android关于RandomAccessFile

RandomAccessFile类
/**
* Allows reading from and writing to a file in a random-access manner. This is
* different from the uni-directional sequential access that a
* {@link FileInputStream} or {@link FileOutputStream} provides. If the file is
* opened in read/write mode, write operations are available as well. The
* position of the next read or write operation can be moved forwards and
* backwards after every operation.
*/

/**
* Constructs a new {@code RandomAccessFile} based on the file named {@code
* fileName} and opens it according to the access string in {@code mode}.
* The file path may be specified absolutely or relative to the system
* property {@code "user.dir"}.
*
* @param fileName
* the name of the file to open.
* @param mode
* the file access <a href="#accessmode">mode</a>, either {@code
* "r"}, {@code "rw"}, {@code "rws"} or {@code "rwd"}.
* @throws FileNotFoundException
* if the file cannot be opened or created according to {@code
* mode}.
* @throws IllegalArgumentException
* if {@code mode} is not {@code "r"}, {@code "rw"}, {@code
* "rws"} or {@code "rwd"}.
*/
public RandomAccessFile(String fileName, String mode) throws FileNotFoundException {
this(new File(fileName), mode);
}