这些天我对使用 java 套接字时的 Tcp 性能感到困惑。其实java代码很简单。详情如下：
- 服务器打开一个端口并开始监听。
- 客户端请求并连接到服务器后，客户端开始写入套接字。
- 服务器收到请求后，它会打开一个新线程来处理这个连接。（此连接为长连接，不会超时）。
- 服务器将继续读取，直到它得到结束分隔符，然后给客户端一个响应并继续再次读取。
- 客户端收到响应后，将再次发送另一个请求。
我发现如果客户端一次写整个消息（包括结束分隔符），通信速度令人满意，速度可以达到每分钟50000条消息。但是，如果客户端分次将字节写入socket，速度会迅速下降，几乎每分钟1400条消息，是原来速度的1/40倍。我对此很困惑。任何人都可以帮我一把吗？任何意见表示赞赏！
我的模拟服务器端如下：
public class ServerForHelp {
final static int BUFSIZE = 10240;
Socket socket;
String delimiter = "" + (char) 28 + (char) 13;
public static void main(String[] args) throws IOException {
ServerSocket ss = new ServerSocket(9200);
System.out.println("begin to accept...");
while (true) {
Socket s = ss.accept();
Thread t = new Thread(new SocketThread1(s));
t.start();
}
}
public String readUntilDelimiter() throws Exception {
StringBuffer stringBuf = new StringBuffer();
InputStream stream = socket.getInputStream();
InputStreamReader reader = null;
reader = new InputStreamReader(stream);
char[] buf = new char[BUFSIZE];
while (true) {
int n = -1;
n = reader.read(buf, 0, BUFSIZE);
if (n == -1) {
return null; // it means the client has closed the connection, so return null.
} else if (n == 0) {
continue; // continue to read the data until got the delimiter from the socket.
}
stringBuf.append(buf, 0, n);
String s = stringBuf.toString();
int delimPos = s.indexOf(delimiter);
if (delimPos >= 0) {
// found the delimiter; return prefix of s up to separator and
// To make the thing simple, I have discarded the content after the delimiter.
String result = s.substring(0, delimPos);
sendTheResponse(socket);
return result;
}
}
}
private void sendTheResponse(Socket socket) throws IOException {
Writer writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
writer.write("Hi, From server response");
writer.flush();
}
}
class SocketThread1 implements Runnable {
Socket socket;
public SocketThread1(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
ServerForHelp server = new ServerForHelp();
server.socket = socket;
while (true) {
try {
if (server.readUntilDelimiter() == null) // it means that the client has closed the connection, exist
break;
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
这是一个普通的套接字编程。
以下是我的客户端：
public void execute() throws Exception{
int msgCnt = 0;
Socket socket = null;
byte[] bufBytes = new byte[512];
long start = 0;
final char START_MESSAGE = 0x0B;
final char END_MESSAGE = 0x1C;
final char END_OF_RECORD = 0x0D;//\r
String MESSAGE = "HELLO, TEST";
socket = new Socket("192.168.81.39", 9200);
OutputStream os = socket.getOutputStream();
InputStream is = socket.getInputStream();
while (System.currentTimeMillis() - start < 60000)
{
// If you send the total message at one time, the speed will be improved significantly
// FORMAT 1
StringBuffer buf = new StringBuffer();
buf.append(START_MESSAGE);
buf.append(MESSAGE);
buf.append(END_MESSAGE);
buf.append(END_OF_RECORD);
os.write(buf.toString().getBytes());
// FORMAT 1 END
//FORMAT 2
// os.write(START_MESSAGE);
// os.write(MESSAGES[port].getBytes());
// os.write(END_MESSAGE);
// os.write(END_OF_RECORD);
//FORMAT 2 END
os.flush();
is.read(bufBytes);
msgCnt++;
System.out.println(msgCnt);
}
System.out.println( msgCnt + " messages per minute");
}
如果我使用“FORMAT 1”发送消息，速度可以达到每分钟 50000 条消息，但如果使用“FORMAT 2”，速度会下降到每分钟 1400 条消息。谁说清楚原因？
我试图尽可能详细地描述，任何帮助将不胜感激。