从一个文件中获得一个字符流

1.利用FileWriter类
2.利用PrintWriter类
3.利用fileoutputstream类，并通过outputstreamwriter类获得writer

FileWriter fw = new FileWriter(new File("c:\a.txt"));
PrintWriter pw = new PrintWriter(fw);
fileoutputstream fos = new FileOutputStream(“newPoem.txt”);
OutputStreamWriter osw = new OutputStreamWriter(fos,”UTF-8″);