从插座的Android阅读挂在第二读取循环 [英] Android reading from Socket hangs on second read loop
问题描述
我实现我的应用程序聊天。连接到一个服务器使用套接字制成。我要注册到该服务器，服务器将aknowledge与答复。
I got to implement a chat in my application. Connection to a server is made using sockets. I should register to that server and the server will aknowledge that with a reply.
我在一个单一的方法来实现这个，我用的BufferedWriter发送命令，然后开始从输入流中读取数据，直到它告诉我，有没有更多的数据。
I have implemented this in a single method where I send the command using a BufferedWriter, and then start reading from the input stream until it tells me there is no more data.
我正确读取服务器的答复。不过，我从来没有从第二个 in.read 通话负值，因此我的方法挡在了while循环保持（在conditionnal声明，我打电话通知）。
I read properly the server reply. However, I never get the negative value from the second in.read call and thus my method stays blocked in the while loop (in the conditionnal statement where I make that call).
应如何与插座呢？我通常做与文件或其他输入毫无问题流。
如果我只读我应该读取的字节数，这是否意味着我要么必须：
If I should read only the bytes I am supposed to read, does that mean that I either have to:
- 在事先知道服务器响应的长度？
- 或使服务器发送一个code，通知它已完成发送它的响应？
目前我做以下内容：
private String sendSocketRequest(String request, boolean skipResponse) throws ChatException {
if (!isConnected()) openConnection();
try {
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(
socket.getOutputStream()), 2048);
out.append(request);
out.flush();
out = null;
} catch (IOException e) {
LogHelper.error("Unable to send socket request: " + request, e);
throw new ChatException("Unable to send socket request: " + request, e);
}
try {
BufferedReader in = new BufferedReader(new InputStreamReader(
socket.getInputStream()), 2048);
StringBuffer response = new StringBuffer();
char[] buffer = new char[2048];
int charsRead = -1;
// >>>>>>>> This is where it gets blocked <<<<<<<<<
while ((charsRead = in.read(buffer)) >= 0) {
if (charsRead > 0) response.append(new String(buffer, 0, charsRead));
}
return response.toString();
} catch (IOException e) {
LogHelper.error("Unable to read socket response: " + request, e);
throw new ChatException("Unable to read socket response: " + request, e);
}
}
连接到服务器与以下方法进行：
Connection to the server is made with the following method:
public synchronized void openConnection() throws ChatException {
try {
socket = new Socket(Constants.API_CHAT_SERVER_ADDRESS, Constants.API_CHAT_SERVER_PORT);
socket.setKeepAlive(true);
LogHelper.debug("CHAT >> Connected to the chat server: " + Constants.API_CHAT_SERVER_ADDRESS);
} catch (UnknownHostException e) {
LogHelper.error("Unable to open chat connection", e);
throw new ChatException("Unable to open chat connection", e);
} catch (IOException e) {
LogHelper.error("Unable to open chat connection", e);
throw new ChatException("Unable to open chat connection", e);
}
}
推荐答案
数据的将被发送的量/通过套接字基于连接接收是协议dependend和不知道的TCP / IP栈，但只应用层
The amount of data to be sent/received over a socket based connection is protocol dependend and not known to the TCP/IP stack, but only to the application layer.
使用的协议是开发商dependend ... ;-)所以来你的问题：
The protocol used is developer dependend ... ;-) so coming to your questions:
如果我只读我应该读取的字节数，这是否意味着我要么必须：
If I should read only the bytes I am supposed to read, does that mean that I either have to:
- 在事先知道服务器响应的长度？
是的，这是一种可能性。
Yes, this is one possibility.
- 或使服务器发送一个code，通知它已完成发送它的响应？
也不错，因为这是另一种可能性。常见的标记是 \\ n 或 \\ r \\ n 。在 NUL / '\\ 0'的性格也可能是有意义的。
Also yes, as this is another possibility. Common markers are \n or \r\n. The NUL/'\0' character also might make sense.
第三个选项是preFIX以恒定的数字描述字节来量字节每一个数据块。
A third option is to prefix each data chunk with a constant number of bytes describing the amount of bytes to come.
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