Java套接字DataInputStream读取未初始化的数据
我正在尝试实现客户机-服务器通信。 我试过异步一个,现在我绑定了同步一个,但只是为了让它工作。我尽可能地删除了不必要的代码,即使经过一天的研究,我也无法让它工作。求你了,如果你能救我,我会非常感激的 我现在将详细说明这个问题,并指出代码的一些部分,尽管下面提供了所有代码 问题是: 在main.java中 我创建一个服务器和客户端,然后发送数据Java套接字DataInputStream读取未初始化的数据,java,sockets,Java,Sockets,我正在尝试实现客户机-服务器通信。 我试过异步一个,现在我绑定了同步一个,但只是为了让它工作。我尽可能地删除了不必要的代码,即使经过一天的研究,我也无法让它工作。求你了,如果你能救我,我会非常感激的 我现在将详细说明这个问题,并指出代码的一些部分,尽管下面提供了所有代码 问题是: 在main.java中 我创建一个服务器和客户端,然后发送数据 s.InitiateRead() 是一个函数,它只会永远循环并尝试从DataInputStream读取int len = BReaderForClien
s.InitiateRead()
是一个函数,它只会永远循环并尝试从DataInputStream读取int
len = BReaderForClient.readInt();
您还可以看到如下代码
c.Send(ByteBuffer.wrap("A".getBytes()));
这只发送数字12,而不是任何A或其他什么,最终在线程中调用的方法位于ClientServerBase.java中:
void Send_Begin(ByteBuffer Data, DataOutputStream OutputStream) {
try {
while(CurrentlyWritingToOutputStream)
{ /* wait */ }
CurrentlyWritingToOutputStream = true;
OutputStream.writeInt(12);
OutputStream.flush();
CurrentlyWritingToOutputStream = false;
Send_End(false);
} catch (IOException e) {
Send_End(true);
}
}
如您所见,我有用于从多个线程写入的信号量
所以我将3倍整数写入流,然后调用线程中的读取,然后继续写入更多。
这个测试的目的是让套接字充满数据,就像在每次发送之间放置Thread.Sleep5000一样,一切都会正常
问题是,当运行时,有时读取输出不是预期的数字12
请注意,main.java中注释的while循环可以取消注释,仍然会给出错误的输出,只是说如果主线程结束,它将终止所有其他线程
所有代码:
main.java
package net;
import java.nio.ByteBuffer;
public class main {
public static void main(String[] args) throws Exception {
Server s = new Server();
s.Start();
if(!s.Listen())
return;
Client c = new Client();
c.Send(ByteBuffer.wrap("A".getBytes()));
c.Send(ByteBuffer.wrap("A".getBytes()));
c.Send(ByteBuffer.wrap("A".getBytes()));
new Thread(new Runnable() {
public void run() {
s.InitiateRead();
}
}).start();
c.Send(ByteBuffer.wrap("A".getBytes()));
c.Send(ByteBuffer.wrap("A".getBytes()));
c.Send(ByteBuffer.wrap("A".getBytes()));
/*while(true)
{}*/
}
}
Server.java
package net;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.ByteBuffer;
public class Server extends ClientServerBase {
public Server()
{
super(ClientServerBase.REAL_TYPE.SERVER);
}
// ======================================================================================
void Accept_Begin() {
Socket socket = null;
try {
socket = serverSocket.accept();
} catch (IOException e) {
Accept_End(true, socket);
return;
}
Accept_End(false, socket);
}
public void InitiateRead()
{
while(true){
int len = 0;
try {
len = BReaderForClient.readInt();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Print("Red: " + len);
}
}
void Accept_End(boolean error, Socket acceptedclient) {
try {
if (!error) {
Print("Client accepted");
Clientsock = acceptedclient;
BwriterForClient = new DataOutputStream(acceptedclient.getOutputStream());
BReaderForClient = new DataInputStream(acceptedclient.getInputStream());
}
} catch (IOException e) {
e.printStackTrace();
}
Accept_Begin();
}
public void close() throws IOException {
BwriterForClient.close();
Clientsock.close();
serverSocket.close();
}
public boolean Listen() {
if(serverSocket == null)
{
Print("Can not listen, Start() was not called.");
return false;
}
new Thread(new Runnable() {
public void run() {
Accept_Begin();
}
}).start();
return true;
}
public boolean Start()
{
try
{
serverSocket = new ServerSocket(1254);
}
catch (IOException e)
{
Print("Can not host, port is probably already in use");
return false;
}
return true;
}
public void Send(ByteBuffer b) {
Send_In_Thread(b, BwriterForClient);
}
Socket Clientsock;
ServerSocket serverSocket;
DataOutputStream BwriterForClient;
DataInputStream BReaderForClient;
}
Client.java
package net;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
public class Client extends ClientServerBase {
public Client() throws UnknownHostException, IOException
{
super(ClientServerBase.REAL_TYPE.CLIENT);
ClientSocket = new Socket("localhost", 1254);
DIS = new DataInputStream(ClientSocket.getInputStream());
DOS = new DataOutputStream(ClientSocket.getOutputStream());
//Read_In_Thread(DIS);
}
public void close() throws IOException {
DIS.close();
DOS.close();
ClientSocket.close();
}
/**
* @brief Sends data to the server. That is done in thread
* @param Data
*/
public void Send(ByteBuffer Data) {
Send_In_Thread(Data, DOS);
}
Socket ClientSocket;
DataInputStream DIS;
DataOutputStream DOS;
}
ClientServerBase.java公共库
package net;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public abstract class ClientServerBase {
protected enum REAL_TYPE
{
CLIENT,
SERVER
}
protected ClientServerBase(final REAL_TYPE r)
{
CurrentlyWritingToOutputStream = false;
ReadThreadRunning = false;
real_type = r;
}
//=============================================================================
protected void Print(String s)
{
if(real_type == REAL_TYPE.CLIENT)
s = "Client: " + s;
else
s = "Server: " + s;
System.out.println(s);
}
void Send_Begin(ByteBuffer Data, DataOutputStream OutputStream) {
try {
while(CurrentlyWritingToOutputStream)
{ /* wait */ }
CurrentlyWritingToOutputStream = true;
OutputStream.writeInt(12);
OutputStream.flush();
CurrentlyWritingToOutputStream = false;
Send_End(false);
} catch (IOException e) {
Send_End(true);
}
}
void Send_End(boolean Error) {
if (!Error)
Print("Data sent sucessfully");
else
Print("There was an error sending data");
}
protected void Send_In_Thread(ByteBuffer Data, DataOutputStream OutputStream) {
new Thread(new Runnable() {
public void run() {
Send_Begin(Data, OutputStream);
}
}).start();
}
boolean ReadThreadRunning;
boolean CurrentlyWritingToOutputStream;
/**
* Real type of object
*/
REAL_TYPE real_type;
}
程序的输出:
Server: Client accepted
Client: Data sent sucessfully
Client: Data sent sucessfully
Client: Data sent sucessfully
Server: Red: 12
Server: Red: 0
Client: Data sent sucessfully
Client: Data sent sucessfully
Server: Red: 3084
Client: Data sent sucessfully
Server: Red: 12
Server: Red: 0
Server: Red: 201326604
如您所见,有时,它读取0,甚至一些未初始化的值。
拜托,你能帮我吗?我无法解释也无法理解,这究竟是怎么可能的。
我使用了所有函数的红色文档,但这仍然是一个谜
非常感谢您提供的任何可能的帮助您正在Listen方法中启动一个线程,该线程调用Accept\u begin->Accept\u end->Accept\u begin->。。。在无限循环中 在Accept_端,您将不断地为客户端和编写器替换breader。这里似乎有点不对劲
此外,您正在进行并行编程。您的发送方法需要同步 虽然它显然不能解决问题本身,但在Java中使用它非常有效,并且与JDK配合使用也很好。我建议坚持使用它,这里没有信号量,只有一个布尔变量,这是不够的。您应该使用同步、等待/通知或适当的信号量。是的,在侦听中我意识到了这一点,将来我希望接受更多的客户端。send方法…在我看来,应该使用布尔变量CurrentlyWritingToOutputStream充分地完成同步,因为一次只有一个线程将写入Stream…哇,非常感谢。我在谷歌上搜索了同步,发现它可以在Java中使用synchronized关键字来完成。到目前为止,当我运行程序12次时,仍然得到相同的输出。谢谢