本文将从申请获取与包装解决、申请传递给Container、Container解决申请流程,这3局部来讲述一次http穿梭之旅。

1 申请包装解决

tomcat组件Connector在启动的时候会监听端口。以JIoEndpoint为例,在其Acceptor类中:

protected class Acceptor extends AbstractEndpoint.Acceptor {    @Override    public void run() {        while (running) {            ……            try {                //以后连接数                countUpOrAwaitConnection();                Socket socket = null;                try {                    //取出队列中的连贯申请                    socket = serverSocketFactory.acceptSocket(serverSocket);                } catch (IOException ioe) {                    countDownConnection();                }                if (running && !paused && setSocketOptions(socket)) {                    //解决申请                    if (!processSocket(socket)) {                        countDownConnection();                        closeSocket(socket);                    }                } else {                    countDownConnection();                    // Close socket right away                    closeSocket(socket);                }            }             ……        }    }}

在下面的代码中,socket = serverSocketFactory.acceptSocket(serverSocket);与客户端建设连贯,将连贯的socket交给processSocket(socket)来解决。在processSocket中,对socket进行包装一下交给线程池来解决:

protected boolean processSocket(Socket socket) {    try {        SocketWrapper<Socket> wrapper = new SocketWrapper<Socket>(socket);        wrapper.setKeepAliveLeft(getMaxKeepAliveRequests());        wrapper.setSecure(isSSLEnabled());        //交给线程池解决连贯        getExecutor().execute(new SocketProcessor(wrapper));    }     ……    return true;}

线程池解决的工作SocketProccessor,通过代码剖析:

protected class SocketProcessor implements Runnable {     protected SocketWrapper<Socket> socket = null;    protected SocketStatus status = null;     @Override    public void run() {        boolean launch = false;        synchronized (socket) {            SocketState state = SocketState.OPEN;            try {                serverSocketFactory.handshake(socket.getSocket());            }             ……            if ((state != SocketState.CLOSED)) {                //委派给Handler来解决                if (status == null) {                    state = handler.process(socket, SocketStatus.OPEN_READ);                } else {                    state = handler.process(socket,status);                }            }}}            ……}

即在SocketProcessor中,将Socket交给handler解决,这个handler就是在Http11Protocol的构造方法中赋值的Http11ConnectionHandler,在该类的父类process办法中通过申请的状态,来创立Http11Processor处理器进行相应的解决,切到Http11Proccessor的父类AbstractHttp11Proccessor中。

public SocketState process(SocketWrapper socketWrapper) {    RequestInfo rp = request.getRequestProcessor();    rp.setStage(org.apache.coyote.Constants.STAGE_PARSE);     // Setting up the I/O    setSocketWrapper(socketWrapper);    getInputBuffer().init(socketWrapper, endpoint);    getOutputBuffer().init(socketWrapper, endpoint);     while (!getErrorState().isError() && keepAlive && !comet && !isAsync() &&            upgradeInbound == null &&            httpUpgradeHandler == null && !endpoint.isPaused()) {        ……        if (!getErrorState().isError()) {            // Setting up filters, and parse some request headers            rp.setStage(org.apache.coyote.Constants.STAGE_PREPARE);            try {                //申请预处理                prepareRequest();            }             ……        }        ……        if (!getErrorState().isError()) {            try {                rp.setStage(org.apache.coyote.Constants.STAGE_SERVICE);                //交由适配器解决                adapter.service(request, response);                 if(keepAlive && !getErrorState().isError() && (                        response.getErrorException() != null ||                                (!isAsync() &&                                statusDropsConnection(response.getStatus())))) {                    setErrorState(ErrorState.CLOSE_CLEAN, null);                }                setCometTimeouts(socketWrapper);            }         }    }    ……}          

能够看到Request和Response的生成,从Socket中获取申请数据,keep-alive解决,数据包装等等信息,最初交给了CoyoteAdapter的service办法

2 申请传递给Container

在CoyoteAdapter的service办法中,次要有2个工作:

•第一个是org.apache.coyote.Request和\
org.apache.coyote.Response到继承自HttpServletRequest的org.apache.catalina.connector.Request和org.apache.catalina.connector.Response转换,和Context,Wrapper定位。

•第二个是将申请交给StandardEngineValve解决。

public void service(org.apache.coyote.Request req,                        org.apache.coyote.Response res) {    ……    postParseSuccess = postParseRequest(req, request, res, response);    ……    connector.getService().getContainer().getPipeline().getFirst().invoke(request, response);    ……}

在postParseRequest办法中代码片段:

connector.getMapper().map(serverName, decodedURI, version,                                      request.getMappingData());request.setContext((Context) request.getMappingData().context);request.setWrapper((Wrapper) request.getMappingData().wrapper);

request通过URI的信息找到属于本人的Context和Wrapper。而这个Mapper保留了所有的容器信息,不记得的同学能够回到Connector的startInternal办法中,最有一行代码是mapperListener.start(); 在MapperListener的start()办法中,

public void startInternal() throws LifecycleException {     setState(LifecycleState.STARTING);    findDefaultHost();     Engine engine = (Engine) connector.getService().getContainer();    addListeners(engine);     Container[] conHosts = engine.findChildren();    for (Container conHost : conHosts) {        Host host = (Host) conHost;        if (!LifecycleState.NEW.equals(host.getState())) {            registerHost(host);        }    }}

MapperListener.startInternal()办法将所有Container容器信息保留到了mapper中。那么,当初初始化把所有容器都增加进去了,如果容器变动了将会怎么样?这就是下面所说的监听器的作用,容器变动了,MapperListener作为监听者。他的生成图示:

通过Mapper找到了该申请对应的Context和Wrapper后,CoyoteAdapter将包装好的申请交给Container解决。

3 Container解决申请流程

从上面的代码片段,咱们很容易追踪整个Container的调用链: 用时序图画进去则是:

最终StandardWrapperValve将申请交给Servlet解决实现。至此一次http申请处理完毕。

作者:京东物流 毕会杰

内容起源:京东云开发者社区