ObjectInputStream(socket.getInputStream());不起作用 [英] ObjectInputStream(socket.getInputStream()); does not work
问题描述
我正在编写一个类来与服务器通信，但是当它尝试在输入流的帮助下构建 ObjectInputStream 时，程序会冻结.没有异常，程序仍在运行，但挂在尝试构造 ObjectInputstream 的行中.
I'm programming a class to communicate to a server but when it tries to construct the ObjectInputStream with the help of the inputstream the program is freezing. Theres is no Exception and the program is still running but hanging in the line where it tries to construct the ObjectInputstream.
这里是我的问题所在方法的代码:
Heres the code of the method where my problem is located:
@Override
public void connect(String ip, int port) throws UnknownHostException, IOException {
Socket socket = new Socket(ip, port);
out = new ObjectOutputStream(socket.getOutputStream());
InputStream is = socket.getInputStream();
in = new ObjectInputStream(is);
}
这是整个班级的代码:
package Client;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class MessageStreamerImpl implements MessageStreamer {
ObjectOutputStream out;
ObjectInputStream in;
public MessageStreamerImpl(String ip, int port) throws UnknownHostException, IOException{
connect(ip, port);
}
public MessageStreamerImpl(){
}
@Override
public void send(Object message) throws IOException {
if(out == null) throw new IOException();
out.writeObject(message);
out.flush();
}
@Override
public Object receive() throws IOException{
try {
return in.readObject();
} catch (ClassNotFoundException e) {
throw new IOException();
}
}
@Override
public void connect(String ip, int port) throws UnknownHostException, IOException {
Socket socket = new Socket(ip, port);
out = new ObjectOutputStream(socket.getOutputStream());
InputStream is = socket.getInputStream();
in = new ObjectInputStream(is);
}
}
在查看 Google 时，我发现了这个:http://www.coderanch.com/t/232944/threads/java/Socket-getInputStream-block.但是我还是不知道怎么解决这个问题，因为我的ObjectOutputStream构造函数在ObjectInputStream之前.
While looking at Google I found this: http://www.coderanch.com/t/232944/threads/java/Socket-getInputStream-block. But I still don't know how to solve the problem, because my ObjectOutputStream constructor is before the one for the ObjectInputStream.
这是我的服务器代码，也许它会有所帮助;)
Here is my server code, maybe it will help ;)
package Server;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;
public class Server {
ArrayList<Socket> clients = new ArrayList<Socket>();
public Server(int port){
try {
ServerSocket mySocket = new ServerSocket(port);
waitForClients(mySocket);
} catch (IOException e) {
System.out.println("Unable to start.");
e.printStackTrace();
}
}
private void waitForClients(ServerSocket mySocket) {
while(true){
try {
System.out.println("Ready to receive");
Socket client = mySocket.accept();
clients.add(client);
System.out.println(client.getInetAddress().getHostAddress()+" connected to the Server");
Thread t = new Thread(new ClientHandler(client));
t.start();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void shareToAll(Object objectToSchare){
for(Socket client:clients){
ObjectOutputStream oos;
try {
oos = new ObjectOutputStream(client.getOutputStream());
oos.writeObject(objectToSchare);
oos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
private class ClientHandler implements Runnable{
Socket clientSocket;
public ClientHandler(Socket clientSocket){
this.clientSocket = clientSocket;
}
@Override
public void run() {
try {
ObjectInputStream ois = new ObjectInputStream(clientSocket.getInputStream());
while(true){
try {
ois.readObject();
} catch (ClassNotFoundException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}catch(SocketException e){
System.out.println(clientSocket.getInetAddress().getHostAddress()+" disconnected from the Server");
clients.remove(clientSocket);
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
感谢您的帮助我找到了错误.这是在服务器类，它必须看起来像这样:
Thanks for your help I found the fault. It was at the server class which has to look like this:
package Server;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;
public class Server {
ArrayList<ObjectOutputStream> clientstreams = new ArrayList<ObjectOutputStream>();
public Server(int port){
try {
ServerSocket mySocket = new ServerSocket(port);
waitForClients(mySocket);
} catch (IOException e) {
System.out.println("Unable to start.");
e.printStackTrace();
}
}
private void waitForClients(ServerSocket mySocket) {
while(true){
try {
System.out.println("Ready to receive");
Socket client = mySocket.accept();
clientstreams.add(new ObjectOutputStream(client.getOutputStream()));
System.out.println(client.getInetAddress().getHostAddress()+" connected to the Server");
Thread t = new Thread(new ClientHandler(client));
t.start();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void shareToAll(Object objectToSchare){
for(ObjectOutputStream stream:clientstreams){
try {
stream.writeObject(objectToSchare);
stream.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
private class ClientHandler implements Runnable{
Socket clientSocket;
public ClientHandler(Socket clientSocket){
this.clientSocket = clientSocket;
}
@Override
public void run() {
try {
ObjectInputStream ois = new ObjectInputStream(clientSocket.getInputStream());
while(true){
try {
ois.readObject();
} catch (ClassNotFoundException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}catch(SocketException e){
System.out.println(clientSocket.getInetAddress().getHostAddress()+" disconnected from the Server");
clientstreams.remove(clientSocket);
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
您在 waitForClients() 方法中看到的变化最多，但我也改变了我的 ArrayList 和 shareToAll 方法的概念.
The most changes you see at the method waitForClients() but I changed, too the concept of my ArrayList and the shareToAll method.
推荐答案
ObjectInputStream 构造函数从给定的 InputStream 读取数据.为了使其工作，在尝试打开 ObjectInputStream 之前，您必须在构造之后立即刷新 ObjectOutputStream(以写入初始标头).此外，如果您想为每个连接发送多个对象，您必须打开 ObjectOutputStream 一次并在套接字的生命周期内使用它(例如您的 shareToAll 方法).
The ObjectInputStream constructor reads data from the given InputStream. In order for this to work, you must flush the ObjectOutputStream immediately after construction (to write the initial header) before you attempt to open the ObjectInputStream. Also, if you want to send more than one object per connection, you must open the ObjectOutputStream once and use it for the lifetime of the socket (e.g. your shareToAll method).
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