[英]JAVA Client/Server Calculator Example
我們被分配了一個網絡任務來實施一個客戶/服務器項目。 我們提供的一個示例是“客戶端/服務器計算器”程序。 我已經在下面發布了這兩個類的代碼。 我正在使用eclipse,在“運行配置”設置中,輸入“ ADD,5,6”作為客戶端程序的參數,但輸出為空。 你們能看到為什么會這樣嗎?
客戶代碼:
package networking;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class CalculatorClient {
/**
* @param args
* @throws IOException
* @throws UnknownHostException
*/
public static void main(String[] args) throws UnknownHostException, IOException {
String operation = args[0];
// Create a new socket object and names it socket
// the constructor requires the name of the computer and the port number to which you want to connect
Socket socket = new Socket("localhost", CalculatorServer.PORT_NO);
// gets the socket's input stream and opens a BufferedReader on it.
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
// gets the socket's output stream and opens a PrintWriter on it
PrintWriter pw = new PrintWriter(socket.getOutputStream());
pw.println(operation);
pw.flush();
if (!"quit".equals(operation.trim())) {
String line = reader.readLine();
reader.close();
System.out.println("Line 36 in Client");
System.out.println("result: " + line);
System.out.println("Line 38 in Client");
}
socket.close();
}
}
服務器代碼:
package networking;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Support add, subtraction, multiplication, division
* @author hluu
*
*/
public class CalculatorServer {
enum OPERATOR { ADD, SUB, MULT, DIV };
public static final int PORT_NO = 8888;
/**
* @param args
* @throws IOException
* @throws InterruptedException
*/
public static void main(String[] args) throws IOException, InterruptedException {
ServerSocket serverSocket = new ServerSocket(PORT_NO);
System.out.println("... server is accepting request");
while (true) {
Socket socket = serverSocket.accept();
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String line = reader.readLine();
System.out.println("got request: " + line);
System.out.println("Right after getting request");
if (line.trim().startsWith("quit")) {
System.out.println("... server shutting down ...");
socket.close();
break;
} else {
System.out.println("Entering Else");
System.out.println(line);
processRequest(socket, line);
}
}
System.out.println("... closing server socket ...");
serverSocket.close();
}
private static void processRequest(Socket socket, String line) throws IOException, InterruptedException {
PrintWriter pw = new PrintWriter(socket.getOutputStream());
String[] tokens = line.split(" ");
if (tokens.length != 2) {
pw.println("invalid command: " + line);
socket.close();
return;
}
String[] operands = tokens[1].split(",");
if (operands.length != 2) {
pw.println("invalid command: " + line);
socket.close();
return;
}
String operator = tokens[0].trim();
try {
Double operand1 = Double.valueOf(operands[0].trim());
Double operand2 = Double.valueOf(operands[1].trim());
System.out.println(operand1);System.out.println(operand2);
double result = 0;
OPERATOR op = OPERATOR.valueOf(operator.toUpperCase());
switch (op) {
case ADD:
result = operand1 + operand2;
break;
case SUB:
System.out.println("Entering SUB");
result = operand1 - operand2;
break;
case MULT:
result = operand1 * operand2;
break;
case DIV:
result = operand1 / operand2;
break;
default:
pw.println("invalid operand: " + line);
pw.flush();
socket.close();
return;
}
System.out.println("send back result: " + result );
pw.println(result);
} catch (NumberFormatException nfe) {
pw.println("invalid operand: " + line);
}
pw.flush();
socket.close();
}
}
在大多數情況下,調試是一種查看正在發生的情況的方法。 事實證明,正確的參數格式是:
增加5,6
但是您的CalculatorClient
operation
字符串僅獲取ADD
部分,因為args
內容實際上是: {"ADD", "5,6"}
。 因此,要形成有效的請求,您應該采用以下方式合並輸入:
String operation = args[0] + " " + args[1];
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