我制作了一个客户端服务器应用程序，其中服务器必须向客户端发送电子邮件列表，该电子邮件列表在加载到ListView之后，可以通过menuBar删除它们。在客户端，所有这些操作都是在数据模型中进行的（我遵循MVC模式）。这是服务器：
class ThreadedEchoHandler implements Runnable {
private Socket incoming;
private String nomeAccount = "";
public void run() {
try {
incoming = s.accept();
} catch (IOException ex) {
System.out.println("Unable to accept requests");
}
contenutoTextArea.append("Connected from: " + incoming.getLocalAddress() + "\n");
textarea.setText(contenutoTextArea.toString());
try {
//PHASE 1: The server receives the email
try {
BufferedReader in = new BufferedReader(new InputStreamReader(incoming.getInputStream()));
nomeAccount = in.readLine();
} catch (IOException ex) {
System.out.println("Not works");
}
//PHASE 2: I'm getting all the emails from the files
File dir = new File("src/server/" + nomeAccount);
String[] tmp = new String[100];
int i = 0;
for (File file : dir.listFiles()) {
if (file.isFile() && !(file.getName().equals(".DS_Store"))) {
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String line;
while ((line = br.readLine()) != null) {
tmp[i++] = line;
}
} catch (IOException ex) {
System.out.println("Cannot read from file");
}
}
}
//PHASE 3: The server sends the ArrayList to the client
PrintWriter out = new PrintWriter(incoming.getOutputStream(), true);
for (int j = 0; j < i; j++) {
out.println(tmp[j]); // send the strings to the client
}
} catch (IOException ex) {
System.out.println("Cannot send the strings to the client");
}
//PHASE 4: Here I loop and wait for the client choise
BufferedReader in;
String op;
try {
in = new BufferedReader(new InputStreamReader(incoming.getInputStream()));
while ((op = in.readLine()) != null) {
if (op.equals("Elimina")) {
String tmp = in.readLine();
File file = new File("src/server/" + nomeAccount + "/" + tmp + ".txt");
file.delete();
} else if (op.equals("Invia")) {
//...
} else {
//...
}
}
} catch (IOException ex) {
System.out.println("Non so");
} finally {
try {
incoming.close();
} catch (IOException ex) {
System.out.println("Cannot closing the socket");
}
}
}
}
这些是客户端的方法：
public void loadData() throws IOException, ClassNotFoundException, ParseException {
try {
s = new Socket("127.0.0.1", 5000);
ArrayList<Email> email = new ArrayList<Email>();
DateFormat format = new SimpleDateFormat("dd/MM/yyyy");
Date data;
/* PHASE 1: The client sends a string to the server */
//try {
PrintWriter out = new PrintWriter(s.getOutputStream(), true);
out.println(account); // send the account name to server
/* PHASE 2: The client receives the ArrayList with the emails */
BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
String line;
String message[] = new String[5];
for (int j=0; (line = in.readLine()) != null;) {
message[j++] = line;
if (j==5) {
data = format.parse(message[3]);
email.add(new Email((Integer.parseInt(message[0])), message[1], account, message[2], message[4], data));
j=0;
}
}
//Casting the arrayList
emailList = FXCollections.observableArrayList(email);
//Sorting the emails
Collections.sort(emailList, (Email o1, Email o2) -> {
if (o1.getData() == null || o2.getData() == null) {
return 0;
}
return o1.getData().compareTo(o2.getData());
});
/*} finally {
s.close();*/
//}
} catch (SocketException se) {
emailList.setAll(null, null);
}
}
public void deleteMail(Email da_elim) throws IOException {
int id_del = da_elim.getID();
emailList.remove(da_elim);
PrintWriter out = new PrintWriter(s.getOutputStream(), true);
out.println("Elimina");
out.println(id_del);
}
服务器的阶段1、2、3用于上传电子邮件，并使用loadData（）方法。没有阶段4，该程序将运行。现在，如果我编写了该循环，则客户端的GUI不会加载，并且我无法按DELETE按钮（这会使输入将某些内容（在此消除了文件中）嵌入该循环中）。即使它们是两个不同的线程也不会加载？为什么没有该循环就可以工作呢？
编辑：已实现Listener类，但仍无法正常工作
//PHASE 4: Here I loop and wait for the client choise
BufferedReader in;
String op;
try {
in = new BufferedReader(new InputStreamReader(incoming.getInputStream()));
/*while ((op = in.readLine()) != null) {
System.out.println("OP: " + op);
if (op.equals("Elimina")) {
String tmp = in.readLine();
contenutoTextArea.append("Ho eliminato la mail ").append(tmp).append(" \n");
textarea.setText(contenutoTextArea.toString());
File file = new File("src/server/" + nomeAccount + "/" + tmp + ".txt");
file.delete();
}
}*/
Listener lis = new Listener(in, new LinkedBlockingQueue<String>());
lis.run();
System.out.println("bbbbb");
} catch (IOException ex) {
System.out.println("Unable to read messages");
} finally {
try {
incoming.close();
} catch (IOException ex) {
System.out.println("Cannot close the socket");
}
}
答案 0 :(得分：2)
我认为您应该运行jvisualvm（这是在jdk的/ bin /位置中与jdk一起安装的工具），并查找您在服务器上创建的Thread生命周期。还要检查您的线程是否不执行代码，而只是跳过等待客户端的生命。
该线程是否以某种方式与客户端连接？因为您无法运行客户端应用程序。他们分开了吗？我想到的另一个想法是使用
Platform.runLater(()->{
});
如果您的客户端GUI在JavaFX中。如果要创建GUI，更改字段中的值以及在GUI上执行的任何操作，请使用它。也许您的服务器正在等待用户响应，并且在构建GUI之后？这导致您无法按DELETE按钮。
答案 1 :(得分：2)
我目前无法发表评论，因此无法要求澄清，但我认为我正确地解释了问题所在。 “程序进入等待来自两个控制器的输入的循环时挂起”。假设我理解的正确，最可能的罪魁祸首是缓冲的阅读器无限期挂起，因为它没有收到输入。当我第一次遇到此问题时，我将其扔到了自己的“接收器”类中，并使用一个队列将接收到的所有内容传递到主类中的循环中。我的代码看起来像这样：
import java.io.BufferedReader;
import java.io.IOException;
import java.util.concurrent.BlockingQueue;
public class Listener implements Runnable
{
private BufferedReader br;
private BlockingQueue<String> q;
private boolean shouldClose = false;
public Listener(BufferedReader br, BlockingQueue<String> q)
{
this.q = q;
this.br = br;
}
public void run()
{
loop();
System.out.println("listener has stopped");
}
public void loop()
{
String line = "";
try
{
while((line = br.readLine()) != null && !shouldClose)
{
q.put(line);
}
}
catch (IOException | InterruptedException e)
{
e.printStackTrace();
}
}
public void shutdown()
{
shouldClose = true;
}
}
如果我有任何误解，或者错过了代码中的内容，我们深表歉意。