我正在编写一个 Java 客户端/服务器应用程序，它将在每个程序之间来回传递 2 个映射。客户端填充初始 map 并将其发送到服务器。服务器按预期接收 map 并显示数据。然后，服务器构建响应映射，并将其返回给客户端。客户端按预期接收 map 并显示数据。一切看起来都很好。现在，客户端清除 map 并使用更多数据重新填充 map ，并将 map 发送到服务器。服务器按预期接收它，构建并发送响应映射。客户端读取 map 的“objectinputstream”，但 map 现在是空的。客户端清除 map 并用更多数据重新填充 map ，然后再次将 map 发送到服务器。服务器看似收到了 map ，但显示的数据是第二次成功传输时收到的数据，而不是当前数据。谁能阐明这里发生的事情吗？非常感谢所有帮助!
这是服务器的日志:
- awaiting connection - about to readobject - read this>I-InkjetBadLabel = `Send` - read this>I-LogoPakBadLabel = `Send` - read this>I-InkjetBadLabelAck = `Response` - read this>I-LogoPakBadLabelAck = `Response` - writing this>I-InkjetBadLabel = `Send` - writing this>I-LogoPakBadLabel = `Send` - writing this>I-InkjetBadLabelAck = `Response` - writing this>I-LogoPakBadLabelAck = `Response` - wrote socket - about to readobject - read this>InkjetBadLabel = `False0` - read this>LogoPakBadLabel = `False0` - writing this>InkjetBadLabel = `False0` - writing this>LogoPakBadLabel = `False0` - wrote socket - about to readobject - read this>InkjetBadLabel = `False0` - read this>LogoPakBadLabel = `False0` - writing this>InkjetBadLabel = `False0` - writing this>LogoPakBadLabel = `False0` - wrote socket - about to readobject - read this>InkjetBadLabel = `False0` - read this>LogoPakBadLabel = `False0` - writing this>InkjetBadLabel = `False0` - writing this>LogoPakBadLabel = `False0` - wrote socket - about to readobject - read this>InkjetBadLabel = `False0` - read this>LogoPakBadLabel = `False0` - writing this>InkjetBadLabel = `False0` - writing this>LogoPakBadLabel = `False0` - wrote socket
这是客户端的日志:
- PLC_socket. open!! - istream = new ObjectInputStream - ostream = new ObjectOutputStream - sending externalProgramCommInitializeMap - externalProgramCommInitializeMap =>I-InkjetBadLabel = `Send` - externalProgramCommInitializeMap =>I-LogoPakBadLabel = `Send` - externalProgramCommInitializeMap =>I-InkjetBadLabelAck = `Response` - externalProgramCommInitializeMap =>I-LogoPakBadLabelAck = `Response` - ostream.writeObject - istream.readObject() 1 - initialize received externalProgramCommBitMapOutOfPFC response - - externalProgramCommBitMap =>I-InkjetBadLabel = `Send` - externalProgramCommBitMap =>I-LogoPakBadLabel = `Send` - externalProgramCommBitMap =>I-InkjetBadLabelAck = `Response` - externalProgramCommBitMap =>I-LogoPakBadLabelAck = `Response` - xx=0 - externalProgramCommBitMapIntoPFC.clear - externalProgramCommBitMapIntoPFC =>InkjetBadLabel = `False0` - externalProgramCommBitMapIntoPFC =>LogoPakBadLabel = `False0` - writing map! - ostream.flush - done writing - data - istream.readObject() - data - received externalProgramCommBitMapOutOfPFC response - !!!!!! RESPONSE MAP IS EMPTY !!!!!! - xx=1 - externalProgramCommBitMapIntoPFC.clear - externalProgramCommBitMapIntoPFC =>InkjetBadLabel = `False1` - externalProgramCommBitMapIntoPFC =>LogoPakBadLabel = `False1` - writing map! - ostream.flush - done writing - data - istream.readObject() - data - received externalProgramCommBitMapOutOfPFC response - !!!!!! RESPONSE MAP IS EMPTY !!!!!! - xx=2 - externalProgramCommBitMapIntoPFC.clear - externalProgramCommBitMapIntoPFC =>InkjetBadLabel = `False2` - externalProgramCommBitMapIntoPFC =>LogoPakBadLabel = `False2` - writing map! - ostream.flush - done writing - data - istream.readObject() - data - received externalProgramCommBitMapOutOfPFC response - !!!!!! RESPONSE MAP IS EMPTY !!!!!! - xx=3 - externalProgramCommBitMapIntoPFC.clear - externalProgramCommBitMapIntoPFC =>InkjetBadLabel = `False3` - externalProgramCommBitMapIntoPFC =>LogoPakBadLabel = `False3` - writing map! - ostream.flush - done writing - data - istream.readObject() - data - received externalProgramCommBitMapOutOfPFC response - !!!!!! RESPONSE MAP IS EMPTY !!!!!!
这是我的客户端程序:
package com.agfa.Verify;
import java.io.*;
import java.net.*;
import java.net.UnknownHostException;
import java.util.*;
import org.apache.log4j.Logger;
public class testVerifyScannedLabels implements Serializable {
private static final long serialVersionUID = 1L;
private final Logger log = Logger.getLogger(testVerifyScannedLabels.class.getSimpleName());
private boolean debugEnabled = false;
private Map<String, String> externalProgramCommBitMapIntoPFC = new LinkedHashMap<String, String>();
private Map<String, String> externalProgramCommBitMapOutOfPFC = new LinkedHashMap<String, String>();
private Socket PLC_socket = null;
private Map<String, String> externalProgramCommInitializeMap = new LinkedHashMap<String, String>();
private ObjectOutputStream ostream = null;
private ObjectInputStream istream = null;
private List<String> errorMessages = new ArrayList<String>();
private void initialize() {
externalProgramCommInitializeMap.put("I-InkjetBadLabel", "Send");
externalProgramCommInitializeMap.put("I-LogoPakBadLabel", "Send");
externalProgramCommInitializeMap.put("I-InkjetBadLabelAck", "Response");
externalProgramCommInitializeMap.put("I-LogoPakBadLabelAck", "Response");
}
public testVerifyScannedLabels() {
initialize();
/***********************************************************************
* sockets client for PLC Communicator
**********************************************************************/
if (PLC_socket == null) {
log.debug("PLC_socket == null");
try {
istream = null;
ostream = null;
PLC_socket = new Socket(InetAddress.getLocalHost(), 60103);
PLC_socket.setKeepAlive(true);
log.debug("PLC_socket opened on port 60103");
} catch (NumberFormatException x) {
log.warn("PLC_CommMapPort-NumberFormatException Exception! " + x.getMessage());
} catch (ConnectException x) {
log.warn("PLC_CommMapPort-Connection Exception! " + x.getMessage());
} catch (UnknownHostException x) {
log.warn("PLC_CommMapPort-UnknownHostException Exception! " + x.getMessage());
} catch (IOException x) {
log.warn("PLC_CommMapPort-IOException Exception! " + x.getMessage());
}
}
if (PLC_socket == null) {
log.error("PLC_socket was not established!");
istream = null;
ostream = null;
} else {
log.debug("PLC_socket not null!!!");
try { // Socket client..
if (PLC_socket.isConnected() && !PLC_socket.isClosed()) {
log.info("PLC_socket. open!!");
if (istream == null) {
log.debug("istream = new ObjectInputStream");
istream = new ObjectInputStream(PLC_socket.getInputStream());
}
if (ostream == null) {
log.debug("ostream = new ObjectOutputStream");
ostream = new ObjectOutputStream(PLC_socket.getOutputStream());
log.debug("sending externalProgramCommInitializeMap");
final Iterator<Map.Entry<String, String>> it = externalProgramCommInitializeMap
.entrySet().iterator();
while (it.hasNext()) {
final Map.Entry<String, String> pairs = it.next();
log.debug("externalProgramCommInitializeMap =>" + pairs.getKey()
+ " = `" + pairs.getValue() + "`");
}
log.debug("ostream.writeObject");
ostream.writeObject(externalProgramCommInitializeMap);
log.debug("istream.readObject() 1 ");
externalProgramCommBitMapOutOfPFC = (Map<String, String>) istream
.readObject();
log.debug(" initialize received externalProgramCommBitMapOutOfPFC response -");
final Iterator<Map.Entry<String, String>> rit = externalProgramCommBitMapOutOfPFC
.entrySet().iterator();
while (rit.hasNext()) {
final Map.Entry<String, String> pairs = rit.next();
log.debug("externalProgramCommBitMap =>" + pairs.getKey() + " = `"
+ pairs.getValue() + "`");
}
}
for (int xx = 0; xx < 100; xx++) { // for testing only
log.debug("xx=" + xx);
log.debug("externalProgramCommBitMapIntoPFC.clear ");
externalProgramCommBitMapIntoPFC.clear();
externalProgramCommBitMapIntoPFC.put("InkjetBadLabel", "False" + xx);
externalProgramCommBitMapIntoPFC.put("LogoPakBadLabel", "False" + xx);
externalProgramCommBitMapOutOfPFC.clear();
for (String line : errorMessages) {
log.info("build externalProgramCommBitMapIntoPFC " + line.toUpperCase());
if (line.toUpperCase().contains("INKJET")) {
log.debug("in ink");
externalProgramCommBitMapIntoPFC.put("InkjetBadLabel", "True" + xx);
}
if (line.toUpperCase().contains("LOGOPAK")) {
log.debug("in logo");
externalProgramCommBitMapIntoPFC
.put("LogoPakBadLabel", "True" + xx);
}
}
final Iterator<Map.Entry<String, String>> wit = externalProgramCommBitMapIntoPFC
.entrySet().iterator();
while (wit.hasNext()) {
final Map.Entry<String, String> pairs = wit.next();
log.debug("externalProgramCommBitMapIntoPFC =>" + pairs.getKey()
+ " = `" + pairs.getValue() + "`");
}
log.debug("writing map!");
ostream.writeObject(externalProgramCommBitMapIntoPFC);
log.debug("ostream.flush");
ostream.flush();
log.debug("done writing");
log.debug("data - istream.readObject() ");
externalProgramCommBitMapOutOfPFC = (Map<String, String>) istream
.readObject();
log.debug("data - received externalProgramCommBitMapOutOfPFC response");
final Iterator<Map.Entry<String, String>> rit = externalProgramCommBitMapOutOfPFC
.entrySet().iterator();
if (rit.hasNext()) {
while (rit.hasNext()) {
final Map.Entry<String, String> pairs = rit.next();
log.debug("externalProgramCommBitMap =>" + pairs.getKey() + " = `"
+ pairs.getValue() + "`");
}
} else
log.debug(" !!!!!! RESPONSE MAP IS EMPTY !!!!!!");
Thread.sleep(4000L);
/**/} // end for testing ..
} else {
log.error("VerifyScannedLabels unable to connect to PLC_Datacomm via Sockets");
}
// end of Socket client
} catch (UnknownHostException e) {
log.error("VerifyScannedLabels unable to connect to PLC_Datacomm via Sockets "
+ e.getMessage());
PLC_socket = null;
} catch (IOException e) {
log.error("VerifyScannedLabels unable to connect to PLC_Datacomm via Sockets "
+ e.getMessage());
PLC_socket = null;
} catch (ClassNotFoundException e) {
log.error("VerifyScannedLabels unable to connect to PLC_Datacomm via Sockets "
+ e.getMessage());
PLC_socket = null;
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (debugEnabled) {
log.debug("VerifyScannedLabels processing Ends.");
}
try {
Thread.sleep(1000L);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) {
testVerifyScannedLabels vsl = new testVerifyScannedLabels();
}
}
这是我的服务器程序:
package com.agfa.sockets;
import java.net.*;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.io.*;
import org.apache.log4j.Logger;
public class testSocketThreadSendReceiveMap {
private Logger log = Logger.getLogger(testSocketThreadSendReceiveMap.class.getSimpleName());
private ServerSocket ssock = null;
private Socket socket = null;
private ObjectOutputStream ostream = null;
private ObjectInputStream istream = null;
private Map<String, String> dataMapIntoRemote = new LinkedHashMap<String, String>();
private Map<String, String> dataMapFromRemote = new LinkedHashMap<String, String>();
public static void main(String[] args) {
testSocketThreadSendReceiveMap tSTSRM = new testSocketThreadSendReceiveMap();
}
@SuppressWarnings("unchecked")
public testSocketThreadSendReceiveMap() {
try {
log.info("awaiting connection");
ssock = new ServerSocket(60103);
socket = ssock.accept();
ostream = new ObjectOutputStream(socket.getOutputStream());
istream = new ObjectInputStream(socket.getInputStream());
while (true) {
//log.debug("following is for testing - remove from production");
/*
* in real life dataMapIntoRemote will be provided by parent
* Thread
*/
dataMapIntoRemote.clear();
/****** remove above *****/
dataMapFromRemote.clear();
log.debug("about to readobject");
dataMapFromRemote.putAll((Map<String, String>) istream.readObject());
final Iterator<Map.Entry<String, String>> it = dataMapFromRemote.entrySet()
.iterator();
while (it.hasNext()) {
final Map.Entry<String, String> pairs = it.next();
log.debug("read this>" + pairs.getKey() + " = `" + pairs.getValue() + "`");
//log.debug("following is for testing - remove from production");
/*
* in real life dataMapIntoRemote will be provided by
* parent Thread
*/
dataMapIntoRemote.put(pairs.getKey(), pairs.getValue());
/****** remove above *****/
}
final Iterator<Map.Entry<String, String>> wit = dataMapIntoRemote.entrySet()
.iterator();
while (wit.hasNext()) {
final Map.Entry<String, String> pairs = wit.next();
log.debug("writing this>" + pairs.getKey() + " = `" + pairs.getValue() + "`");
}
ostream.writeObject(dataMapIntoRemote);
ostream.flush();
log.debug("wrote socket");
}
} catch (IOException e) {
log.error("SocketThreadSendReceiveMap-While(True).IOException! " + e.getMessage());
} catch (Exception e) {
log.error("SocketThreadSendReceiveMap-While(True).Exception! " + e.getMessage());
}
try {
log.warn("SocketThreadSendReceiveMap.class socket.close");
socket.close();
} catch (IOException e) {
log.error("SocketThreadSendReceiveMap-socket.close().IOException! " + e.getMessage());
}
}
}
最佳答案
您还需要在调用 ostream.flush() 后立即调用 ostream.reset()。
ObjectOutputStream 维护它所写入的引用的内部映射，以便在您最终多次写入相同的引用(这就是您发送映射时所做的事情)时节省序列化时间。在 flush() 之后调用 reset() 会清除此内部引用表，并导致下次调用 writeObject(object) 时重新序列化对象，无论之前是否传入了相同的引用。
关于Java 客户端/服务器双向套接字不工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16968892/