关于hasnextLine()方法的一些理解

package Service;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class Service_1 {
    public static void main(String [] args) throws IOException{
        ServerSocket ss=new ServerSocket(9999);
        System.out.println("我是服务器"+ss.getInetAddress());
        
        Scanner sc=null;
        PrintWriter pw=null;
        int i=1;
        while(true){
            Socket s=ss.accept();
            System.out.println("有一个端口连接上来"+s.getInetAddress());
            
            //获取输入流
            sc=new Scanner(s.getInputStream());
            pw=new PrintWriter(s.getOutputStream());
        
            
        
//            pw.println("I am Server "+i);
//            pw.flush();
            //System.out.println(sc.hasNextLine());  //如果这里加了这一行会形成阻塞的
            do{
              
                pw.println("I am Server "+i);
                pw.flush();
                if(sc.hasNextLine()){
                    System.out.println("这个客户端对我说:"+sc.nextLine());
                }
                i++;
            }while(true);
        }
    
    }
}

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;


public class TestClient4 {

    /**
     * @param args
     * @throws IOException 
     * @throws  
     */
    public static void main(String[] args) throws  IOException {
        Socket s=new Socket("localhost",9999);
        System.out.println("客户端连接上"+s.getLocalPort());
        
        Scanner sc=new Scanner(s.getInputStream());
        PrintWriter pw=new PrintWriter(s.getOutputStream());
        
        //先接
        while( sc.hasNextLine()){
            String line=sc.nextLine();
            line=new String(line.getBytes(),"UTF-8");
            System.out.println("服务器"+s.getInetAddress()+"客户端说"+line);
            if( "bye".equals(line)){
                System.out.println("服务器"+s.getInetAddress()+"断开了与客户端的连接");
                s.close();
                break;
            }
            //回复服务器
            String response=talk( s.getInetAddress().toString());
            pw.println(response);
            pw.flush();
            if( "bye".equals(response)){
                System.out.println("客户端主动断开与服务器的连接");
                s.close();
                break;
            }
        }
        
        
    }
    
    public static String talk(String client){
        Scanner sc =new Scanner(System.in);
        System.out.println("客户端表达的话:");
        String line=sc.nextLine();
        return line;
    }

}