tomcat源码分析系列之请求处理---关门打狗
??? 上回我们把请求放进来了，这回我们关上门，好好修理修理它，不折腾它一番，休想轻易出去。
要关门打狗，先得知道房子在哪才行啊，上回我们说到proces的处理被委托到Http11Processor类，它就是这套房子！Http11Processor的process方法，就是这间屋子：
/** * Process pipelined HTTP requests on the specified socket. * * @param socketWrapper Socket from which the HTTP requests will be read * and the HTTP responses will be written. * * @throws IOException error during an I/O operation */ @Override public SocketState process(SocketWrapper<Socket> socketWrapper) throws IOException { RequestInfo rp = request.getRequestProcessor(); //第一阶段 ?rp.setStage(org.apache.coyote.Constants.STAGE_PARSE); // Setting up the I/O this.socket = socketWrapper; inputBuffer.setInputStream(socket.getSocket().getInputStream()); outputBuffer.setOutputStream(socket.getSocket().getOutputStream()); // Error flag error = false; keepAlive = true; if (maxKeepAliveRequests > 0) { socketWrapper.decrementKeepAlive(); } int soTimeout = endpoint.getSoTimeout(); int threadRatio = -1; // These may return zero or negative values // Only calculate a thread ratio when both are >0 to ensure we get a // sensible result if (endpoint.getCurrentThreadsBusy() >0 && endpoint.getMaxThreads() >0) { threadRatio = (endpoint.getCurrentThreadsBusy() * 100) / endpoint.getMaxThreads(); } // Disable keep-alive if we are running low on threads if (threadRatio > getDisableKeepAlivePercentage()) { socketWrapper.setKeepAliveLeft(0); } try { socket.getSocket().setSoTimeout(soTimeout); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.debug(sm.getString("http11processor.socket.timeout"), t); error = true; } boolean keptAlive = socketWrapper.isKeptAlive(); while (!error && keepAlive && !endpoint.isPaused()) { // Parsing the request header try { int standardTimeout = 0; if (keptAlive) { if (keepAliveTimeout > 0) { standardTimeout = keepAliveTimeout; } else if (soTimeout > 0) { standardTimeout = soTimeout; } } /* * When there is no data in the buffer and this is not the first * request on this connection and timeouts are being used the * first read for this request may need a different timeout to * take account of time spent waiting for a processing thread. * * This is a little hacky but better than exposing the socket * and the timeout info to the InputBuffer */ if (inputBuffer.lastValid == 0 && socketWrapper.getLastAccess() > -1 && standardTimeout > 0) { long queueTime = System.currentTimeMillis() - socketWrapper.getLastAccess(); int firstReadTimeout; if (queueTime >= standardTimeout) { // Queued for longer than timeout but there might be // data so use shortest possible timeout firstReadTimeout = 1; } else { // Cast is safe since queueTime must be less than // standardTimeout which is an int firstReadTimeout = standardTimeout - (int) queueTime; } socket.getSocket().setSoTimeout(firstReadTimeout); if (!inputBuffer.fill()) { throw new EOFException(sm.getString("iib.eof.error")); } } if (standardTimeout > 0) { socket.getSocket().setSoTimeout(standardTimeout); } /**前面一堆道具，这里正式开始 这是用来读取Http头的，只是用来读取头的哦， * 它负责将二进制流解析到对应的头部 后面我们会放出次方法的实现 **/ inputBuffer.parseRequestLine(false); if (endpoint.isPaused()) { // 503 - Service unavailable response.setStatus(503); adapter.log(request, response, 0); error = true; } else { request.setStartTime(System.currentTimeMillis()); keptAlive = true; if (disableUploadTimeout) { socket.getSocket().setSoTimeout(soTimeout); } else { socket.getSocket().setSoTimeout(connectionUploadTimeout); } /**走到这真坎坷，赶紧把到手的狗处理了吧--先处理头、脚 * 先把头部转化了 **/ ?inputBuffer.parseHeaders(); } } catch (IOException e) { error = true; break; } catch (Throwable t) { ExceptionUtils.handleThrowable(t); if (log.isDebugEnabled()) { log.debug(sm.getString("http11processor.header.parse"), t); } // 400 - Bad Request response.setStatus(400); adapter.log(request, response, 0); error = true; } if (!error) { // Setting up filters, and parse some request headers //第二阶段 ?rp.setStage(org.apache.coyote.Constants.STAGE_PREPARE); try { /**拔毛----预处理请求，解析一些协议上的东西，稍后放出方法**/ ?prepareRequest(); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); if (log.isDebugEnabled()) { log.debug(sm.getString("http11processor.request.prepare"), t); } // 400 - Internal Server Error response.setStatus(400); adapter.log(request, response, 0); error = true; } } if (socketWrapper.getKeepAliveLeft() == 0) { keepAlive = false; } // Process the request in the adapter if (!error) { try { //第三阶段 rp.setStage(org.apache.coyote.Constants.STAGE_SERVICE); //核心处理：去除内脏，烹饪…… 处理请求体 这里又涉及到很多知识了，在下节详细介绍这个过程 ?adapter.service(request, response); // Handle when the response was committed before a serious // error occurred. Throwing a ServletException should both // set the status to 500 and set the errorException. // If we fail here, then the response is likely already // committed, so we can't try and set headers. if(keepAlive && !error) { // Avoid checking twice. error = response.getErrorException() != null || (!isAsync() && statusDropsConnection(response.getStatus())); } } catch (InterruptedIOException e) { error = true; } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.error(sm.getString("http11processor.request.process"), t); // 500 - Internal Server Error response.setStatus(500); adapter.log(request, response, 0); error = true; } } // Finish the handling of the request try { //第四阶段 ?rp.setStage(org.apache.coyote.Constants.STAGE_ENDINPUT); // If we know we are closing the connection, don't drain input. // This way uploading a 100GB file doesn't tie up the thread // if the servlet has rejected it. if(error && !isAsync()) inputBuffer.setSwallowInput(false); if (!isAsync()) //结束烹饪，结束请求 ?endRequest(); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.error(sm.getString("http11processor.request.finish"), t); // 500 - Internal Server Error response.setStatus(500); adapter.log(request, response, 0); error = true; } try { //第五阶段 ?rp.setStage(org.apache.coyote.Constants.STAGE_ENDOUTPUT); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.error(sm.getString("http11processor.response.finish"), t); error = true; } // If there was an error, make sure the request is counted as // and error, and update the statistics counter if (error) { response.setStatus(500); } //收尾阶段：将狗肉盛盘 更新统计数据 ?request.updateCounters(); //第六阶段 收尾阶段：收拾后厨 清楚数据，等待下一个请求，计数器 rp.setStage(org.apache.coyote.Constants.STAGE_KEEPALIVE); // Don't reset the param - we'll see it as ended. Next request // will reset it // thrA.setParam(null); // Next request if (!isAsync() || error) { inputBuffer.nextRequest(); outputBuffer.nextRequest(); } // If we don't have a pipe-lined request allow this thread to be // used by another connection if (isAsync() || error || inputBuffer.lastValid == 0) { break; } if (maxKeepAliveRequests > 0) { socketWrapper.decrementKeepAlive(); } } //第七阶段：收工 上狗肉 rp.setStage(org.apache.coyote.Constants.STAGE_ENDED); if (error || endpoint.isPaused()) { return SocketState.CLOSED; } else if (isAsync()) { return SocketState.LONG; } else { if (!keepAlive) { return SocketState.CLOSED; } else { return SocketState.OPEN; } } }这个过程还是挺复杂的（你以为吃顿狗肉这么容易？），分七个阶段：
第一阶段：处理头部，可能抛503和400异常；
第二阶段：预处理请求体，主要解析请求的部分header和解析url，可能抛400异常；
第三阶段：处理请求（最核心的阶段），可能抛500异常；
第四阶段：结束请求，可能抛500异常；
第五阶段：更新统计计数，可能抛500异常；
第六阶段：整理线程，准备接受下一个请求；
第七阶段：结束
走完这七步，香喷喷的狗肉就上桌了！！
，不过先别动筷子，我们还要补上前面提到的几个方法：
处理头部：
/** * Read the request line. This function is meant to be used during the * HTTP request header parsing. Do NOT attempt to read the request body * using it. * * @throws IOException If an exception occurs during the underlying socket * read operations, or if the given buffer is not big enough to accommodate * the whole line. */ @Override public boolean parseRequestLine(boolean useAvailableDataOnly) throws IOException { int start = 0; // // Skipping blank lines // byte chr = 0; do { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } chr = buf[pos++]; } while ((chr == Constants.CR) || (chr == Constants.LF)); pos--; // Mark the current buffer position start = pos; // // Reading the method name // Method name is always US-ASCII // boolean space = false; while (!space) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } // Spec says no CR or LF in method name if (buf[pos] == Constants.CR || buf[pos] == Constants.LF) { throw new IllegalArgumentException( sm.getString("iib.invalidmethod")); } // Spec says single SP but it also says be tolerant of HT if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) { space = true; request.method().setBytes(buf, start, pos - start); } pos++; } // Spec says single SP but also says be tolerant of multiple and/or HT while (space) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) { pos++; } else { space = false; } } // Mark the current buffer position start = pos; int end = 0; int questionPos = -1; // // Reading the URI // boolean eol = false; while (!space) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } // Spec says single SP but it also says be tolerant of HT if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) { space = true; end = pos; } else if ((buf[pos] == Constants.CR) || (buf[pos] == Constants.LF)) { // HTTP/0.9 style request eol = true; space = true; end = pos; } else if ((buf[pos] == Constants.QUESTION) && (questionPos == -1)) { questionPos = pos; } pos++; } request.unparsedURI().setBytes(buf, start, end - start); if (questionPos >= 0) { request.queryString().setBytes(buf, questionPos + 1, end - questionPos - 1); request.requestURI().setBytes(buf, start, questionPos - start); } else { request.requestURI().setBytes(buf, start, end - start); } // Spec says single SP but also says be tolerant of multiple and/or HT while (space) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) { pos++; } else { space = false; } } // Mark the current buffer position start = pos; end = 0; // // Reading the protocol // Protocol is always US-ASCII // while (!eol) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if (buf[pos] == Constants.CR) { end = pos; } else if (buf[pos] == Constants.LF) { if (end == 0) end = pos; eol = true; } pos++; } if ((end - start) > 0) { request.protocol().setBytes(buf, start, end - start); } else { request.protocol().setString(""); } return true; }?这个方法没什么好说，接下来看
/** * Parse an HTTP header. * * @return false after reading a blank line (which indicates that the * HTTP header parsing is done */ @SuppressWarnings("null") // headerValue cannot be null public boolean parseHeader() throws IOException { // // Check for blank line // byte chr = 0; while (true) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } chr = buf[pos]; if ((chr == Constants.CR) || (chr == Constants.LF)) { if (chr == Constants.LF) { pos++; return false; } } else { break; } pos++; } // Mark the current buffer position int start = pos; // // Reading the header name // Header name is always US-ASCII // boolean colon = false; MessageBytes headerValue = null; while (!colon) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if (buf[pos] == Constants.COLON) { colon = true; headerValue = headers.addValue(buf, start, pos - start); } else if (!HTTP_TOKEN_CHAR[buf[pos]]) { // If a non-token header is detected, skip the line and // ignore the header skipLine(start); return true; } chr = buf[pos]; if ((chr >= Constants.A) && (chr <= Constants.Z)) { buf[pos] = (byte) (chr - Constants.LC_OFFSET); } pos++; } // Mark the current buffer position start = pos; int realPos = pos; // // Reading the header value (which can be spanned over multiple lines) // boolean eol = false; boolean validLine = true; while (validLine) { boolean space = true; // Skipping spaces while (space) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if ((buf[pos] == Constants.SP) || (buf[pos] == Constants.HT)) { pos++; } else { space = false; } } int lastSignificantChar = realPos; // Reading bytes until the end of the line while (!eol) { // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } if (buf[pos] == Constants.CR) { // Skip } else if (buf[pos] == Constants.LF) { eol = true; } else if (buf[pos] == Constants.SP) { buf[realPos] = buf[pos]; realPos++; } else { buf[realPos] = buf[pos]; realPos++; lastSignificantChar = realPos; } pos++; } realPos = lastSignificantChar; // Checking the first character of the new line. If the character // is a LWS, then it's a multiline header // Read new bytes if needed if (pos >= lastValid) { if (!fill()) throw new EOFException(sm.getString("iib.eof.error")); } chr = buf[pos]; if ((chr != Constants.SP) && (chr != Constants.HT)) { validLine = false; } else { eol = false; // Copying one extra space in the buffer (since there must // be at least one space inserted between the lines) buf[realPos] = chr; realPos++; } } // Set the header value headerValue.setBytes(buf, start, realPos - start); return true; }?/** * After reading the request headers, we have to setup the request filters. */ protected void prepareRequest() { http11 = true; http09 = false; contentDelimitation = false; expectation = false; prepareRequestInternal(); if (endpoint.isSSLEnabled()) { request.scheme().setString("https"); } MessageBytes protocolMB = request.protocol(); if (protocolMB.equals(Constants.HTTP_11)) { http11 = true; protocolMB.setString(Constants.HTTP_11); } else if (protocolMB.equals(Constants.HTTP_10)) { http11 = false; keepAlive = false; protocolMB.setString(Constants.HTTP_10); } else if (protocolMB.equals("")) { // HTTP/0.9 http09 = true; http11 = false; keepAlive = false; } else { // Unsupported protocol http11 = false; error = true; // Send 505; Unsupported HTTP version if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("http11processor.request.prepare")+ " Unsupported HTTP version \""+protocolMB+"\""); } response.setStatus(505); adapter.log(request, response, 0); } MessageBytes methodMB = request.method(); if (methodMB.equals(Constants.GET)) { methodMB.setString(Constants.GET); } else if (methodMB.equals(Constants.POST)) { methodMB.setString(Constants.POST); } MimeHeaders headers = request.getMimeHeaders(); // Check connection header MessageBytes connectionValueMB = headers.getValue("connection"); if (connectionValueMB != null) { ByteChunk connectionValueBC = connectionValueMB.getByteChunk(); if (findBytes(connectionValueBC, Constants.CLOSE_BYTES) != -1) { keepAlive = false; } else if (findBytes(connectionValueBC, Constants.KEEPALIVE_BYTES) != -1) { keepAlive = true; } } MessageBytes expectMB = null; if (http11) expectMB = headers.getValue("expect"); if ((expectMB != null) && (expectMB.indexOfIgnoreCase("100-continue", 0) != -1)) { getInputBuffer().setSwallowInput(false); expectation = true; } // Check user-agent header if ((restrictedUserAgents != null) && ((http11) || (keepAlive))) { MessageBytes userAgentValueMB = headers.getValue("user-agent"); // Check in the restricted list, and adjust the http11 // and keepAlive flags accordingly if(userAgentValueMB != null) { String userAgentValue = userAgentValueMB.toString(); if (restrictedUserAgents != null && restrictedUserAgents.matcher(userAgentValue).matches()) { http11 = false; keepAlive = false; } } } // Check for a full URI (including protocol://host:port/) ByteChunk uriBC = request.requestURI().getByteChunk(); if (uriBC.startsWithIgnoreCase("http", 0)) { int pos = uriBC.indexOf("://", 0, 3, 4); int uriBCStart = uriBC.getStart(); int slashPos = -1; if (pos != -1) { byte[] uriB = uriBC.getBytes(); slashPos = uriBC.indexOf('/', pos + 3); if (slashPos == -1) { slashPos = uriBC.getLength(); // Set URI as "/" request.requestURI().setBytes (uriB, uriBCStart + pos + 1, 1); } else { request.requestURI().setBytes (uriB, uriBCStart + slashPos, uriBC.getLength() - slashPos); } MessageBytes hostMB = headers.setValue("host"); hostMB.setBytes(uriB, uriBCStart + pos + 3, slashPos - pos - 3); } } // Input filter setup InputFilter[] inputFilters = getInputBuffer().getFilters(); // Parse transfer-encoding header MessageBytes transferEncodingValueMB = null; if (http11) transferEncodingValueMB = headers.getValue("transfer-encoding"); if (transferEncodingValueMB != null) { String transferEncodingValue = transferEncodingValueMB.toString(); // Parse the comma separated list. "identity" codings are ignored int startPos = 0; int commaPos = transferEncodingValue.indexOf(','); String encodingName = null; while (commaPos != -1) { encodingName = transferEncodingValue.substring (startPos, commaPos).toLowerCase(Locale.ENGLISH).trim(); if (!addInputFilter(inputFilters, encodingName)) { // Unsupported transfer encoding error = true; // 501 - Unimplemented response.setStatus(501); adapter.log(request, response, 0); } startPos = commaPos + 1; commaPos = transferEncodingValue.indexOf(',', startPos); } encodingName = transferEncodingValue.substring(startPos) .toLowerCase(Locale.ENGLISH).trim(); if (!addInputFilter(inputFilters, encodingName)) { // Unsupported transfer encoding error = true; // 501 - Unimplemented if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("http11processor.request.prepare")+ " Unsupported transfer encoding \""+encodingName+"\""); } response.setStatus(501); adapter.log(request, response, 0); } } // Parse content-length header long contentLength = request.getContentLengthLong(); if (contentLength >= 0 && !contentDelimitation) { getInputBuffer().addActiveFilter (inputFilters[Constants.IDENTITY_FILTER]); contentDelimitation = true; } MessageBytes valueMB = headers.getValue("host"); // Check host header if (http11 && (valueMB == null)) { error = true; // 400 - Bad request if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("http11processor.request.prepare")+ " host header missing"); } response.setStatus(400); adapter.log(request, response, 0); } parseHost(valueMB); if (!contentDelimitation) { // If there's no content length // (broken HTTP/1.0 or HTTP/1.1), assume // the client is not broken and didn't send a body getInputBuffer().addActiveFilter (inputFilters[Constants.VOID_FILTER]); contentDelimitation = true; } // Advertise sendfile support through a request attribute if (endpoint.getUseSendfile()) { request.setAttribute("org.apache.tomcat.sendfile.support", Boolean.TRUE); } // Advertise comet support through a request attribute if (endpoint.getUseComet()) { request.setAttribute("org.apache.tomcat.comet.support", Boolean.TRUE); } // Advertise comet timeout support if (endpoint.getUseCometTimeout()) { request.setAttribute("org.apache.tomcat.comet.timeout.support", Boolean.TRUE); } }?这几个方法没什么好说，感兴趣就看一下就行了。