fileutils.java

java上传文件的一个例子。使用了apache的第三方开源组件。

    //-----------------------------------------------------------------------
    /**
     * Writes a String to a file creating the file if it does not exist.
     * <p>
     * There is no writeStringToFile method without encoding parameter because
     * the default encoding can differ between platforms and will have
     * inconsistent results.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param encoding  the encoding to use, null means platform default
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     */
    public static void writeStringToFile(File file,
            String data, String encoding) throws IOException {
        OutputStream out = new FileOutputStream(file);
        try {
            IOUtils.write(data, out, encoding);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * Writes a byte array to a file creating the file if it does not exist.
     *
     * @param file  the file to write to
     * @param data  the content to write to the file
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.1
     */
    public static void writeByteArrayToFile(
            File file, byte[] data) throws IOException {
        OutputStream out = new FileOutputStream(file);
        try {
            out.write(data);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The specified character encoding and the default line ending will be used.
     * <p>
     * There is no writeLines method without encoding parameter because
     * the default encoding can differ between platforms and will have
     * inconsistent results.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, null means platform default
     * @param lines  the lines to write, null entries produce blank lines
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 1.1
     */
    public static void writeLines(File file, String encoding, Collection lines) throws IOException {
        writeLines(file, encoding, lines, null);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The specified character encoding and the line ending will be used.
     * <p>
     * There is no writeLines method without encoding parameter because
     * the default encoding can differ between platforms and will have
     * inconsistent results.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, null means platform default
     * @param lines  the lines to write, null entries produce blank lines
     * @param lineEnding  the line separator to use, null is system default
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 1.1
     */
    public static void writeLines(File file, String encoding, Collection lines, String lineEnding) throws IOException {
        OutputStream out = new FileOutputStream(file);
        try {
            IOUtils.writeLines(lines, lineEnding, out, encoding);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Delete a file. If file is a directory, delete it and all sub-directories.
     * <p>
     * The difference between File.delete() and this method are:
     * <ul>
     * <li>A directory to be deleted does not have to be empty.</li>
     * <li>You get exceptions when a file or directory cannot be deleted.
     *      (java.io.File methods returns a boolean)</li>
     * </ul>
     *
     * @param file  file or directory to delete, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException in case deletion is unsuccessful
     */
    public static void forceDelete(File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectory(file);
        } else {
            if (!file.exists()) {
                throw new FileNotFoundException("File does not exist: " + file);
            }
            if (!file.delete()) {
                String message =
                    "Unable to delete file: " + file;
                throw new IOException(message);
            }
        }
    }

    /**
     * Schedule a file to be deleted when JVM exits.
     * If file is directory delete it and all sub-directories.
     *
     * @param file  file or directory to delete, not null
     * @throws NullPointerException if the file is null
     * @throws IOException in case deletion is unsuccessful
     */
    public static void forceDeleteOnExit(File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectoryOnExit(file);
        } else {
            file.deleteOnExit();
        }
    }

    /**
     * Recursively schedule directory for deletion on JVM exit.
     *
     * @param directory  directory to delete, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException in case deletion is unsuccessful
     */
    private static void deleteDirectoryOnExit(File directory) throws IOException {
        if (!directory.exists()) {
            return;
        }

        cleanDirectoryOnExit(directory);
        directory.deleteOnExit();
    }

    /**
     * Clean a directory without deleting it.
     *
     * @param directory  directory to clean, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException in case cleaning is unsuccessful
     */
    private static void cleanDirectoryOnExit(File directory) throws IOException {
        if (!directory.exists()) {
            String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }

        if (!directory.isDirectory()) {
            String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }

        File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            throw new IOException("Failed to list contents of " + directory);
        }

        IOException exception = null;
        for (int i = 0; i < files.length; i++) {
            File file = files[i];
            try {
                forceDeleteOnExit(file);
            } catch (IOException ioe) {
                exception = ioe;
            }
        }

        if (null != exception) {
            throw exception;
        }
    }

    /**
     * Make a directory, including any necessary but nonexistent parent
     * directories. If there already exists a file with specified name or
     * the directory cannot be created then an exception is thrown.
     *
     * @param directory  directory to create, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException if the directory cannot be created
     */
    public static void forceMkdir(File directory) throws IOException {
        if (directory.exists()) {
            if (directory.isFile()) {
                String message =
                    "File "
                        + directory
                        + " exists and is "
                        + "not a directory. Unable to create directory.";
                throw new IOException(message);
            }
        } else {
            if (!directory.mkdirs()) {
                String message =
                    "Unable to create directory " + directory;
                throw new IOException(message);
            }
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Recursively count size of a directory (sum of the length of all files).
     *
     * @param directory  directory to inspect, not null
     * @return size of directory in bytes, 0 if directory is security restricted
     * @throws NullPointerException if the directory is null
     */
    public static long sizeOfDirectory(File directory) {
        if (!directory.exists()) {
            String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }

        if (!directory.isDirectory()) {
            String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }

        long size = 0;

        File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            return 0L;
        }
        for (int i = 0; i < files.length; i++) {
            File file = files[i];

            if (file.isDirectory()) {
                size += sizeOfDirectory(file);
            } else {
                size += file.length();
            }
        }

        return size;
    }

    //-----------------------------------------------------------------------
    /**
     * Tests if the specified <code>File</code> is newer than the reference
     * <code>File</code>.
     *
     * @param file  the <code>File</code> of which the modification date must
     * be compared, not null
     * @param reference  the <code>File</code> of which the modification date
     * is used, not null
     * @return true if the <code>File</code> exists and has been modified more
     * recently than the reference <code>File</code>
     * @throws IllegalArgumentException if the file is null
     * @throws IllegalArgumentException if the reference file is null or doesn't exist
     */
     public static boolean isFileNewer(File file, File reference) {
        if (reference == null) {
            throw new IllegalArgumentException("No specified reference file");
        }
        if (!reference.exists()) {
            throw new IllegalArgumentException("The reference file '"
                    + file + "' doesn't exist");
        }
        return isFileNewer(file, reference.lastModified());
    }

    /**
     * Tests if the specified <code>File</code> is newer than the specified
     * <code>Date</code>.
     * 
     * @param file  the <code>File</code> of which the modification date
     * must be compared, not null
     * @param date  the date reference, not null
     * @return true if the <code>File</code> exists and has been modified
     * after the given <code>Date</code>.
     * @throws IllegalArgumentException if the file is null
     * @throws IllegalArgumentException if the date is null
     */
    public static boolean isFileNewer(File file, Date date) {
        if (date == null) {
            throw new IllegalArgumentException("No specified date");
        }
        return isFileNewer(file, date.getTime());
    }

    /**
     * Tests if the specified <code>File</code> is newer than the specified
     * time reference.
     *
     * @param file  the <code>File</code> of which the modification date must
     * be compared, not null
     * @param timeMillis  the time reference measured in milliseconds since the
     * epoch (00:00:00 GMT, January 1, 1970)
     * @return true if the <code>File</code> exists and has been modified after
     * the given time reference.
     * @throws IllegalArgumentException if the file is null
     */
     public static boolean isFileNewer(File file, long timeMillis) {
        if (file == null) {
            throw new IllegalArgumentException("No specified file");
        }
        if (!file.exists()) {
            return false;
        }
        return file.lastModified() > timeMillis;
    }

}