public static boolean contentEquals(File file1, File file2) throws IOException {
        boolean file1Exists = file1.exists();
        if (file1Exists != file2.exists()) {
            return false;
        }

        if (!file1Exists) {
            // two not existing files are equal
            return true;
        }

        if (file1.isDirectory() || file2.isDirectory()) {
            // don't want to compare directory contents
            throw new IOException("Can't compare directories, only files");
        }

        if (file1.length() != file2.length()) {
            // lengths differ, cannot be equal
            return false;
        }

        if (file1.getCanonicalFile().equals(file2.getCanonicalFile())) {
            // same file
            return true;
        }

        InputStream input1 = null;
        InputStream input2 = null;
        try {
            input1 = new FileInputStream(file1);
            input2 = new FileInputStream(file2);
            return contentEquals(input1, input2);

        } finally {
            input1.close();
            input2.close();
        }
    }


    public static boolean contentEquals(InputStream input1, InputStream input2)
            throws IOException {
        if (!(input1 instanceof BufferedInputStream)) {
            input1 = new BufferedInputStream(input1);
        }
        if (!(input2 instanceof BufferedInputStream)) {
            input2 = new BufferedInputStream(input2);
        }

        int ch = input1.read();
        while (-1 != ch) {
            int ch2 = input2.read();
            if (ch != ch2) {
                return false;
            }
            ch = input1.read();
        }

        int ch2 = input2.read();
        return (ch2 == -1);
    }