@Test
public void test4(){
    FileReader fr = null;
    FileWriter fw = null;
    try {
        fr = new FileReader("hello.txt");
        fw = new FileWriter("hello1.txt");

        char[] cbuf = new char[5];
        int len;
        while ((len = fr.read(cbuf)) != -1){
            fw.write(cbuf, 0, len);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        if (fw != null){
            try {
                fw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (fr != null){
            try {
                fr.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}