因此，对于我正在进行的类，我们有基于Java套接字的赋值，我们必须将一个字符串从客户端传递到服务器端，这将删除所有前导和尾随空白。代码如下：
TrimClient：
import java.io.*;
import java.net.*;
public class TrimClient
{
public static void main (String [] args)
{
Socket s; //Client socket for connecting to the server
String server = "localhost"; //Use localhost by default
int serverPort = 1221; //Use port 1221 by default
InetAddress local, remote; //Local and remote addresses
int localPort, remotePort; //Local and remote ports
//For input and output
BufferedReader socketIn; //Socket input
PrintWriter socketOut; //Socket output
BufferedReader keyboardIn; //Keyboard input
String userInput, serverResult;
//Process command line arguments
//Error if more than two command line arguments
if (args.length > 2)
{
System.out.println("Usage: java TrimClient "
+ "[-port=<number>] [server]");
System.exit(-1);
}
//If two arguments, only one should start with '-'
if (args.length == 2)
{
if ((args[0].charAt(0) == '-' &&
args[1].charAt(0) == '-' ) ||
(args[0].charAt(0) != '-' &&
args[1].charAt(0) != '-' ))
{
System.out.println("Usage: "
+ "java TrimClient "
+ "[-port=<number>] [server]");
System.exit(-1);
}
}
//Set the server and server port suitably
for (int i = 0; i < args.length; i++)
{
if (args[i].charAt(0) != '-')
server = args[i];
if (args[i].startsWith("-port="))
serverPort = Integer.parseInt(args[i].substring(6));
}
//Set up keyboard input and print greeting
keyboardIn = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Hello, you have invoked a Trim Client");
System.out.println("You have requested a connection to " +
server + " at port " + serverPort);
System.out.println(); //Blank line
//Establish socket connection and communicate
try
{
//Establish connection
s = new Socket(server, serverPort);
//Report connection status
local = s.getLocalAddress(); remote = s.getInetAddress();
localPort = s.getLocalPort(); remotePort = s.getPort();
System.out.println ("Client side");
System.out.println (" " + local.getHostName()
+ "[" + local.getHostAddress() + "]"
+ " at port " + localPort);
System.out.println ("Server side");
System.out.println (" " + remote.getHostName()
+ "[" + remote.getHostAddress() + "]"
+ " at port " + remotePort);
System.out.println(); //Blank line
//TCP provides a full-duplex byte stream service
//For UNICODE and line support, we need BufferedReader
//and PrintWriter objects
socketIn = new BufferedReader(new InputStreamReader(s.getInputStream()));
socketOut = new PrintWriter(s.getOutputStream(), true);
//Interact with user
System.out.print("Enter a string (or press "Enter" to quit): ");
userInput = keyboardIn.readLine();
//Loop until user indicates termination
while (!userInput.equalsIgnoreCase(" "))
{
//Send user input to server
socketOut.println(userInput);
//Get server response
serverResult = socketIn.readLine();
//Report server response
System.out.println(serverResult);
System.out.println(); //Blank line
//Get new string
System.out.print("Enter a string (or press "Enter" to quit): ");
userInput = keyboardIn.readLine();
}
//Signal the server to quit
socketOut.println(userInput);
//Close all streams and socket
keyboardIn.close();
socketIn.close();
socketOut.close();
s.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
TrimServer：
import java.io.*;
import java.net.*;
public class TrimServer
{
public static void main (String [] args)
{
ServerSocket ss = null; //Server socket to offer service
Socket s; //Socket to accept connection
int serverPort = 1221; //Use port 1221 by default
InetAddress local, remote; //Local and remote addresses
int localPort, remotePort; //Local and remote ports
//For input and output
BufferedReader socketIn; //Socket input
PrintWriter socketOut; //Socket output
String clientInput; //String sent by client
String serverResult; //String to be sent back
//Process command line arguments
//Error if more than one command line argument
if (args.length > 1)
{
System.out.println("Usage: java TrimServer "
+ "[-port=<number>]");
System.exit(-1);
}
//Set the server port suitably
if ((args.length == 1) &&
(args[0].startsWith("-port=")))
serverPort = Integer.parseInt(args[0].substring(6));
//Print greeting
System.out.println("Hello, you have invoked a Trim Server");
System.out.println("You have requested that service be started at port " + serverPort);
System.out.println(); //Blank line
//Establish requested service
try
{
ss = new ServerSocket(serverPort);
}
catch (Exception e)
{
e.printStackTrace();
}
//Report status
System.out.println("Trim Server is ready"
+ " for service at port " + serverPort);
System.out.println(); //Blank line
//Server stops only when the process is terminated
//Enter a forever loop to offer service
for (;;)
{
try
{
//Wait and accept connection
s = ss.accept(); //Accept connection on server socket
//Report connection status
System.out.println("Accepted connection");
local = s.getLocalAddress(); remote = s.getInetAddress();
localPort = s.getLocalPort(); remotePort = s.getPort();
System.out.println ("Server side");
System.out.println (" " + local.getHostName()
+ "[" + local.getHostAddress() + "]"
+ " at port " + localPort);
System.out.println ("Client side");
System.out.println (" " + remote.getHostName()
+ "[" + remote.getHostAddress() + "]"
+ " at port " + remotePort);
System.out.println(); //Blank line
socketIn = new BufferedReader(new InputStreamReader(s.getInputStream()));
socketOut = new PrintWriter(s.getOutputStream(), true);
//Interact with client
//Read string from client
clientInput = socketIn.readLine();
//Loop until client indicates termination
while (!clientInput.equalsIgnoreCase(" "))
{
//Trims all leading and trailing whitespace
serverResult = clientInput.trim();
//Log work done
System.out.println("Server received: "
+ clientInput);
System.out.println("Server responded: "
+ serverResult);
System.out.println(); //Blank line
//Send response to client
socketOut.println(serverResult);
//Get new string
clientInput = socketIn.readLine();
}
//Close all streams, socket and report
socketIn.close();
socketOut.close();
s.close();
System.out.println("Closed connection");
System.out.println(); //Blank line
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
}
我必须使用PuTTy连接到我们学校的服务器以进行此分配，但是当我使用以下方式调用服务器和客户端连接时：
java TrimServer -port=1221
java TrimClient -port=1221 **********
我收到一条错误，指出线程“main”中的异常java.lang.NoClassDefFoundError：Trim Server
Caused by: java.lang.ClassNotFoundException: TrimServer
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Naitve Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)