import java.net.*;
import java.io.*;
public class ClientSocketDemo 
{
	//聲明客戶端Socket對象socket
	Socket socket = null;
	
	//聲明客戶器端數據輸入輸出流
    DataInputStream in;
    DataOutputStream out;
    
    //聲明字符串數組對象response，用于存儲從服務器接收到的信息
    String response[];

    //執行過程中，沒有參數時的構造方法，本地服務器在本地，取默認端口10745
	public ClientSocketDemo()   
	{   
		try
		{
			//創建客戶端socket，服務器地址取本地，端口號為10745
			socket = new Socket("localhost",10745);
			
			//創建客戶端數據輸入輸出流，用于對服務器端發送或接收數據
            in = new DataInputStream(socket.getInputStream());
            out = new DataOutputStream(socket.getOutputStream());
            
            //獲取客戶端地址及端口號
            String ip = String.valueOf(socket.getLocalAddress());
            String port = String.valueOf(socket.getLocalPort());
            
            //向服務器發送數據
            out.writeUTF("Hello Server.This connection is from client.");
            out.writeUTF(ip);
            out.writeUTF(port);
            
            //從服務器接收數據
            response = new String[3];
            for (int i = 0; i < response.length; i++) 
            {
            	response[i] = in.readUTF();
                System.out.println(response[i]);				
			}     
		}
		catch(UnknownHostException e){e.printStackTrace();}
		catch(IOException e){e.printStackTrace();}
	}
	
	//執行過程中，有一個參數時的構造方法，參數指定服務器地址，取默認端口10745
	public ClientSocketDemo(String hostname)
	{
		try
		{
			//創建客戶端socket，hostname參數指定服務器地址，端口號為10745
			socket = new Socket(hostname,10745);
            in = new DataInputStream(socket.getInputStream());
            out = new DataOutputStream(socket.getOutputStream());
            
            String ip = String.valueOf(socket.getLocalAddress());
            String port = String.valueOf(socket.getLocalPort());
            
            out.writeUTF("Hello Server.This connection is from client.");
            out.writeUTF(ip);
            out.writeUTF(port);
            
            response = new String[3];
            for (int i = 0; i < response.length; i++) 
            {
            	response[i] = in.readUTF();
                System.out.println(response[i]);				
			} 
		}
		catch(UnknownHostException e){e.printStackTrace();}
		catch(IOException e){e.printStackTrace();}
	}
	
	//執行過程中，有兩個個參數時的構造方法，第一個參數hostname指定服務器地址
	//第一個參數serverPort指定服務器端口號
	public ClientSocketDemo(String hostname,String serverPort)
	{
		try
		{
			socket = new Socket(hostname,Integer.parseInt(serverPort));
            in = new DataInputStream(socket.getInputStream());
            out = new DataOutputStream(socket.getOutputStream());
            
            String ip = String.valueOf(socket.getLocalAddress());
            String port = String.valueOf(socket.getLocalPort());
            
            out.writeUTF("Hello Server.This connection is from client.");
            out.writeUTF(ip);
            out.writeUTF(port);
            
            response = new String[3];
            for (int i = 0; i < response.length; i++) 
            {
            	response[i] = in.readUTF();
                System.out.println(response[i]);				
			} 
		}
		catch(UnknownHostException e){e.printStackTrace();}
		catch(IOException e){e.printStackTrace();}
	}
	
	public static void main(String[] args) 
	{
		String comd[] = args;
		if(comd.length == 0)
		{
			System.out.println("Use localhost(127.0.0.1) and default port");
			ClientSocketDemo demo = new ClientSocketDemo();	
		}
		else if(comd.length == 1)
		{
			System.out.println("Use default port");
			ClientSocketDemo demo = new ClientSocketDemo(args[0]);	
		}
		else if(comd.length == 2)
		{
			System.out.println("Hostname and port are named by user");
			ClientSocketDemo demo = new ClientSocketDemo(args[0],args[1]);	
		}
		else System.out.println("ERROR");
	}
}