在java里边，如何实现对包的定义和引用，？

定义：package+ 包名;
引用：import+ 包名;
例如:javabao
定义一个包名时,用上面定义的文件夹,如下:
package javabao;
把这条语句放在程序的最前面;例如
package javabao;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Test extends HttpServlet{
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html");
PrintWriter ut=response.getWriter();
out.println("
This is a servlet test.
");