Example usage for java.io RandomAccessFile seek

Introduction

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

Prototype

public void seek(long pos) throws IOException 

Source Link

Document

Sets the file-pointer offset, measured from the beginning of this file, at which the next read or write occurs.

Usage

From source file:org.ms123.common.git.GitServiceImpl.java

protected static String getFileType(File file) {
    if (file.isDirectory()) {
        return "sw.directory";
    } else if (file.toString().endsWith(".txt")) {
        return "text/plain";
    } else if (file.toString().endsWith(".jpeg") || file.toString().endsWith(".jpg")) {
        return "image/jpeg";
    } else if (file.toString().endsWith(".png")) {
        return "image/png";
    } else if (file.toString().endsWith(".svg")) {
        return "image/svg+xml";
    } else if (file.toString().endsWith(".xml")) {
        return "text/xml";
    } else if (file.toString().endsWith(".woff") || file.toString().endsWith(".woff.gz")) {
        return "application/x-font-woff";
    } else if (file.toString().endsWith(".js") || file.toString().endsWith(".js.gz")) {
        return "text/javascript";
    } else if (file.toString().endsWith(".adoc") || file.toString().endsWith(".adoc.gz")) {
        return "text/x-asciidoc";
    } else if (file.toString().endsWith(".html") || file.toString().endsWith(".html.gz")) {
        return "text/html";
    } else if (file.toString().endsWith(".css") || file.toString().endsWith(".css.gz")) {
        return "text/css";
    } else if (file.toString().endsWith(".yaml") || file.toString().endsWith(".yml")) {
        return "text/x-yaml";
    } else if (file.toString().endsWith(".json") || file.toString().endsWith(".json.gz")) {
        return "application/json";
    } else if (file.toString().endsWith(".odt")) {
        return "application/vnd.oasis.opendocument.text";
    } else if (file.toString().endsWith(".groovy")) {
        return "sw.groovy";
    } else if (file.toString().endsWith(".java")) {
        return "sw.java";
    }//w  w  w  .  j  a v  a  2s .c o m
    RandomAccessFile r = null;
    try {
        int lnr = 0;
        r = new RandomAccessFile(file, "r");
        int i = r.readInt();
        if (i == 1534293853) {
            r.seek(0);
            while (true) {
                String line = r.readLine();
                if (line == null) {
                    break;
                }
                if (lnr == 0 && !line.startsWith("[sw]"))
                    break;
                if (line.trim().startsWith("type")) {
                    int eq = line.indexOf("=");
                    if (eq != -1) {
                        return line.substring(eq + 1).trim();
                    }
                }
                lnr++;
                if (lnr > 20)
                    break;
            }
        } else if (i == -2555936) {
            return "image/jpeg";
        } else if (i == -1991225785) {
            return "image/png";
        }
    } catch (Exception e) {
        return "sw.unknown";
    } finally {
        closeFile(r);
    }
    return detectFileType(file);
}

---

From source file:org.exist.util.VirtualTempFile.java

/**
  * The method <code>getChunk</code>
  */*from w  w  w.java2 s.c  om*/
  * @param offset a <code>long</code> value
  * @return a <code>byte[]</code> value
  * @exception IOException if an error occurs
  */
public byte[] getChunk(long offset) throws IOException {
    byte[] data = null;

    if (os != null) {
        close();
    }

    if (tempFile != null) {
        final RandomAccessFile raf = new RandomAccessFile(tempFile, "r");
        raf.seek(offset);
        long remaining = raf.length() - offset;
        if (remaining > maxChunkSize) {
            remaining = maxChunkSize;
        } else if (remaining < 0) {
            remaining = 0;
        }
        data = new byte[(int) remaining];
        raf.readFully(data);
        raf.close();
    } else if (tempBuffer != null) {
        long remaining = tempBuffer.length - offset;
        if (remaining > maxChunkSize) {
            remaining = maxChunkSize;
        } else if (remaining < 0) {
            remaining = 0;
        }
        data = new byte[(int) remaining];
        if (remaining > 0) {
            System.arraycopy(tempBuffer, (int) offset, data, 0, (int) remaining);
        }
    }

    return data;
}

---

From source file:hudson.util.TextFile.java

/**
 * Efficiently reads the last N characters (or shorter, if the whole file is shorter than that.)
 *
 * <p>/*from w  w w.j  a v  a 2 s .  com*/
 * This method first tries to just read the tail section of the file to get the necessary chars.
 * To handle multi-byte variable length encoding (such as UTF-8), we read a larger than
 * necessary chunk.
 *
 * <p>
 * Some multi-byte encoding, such as Shift-JIS (http://en.wikipedia.org/wiki/Shift_JIS) doesn't
 * allow the first byte and the second byte of a single char to be unambiguously identified,
 * so it is possible that we end up decoding incorrectly if we start reading in the middle of a multi-byte
 * character. All the CJK multi-byte encodings that I know of are self-correcting; as they are ASCII-compatible,
 * any ASCII characters or control characters will bring the decoding back in sync, so the worst
 * case we just have some garbage in the beginning that needs to be discarded. To accommodate this,
 * we read additional 1024 bytes.
 *
 * <p>
 * Other encodings, such as UTF-8, are better in that the character boundary is unambiguous,
 * so there can be at most one garbage char. For dealing with UTF-16 and UTF-32, we read at
 * 4 bytes boundary (all the constants and multipliers are multiples of 4.)
 *
 * <p>
 * Note that it is possible to construct a contrived input that fools this algorithm, and in this method
 * we are willing to live with a small possibility of that to avoid reading the whole text. In practice,
 * such an input is very unlikely.
 *
 * <p>
 * So all in all, this algorithm should work decently, and it works quite efficiently on a large text.
 */
public @Nonnull String fastTail(int numChars, Charset cs) throws IOException {
    RandomAccessFile raf = new RandomAccessFile(file, "r");

    try {
        long len = raf.length();
        // err on the safe side and assume each char occupies 4 bytes
        // additional 1024 byte margin is to bring us back in sync in case we started reading from non-char boundary.
        long pos = Math.max(0, len - (numChars * 4 + 1024));
        raf.seek(pos);

        byte[] tail = new byte[(int) (len - pos)];
        raf.readFully(tail);

        String tails = cs.decode(java.nio.ByteBuffer.wrap(tail)).toString();

        return new String(tails.substring(Math.max(0, tails.length() - numChars))); // trim the baggage of substring by allocating a new String
    } finally {
        raf.close();
    }
}

---

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

public boolean isConversionNeeded(StorageDirectory sd) throws IOException {
    File oldF = new File(sd.getRoot(), "storage");
    if (!oldF.exists())
        return false;
    // check the layout version inside the storage file
    // Lock and Read old storage file
    RandomAccessFile oldFile = new RandomAccessFile(oldF, "rws");
    FileLock oldLock = oldFile.getChannel().tryLock();
    try {/*from   www . j a v  a2s .co  m*/
        oldFile.seek(0);
        int oldVersion = oldFile.readInt();
        if (oldVersion < LAST_PRE_UPGRADE_LAYOUT_VERSION)
            return false;
    } finally {
        oldLock.release();
        oldFile.close();
    }
    return true;
}

---

From source file:com.jk.framework.util.FakeRunnable.java

/**
 * Write on file.//from   ww w  .j av  a 2 s .co m
 *
 * @author Mohamde Kiswani
 * @param file
 *            the file
 * @param string
 *            the string
 * @param lineIndex
 *            the line index
 * @throws IOException
 *             Signals that an I/O exception has occurred.
 * @since 28-1-2010
 * @description : to write on file by using random access ssechanism
 */
public static void writeOnFile(final File file, final String string, final long lineIndex) throws IOException {
    final RandomAccessFile rand = new RandomAccessFile(file, "rw");
    rand.seek(lineIndex); // Seek to lineIndex of file
    rand.writeBytes(string); // Write end of file
    rand.close();
}

---

From source file:org.apache.sshd.server.filesystem.NativeSshFile.java

/**
 * Create output stream for writing.//from w  w  w  .  j av  a  2 s.c o m
 */
public OutputStream createOutputStream(final long offset) throws IOException {

    // permission check
    if (!isWritable()) {
        throw new IOException("No write permission : " + file.getName());
    }

    // create output stream
    final RandomAccessFile raf = new RandomAccessFile(file, "rw");
    raf.setLength(offset);
    raf.seek(offset);

    // The IBM jre needs to have both the stream and the random access file
    // objects closed to actually close the file
    return new FileOutputStream(raf.getFD()) {
        public void close() throws IOException {
            super.close();
            raf.close();
        }
    };
}

---

From source file:org.patientview.monitoring.ImportMonitor.java

/**
 * Returns the last N lines of a file. Assumes lines are terminated by |n ascii character
 *//*from   w w  w. j a  v  a  2 s .  co m*/
private static List<String> getLastNLinesOfFile(int numberOfLinesToReturn) {
    List<String> lastNLines = new ArrayList<String>();
    java.io.RandomAccessFile fileHandler = null;

    try {
        File file = getTodaysCountFile();

        fileHandler = new java.io.RandomAccessFile(file, "r");

        long totalNumberOfCharactersInFile = file.length() - 1;

        StringBuilder sb = new StringBuilder();
        int numberOfLinesRead = 0;

        /**
         * loop through characters in file, construct lines out of characters, add lines to a list
         */
        for (long currentCharacter = totalNumberOfCharactersInFile; currentCharacter != -1; currentCharacter--) {
            fileHandler.seek(currentCharacter);

            int readByte = fileHandler.readByte();

            if (readByte == LINE_FEED || readByte == CARRIAGE_RETURN) {
                if (numberOfLinesRead == numberOfLinesToReturn) {
                    break;
                }

                numberOfLinesRead++;

                /**
                 * add line to line list
                 */
                String currentLine = sb.reverse().toString();
                sb = new StringBuilder();

                if (StringUtils.isNotBlank(currentLine)) {
                    lastNLines.add(currentLine);
                } else {
                    LOGGER.error("Read line does not contain any data");
                    continue;
                }
            } else {
                sb.append((char) readByte);
            }
        }

        /**
         * add the last line
         */
        lastNLines.add(sb.reverse().toString());
    } catch (Exception e) {
        LOGGER.error("Can not find today's file", e);
    } finally {
        if (fileHandler != null) {
            try {
                fileHandler.close();
            } catch (IOException e) {
                fileHandler = null;
            }
        }
    }

    return lastNLines;
}

---

From source file:org.apache.hadoop.hdfs.TestReplication.java

public void testPendingReplicationRetry() throws IOException {

    MiniDFSCluster cluster = null;/*w  ww  .j  ava  2 s .  c o m*/
    int numDataNodes = 4;
    String testFile = "/replication-test-file";
    Path testPath = new Path(testFile);

    byte buffer[] = new byte[1024];
    for (int i = 0; i < buffer.length; i++) {
        buffer[i] = '1';
    }

    try {
        Configuration conf = new Configuration();
        conf.set("dfs.replication", Integer.toString(numDataNodes));
        //first time format
        cluster = new MiniDFSCluster(0, conf, numDataNodes, true, true, null, null);
        cluster.waitActive();
        DFSClient dfsClient = new DFSClient(new InetSocketAddress("localhost", cluster.getNameNodePort()),
                conf);

        OutputStream out = cluster.getFileSystem().create(testPath);
        out.write(buffer);
        out.close();

        waitForBlockReplication(testFile, dfsClient.namenode, numDataNodes, -1);

        // get first block of the file.
        String block = dfsClient.namenode.getBlockLocations(testFile, 0, Long.MAX_VALUE).get(0).getBlock()
                .getBlockName();

        cluster.shutdown();
        cluster = null;

        //Now mess up some of the replicas.
        //Delete the first and corrupt the next two.
        File baseDir = new File(System.getProperty("test.build.data"), "dfs/data");
        for (int i = 0; i < 25; i++) {
            buffer[i] = '0';
        }

        int fileCount = 0;
        for (int i = 0; i < 6; i++) {
            File blockFile = new File(baseDir, "data" + (i + 1) + "/current/" + block);
            LOG.info("Checking for file " + blockFile);

            if (blockFile.exists()) {
                if (fileCount == 0) {
                    LOG.info("Deleting file " + blockFile);
                    assertTrue(blockFile.delete());
                } else {
                    // corrupt it.
                    LOG.info("Corrupting file " + blockFile);
                    long len = blockFile.length();
                    assertTrue(len > 50);
                    RandomAccessFile blockOut = new RandomAccessFile(blockFile, "rw");
                    try {
                        blockOut.seek(len / 3);
                        blockOut.write(buffer, 0, 25);
                    } finally {
                        blockOut.close();
                    }
                }
                fileCount++;
            }
        }
        assertEquals(3, fileCount);

        /* Start the MiniDFSCluster with more datanodes since once a writeBlock
         * to a datanode node fails, same block can not be written to it
         * immediately. In our case some replication attempts will fail.
         */

        LOG.info("Restarting minicluster after deleting a replica and corrupting 2 crcs");
        conf = new Configuration();
        conf.set("dfs.replication", Integer.toString(numDataNodes));
        conf.set("dfs.replication.pending.timeout.sec", Integer.toString(2));
        conf.set("dfs.datanode.block.write.timeout.sec", Integer.toString(5));
        conf.set("dfs.safemode.threshold.pct", "0.75f"); // only 3 copies exist

        cluster = new MiniDFSCluster(0, conf, numDataNodes * 2, false, true, null, null);
        cluster.waitActive();

        dfsClient = new DFSClient(new InetSocketAddress("localhost", cluster.getNameNodePort()), conf);

        waitForBlockReplication(testFile, dfsClient.namenode, numDataNodes, -1);

    } finally {
        if (cluster != null) {
            cluster.shutdown();
        }
    }
}

---

From source file:edu.harvard.i2b2.patientMapping.ui.PatientIDConversionJFrame.java

private void append(RandomAccessFile f, String outString) throws IOException {
    try {/* w  ww  . ja va  2 s . co  m*/
        f.seek(f.length());
        f.writeBytes(outString);
    } catch (IOException e) {
        throw new IOException("trouble writing to random access file.");
    }
    return;
}

---

From source file:com.microsoft.azure.management.datalake.store.uploader.SingleSegmentUploader.java

/**
 * Opens the input stream./*w w  w.  j  a va 2 s  .c  o  m*/
 * @return A {@link RandomAccessFile} stream of the file being uploaded.
 * @throws IOException Thrown if the input stream cannot be opened due to file accessibility or existence.
 */
private RandomAccessFile openInputStream() throws IOException {
    RandomAccessFile stream = new RandomAccessFile(metadata.getInputFilePath(), "r");

    if (segmentMetadata.getOffset() >= stream.length()) {
        throw new IllegalArgumentException("StartOffset is beyond the end of the input file");
    }

    // always seek from the beginning of the file
    stream.seek(0);
    stream.seek(segmentMetadata.getOffset());
    return stream;
}

---

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