {} of tar file {}", length, name);
        return null; // unexpected file size
    }

    // read the index metadata just before the two final zero blocks
    ByteBuffer meta = ByteBuffer.allocate(16);
    file.seek(length - 2 * BLOCK_SIZE - 16);
    file.readFully(meta.array());
    int crc32 = meta.getInt();
    int count = meta.getInt();
    int bytes = meta.getInt();
    int magic = meta.getInt();

    if (magic != INDEX_MAGIC) {
        return null; // magic byte mismatch
    }

    if (count < 1 || bytes < count * TarEntry.SIZE + 16 || bytes % BLOCK_SIZE != 0) {
        log.warn("Invalid index metadata in tar file {}", name);
        return null; // impossible entry and/or byte counts
    }

    // this involves seeking backwards in the file, which might not
    // perform well, but that's OK since we only do this once per file
    ByteBuffer index = ByteBuffer.allocate(count * TarEntry.SIZE);
    file.seek(length - 2 * BLOCK_SIZE - 16 - count * TarEntry.SIZE);
    file.readFully(index.array());
    index.mark();

    CRC32 checksum = new CRC32();
    long limit = length - 2 * BLOCK_SIZE - bytes - BLOCK_SIZE;
    long lastmsb = Long.MIN_VALUE;
    long lastlsb = Long.MIN_VALUE;
    byte[] entry = new byte[TarEntry.SIZE];
    for (int i = 0; i < count; i++) {
        index.get(entry);
        checksum.update(entry);

        ByteBuffer buffer = wrap(entry);
        long msb = buffer.getLong();
        long lsb = buffer.getLong();
        int offset = buffer.getInt();
        int size = buffer.getInt();

        if (lastmsb > msb || (lastmsb == msb && lastlsb > lsb)) {
            log.warn("Incorrect index ordering in tar file {}", name);
            return null;
        } else if (lastmsb == msb && lastlsb == lsb && i > 0) {
            log.warn("Duplicate index entry in tar file {}", name);
            return null;
        } else if (offset < 0 || offset % BLOCK_SIZE != 0) {
            log.warn("Invalid index entry offset in tar file {}", name);
            return null;
        } else if (size < 1 || offset + size > limit) {
            log.warn("Invalid index entry size in tar file {}", name);
            return null;
        }

        lastmsb = msb;
        lastlsb = lsb;
    }

    if (crc32 != (int) checksum.getValue()) {
        log.warn("Invalid index checksum in tar file {}", name);
        return null; // checksum mismatch
    }

    index.reset();
    return index;
}

---

From source file:org.jevis.commons.JEVisFileImp.java

@Override
public void loadFromFile(File file) throws IOException {

    RandomAccessFile f = new RandomAccessFile(file, "r");
    byte[] bytes = new byte[(int) f.length()];
    f.read(bytes);//w ww .jav a 2  s  .  c  o  m
    this.bytes = bytes;

    f.close();

}

---

From source file:org.apache.jackrabbit.oak.plugins.segment.file.TarReader.java

/**
 * Scans through the tar file, looking for all segment entries.
 *
 * @throws IOException if the tar file could not be read
 *///from ww  w. ja v  a  2  s  .  co  m
private static void recoverEntries(File file, RandomAccessFile access, LinkedHashMap<UUID, byte[]> entries)
        throws IOException {
    byte[] header = new byte[BLOCK_SIZE];
    while (access.getFilePointer() + BLOCK_SIZE <= access.length()) {
        // read the tar header block
        access.readFully(header);

        // compute the header checksum
        int sum = 0;
        for (int i = 0; i < BLOCK_SIZE; i++) {
            sum += header[i] & 0xff;
        }

        // identify possible zero block
        if (sum == 0 && access.getFilePointer() + 2 * BLOCK_SIZE == access.length()) {
            return; // found the zero blocks at the end of the file
        }

        // replace the actual stored checksum with spaces for comparison
        for (int i = 148; i < 148 + 8; i++) {
            sum -= header[i] & 0xff;
            sum += ' ';
        }

        byte[] checkbytes = String.format("%06o\0 ", sum).getBytes(UTF_8);
        for (int i = 0; i < checkbytes.length; i++) {
            if (checkbytes[i] != header[148 + i]) {
                log.warn("Invalid entry checksum at offset {} in tar file {}, skipping...",
                        access.getFilePointer() - BLOCK_SIZE, file);
            }
        }

        // The header checksum passes, so read the entry name and size
        ByteBuffer buffer = ByteBuffer.wrap(header);
        String name = readString(buffer, 100);
        buffer.position(124);
        int size = readNumber(buffer, 12);
        if (access.getFilePointer() + size > access.length()) {
            // checksum was correct, so the size field should be accurate
            log.warn("Partial entry {} in tar file {}, ignoring...", name, file);
            return;
        }

        Matcher matcher = NAME_PATTERN.matcher(name);
        if (matcher.matches()) {
            UUID id = UUID.fromString(matcher.group(1));

            String checksum = matcher.group(3);
            if (checksum != null || !entries.containsKey(id)) {
                byte[] data = new byte[size];
                access.readFully(data);

                // skip possible padding to stay at block boundaries
                long position = access.getFilePointer();
                long remainder = position % BLOCK_SIZE;
                if (remainder != 0) {
                    access.seek(position + (BLOCK_SIZE - remainder));
                }

                if (checksum != null) {
                    CRC32 crc = new CRC32();
                    crc.update(data);
                    if (crc.getValue() != Long.parseLong(checksum, 16)) {
                        log.warn("Checksum mismatch in entry {} of tar file {}, skipping...", name, file);
                        continue;
                    }
                }

                entries.put(id, data);
            }
        } else if (!name.equals(file.getName() + ".idx")) {
            log.warn("Unexpected entry {} in tar file {}, skipping...", name, file);
            long position = access.getFilePointer() + size;
            long remainder = position % BLOCK_SIZE;
            if (remainder != 0) {
                position += BLOCK_SIZE - remainder;
            }
            access.seek(position);
        }
    }
}

---

From source file:eu.trentorise.smartcampus.feedback.test.TestFeedbackManagers.java

private byte[] readTestFile() throws IOException {
    RandomAccessFile f = new RandomAccessFile("src/test/resources/android.jpg", "r");
    byte[] b = new byte[(int) f.length()];
    f.read(b);/*  w  w w  . j a  v a 2s  .  c  om*/
    f.close();
    return b;
}

---

From source file:ch.cyberduck.core.io.FileBuffer.java

@Override
public synchronized int read(final byte[] chunk, final Long offset) throws IOException {
    final RandomAccessFile file = random();
    if (offset < file.length()) {
        file.seek(offset);/*from   www. j ava 2s  . co  m*/
        if (chunk.length + offset > file.length()) {
            return file.read(chunk, 0, (int) (file.length() - offset));
        } else {
            return file.read(chunk, 0, chunk.length);
        }
    } else {
        final NullInputStream nullStream = new NullInputStream(length);
        if (nullStream.available() > 0) {
            nullStream.skip(offset);
            return nullStream.read(chunk, 0, chunk.length);
        } else {
            return IOUtils.EOF;
        }
    }
}

---

From source file:org.waveprotocol.box.server.persistence.file.DeltaStoreTest.java

public void testRecoverFromTruncatedDeltas() throws Exception {
    // Create an entry with one record. Shrink the file byte by byte and ensure
    // we can read it without crashing.
    DeltaStore store = newDeltaStore();//  w  w w  . java  2  s.  c om
    WaveletDeltaRecord written = createRecord();
    File deltaFile = FileDeltaCollection.deltasFile(path.getAbsolutePath(), WAVE1_WAVELET1);

    long toRemove = 1;
    while (true) {
        // This generates the full file.
        DeltasAccess wavelet = store.open(WAVE1_WAVELET1);
        wavelet.append(ImmutableList.of(written));
        wavelet.close();

        RandomAccessFile file = new RandomAccessFile(deltaFile, "rw");
        if (toRemove > file.length()) {
            file.close();
            break;
        }
        // eat the planned number of bytes
        LOG.info("trying to remove " + toRemove + " bytes");
        file.setLength(file.length() - toRemove);
        file.close();

        wavelet = store.open(WAVE1_WAVELET1);
        WaveletDeltaRecord read = wavelet.getDelta(0);
        assertNull("got an unexpected record " + read, read);
        wavelet.close();
        toRemove++;
    }
}

---

From source file:ch.cyberduck.core.io.FileBuffer.java

@Override
public void truncate(final Long length) {
    this.length = length;
    if (temporary.exists()) {
        try {/*w  ww.jav a2 s  . c o  m*/
            final RandomAccessFile file = random();
            if (length < file.length()) {
                // Truncate current
                file.setLength(length);
            }
        } catch (IOException e) {
            log.warn(String.format("Failure truncating file %s to %d", temporary, length));
        }
    }
}

---

From source file:jp.andeb.obbutil.ObbUtilMain.java

private static boolean doRemove(String[] args) {
    if (args.length != 1) {
        printUsage(PROGNAME);//from w  ww.j  a va 2  s  .co  m
        return false;
    }
    final File targetFile = new File(args[0]);
    final RandomAccessFile targetRaFile;
    try {
        targetRaFile = new RandomAccessFile(targetFile, "rw");
    } catch (FileNotFoundException e) {
        System.err.println("????: " + targetFile.getPath());
        return false;
    }
    try {
        final ObbInfoV1 obbInfo;
        try {
            obbInfo = ObbInfoV1.fromFile(targetRaFile);
        } catch (IOException e) {
            System.err
                    .println("????????: " + targetFile.getPath());
            return false;
        } catch (NotObbException e) {
            System.err.println(
                    "? OBB ???????: " + targetFile.getPath());
            return false;
        }

        final ByteBuffer obbInfoBytes = obbInfo.toBytes();
        targetRaFile.setLength(targetRaFile.length() - obbInfoBytes.remaining());
    } catch (IOException e) {
        System.err.println("OBB ??????: " + targetFile.getPath());
        return false;
    } finally {
        try {
            targetRaFile.close();
        } catch (IOException e) {
            System.err.println("OBB ??????: " + targetFile.getPath());
            return false;
        }
    }

    System.err.println("OBB ???????: " + targetFile.getPath());
    return true;
}

---

From source file:com.louding.frame.http.download.FileEntityHandler.java

public File handleEntity(HttpEntity entity, DownloadProgress callback, File save, boolean isResume)
        throws IOException {
    long current = 0;
    RandomAccessFile file = new RandomAccessFile(save, "rw");
    if (isResume) {
        current = file.length();
    }//from w ww . jav  a 2  s. c  om
    InputStream input = entity.getContent();
    long count = entity.getContentLength() + current;
    if (mStop) {
        FileUtils.closeIO(file);
        return save;
    }
    // ???????
    /**
     *  <br>
     * current = input.skip(current); <br>
     * file.seek(current); <br>
     * ?JDKInputstream.skip(long i)i<br>
     * ? n ???????
     */
    file.seek(input.skip(current));

    int readLen = 0;
    byte[] buffer = new byte[1024];

    while ((readLen = input.read(buffer, 0, 1024)) != -1) {
        if (mStop) {
            break;
        } else {
            file.write(buffer, 0, readLen);
            current += readLen;
            callback.onProgress(count, current);
        }
    }
    callback.onProgress(count, current);

    if (mStop && current < count) { // ?
        FileUtils.closeIO(file);
        throw new IOException("user stop download thread");
    }
    FileUtils.closeIO(file);
    return save;
}

---

• «
• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• »