解决DataOutputStream乱码的问题

public final void writeBytes(String s)
public final void writeChars(String s)
public final void writeUTF(String str)

File file = new File("d:"+File.separator+"test.txt");
   DataOutputStream dos = new DataOutputStream(new FileOutputStream(file));
   dos.writeBytes("你好");
   dos.writeChars("你好");
   dos.writeUTF("你好");
   dos.flush();
   dos.close();
   
   DataInputStream dis = new DataInputStream(new FileInputStream(file));
   byte[] b = new byte[2];
   dis.read(b);
            //  `}
   System.out.println(new String(b, 0, 2));
   
   char[] c = new char[2];
   for (int i = 0; i < 2; i++) {
    c[i] = dis.readChar();
   }
            //你好
   System.out.println(new String(c, 0, 2));
   //你好
   System.out.println(dis.readUTF());

public final void writeBytes(String s) throws IOException {
        int len = s.length();
        for (int i = 0 ; i < len ; i++) {
            out.write((byte)s.charAt(i));
        }
        incCount(len);
    }

OutputStreamWriter oStreamWriter = new OutputStreamWriter(new FileOutputStream(file), "utf-8");
oStreamWriter.append(str);
oStreamWriter.close();