问题描述
我对RMI系统进行了新的测试。但是，有一个问题。它没有打印出假定的选择，而是打印出了
欢迎来到CrewCuts 您是客户还是理发师？ 键入退出离开。 java.lang.NullPointerException 在CrewCutsClient.main（CrewCutsClient.java:172）
它应该一直显示到出口离开为止。稍后，用户输入将确定它将返回什么功能。取决于是客户还是理发师。
客户：
import java.rmi.Naming;
import java.rmi.remoteexception;
import java.net.MalformedURLException;
import java.rmi.NotBoundException;
import java.io.*;
public class CrewCutsClient {
CrewCuts cc;
int user_type;
BufferedReader input;
public CrewCutsClient(){
try {
CrewCuts cc = (CrewCuts)
Naming.lookup("rmi://localhost/CrewCuts");
BufferedReader input =
new BufferedReader(new InputStreamReader(system.in));
}
catch (MalformedURLException murle) {
System.out.println();
System.out.println("MalformedURLException");
System.out.println(murle);
}
catch (remoteexception re) {
System.out.println();
System.out.println("remoteexception");
System.out.println(re);
}
catch (NotBoundException nbe) {
System.out.println();
System.out.println("NotBoundException");
System.out.println(nbe);
}
}
private void booking_customer() {
try {
boolean repeat;
do {
repeat = false;
System.out.println("Please state your day of booking (Monday,Tuesday,Wednesday,Friday,Saturday,Sunday");
String day = input.readLine();
System.out.println("Select your type of appointment (Hair cut/hair cleansing/hair dye");
String service = input.readLine();
System.out.println("Your day of appointment shall be: '" + day);
System.out.println("Your service shall be: '" + service);
} while (repeat);
} catch (Exception e) {
e.printstacktrace();
}
}
private void logout(){
try {
boolean isSuccess = cc.logout(user_type);
if (isSuccess) {
user_type = 0;
System.out.println("Successfully logged out");
} else {
System.out.println("Failed to log out");
}
} catch (Exception e) {
e.printstacktrace();
}
}
private void customer_info() {
try {
boolean repeat;
do {
repeat = false;
System.out.println("Please enter your name");
String custname = input.readLine();
System.out.println("Please enter your contact number");
String custcontact = input.readLine();
System.out.println("Hello Mr/Mrs. '" + custname);
System.out.println("We shall contact you through this number: '" + custcontact);
} while (repeat);
} catch (Exception e) {
e.printstacktrace();
}
}
private void barber_open() {
try {
boolean repeat;
do {
repeat = false;
System.out.println("Until what time are you open?");
String first = input.readLine();
System.out.println("We will update it on the server.");
} while (repeat);
} catch (Exception e) {
e.printstacktrace();
}
}
public void customer() {
try {
boolean repeat;
do {
repeat = false;
customer();
System.out.println("Press 1 to make a booking.");
System.out.println("Press 2 to insert your info.");
System.out.println("Press 3 to exit.");
String resp = input.readLine();
switch (resp.toLowerCase()) {
case "3":
case "exit":
break;
case "1":
booking_customer();
break;
case "2":
customer_info();
break;
default:
System.out.println("Please enter a valid input value");
repeat = true;
break;
}
} while(repeat);
} catch (Exception e) {
e.printstacktrace();
}
}
public void barber() {
try {
boolean repeat;
do {
repeat = false;
barber();
System.out.println("Are you open today? Type Y for Yes,N for No.");
System.out.println("Enter 'exit' to return to main menu");
String resp = input.readLine();
switch (resp.toLowerCase()) {
case "0":
case "exit":
break;
case "Y":
case "yes":
case "Yes":
barber_open();
break;
case "N":
case "no":
case "No":
break;
default:
System.out.println("Please enter a valid input value");
repeat = true;
break;
}
} while(repeat);
} catch (Exception e) {
e.printstacktrace();
}
}
public static void main(String[] args) {
CrewCutsClient client = new CrewCutsClient();
try {
System.out.println("Welcome to CrewCuts");
System.out.flush();
System.out.println("Are you a Customer or Barber?");
System.out.println("Type Exit to leave.");
String resp = client.input.readLine();
switch (resp.toLowerCase()) {
case "exit":
client.logout();
break;
case "customer":
client.customer();
break;
case "barber":
client.barber();
break;
default:
System.out.println("Please enter either Customer or Barber.");
break;
}
System.out.println("Press Enter to continue");
String ignore_input = client.input.readLine();
} catch (remoteexception re) {
System.out.println();
System.out.println("remoteexception");
System.out.println(re);
} catch (java.lang.ArithmeticException ae) {
System.out.println();
System.out.println("java.lang.ArithmeticException");
System.out.println(ae);
} catch (Exception e) {
e.printstacktrace();
}}}
服务器
import java.rmi.Naming;
public class CrewCutsServer {
public CrewCutsServer() {
try {
CrewCuts cc = new CrewCutsImpl();
Naming.rebind("rmi://localhost:1099/CrewCuts",cc);
} catch (Exception e) {
System.out.println("Trouble: " + e);
}
}
public static void main(String args[]) {
new CrewCutsServer();
}}
实施
public class CrewCutsImpl extends java.rmi.server.UnicastRemoteObject implements CrewCuts {
public CrewCutsImpl() throws java.rmi.remoteexception {
super();
}
public long add(long a,long b)
throws java.rmi.remoteexception {
return a + b;
}
public long sub(long a,long b)
throws java.rmi.remoteexception {
return a - b;
}
public long mul(long a,long b)
throws java.rmi.remoteexception {
return a * b;
}
public long div(long a,long b)
throws java.rmi.remoteexception {
return a / b;
}
public boolean logout (int user_type) throws java.rmi.remoteexception{
return true;
}
public int customer(int user_type) throws java.rmi.remoteexception {
return(user_type);
}
public int barber(int user_type) throws java.rmi.remoteexception {
return(user_type);
}}
接口
public interface CrewCuts extends java.rmi.Remote {
public int customer(int user_type)
throws java.rmi.remoteexception;
public int barber(int user_type)
throws java.rmi.remoteexception;
public boolean logout(int user_type)
throws java.rmi.remoteexception;
public long add(long a,long b)
throws java.rmi.remoteexception;
public long sub(long a,long b)
throws java.rmi.remoteexception;
public long mul(long a,long b)
throws java.rmi.remoteexception;
public long div(long a,long b)
throws java.rmi.remoteexception;
}
解决方法
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