使用DataOutputStream将消息写入客户端套接字到服务器套接字只在关闭客户端套接字后发送，为什么？

Question

我用Java编写了套接字客户端程序。我正在使用DataOutputStream向服务器套接字发送消息。有时DataOutputstream上的writed消息不会发送到ServerSocket。我想是因为我发了信息后没有脸红。我这样做，但没有用。如果我终止类执行，那么只有我从ServerSocket接收消息。

我的代码：

public class LoggingClient {


LinkedBlockingQueue<byte[]> messages = new LinkedBlockingQueue<byte[]>();

public static LoggingClient clientObj;

/*
 * waiting 2 seconds for connecting centralized log server . If it's not reachable writing log's in local machine
 * this log's will be collected on eclipse restart.
 */
public static final int SOCKET_TIMEOUT = 2000;
/**
 * Server which the log server is currently running.
 */
public static final  String SERVER = "bharathi";
/**
 * Port which the log server is running.
 */
public static final int PORT = 10000;

/**
 * Client socket used to connect the server .
 */
Socket client = null;

public static Logger logger = Logger.getLogger(LoggingClient.class.getName());


/**
 * Used to write given logs into client output stream.
 */
DataOutputStream out = null;

public boolean isConnected = false;

/**
 * Used for preventing instaniate LoggingClient without calling getInstance method.
 */
private LoggingClient(){

}

/**
 * Clear's the socket and initialize new socket .
 */
public void init(){
try{
    clear();
    client = new Socket();
        client.setTcpNoDelay(true);
    client.connect(new InetSocketAddress(SERVER,PORT),SOCKET_TIMEOUT); //trying to make connection within two seconds.
    out = new DataOutputStream(client.getOutputStream());
    isConnected = true;
}catch(Exception e){
    isConnected = false;
}
}

public static LoggingClient getInstance(){
if(clientObj == null){
    clientObj = new LoggingClient();
}
return clientObj;
}

public void clear(){
try{
    if(out != null){
    out.close(); //if we call close method it invokes flush and then closes the DataOutputStream.
    }

    if(client != null){
    client.close();
    }
}catch(Exception e){
    logger.log(Level.INFO,"Error while closing connection , reason {0}",e);
}finally{
    try{
    client.close();
    out.close();
    }catch(Exception e){

    }
    isConnected = false;
}
}


/**
 * Adding this message into a queue . Scheduled thread will get this logs and push into central logging server.
 * @param message
 */
public synchronized void write(byte[] message){
if(!isConnected){ //has connection.
    init();
}
messages.add(message); //adding message to this queue . Background thread will collect the log message and sent it to the central log server.
}

/**
 * Sending logs into central log server . If it's not reachable write into local machine.
 * @param message
 */
public void sendLog(byte[] message){
try {
    out.write(message);
    out.flush();
} catch (Exception e) {
    writeInLocalMachine(localLoggingPath, message); //in case of failure writing logs in local machine . Sync this logs when restart of eclipse.
}
}

/**
 * Writing log's into his machine this log will be synced on plugin startup.
 * @param file - File path.
 * @param message - Message  to log.
 */
public static void writeInLocalMachine(String file, byte[] message) {
FileOutputStream fileWriter = null;
File f = new File(file);
try {
    if(!f.exists()){
    f.createNewFile();
    }
    fileWriter = new FileOutputStream(file, true);
    fileWriter.write(message);
    fileWriter.flush();
} catch (Exception e) {
   logger.log(
        Level.WARNING,
        "This may be due to given file not found in system , reason {0}",
        e);
} finally {
    try{
    fileWriter.close();
    }catch(Exception e){

    }
}
}

/**
 * @return - Recently received message from queue . Returns null if it's empty.
 */
public byte[] getMessage(){
return messages.poll(); //returns the head element and deletes it.
}

public class LogTest implements Runnable {

public static final String LINE_SEPARATOR = System.getProperty("line.separator");


@Override
public void run() {
while(true){
    try{
        LoggingClient client = LoggingClient.getInstance();
        byte[] message = client.getMessage();
        if(message != null){
            client.sendLog(message);
        }
    }catch(Exception e){

    }
}
}

public static void startSending(){
for(int i=0;i<10000;i++){
    String msg = "msg number" + i+LINE_SEPARATOR;
    LoggingClient.getInstance().write(msg.getBytes());
}
}

public static void main(String args[]){
    LoggingClient c = LoggingClient.getInstance();
    System.out.println("START TIME " + System.currentTimeMillis());
    Thread t = new Thread(new LogTest(),"LOG MESSAGER");
    t.start();
    startSending();
    System.out.println("END TIME " + System.currentTimeMillis());
}

START TIME 1340815857896
END TIME 1340815858063

已完成将消息放入队列。无限while循环将负责向服务器套接字发送日志。

文件中存储的内容是0字节为什么？.如果我停止运行类，我会收到发送的消息，为什么？

Answer 1

您已经发布了太多的代码，但是在这些情况下，100次中有99次您只在流/程序关闭后才看到数据，您的问题是您从来没有在写入数据后刷新数据