Writer

Appendable 接口可以将 char 类型的数据读入到数据缓冲区

OutputStreamWriter 处理流

OutputStreamWriter 的功能是将输出字节流转成输出字符流，与 InputStreamReader 相对应的，将输入字节流转成输入字符流

public class Test {
    public static void main(String[] args) throws Exception {
        Writer writer = new FileWriter("/Users/du/Desktop/copy.txt");
        //writer.write("你好");
//        char[] chars = {'你','好','世','界'};
//        writer.write(chars,2,2);
        String str = "Hello World,你好世界";
        writer.write(str,10,6);
        writer.flush();
        writer.close();
    }
}