TCP服务器接受连接后新线程的代码不执行
Code of new thread after accepting the connection in TCP server isn't executed
我有以下 TCP 服务器:
public class Server {
private Connection db;
private Statement statement;
private ServerSocket socket;
public static void main(String[] args) {
Server server = new Server();
server.initializeServer();
System.out.println("Server initialized");
server.listenConnections();
}
private void initializeServer() {
try {
db = DriverManager.getConnection("jdbc:mysql://localhost:3306/courseworkschema" +
"?verifyServerCertificate=false" +
"&useSSL=false" +
"&requireSSL=false" +
"&useLegacyDatetimeCode=false" +
"&" +
"&serverTimezone=UTC",
"Sergei",
"12345");
statement = db.createStatement();
socket = new ServerSocket(1024);
} catch (SQLException | IOException e) {
e.printStackTrace();
}
}
private void listenConnections() {
System.out.println("Listening connections ... ");
while (true) {
try {
Socket client = socket.accept();
new Thread(() -> {
System.out.println("Client accepted");
try {
OutputStream outputStream = client.getOutputStream();
InputStream inputStream = client.getInputStream();
String clientAction;
String queryContent;
boolean flag = true;
while (flag) {
byte[] msg = new byte[100];
int k = inputStream.read(msg);
clientAction = new String(msg, 0, k);
clientAction = clientAction.trim();
msg = new byte[100];
k = inputStream.read(msg);
queryContent = new String(msg, 0, k);
queryContent = queryContent.trim();
System.out.println(clientAction);
System.out.println(queryContent);
if (clientAction.equalsIgnoreCase("END")) {
flag = false;
}
else if (clientAction.equalsIgnoreCase("LOGIN")) {
System.out.println("Login action");
}
}
} catch (IOException e) {
e.printStackTrace();
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
创建此服务器是为了与数据库通信。这是我尝试连接到此服务器的方式L
public class LoginController {
private LoginWindow window;
private Socket socket;
private InputStream is;
private OutputStream os;
public LoginController() {
connectToServer();
}
public void logInUser(String login, String password) {
if (!login.isEmpty() && !password.isEmpty()) {
sendDataToServer("LOGIN");
sendDataToServer("");
} else {
window.showMessageDialog("Fill the fields!", JOptionPane.ERROR_MESSAGE);
}
}
public void attachView(LoginWindow window) {
this.window = window;
}
private void connectToServer() {
try {
socket = new Socket("127.0.0.1", 1024);
System.out.println("Connected");
} catch (IOException e) {
e.printStackTrace();
}
}
private void sendDataToServer(String res) {
try {
os = socket.getOutputStream();
os.write(res.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
}
当我运行服务器然后是客户端时,我在服务器中有这样的日志:
Server initialized
Listening connections ...
Process finished with exit code -1
所以,我无法理解为什么服务器不等待并接受来自客户端的连接,而是在初始化和监听后关闭。那么,怎么回事?我将不胜感激任何帮助。提前致谢!
UPD
当我 运行 我的应用程序开始工作时,我发现 Thread 块中的代码未执行。我也想不明白,为什么会这样
在您的 private void listenConnections()
中,您正在创建一个 Thread
对象,但您没有告诉它在创建后启动,因此它不会执行。
您的线程创建行应如下所示:
new Thread(() -> {
//your code
}).start();
来自 javadocs:
https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html#start()
public void start()
Causes this thread to begin execution; the Java Virtual Machine calls
the run method of this thread. The result is that two threads are
running concurrently: the current thread (which returns from the call
to the start method) and the other thread (which executes its run
method).
It is never legal to start a thread more than once. In particular, a
thread may not be restarted once it has completed execution.
Throws: IllegalThreadStateException - if the thread was already
started.
See Also: run(), stop()
我有以下 TCP 服务器:
public class Server {
private Connection db;
private Statement statement;
private ServerSocket socket;
public static void main(String[] args) {
Server server = new Server();
server.initializeServer();
System.out.println("Server initialized");
server.listenConnections();
}
private void initializeServer() {
try {
db = DriverManager.getConnection("jdbc:mysql://localhost:3306/courseworkschema" +
"?verifyServerCertificate=false" +
"&useSSL=false" +
"&requireSSL=false" +
"&useLegacyDatetimeCode=false" +
"&" +
"&serverTimezone=UTC",
"Sergei",
"12345");
statement = db.createStatement();
socket = new ServerSocket(1024);
} catch (SQLException | IOException e) {
e.printStackTrace();
}
}
private void listenConnections() {
System.out.println("Listening connections ... ");
while (true) {
try {
Socket client = socket.accept();
new Thread(() -> {
System.out.println("Client accepted");
try {
OutputStream outputStream = client.getOutputStream();
InputStream inputStream = client.getInputStream();
String clientAction;
String queryContent;
boolean flag = true;
while (flag) {
byte[] msg = new byte[100];
int k = inputStream.read(msg);
clientAction = new String(msg, 0, k);
clientAction = clientAction.trim();
msg = new byte[100];
k = inputStream.read(msg);
queryContent = new String(msg, 0, k);
queryContent = queryContent.trim();
System.out.println(clientAction);
System.out.println(queryContent);
if (clientAction.equalsIgnoreCase("END")) {
flag = false;
}
else if (clientAction.equalsIgnoreCase("LOGIN")) {
System.out.println("Login action");
}
}
} catch (IOException e) {
e.printStackTrace();
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
创建此服务器是为了与数据库通信。这是我尝试连接到此服务器的方式L
public class LoginController {
private LoginWindow window;
private Socket socket;
private InputStream is;
private OutputStream os;
public LoginController() {
connectToServer();
}
public void logInUser(String login, String password) {
if (!login.isEmpty() && !password.isEmpty()) {
sendDataToServer("LOGIN");
sendDataToServer("");
} else {
window.showMessageDialog("Fill the fields!", JOptionPane.ERROR_MESSAGE);
}
}
public void attachView(LoginWindow window) {
this.window = window;
}
private void connectToServer() {
try {
socket = new Socket("127.0.0.1", 1024);
System.out.println("Connected");
} catch (IOException e) {
e.printStackTrace();
}
}
private void sendDataToServer(String res) {
try {
os = socket.getOutputStream();
os.write(res.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
}
当我运行服务器然后是客户端时,我在服务器中有这样的日志:
Server initialized
Listening connections ...
Process finished with exit code -1
所以,我无法理解为什么服务器不等待并接受来自客户端的连接,而是在初始化和监听后关闭。那么,怎么回事?我将不胜感激任何帮助。提前致谢!
UPD
当我 运行 我的应用程序开始工作时,我发现 Thread 块中的代码未执行。我也想不明白,为什么会这样
在您的 private void listenConnections()
中,您正在创建一个 Thread
对象,但您没有告诉它在创建后启动,因此它不会执行。
您的线程创建行应如下所示:
new Thread(() -> {
//your code
}).start();
来自 javadocs: https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html#start()
public void start()
Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread. The result is that two threads are running concurrently: the current thread (which returns from the call to the start method) and the other thread (which executes its run method).
It is never legal to start a thread more than once. In particular, a thread may not be restarted once it has completed execution.
Throws: IllegalThreadStateException - if the thread was already started.
See Also: run(), stop()