文件的长度，究竟是算什么值？

File file = new File("newke.jpg");
        InputStream in = null;
        int length = 0;
        in = new BufferedInputStream(new FileInputStream(file));
        length = (int)file.length();

file.length() 可以得到一个长度。这里是图片，这样获取是文件长度是否正确？？


如果是文本文件，那么这个长度是字符数，还是字节数呢？
[解决办法]
The length, in bytes, of the file denoted by this abstract pathname
字节
[解决办法]

/**
     * Returns the length of the file denoted by this abstract pathname.
     * The return value is unspecified if this pathname denotes a directory.
     *
     * @return  The length, in bytes, of the file denoted by this abstract
     *          pathname, or <code>0L</code> if the file does not exist.  Some
     *          operating systems may return <code>0L</code> for pathnames
     *          denoting system-dependent entities such as devices or pipes.
     *
     * @throws  SecurityException
     *          If a security manager exists and its <code>{@link
     *          java.lang.SecurityManager#checkRead(java.lang.String)}</code>
     *          method denies read access to the file 
 
     */
    public long length() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
    security.checkRead(path);
}
return fs.getLength(this);
    }

  /**
     * Return the length in bytes of the file denoted by the given abstract
     * pathname, or zero if it does not exist, is a directory, or some other
     * I/O error occurs.
     */
    public abstract long getLength(File f);

字节数，注释里面说明了。