【发布时间】：2016-10-07 04:49:16
【问题描述】：
当我运行这个程序时，客户端类提示用户输入一个命令，该命令应该转到服务器类并打开一个文件并读取该文件的每一行并将字节长度返回给客户端类被显示。
不幸的是，一旦我输入命令，什么都没有发生并且不知道为什么。
TCP 客户端类
package TcpClient;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Socket;
import java.io.*;
public class TcpClient {
public static void main(String[] args) {
String temp;
String displayBytes;
try {
//create input stream
BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
//create client socket, connect to server
Socket clientSocket = new Socket("localhost",5555);
//create output stream attached to socket
DataOutputStream outToServer =
new DataOutputStream(clientSocket.getOutputStream());
System.out.print("Command : ");
//create input stream attached to socket
BufferedReader inFromServer =
new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
temp = inFromUser.readLine();
//send line to server
outToServer.writeBytes(temp);
//read line from server
//displayBytes = inFromServer.readLine();
while((displayBytes = inFromServer.readLine()) != null) {
System.out.print(displayBytes);
}
//clientSocket.close();
}
catch(Exception ex) {
}
}
}
TCP 服务器类
package TcpServer;
import java.io.BufferedReader;
import java.io.*;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServer {
public static void main(String[] args) {
// The name of the file to open.
String fileName = "input.txt";
// This will reference one line at a time
String line = null;
String holder=null;
String clientWord;
int bytNumber;
try {
//create welcoming socket at port 5555
ServerSocket welcomeSocket = new ServerSocket(5555);
//wait, on welcoming socket for contact by client
Socket connectionSocket = welcomeSocket.accept();
//create input stream, attached to socket
BufferedReader inFromClient =
new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
//create output stream, attached to socket
DataOutputStream outToClient =
new DataOutputStream(connectionSocket.getOutputStream());
//read in line from socket
clientWord = inFromClient.readLine();
if(clientWord.equals("query")) {
try {
// FileReader reads text files in the default encoding.
FileReader fileReader = new FileReader(fileName);
// Always wrap FileReader in BufferedReader.
BufferedReader buffer = new BufferedReader(fileReader);
while((line = buffer.readLine()) != null) {
System.out.println(line);
bytNumber = line.getBytes().length;
holder=Integer.toString(bytNumber);
//pr.println(bytNumber);//only printing first line not going until eof
outToClient.writeBytes(holder);
// line = buffer.readLine();
// pr.flush();
}
// Always close files.
buffer.close();
}
catch(FileNotFoundException ex) {
System.out.println("Unable to open file '" + fileName + "'");
}
catch(IOException ex) {
System.out.println ("Error reading file '" + fileName + "'");
// Or we could just do this:
// ex.printStackTrace();
}
}// end if statement
}
catch(Exception ex) {
}
}
}
【问题讨论】：
-
您应该首先不忽略客户端类中的异常。你看，忽略错误消息并不是调试的好方法......
-
我得到的唯一消息是关闭 clientSocket 的警告，但是当我这样做时，我仍然得到相同的输出。
-
可能会出现各种问题，比如这里或那里没有正确关闭套接字，或者连接问题，......所以，提示：尝试在调试器中运行。添加打印语句以查看发生了什么；也许首先：阅读分步教程（如docs.oracle.com/javase/tutorial/networking/sockets/…），指导您完成客户端/服务器通信的整个过程。
-
@n00bie1221 具有讽刺意味的是，您的一个 catch 块包含注释“或者我们可以这样做：ex.printStackTrace();”但是您选择不来执行此操作，这是您显示的代码中最严重的错误。