英文:
DataInputStream readUTF crashing program
问题
以下是翻译好的内容：
发送部分：
while(scanning){
try {
clientSocket = new Socket(HOST, PORT);
dataInput = new DataInputStream(clientSocket.getInputStream());
dataOutput = new DataOutputStream(clientSocket.getOutputStream());
System.out.println("Connected to server");
receiverThread = new ReceiverThread(clientSocket, dataInput, dataOutput);
receiverThread.start();
scanning = false;
Map<String, String> jsonMap = new HashMap<String,String>();
jsonMap.put("UserName", "TestName");
jsonMap.put("FileName", "TestFileName.txt");
jsonMap.put("FileSize", "1234");
//发送文件
File f = new File("test.txt");
System.out.println("F length" + f.length());
dataOutput.writeByte(1);
dataOutput.writeUTF(String.valueOf(jsonMap));
dataOutput.writeByte(2);
dataOutput.write(Integer.parseInt(String.valueOf(f.length())));
//发送文件内容
//sendFile(f.getAbsolutePath(), f.length(), receiverThread.getDataOutputStream());
//发送结束
} catch (ConnectException e) {
System.out.println("Server not available");
} catch (SocketException e) {
System.out.println("Connection broken");
} catch (Exception e) {
System.out.println("ERROR " + e);
} finally {
if (receiverThread != null)
try {
receiverThread.interrupt();
} catch (Exception e) {
}
}
}
接收部分：
while (true) {
try {
messageType = dataInput.readByte();
switch (messageType){
case 1:
System.out.println("TEST " + dataInput.readUTF());
message = dataInput.readUTF();
System.out.println("TTTT " + message);
stringToMap(message);
System.out.println("TEST MAP UN1 ");
System.out.println("TEST map " + map.get("UserName"));
System.out.println("TEST MAP UN2 ");
break;
case 2:
saveFile(clientSocket);
break;
default:
throw new IllegalStateException("Unexpected value: " + messageType);
}
System.out.println("TEST MESSAGE ");
} catch (Exception e) {
System.out.println("ERROR " + Arrays.toString(e.getStackTrace()));
System.out.println("ERROR " + e.getMessage());
System.exit(2);
}
}
关于以下代码段：
System.out.println("TEST " + dataInput.readUTF());
它可以正常工作，但是当您尝试将其分配给字符串变量时，程序不会崩溃、不会抛出错误，只是停在System.out.println语句上，您有没有任何想法为什么？
可能的原因是，您在读取UTF格式的字符串后，尝试将其分配给字符串变量。然而，在这之后，还有另一个读取UTF字符串的操作，这可能导致数据读取的不同步，从而影响后续的代码执行。您可以尝试将接收代码修改为：
case 1:
System.out.println("TEST " + dataInput.readUTF());
message = dataInput.readUTF(); // 只读取一次
System.out.println("TTTT " + message);
stringToMap(message);
System.out.println("TEST MAP UN1 ");
System.out.println("TEST map " + map.get("UserName"));
System.out.println("TEST MAP UN2 ");
break;
这样可以确保在进行其他操作之前只读取一次UTF字符串。这有助于保持数据同步，避免读取不正确的数据。
英文:
I have question, I'm trying to send Map<String,String> using socket like below
while(scanning){
try {
clientSocket = new Socket(HOST, PORT);
dataInput = new DataInputStream(clientSocket.getInputStream());
dataOutput = new DataOutputStream(clientSocket.getOutputStream());
System.out.println("Connected to server");
receiverThread = new ReceiverThread(clientSocket, dataInput, dataOutput);
receiverThread.start();
scanning = false;
Map<String, String> jsonMap = new HashMap<String,String>();
jsonMap.put("UserName", "TestName");
jsonMap.put("FileName", "TestFileName.txt");
jsonMap.put("FileSize", "1234");
//sending file
File f = new File("test.txt");
System.out.println("F length"+ f.length());
dataOutput.writeByte(1);
dataOutput.writeUTF(String.valueOf(jsonMap));
dataOutput.writeByte(2);
dataOutput.write(Integer.parseInt(String.valueOf(f.length())));
//sendFile(f.getAbsolutePath(),f.length(), receiverThread.getDataOutputStream());
//end sending
} catch (ConnectException e) {
System.out.println("Server not available");
} catch (SocketException e) {
System.out.println("Connection broken");
} catch (Exception e) {
System.out.println("ERROR " + e);
} finally {
if (receiverThread != null)
try {
receiverThread.interrupt();
} catch (Exception e) {
}
}
and I'm receiving like this
while (true) {
try {
messageType = dataInput.readByte();
switch (messageType){
case 1:
System.out.println("TEST " + dataInput.readUTF());
message = dataInput.readUTF();
System.out.println("TTTT " + message);
stringToMap(message);
System.out.println("TEST MAP UN1 ");
System.out.println("TEST map " + map.get("UserName"));
System.out.println("TEST MAP UN2 ");
break;
case 2:
saveFile(clientSocket);
break;
default:
throw new IllegalStateException("Unexpected value: " + messageType);
}
System.out.println("TEST MESSAGE ");
} catch (Exception e) {
System.out.println("ERROR " + Arrays.toString(e.getStackTrace()));
System.out.println("ERROR " + e.getMessage());
System.exit(2);
}
and when i do this :
System.out.println("TEST " + dataInput.readUTF());
It's works, but when i try to assigne to String variable program do nothing, it's not crashing, not throwing error just stop on the System.out.println...
someone have any idea why ?
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