fileutil.java

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            input = new BufferedInputStream(new FileInputStream(srcFile), 1024);
            while (true) {
                int length = input.read(block);
                if (length == -1) break;// end of file
                output.write(block, 0, length);
            }
        } finally {
            if (input != null) {
                try {
                    input.close();
                } catch (IOException ex) {
                    // just ignore
                }
            }
        }
    }

    /**
     * This method could be used to override the path to WEB-INF/classes
     * It can be set when the web app is inited
     * @param path String : new path to override the default path
     */
    public static void setServletClassesPath(String path) {
        log.debug("FileUtil.setServletClassesPath called with path = " + path);

        servletClassesPath = path;

        if (servletClassesPath == null) {
            // From mvnForum.com thread 2243:
            // I am deploying the MVNForum as an ear in Linux box so context real path turns out to be null.
            return;
        }
        if (servletClassesPath.endsWith(File.separator) == false) {
            servletClassesPath = servletClassesPath + File.separatorChar;
            log.debug("FileUtil.setServletClassesPath change path to value = " + servletClassesPath);
        }
    }

    /**
     * This function is used to get the classpath of a reference of one class
     * First, this method tries to get the path from system properties
     * named "mvncore.context.path" (can be configed in web.xml). If it cannot
     * find this parameter, then it will tries to load from the ClassLoader
     * @todo FIXME: load from ClassLoader is not correct on Resin/Linux
     */
    public static String getServletClassesPath() {
        if (servletClassesPath == null) {
            String strPath = System.getProperty("mvncore.context.path");
            if (strPath != null && (strPath.length() > 0)) {
                servletClassesPath = strPath;
            } else {
                ClassLoader classLoader = instance.getClass().getClassLoader();
                URL url = classLoader.getResource("/");
                if (url == null) {
                    // not run on the Servlet environment
                    servletClassesPath = ".";
                } else {
                    servletClassesPath = url.getPath();
                }
            }
            log.debug("servletClassesPath = " + servletClassesPath);
            if (servletClassesPath.endsWith(File.separator) == false) {
                servletClassesPath = servletClassesPath + File.separatorChar;
                //log.warn("servletClassesPath does not end with /: " + servletClassesPath);
            }
        }
        return servletClassesPath;
    }

    /**
     * This method create a file text/css
     * NOTE: This method closes the inputStream after it have done its work.
     *
     * @param inputStream     the stream of a text/css file
     * @param cssFile   the output file, have the ".css" extension or orther extension
     * @throws IOException
     * @throws BadInputException
     * @throws AssertionException
     */
    public static void createTextFile(InputStream inputStream, String textFile)
        throws IOException {

        if (inputStream == null) {
            throw new IllegalArgumentException("Does not accept null input");
        }
        OutputStream outputStream = null;
        try {
            byte[] srcByte = FileUtil.getBytes(inputStream);
            outputStream = new FileOutputStream(textFile);
            outputStream.write(srcByte);
            return;
        } catch (IOException e) {
            log.error("Error", e);
            throw e;
        } finally { // this finally is very important
            inputStream.close();
            if (outputStream != null) outputStream.close();
        }
    }

    /**
     * Write content to a fileName with the destEncoding
     *
     * @param content String
     * @param fileName String
     * @param destEncoding String
     * @throws FileNotFoundException
     * @throws IOException
     */
    public static void writeFile(String content, String fileName, String destEncoding)
        throws FileNotFoundException, IOException {

        File file = null;
        try {
            file = new File(fileName);
            if (file.isFile() == false) {
                throw new IOException("'" + fileName + "' is not a file.");
            }
            if (file.canWrite() == false) {
                throw new IOException("'" + fileName + "' is a read-only file.");
            }
        } finally {
            // we dont have to close File here
        }

        BufferedWriter out = null;
        try {
            FileOutputStream fos = new FileOutputStream(fileName);
            out = new BufferedWriter(new OutputStreamWriter(fos, destEncoding));

            out.write(content);
            out.flush();
        } catch (FileNotFoundException fe) {
            log.error("Error", fe);
            throw fe;
        } catch (IOException e) {
            log.error("Error", e);
            throw e;
        } finally {
            try {
                if (out != null) out.close();
            } catch (IOException ex) {}
        }
    }

    public static String readFile(String fileName, String srcEncoding)
        throws FileNotFoundException, IOException {

        File file = null;
        try {
            file = new File(fileName);
            if (file.isFile() == false) {
                throw new IOException("'" + fileName + "' is not a file.");
            }
        } finally {
            // we dont have to close File here
        }

        BufferedReader reader = null;
        try {
            StringBuffer result = new StringBuffer(1024);
            FileInputStream fis = new FileInputStream(fileName);
            reader = new BufferedReader(new InputStreamReader(fis, srcEncoding));

            char[] block = new char[512];
            while (true) {
                int readLength = reader.read(block);
                if (readLength == -1) break;// end of file
                result.append(block, 0, readLength);
            }
            return result.toString();
        } catch (FileNotFoundException fe) {
            log.error("Error", fe);
            throw fe;
        } catch (IOException e) {
            log.error("Error", e);
            throw e;
        } finally {
            try {
                if (reader != null) reader.close();
            } catch (IOException ex) {}
        }
    }

    /*
     *  1  ABC
     *  2  abC Gia su doc tu dong 1 lay ca thay 5 dong => 1 --> 5
     *  3  ABC
     */
    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 {
            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;
    }

    public static String getHumanSize(long size) {

        int sizeToStringLength = String.valueOf(size).length();
        String humanSize = "";
        DecimalFormat formatter = new DecimalFormat("##0.##");
        if (sizeToStringLength > 9) {
            humanSize += formatter.format((double) size / (1024 * 1024 * 1024)) + " GB";
        } else if (sizeToStringLength > 6) {
            humanSize += formatter.format((double) size / (1024 * 1024)) + " MB";
        } else if (sizeToStringLength > 3) {
            humanSize += formatter.format((double) size / 1024) + " KB";
        } else {
            humanSize += String.valueOf(size) + " Bytes";
        }
        return humanSize;
    }
}