目錄前言
我們提供的服務有：成都網(wǎng)站制作、成都做網(wǎng)站、微信公眾號開發(fā)、網(wǎng)站優(yōu)化、網(wǎng)站認證、城廂ssl等。為上1000+企事業(yè)單位解決了網(wǎng)站和推廣的問題。提供周到的售前咨詢和貼心的售后服務，是有科學管理、有技術(shù)的城廂網(wǎng)站制作公司
Tomcat最全UML類圖
Tomcat請求處理過程：
Connector對象創(chuàng)建的時候，會創(chuàng)建Http11NioProtocol的ProtocolHandler，在Connector的startInteral方法中，會啟動AbstractProtocol，AbstractProtocol啟動NioEndPoint進行監(jiān)聽客戶端的請求，EndPoint接受到客戶端的請求之后，會交給Container去處理請求。請求從Engine開始經(jīng)過的所有容器都含有責任鏈模式，每經(jīng)過一個容器都會調(diào)用該容器的責任鏈對請求進行處理。一、EndPoint
默認的EndPoint實現(xiàn)是NioEndPoint，NioEndPoint有四個內(nèi)部類，分別是Poller、Acceptor、PollerEvent、SocketProcessor、NioSocketWrapper。（1）Acceptor負責監(jiān)聽用戶的請求，監(jiān)聽到用戶請求之后，調(diào)用getPoller0().register(channel);先將當前請求封裝成PollerEvent，new PollerEvent(socket, ka, OP_REGISTER); 將當前請求，封裝成注冊事件，并添加到PollerEvent隊列中，然后將PollerEvent注冊到Poller的Selector對象
上面。
（2）Poller線程會一直遍歷可以處理的事件（netty的selestor），當找到需要處理的事件之后，調(diào)用processKey(sk, socketWrapper);對，執(zhí)行要處理的PollerEvent的run方法，對請求進行處理。
（3）PollerEvent繼承自Runnable接口，在其run方法里面,如果是PollerEvent的事件是注冊OP_REGISTER，那么就將當前的socket注冊到Poller的selector上。public void run() { if (interestOps == OP_REGISTER) { try { // 核心代碼，終于找到了?。。。。? // 當事件是注冊的時候，將當前的NioSocketChannel注冊到Poller的Selector上。 socket.getIOChannel().register( socket.getPoller().getSelector(), SelectionKey.OP_READ, socketWrapper); } catch (Exception x) { log.error(sm.getString("endpoint.nio.registerFail"), x); } } else { final SelectionKey key = socket.getIOChannel().keyFor(socket.getPoller().getSelector()); try { if (key == null) { // The key was cancelled (e.g. due to socket closure) // and removed from the selector while it was being // processed. Count down the connections at this point // since it won't have been counted down when the socket // closed. // SelectionKey被取消的時候需要將SelectionKey對應的EndPoint的Connection計數(shù)器，減一 socket.socketWrapper.getEndpoint().countDownConnection(); ((NioSocketWrapper) socket.socketWrapper).closed = true; } else { final NioSocketWrapper socketWrapper = (NioSocketWrapper) key.attachment(); if (socketWrapper != null) { //we are registering the key to start with, reset the fairness counter. int ops = key.interestOps() | interestOps; socketWrapper.interestOps(ops); key.interestOps(ops); } else { socket.getPoller().cancelledKey(key); } } } catch (CancelledKeyException ckx) { try { socket.getPoller().cancelledKey(key); } catch (Exception ignore) { } } } }
（4）Poller線程內(nèi)會執(zhí)行keyCount = selector.select(selectorTimeout);獲取當前需要處理的SelectionKey的數(shù)量，然后當keyCount大于0時，會獲取selector的迭代器，遍歷所有需要的selectionkey，并對其進行處理。在這里將socket的事件封裝成NioSocketWrapper。// 得到selectedKeys的迭代器Iterator
protected void processKey(SelectionKey sk, NioSocketWrapper attachment) { try { if (close) { // 如果Poller已經(jīng)關閉了，就取消key cancelledKey(sk); } else if (sk.isValid() && attachment != null) { if (sk.isReadable() || sk.isWritable()) { if (attachment.getSendfileData() != null) { processSendfile(sk, attachment, false); } else { unreg(sk, attachment, sk.readyOps()); boolean closeSocket = false; // Read goes before write // 讀優(yōu)于寫 // 如果SelectionKey對應的Channel已經(jīng)準備好了讀 // 就對NioSocketWrapper進行讀操作 if (sk.isReadable()) { if (!processSocket(attachment, SocketEvent.OPEN_READ, true)) { closeSocket = true; } } // 如果SelectionKey對應的Channel已經(jīng)準備好了寫 // 就對NioSocketWrapper進行寫操作 if (!closeSocket && sk.isWritable()) { if (!processSocket(attachment, SocketEvent.OPEN_WRITE, true)) { closeSocket = true; } } if (closeSocket) { // 如果已經(jīng)關閉了，就取消key cancelledKey(sk); } } } }
AbatractEndPoint.processSocket方法首先從緩存中獲取SocketProcessor類，如果緩存中沒有就創(chuàng)建一個，SocketProcessorBase接口對應的就是NioEndPoint.SocketProcessor，也就是Worker。將對應的SocketProcessor類放入到線程池中執(zhí)行。public boolean processSocket(SocketWrapperBase socketWrapper, SocketEvent event, boolean dispatch) { // 得到socket的處理器 // Connector在構(gòu)造函數(shù)里面已經(jīng)指定了協(xié)議：org.apache.coyote.http11.Http11NioProtocol。 SocketProcessorBase sc = processorCache.pop(); if (sc == null) { // 如果沒有，就創(chuàng)建一個Socket的處理器。創(chuàng)建的時候指定socketWrapper以及socket的事件。 sc = createSocketProcessor(socketWrapper, event); } else { sc.reset(socketWrapper, event); } //socket的處理交給了線程池去處理。 Executor executor = getExecutor(); if (dispatch && executor != null) { executor.execute(sc); } else { sc.run(); }
public static class NioSocketWrapper extends SocketWrapperBase
（6）NioEndPoint.SocketProcessor（Worker）繼承了Runnable接口，負責對socket的g各種事件進行處理。讀事件、寫事件、停止時間、超時事件、斷連事件、錯誤時間、連接失敗事件。
SocketProcessor的doRun方法，會根據(jù)SocketState進行處理，SocketState 為STOP、DISCONNECT或者ERROR的時候就進行關閉，SocketWrapperBase對應的selector事件，得到指定的Handler處理器進行處理。@Override protected void doRun() { NioChannel socket = socketWrapper.getSocket(); SelectionKey key = socket.getIOChannel().keyFor(socket.getPoller().getSelector()); try { int handshake = -1; try { if (key != null) { if (socket.isHandshakeComplete()) { // 是否已經(jīng)握手成功，不需要TLS(加密)握手，就讓處理器對socket和event的組合進行處理。 handshake = 0; } else if (event == SocketEvent.STOP || event == SocketEvent.DISCONNECT || event == SocketEvent.ERROR) { // 不能夠完成TLS握手，就把他認為是TLS握手失敗。 handshake = -1; } else { handshake = socket.handshake(key.isReadable(), key.isWritable()); // The handshake process reads/writes from/to the // socket. status may therefore be OPEN_WRITE once // the handshake completes. However, the handshake // happens when the socket is opened so the status // must always be OPEN_READ after it completes. It // is OK to always set this as it is only used if // the handshake completes. // 握手從/向socket讀/寫時，握手一旦完成狀態(tài)應該為OPEN_WRITE， // 握手是在套接字打開時發(fā)生的，因此在完成后狀態(tài)必須始終為OPEN_READ // 始終設置此選項是可以的，因為它僅在握手完成時使用。 event = SocketEvent.OPEN_READ; } } } catch (IOException x) { handshake = -1; if (log.isDebugEnabled()) log.debug("Error during SSL handshake", x); } catch (CancelledKeyException ckx) { handshake = -1; } if (handshake == 0) { SocketState state = SocketState.OPEN; // Process the request from this socket if (event == null) { // 調(diào)用處理器進行處理。 // NioEndPoint的默認Handler是Http11的 // 這里的Handler是AbstractProtocol.ConnectionHandler // 這個Handler的設置方法是： // 首先在Connector類的構(gòu)造函數(shù)中，將默認的ProtocolHandler設置為org.apache.coyote.http11.Http11NioProtocol // AbstractHttp11Protocol的構(gòu)造函數(shù)里面創(chuàng)建了Handler類ConnectionHandler state = getHandler().process(socketWrapper, SocketEvent.OPEN_READ); } else { state = getHandler().process(socketWrapper, event); } // 如果返回的狀態(tài)是SocketState，那么就關掉連接 if (state == SocketState.CLOSED) { close(socket, key); } } else if (handshake == -1) { getHandler().process(socketWrapper, SocketEvent.CONNECT_FAIL); close(socket, key); } else if (handshake == SelectionKey.OP_READ) { // 如果是SelectionKey.OP_READ，也就是讀事件的話，就將OP_READ時間設置到socketWrapper socketWrapper.registerReadInterest(); } else if (handshake == SelectionKey.OP_WRITE) { // 如果是SelectionKey.OP_WRITE，也就是讀事件的話，就將OP_WRITE事件設置到socketWrapper socketWrapper.registerWriteInterest(); }二、ConnectionHandler
（1）ConnectionHandler用于根據(jù)Socket連接找到相應的Engine處理器。
上面是SocketProcessor的doRun方法，執(zhí)行了getHandler().process(socketWrapper, SocketEvent.OPEN_READ);;process方法是首先在Map緩存中查找當前socket是否存在對應的processor，如果不存在，再去可循環(huán)的處理器棧中查找是否存在，如果不存在就創(chuàng)建相應的Processor，然后將新創(chuàng)建的Processor與Socket建立映射，存在connection的Map中。在任何一個階段得到Processor對象之后，會執(zhí)行processor的process方法state = processor.process(wrapper, status);protected static class ConnectionHandler implements AbstractEndpoint.Handler { private final AbstractProtocol proto; private final RequestGroupInfo global = new RequestGroupInfo(); private final AtomicLong registerCount = new AtomicLong(0); // 終于找到了這個集合，給Socket和處理器建立連接 // 對每個有效鏈接都會緩存進這里，用于連接選擇一個合適的Processor實現(xiàn)以進行請求處理。 private final Map wrapper, SocketEvent status) { if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.process", wrapper.getSocket(), status)); } if (wrapper == null) { // wrapper == null 表示Socket已經(jīng)被關閉了，所以不需要做任何操作。 return SocketState.CLOSED; } // 得到wrapper內(nèi)的Socket對象 S socket = wrapper.getSocket(); // 從Map緩沖區(qū)中得到socket對應的處理器。 Processor processor = connections.get(socket); if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.connectionsGet", processor, socket)); } // Timeouts are calculated on a dedicated thread and then // dispatched. Because of delays in the dispatch process, the // timeout may no longer be required. Check here and avoid // unnecessary processing. // 超時是在專用線程上計算的，然后被調(diào)度。 // 因為調(diào)度過程中的延遲，可能不再需要超時。檢查這里，避免不必要的處理。 if (SocketEvent.TIMEOUT == status && (processor == null || !processor.isAsync() && !processor.isUpgrade() || processor.isAsync() && !processor.checkAsyncTimeoutGeneration())) { // This is effectively a NO-OP return SocketState.OPEN; } // 如果Map緩存存在該socket相關的處理器 if (processor != null) { // Make sure an async timeout doesn't fire // 確保沒有觸發(fā)異步超時 getProtocol().removeWaitingProcessor(processor); } else if (status == SocketEvent.DISCONNECT || status == SocketEvent.ERROR) { // Nothing to do. Endpoint requested a close and there is no // longer a processor associated with this socket. // SocketEvent事件是關閉，或者SocketEvent時間出錯，此時不需要做任何操作。 // Endpoint需要一個CLOSED的信號，并且這里不再有與這個socket有關聯(lián)了 return SocketState.CLOSED; } ContainerThreadMarker.set(); try { // Map緩存不存在該socket相關的處理器 if (processor == null) { String negotiatedProtocol = wrapper.getNegotiatedProtocol(); // OpenSSL typically returns null whereas JSSE typically // returns "" when no protocol is negotiated // OpenSSL通常返回null，而JSSE通常在沒有協(xié)議協(xié)商時返回"" if (negotiatedProtocol != null && negotiatedProtocol.length() > 0) { // 獲取協(xié)商協(xié)議 UpgradeProtocol upgradeProtocol = getProtocol().getNegotiatedProtocol(negotiatedProtocol); if (upgradeProtocol != null) { // 升級協(xié)議為空 processor = upgradeProtocol.getProcessor(wrapper, getProtocol().getAdapter()); if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.processorCreate", processor)); } } else if (negotiatedProtocol.equals("http/1.1")) { // Explicitly negotiated the default protocol. // Obtain a processor below. } else { // TODO: // OpenSSL 1.0.2's ALPN callback doesn't support // failing the handshake with an error if no // protocol can be negotiated. Therefore, we need to // fail the connection here. Once this is fixed, // replace the code below with the commented out // block. if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.negotiatedProcessor.fail", negotiatedProtocol)); } return SocketState.CLOSED; /* * To replace the code above once OpenSSL 1.1.0 is * used. // Failed to create processor. This is a bug. throw new IllegalStateException(sm.getString( "abstractConnectionHandler.negotiatedProcessor.fail", negotiatedProtocol)); */ } } } // 經(jīng)過上面的操作，processor還是null的話。 if (processor == null) { // 從recycledProcessors可循環(huán)processors中獲取processor processor = recycledProcessors.pop(); if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.processorPop", processor)); } } if (processor == null) { // 創(chuàng)建處理器 processor = getProtocol().createProcessor(); register(processor); if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.processorCreate", processor)); } } processor.setSslSupport( wrapper.getSslSupport(getProtocol().getClientCertProvider())); // 將socket和processor建立關聯(lián)。 connections.put(socket, processor); SocketState state = SocketState.CLOSED; do { // 調(diào)用processor的process方法。 state = processor.process(wrapper, status); // processor的process方法返回升級狀態(tài) if (state == SocketState.UPGRADING) { // Get the HTTP upgrade handler // 得到HTTP的升級句柄 UpgradeToken upgradeToken = processor.getUpgradeToken(); // Retrieve leftover input // 檢索剩余輸入 ByteBuffer leftOverInput = processor.getLeftoverInput(); if (upgradeToken == null) { // Assume direct HTTP/2 connection UpgradeProtocol upgradeProtocol = getProtocol().getUpgradeProtocol("h2c"); if (upgradeProtocol != null) { // Release the Http11 processor to be re-used release(processor); // Create the upgrade processor processor = upgradeProtocol.getProcessor(wrapper, getProtocol().getAdapter()); wrapper.unRead(leftOverInput); // Associate with the processor with the connection connections.put(socket, processor); } else { if (getLog().isDebugEnabled()) { getLog().debug(sm.getString( "abstractConnectionHandler.negotiatedProcessor.fail", "h2c")); } // Exit loop and trigger appropriate clean-up state = SocketState.CLOSED; } } else { HttpUpgradeHandler httpUpgradeHandler = upgradeToken.getHttpUpgradeHandler(); // Release the Http11 processor to be re-used release(processor); // Create the upgrade processor processor = getProtocol().createUpgradeProcessor(wrapper, upgradeToken); if (getLog().isDebugEnabled()) { getLog().debug(sm.getString("abstractConnectionHandler.upgradeCreate", processor, wrapper)); } wrapper.unRead(leftOverInput); // Associate with the processor with the connection connections.put(socket, processor); // Initialise the upgrade handler (which may trigger // some IO using the new protocol which is why the lines // above are necessary) // This cast should be safe. If it fails the error // handling for the surrounding try/catch will deal with // it. if (upgradeToken.getInstanceManager() == null) { httpUpgradeHandler.init((WebConnection) processor); } else { ClassLoader oldCL = upgradeToken.getContextBind().bind(false, null); try { httpUpgradeHandler.init((WebConnection) processor); } finally { upgradeToken.getContextBind().unbind(false, oldCL); } } } } } while (state == SocketState.UPGRADING);
@Override public SocketState service(SocketWrapperBase<?> socketWrapper) throws IOException { // 上面省略n行 // 調(diào)用Coyote的service方法 getAdapter().service(request, response); // 下面省略n行三、Coyote
回顧一下CoyoteAdapter的創(chuàng)建是在Connector的initInternal方法。@Override public SocketState service(SocketWrapperBase<?> socketWrapper) throws IOException { // 上面省略n行 // 調(diào)用Coyote的service方法 getAdapter().service(request, response); // 下面省略n行
Coyote的作用就是coyote.Request和coyote.Rsponse轉(zhuǎn)成HttpServletRequest和HttpServletRsponse。然后，因為Connector在init的時候，將自己注入到了CoyoteAdapter中，所以，直接通過connector.getService()方法就可以拿到Service，然后從Service開始調(diào)用責任鏈模式，進行處理。@Override public SocketState service(SocketWrapperBase<?> socketWrapper) throws IOException { // 上面省略n行 // 調(diào)用Coyote的service方法 getAdapter().service(request, response); // 下面省略n行四、容器責任鏈模式
接下來就是從StandradEngine開始的責任鏈模式。首先執(zhí)行StandradEngine的責任鏈模式，找到合適的Engine，合適的Engine在通過責任鏈模式找到合適的Context，直到找到StandardWrapperValve。最后執(zhí)行到StandardWrapperValve的invoke方法。首先查看Context和Wrapper是不是不可用了，如果可用，并且Servelt還沒有被初始化，就執(zhí)行初始化操作。如果是單線程模式就直接返回之前創(chuàng)建好的Servelt，如果是多線程模式，就先創(chuàng)建一個Servelt對象進行返回。@Override public final void invoke(Request request, Response response) throws IOException, ServletException { // 初始化我們需要的本地變量 boolean unavailable = false; Throwable throwable = null; // This should be a Request attribute... long t1 = System.currentTimeMillis(); // 原子類AtomicInteger，CAS操作，表示請求的數(shù)量。 requestCount.incrementAndGet(); StandardWrapper wrapper = (StandardWrapper) getContainer(); Servlet servlet = null; Context context = (Context) wrapper.getParent(); // 檢查當前的Context應用是否已經(jīng)被標注為不可以使用 if (!context.getState().isAvailable()) { // 如果當前應用不可以使用的話，就報503錯誤。 response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, sm.getString("standardContext.isUnavailable")); unavailable = true; } // 檢查Servelt是否被標記為不可使用 if (!unavailable && wrapper.isUnavailable()) { container.getLogger().info(sm.getString("standardWrapper.isUnavailable", wrapper.getName())); long available = wrapper.getAvailable(); if ((available > 0L) && (available < Long.MAX_VALUE)) { response.setDateHeader("Retry-After", available); response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, sm.getString("standardWrapper.isUnavailable", wrapper.getName())); } else if (available == Long.MAX_VALUE) { response.sendError(HttpServletResponse.SC_NOT_FOUND, sm.getString("standardWrapper.notFound", wrapper.getName())); } unavailable = true; } // Servelt是第一次調(diào)用的時候初始化 try { if (!unavailable) { // 如果此時Servelt還沒有被初始化，就分配一個Servelt實例來處理request請求。 servlet = wrapper.allocate(); } /// 省略代碼.......................................... // // 給該request創(chuàng)建Filter過濾鏈。Filter過濾鏈執(zhí)行完之后，會執(zhí)行Servelt ApplicationFilterChain filterChain = ApplicationFilterFactory.createFilterChain(request, wrapper, servlet); // Call the filter chain for this request // NOTE: This also calls the servlet's service() method try { if ((servlet != null) && (filterChain != null)) { // Swallow output if needed if (context.getSwallowOutput()) { try { SystemLogHandler.startCapture(); if (request.isAsyncDispatching()) { request.getAsyncContextInternal().doInternalDispatch(); } else { // 調(diào)用過濾鏈 filterChain.doFilter(request.getRequest(), response.getResponse()); } /// 省略代碼..........................................
到此這篇關于Tomcat源碼解析之Web請求與處理的文章就介紹到這了,更多相關Tomcat的Web請求與處理內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關文章希望大家以后多多支持腳本之家！
重慶分公司
重慶分公司
