DataInputStream与DataOutputStream类的学习

DataOutputStream类提供了3个写入字符串的方法:
----public writeChars(String s)
----public writeBytes(String s)
----public writeUTF(String s)

对应的DataInputStream类只提供了readUTF的方法;

看了下java视频,也不知道具体怎么解决的,还是先学习下能看懂的吧:
下面给段java代码进行测试:

package cn.com;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class DataStreamTest {

	public static void main(String[] args) {
		// writing data to a File or to a FileDescriptor
		try {
			FileOutputStream fos = new FileOutputStream("count.txt");
			BufferedOutputStream bos = new BufferedOutputStream(fos);
			DataOutputStream dos = new DataOutputStream(bos);

			//写入UTF长度
			dos.writeUTF("ab中国");
			dos.writeBytes("ab中国");
			dos.writeChars("ab中国");
			// 只需关闭最上层流对象
			dos.close();

			FileInputStream fis = new FileInputStream("count.txt");
			BufferedInputStream bis = new BufferedInputStream(fis);
			DataInputStream dis = new DataInputStream(bis);

			System.out.println(dis.readUTF());

			byte[] bus = new byte[1024];

			int len = dis.read(bus);
			System.out.println(new String(bus, 0, len));

		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
}