dateathost.java

learning java的源代码。书中每个实例都有相关的代码example。

//file: DateAtHost.java
import java.net.Socket;
import java.io.*;

public class DateAtHost extends java.util.Date {
    static int timePort = 37;
    // seconds from start of 20th century to Jan 1, 1970 00:00 GMT
    static final long offset = 2208988800L;

    public DateAtHost( String host ) throws IOException {
        this( host, timePort );
    }

    public DateAtHost( String host, int port ) throws IOException {
        Socket server = new Socket( host, port );
        DataInputStream din =
          new DataInputStream( server.getInputStream(  ) );
        int time = din.readInt(  );
        server.close(  );

        setTime( (((1L << 32) + time) - offset) * 1000 );
    }
}