深入刨析tomcat 之---第3篇 HTTP/1.1 长连接的实现原理
2021-07-23 22:55
标签：数据 shu parse cling ppi span stat and readline writedby 张艳涛 长连接是HTTP/1.1的特征之一,1.1出现的原因是因为一个客户请求一个网页,这是一个http请求,这个网页中如果有图片,那么也会变为一个http请求,对于java客户端,一个http请求 是通过socket.getinputstream.cast(PrintWriter).println("http请求头"),如果俩个请求都通过一个socket来写数据,那么这个就是http长连接,如果你写一个简单http服务器,那你实现的就不是长连接,每次请求都把socket.close()了, 所以判断一个http请求时不是长连接就是判断socket.close有没有执行 那么我们来看tomcat是如何实现长连接了的,对应深入理解tomcat第4章 进入方法 进入方法 接着进入 接着进入 接着 上述俩个方法中的fill() 的is.read() 底层就是socket.getInputStream进行读到缓冲区 这个方法是有阻塞的,那么就实现了处理完一个http请求,接着读取第二个请求 如果以上过程报错,跳出while循环 关闭socket,那么就断开了socket长连接 此文结束 深入刨析tomcat 之---第3篇 HTTP/1.1 长连接的实现原理 标签：数据 shu parse cling ppi span stat and readline 原文地址：https://www.cnblogs.com/zytcomeon/p/14964551.html实现思路是,如果socket不断开的话,那么socket.getInputStream(),得到的in流 会调用in.read()方法,进行阻塞,如果来了数据,读取新进来的请求,如果满足http协议进行解析;
HttpProcessor类
public void run() {
// Process requests until we receive a shutdown signal
while (!stopped) {
// Wait for the next socket to be assigned
Socket socket = await();
if (socket == null)
continue;
// Process the request from this socket
try {
process(socket);
} catch (Throwable t) {
log("process.invoke", t);
}
// Finish up this request
connector.recycle(this);
}
// Tell threadStop() we have shut ourselves down successfully
synchronized (threadSync) {
threadSync.notifyAll();
}
}
private void process(Socket socket) {
boolean ok = true;
boolean finishResponse = true;
SocketInputStream input = null;
OutputStream output = null;
// Construct and initialize the objects we will need
try {
input = new SocketInputStream(socket.getInputStream(),
connector.getBufferSize());
} catch (Exception e) {
log("process.create", e);
ok = false;
}
keepAlive = true;
while (!stopped && ok && keepAlive) {
finishResponse = true;
try {
request.setStream(input);
request.setResponse(response);
output = socket.getOutputStream();
response.setStream(output);
response.setRequest(request);
((HttpServletResponse) response.getResponse()).setHeader
("Server", SERVER_INFO);
} catch (Exception e) {
log("process.create", e);
ok = false;
}
// Parse the incoming request
try {
if (ok) {
parseConnection(socket);
parseRequest(input, output);
if (!request.getRequest().getProtocol()
.startsWith("HTTP/0"))
parseHeaders(input);
if (http11) {
// Sending a request acknowledge back to the client if
// requested.
ackRequest(output);
// If the protocol is HTTP/1.1, chunking is allowed.
if (connector.isChunkingAllowed())
response.setAllowChunking(true);
}
}
异常...略
}
// Finish up the handling of the request
if (finishResponse) {
try {
response.finishResponse();
} catch (IOException e) {
ok = false;
} catch (Throwable e) {
log("process.invoke", e);
ok = false;
}
try {
request.finishRequest();
} catch (IOException e) {
ok = false;
} catch (Throwable e) {
log("process.invoke", e);
ok = false;
}
try {
if (output != null)
output.flush();
} catch (IOException e) {
ok = false;
}
}
// We have to check if the connection closure has been requested
// by the application or the response stream (in case of HTTP/1.0
// and keep-alive).
if ( "close".equals(response.getHeader("Connection")) ) {
keepAlive = false;
}
// End of request processing
status = Constants.PROCESSOR_IDLE;
// Recycling the request and the response objects
request.recycle();
response.recycle();
}
try {
shutdownInput(input);
socket.close();
} catch (IOException e) {
;
} catch (Throwable e) {
log("process.invoke", e);
}
socket = null;
}
input.readRequestLine(requestLine);
public void readRequestLine(HttpRequestLine requestLine)
throws IOException {
// Recycling check
if (requestLine.methodEnd != 0)
requestLine.recycle();
// Checking for a blank line
int chr = 0;
do { // Skipping CR or LF
try {
chr = read();
} catch (IOException e) {
chr = -1;
}
} while ((chr == CR) || (chr == LF));
if (chr == -1)
throw new EOFException
(sm.getString("requestStream.readline.error"));
pos--;
// Reading the method name
public int read()
throws IOException {
if (pos >= count) {//读到了结尾
fill();
if (pos >= count)
return -1;
}
return buf[pos++] & 0xff;
}
/**
* Fill the internal buffer using data from the undelying input stream.
*/
protected void fill()
throws IOException {
pos = 0;
count = 0;
int nRead = is.read(buf, 0, buf.length);
if (nRead > 0) {
count = nRead;
}
}
parseRequest(input, output);
//input的构造方法
input = new SocketInputStream(socket.getInputStream(),
connector.getBufferSize());
//
public SocketInputStream(InputStream is, int bufferSize) {
this.is = is;
buf = new byte[bufferSize];
}
try {
shutdownInput(input);
socket.close();
} catch (IOException e) {
;
} catch (Throwable e) {
log("process.invoke", e);
}
socket = null;
文章标题：深入刨析tomcat 之---第3篇 HTTP/1.1 长连接的实现原理
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