字符流Reader、Writer，字符转换流 OutputStreamWriter、InputStreamReader

Reader、Writer是所有字符流的超类。

Writer类方法

void write(String str)

void write(char[] cbuf, int off, int len);

void flush()

void close

OutputStreamWriter构造方法字符编码默认为系统编码，可以不写

FileWriter的append默认为false，可以不写。另一个构造(File file, boolean append)

        Writer out = new FileWriter("E:/a.txt", true);

        OutputStream ops = new FileOutputStream("E:/a.txt", true);
        Writer out = new OutputStreamWriter(ops, "GBK");  // 默认系统编码，可以不写

Reader类

int read(char[] cbuf)

InputStreamReader与OutputStreamWriter类似

FileReader 与 FileWriter类似’

        Reader in = new FileReader("E:/gbk.txt");

        InputStream inStream = new FileInputStream("E/gbk.txt");
        Reader in = new InputStreamReader(inStream, "gbk");