tomcat请求数据解析过程

前面提到tomcat请求处理的io交互过程，现在开始看下经过io交互后tomcat是怎么处理请求数据的。首先到AbstractProtocol.java中的process方法，注意这个方法是在tomcat线程池分配的线程调用的。生成用来对请求字节流数据进行解析的Http11Processor。

        public SocketState process(SocketWrapperBase<S> wrapper, SocketEvent status) {......Processor processor = (Processor) wrapper.takeCurrentProcessor();......try {......if (processor == null) {processor = recycledProcessors.pop();......}if (processor == null) {processor = getProtocol().createProcessor();register(processor);......}do {state = processor.process(wrapper, status);......} while (state == SocketState.UPGRADING);}
//默认为 Http11Processor    protected Processor createProcessor() {Http11Processor processor = new Http11Processor(this, adapter);return processor;}

然后在生成的Http11Processor的service方法中对请求字节流数据进行正式的解析。

• 请求行解析
  请求行格式如GET / HTTP/1.1，首先跳过空行，然后读取请求方式，再读取请求url，之后解析协议版本，逻辑很清晰。注意这里是在fill(false)方法中读取nio的ByteBuffer的数据。

boolean parseRequestLine(boolean keptAlive, int connectionTimeout, int keepAliveTimeout) throws IOException {// check stateif (!parsingRequestLine) {return true;}//// Skipping blank lines// 跳过空行if (parsingRequestLinePhase < 2) {do {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (keptAlive) {// Haven't read any request data yet so use the keep-alive// timeout.wrapper.setReadTimeout(keepAliveTimeout);}//读取nio中ByteBuffer中数据if (!fill(false)) {// A read is pending, so no longer in initial stateparsingRequestLinePhase = 1;return false;}// At least one byte of the request has been received.// Switch to the socket timeout.wrapper.setReadTimeout(connectionTimeout);}if (!keptAlive && byteBuffer.position() == 0 && byteBuffer.limit() >= CLIENT_PREFACE_START.length) {boolean prefaceMatch = true;for (int i = 0; i < CLIENT_PREFACE_START.length && prefaceMatch; i++) {if (CLIENT_PREFACE_START[i] != byteBuffer.get(i)) {prefaceMatch = false;}}if (prefaceMatch) {// HTTP/2 preface matchedparsingRequestLinePhase = -1;return false;}}// Set the start time once we start reading data (even if it is// just skipping blank lines)if (request.getStartTime() < 0) {request.setStartTime(System.currentTimeMillis());}chr = byteBuffer.get();} while (chr == Constants.CR || chr == Constants.LF);byteBuffer.position(byteBuffer.position() - 1);parsingRequestLineStart = byteBuffer.position();parsingRequestLinePhase = 2;}//解析请求方式if (parsingRequestLinePhase == 2) {//// Reading the method name// Method name is a token//boolean space = false;while (!space) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return false;}}// Spec says method name is a token followed by a single SP but// also be tolerant of multiple SP and/or HT.int pos = byteBuffer.position();chr = byteBuffer.get();//http请求的开头字符为请求方式，以 空格(' ')或制表('\t')结尾if (chr == Constants.SP || chr == Constants.HT) {space = true;request.method().setBytes(byteBuffer.array(), parsingRequestLineStart,pos - parsingRequestLineStart);} else if (!HttpParser.isToken(chr)) {// Avoid unknown protocol triggering an additional errorrequest.protocol().setString(Constants.HTTP_11);String invalidMethodValue = parseInvalid(parsingRequestLineStart, byteBuffer);throw new IllegalArgumentException(sm.getString("iib.invalidmethod", invalidMethodValue));}}parsingRequestLinePhase = 3;}// 去除空字符if (parsingRequestLinePhase == 3) {// Spec says single SP but also be tolerant of multiple SP and/or HTboolean space = true;while (space) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return false;}}chr = byteBuffer.get();if (chr != Constants.SP && chr != Constants.HT) {space = false;byteBuffer.position(byteBuffer.position() - 1);}}parsingRequestLineStart = byteBuffer.position();parsingRequestLinePhase = 4;}//解析urlif (parsingRequestLinePhase == 4) {// Mark the current buffer positionint end = 0;//// Reading the URI//boolean space = false;while (!space) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return false;}}int pos = byteBuffer.position();prevChr = chr;chr = byteBuffer.get();if (prevChr == Constants.CR && chr != Constants.LF) {// CR not followed by LF so not an HTTP/0.9 request and// therefore invalid. Trigger error handling.// Avoid unknown protocol triggering an additional errorrequest.protocol().setString(Constants.HTTP_11);String invalidRequestTarget = parseInvalid(parsingRequestLineStart, byteBuffer);throw new IllegalArgumentException(sm.getString("iib.invalidRequestTarget", invalidRequestTarget));}if (chr == Constants.SP || chr == Constants.HT) {space = true;end = pos;} else if (chr == Constants.CR) {// HTTP/0.9 style request. CR is optional. LF is not.} else if (chr == Constants.LF) {// HTTP/0.9 style request// Stop this processing loopspace = true;// Set blank protocol (indicates HTTP/0.9)request.protocol().setString("");// Skip the protocol processingparsingRequestLinePhase = 7;if (prevChr == Constants.CR) {end = pos - 1;} else {end = pos;}} else if (chr == Constants.QUESTION && parsingRequestLineQPos == -1) {parsingRequestLineQPos = pos;} else if (parsingRequestLineQPos != -1 && !httpParser.isQueryRelaxed(chr)) {// Avoid unknown protocol triggering an additional errorrequest.protocol().setString(Constants.HTTP_11);// %nn decoding will be checked at the point of decodingString invalidRequestTarget = parseInvalid(parsingRequestLineStart, byteBuffer);throw new IllegalArgumentException(sm.getString("iib.invalidRequestTarget", invalidRequestTarget));} else if (httpParser.isNotRequestTargetRelaxed(chr)) {// Avoid unknown protocol triggering an additional errorrequest.protocol().setString(Constants.HTTP_11);// This is a general check that aims to catch problems early// Detailed checking of each part of the request target will// happen in Http11Processor#prepareRequest()String invalidRequestTarget = parseInvalid(parsingRequestLineStart, byteBuffer);throw new IllegalArgumentException(sm.getString("iib.invalidRequestTarget", invalidRequestTarget));}}if (parsingRequestLineQPos >= 0) {request.queryString().setBytes(byteBuffer.array(), parsingRequestLineQPos + 1,end - parsingRequestLineQPos - 1);request.requestURI().setBytes(byteBuffer.array(), parsingRequestLineStart,parsingRequestLineQPos - parsingRequestLineStart);} else {//把解析到的url记下来request.requestURI().setBytes(byteBuffer.array(), parsingRequestLineStart,end - parsingRequestLineStart);}// HTTP/0.9 processing jumps to stage 7.// Don't want to overwrite that here.if (parsingRequestLinePhase == 4) {parsingRequestLinePhase = 5;}}if (parsingRequestLinePhase == 5) {// Spec says single SP but also be tolerant of multiple and/or HTboolean space = true;while (space) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return false;}}byte chr = byteBuffer.get();if (chr != Constants.SP && chr != Constants.HT) {space = false;byteBuffer.position(byteBuffer.position() - 1);}}parsingRequestLineStart = byteBuffer.position();parsingRequestLinePhase = 6;// Mark the current buffer positionend = 0;}//协议版本if (parsingRequestLinePhase == 6) {//// Reading the protocol// Protocol is always "HTTP/" DIGIT "." DIGIT//while (!parsingRequestLineEol) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return false;}}int pos = byteBuffer.position();prevChr = chr;chr = byteBuffer.get();if (chr == Constants.CR) {// Possible end of request line. Need LF next else invalid.} else if (prevChr == Constants.CR && chr == Constants.LF) {// CRLF is the standard line terminatorend = pos - 1;parsingRequestLineEol = true;} else if (chr == Constants.LF) {// LF is an optional line terminatorend = pos;parsingRequestLineEol = true;} else if (prevChr == Constants.CR || !HttpParser.isHttpProtocol(chr)) {String invalidProtocol = parseInvalid(parsingRequestLineStart, byteBuffer);throw new IllegalArgumentException(sm.getString("iib.invalidHttpProtocol", invalidProtocol));}}if (end - parsingRequestLineStart > 0) {request.protocol().setBytes(byteBuffer.array(), parsingRequestLineStart, end - parsingRequestLineStart);parsingRequestLinePhase = 7;}// If no protocol is found, the ISE below will be triggered.}if (parsingRequestLinePhase == 7) {// Parsing is complete. Return and clean-up.parsingRequestLine = false;parsingRequestLinePhase = 0;parsingRequestLineEol = false;parsingRequestLineStart = 0;return true;}throw new IllegalStateException(sm.getString("iib.invalidPhase", Integer.valueOf(parsingRequestLinePhase)));}

• 请求头解析
  http请求头格式如name:value，解析先按行读取字符串，读取到":“则认为读到一个请求头，使用MimeHeaderField封装请求头字段，并返回当前请求头的value值到headerData.headerValue，再继续读取字节，读到”\r"为止，然后转换成字符串headerData.headerValue.setBytes(byteBuffer.array(), headerData.start,headerData.lastSignificantChar - headerData.start);保存到headerData.headerValue引用指向的MimeHeaderField对象。

private HeaderParseStatus parseHeader() throws IOException {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {return HeaderParseStatus.NEED_MORE_DATA;}}prevChr = chr;chr = byteBuffer.get();if (chr == Constants.CR && prevChr != Constants.CR) {// Possible start of CRLF - process the next byte.} else if (chr == Constants.LF) {// CRLF or LF is an acceptable line terminatorreturn HeaderParseStatus.DONE;} else {if (prevChr == Constants.CR) {// Must have read two bytes (first was CR, second was not LF)byteBuffer.position(byteBuffer.position() - 2);} else {// Must have only read one bytebyteBuffer.position(byteBuffer.position() - 1);}break;}}if (headerParsePos == HeaderParsePosition.HEADER_START) {// Mark the current buffer positionheaderData.start = byteBuffer.position();headerData.lineStart = headerData.start;headerParsePos = HeaderParsePosition.HEADER_NAME;}//// Reading the header name// Header name is always US-ASCII//while (headerParsePos == HeaderParsePosition.HEADER_NAME) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) { // parse headerreturn HeaderParseStatus.NEED_MORE_DATA;}}int pos = byteBuffer.position();chr = byteBuffer.get();if (chr == Constants.COLON) {if (headerData.start == pos) {// Zero length header name - not valid.// skipLine() will handle the errorreturn skipLine(false);}headerParsePos = HeaderParsePosition.HEADER_VALUE_START;headerData.headerValue = headers.addValue(byteBuffer.array(), headerData.start, pos - headerData.start);pos = byteBuffer.position();// Mark the current buffer positionheaderData.start = pos;headerData.realPos = pos;headerData.lastSignificantChar = pos;break;} else if (!HttpParser.isToken(chr)) {// Non-token characters are illegal in header names// Parsing continues so the error can be reported in contextheaderData.lastSignificantChar = pos;byteBuffer.position(byteBuffer.position() - 1);// skipLine() will handle the errorreturn skipLine(false);}// chr is next byte of header name. Convert to lowercase.if (chr >= Constants.A && chr <= Constants.Z) {byteBuffer.put(pos, (byte) (chr - Constants.LC_OFFSET));}}// Skip the line and ignore the headerif (headerParsePos == HeaderParsePosition.HEADER_SKIPLINE) {return skipLine(false);}//// Reading the header value (which can be spanned over multiple lines)//while (headerParsePos == HeaderParsePosition.HEADER_VALUE_START ||headerParsePos == HeaderParsePosition.HEADER_VALUE ||headerParsePos == HeaderParsePosition.HEADER_MULTI_LINE) {if (headerParsePos == HeaderParsePosition.HEADER_VALUE_START) {// Skipping spaceswhile (true) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {// parse header// HEADER_VALUE_STARTreturn HeaderParseStatus.NEED_MORE_DATA;}}chr = byteBuffer.get();if (chr != Constants.SP && chr != Constants.HT) {headerParsePos = HeaderParsePosition.HEADER_VALUE;byteBuffer.position(byteBuffer.position() - 1);// Avoids prevChr = chr at start of header value// parsing which causes problems when chr is CR// (in the case of an empty header value)chr = 0;break;}}}if (headerParsePos == HeaderParsePosition.HEADER_VALUE) {// Reading bytes until the end of the lineboolean eol = false;while (!eol) {// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {// parse header// HEADER_VALUEreturn HeaderParseStatus.NEED_MORE_DATA;}}prevChr = chr;chr = byteBuffer.get();if (chr == Constants.CR && prevChr != Constants.CR) {// CR is only permitted at the start of a CRLF sequence.// Possible start of CRLF - process the next byte.} else if (chr == Constants.LF) {// CRLF or LF is an acceptable line terminatoreol = true;} else if (prevChr == Constants.CR) {// Invalid value - also need to delete headerreturn skipLine(true);} else if (HttpParser.isControl(chr) && chr != Constants.HT) {// Invalid value - also need to delete headerreturn skipLine(true);} else if (chr == Constants.SP || chr == Constants.HT) {byteBuffer.put(headerData.realPos, chr);headerData.realPos++;} else {byteBuffer.put(headerData.realPos, chr);headerData.realPos++;headerData.lastSignificantChar = headerData.realPos;}}// Ignore whitespaces at the end of the lineheaderData.realPos = headerData.lastSignificantChar;// Checking the first character of the new line. If the character// is a LWS, then it's a multiline headerheaderParsePos = HeaderParsePosition.HEADER_MULTI_LINE;}// Read new bytes if neededif (byteBuffer.position() >= byteBuffer.limit()) {if (!fill(false)) {// parse header// HEADER_MULTI_LINEreturn HeaderParseStatus.NEED_MORE_DATA;}}byte peek = byteBuffer.get(byteBuffer.position());if (headerParsePos == HeaderParsePosition.HEADER_MULTI_LINE) {if (peek != Constants.SP && peek != Constants.HT) {headerParsePos = HeaderParsePosition.HEADER_START;break;} else {// Copying one extra space in the buffer (since there must// be at least one space inserted between the lines)byteBuffer.put(headerData.realPos, peek);headerData.realPos++;headerParsePos = HeaderParsePosition.HEADER_VALUE_START;}}}// Set the header valueheaderData.headerValue.setBytes(byteBuffer.array(), headerData.start,headerData.lastSignificantChar - headerData.start);headerData.recycle();return HeaderParseStatus.HAVE_MORE_HEADERS;}

• 请求体解析
  请求体获取方式如下，从请求request中拿到BufferedReader,然后调用readLine就行。

        BufferedReader reader = request.getReader();String line;while ((line=reader.readLine())!=null){System.out.println(line);}

tomcat会用CoyoteReader去封装内置的inputBuffer，生成BufferedReader。

    public BufferedReader getReader() throws IOException {if (usingInputStream) {throw new IllegalStateException(sm.getString("coyoteRequest.getReader.ise"));}if (coyoteRequest.getCharacterEncoding() == null) {Context context = getContext();if (context != null) {String enc = context.getRequestCharacterEncoding();if (enc != null) {setCharacterEncoding(enc);}}}usingReader = true;inputBuffer.checkConverter();if (reader == null) {reader = new CoyoteReader(inputBuffer);}return reader;}

其实也很简答，就是到内置的缓冲区中读取数据，然后使用编码成字符串即可。

    public String readLine() throws IOException {if (lineBuffer == null) {lineBuffer = new char[MAX_LINE_LENGTH];}String result = null;int pos = 0;int end = -1;int skip = -1;StringBuilder aggregator = null;while (end < 0) {mark(MAX_LINE_LENGTH);while ((pos < MAX_LINE_LENGTH) && (end < 0)) {int nRead = read(lineBuffer, pos, MAX_LINE_LENGTH - pos);if (nRead < 0) {if (pos == 0 && aggregator == null) {return null;}end = pos;skip = pos;}for (int i = pos; (i < (pos + nRead)) && (end < 0); i++) {if (lineBuffer[i] == LINE_SEP[0]) {end = i;skip = i + 1;char nextchar;if (i == (pos + nRead - 1)) {nextchar = (char) read();} else {nextchar = lineBuffer[i + 1];}if (nextchar == LINE_SEP[1]) {skip++;}} else if (lineBuffer[i] == LINE_SEP[1]) {end = i;skip = i + 1;}}if (nRead > 0) {pos += nRead;}}if (end < 0) {if (aggregator == null) {aggregator = new StringBuilder();}aggregator.append(lineBuffer);pos = 0;} else {reset();// No need to check return value. We know there are at least skip characters available.skip(skip);}}if (aggregator == null) {result = new String(lineBuffer, 0, end);} else {aggregator.append(lineBuffer, 0, end);result = aggregator.toString();}return result;}