Connector组件是Tomcat两个核心组件之一(另一个是Container),主要任务是负责接收客户端发过来的TCP连接请求,创建一个Request和Response对象用于和请求端交换数据。
Tomcat使用Apache Coyote库来处理网络I/O的。
Connector是通过适配器将自己“置入”这个框架中的,具体是org.apache.catalina.connector.CoyoteAdapter。Adapter位于Coyote框架处理请求的末端,解析和得到的org.apache.coyote.Request和org.apache.coyote.Response将会传入Adapter,该对象负责将http request解析成HttpServletRequest对象,之后绑定相应的容器,然后从engine开始逐层调用valve直至该servlet。
Connector负责创建Adapter(CoyoteAdapter)和ProtocolHandler,
ProtocolHandler负责根据具体的协议和I/O模型对请求数据进行接受,解析和处理,然后创建并委托Endpoint进行具体的处理。
Endpoint经过一层处理后将请求传入Processor,最终由Processor将请求传入Adapter进而进入容器。
Tomcat有四种不同的协议可供选择,类型包括BIO,AIO,NIO,APR,接口的具体实现是:
ProtocolHandler——>Http11NioProtocol;
Endpoint——>NioEndpoint;
Processor——Http11NioProcessor;
Request和Response对象的创建:
AbstractProcessor负责创建org.apache.coyote.Request和org.apache.coyote.Response;
CoyoteAdapter调用Connector.createRequset()和createResponse()创建org.apache.catalina.connector.Request和Response这就是实现了我们熟悉的HttpServletRequest和HttpServletResponse接口的贯穿整个容器,Filter&Servlet生命周期的两个对象了。
请求是如何传入容器的最终到达Servlet的:
Acceptor: 负责在一个后台线程中指定端口上接收客户端发送的请求,
SocketProcessor: 根据socket的状态进行第一层处理,另外SSL的握手也是由它负责.
Http11ConnectionHandler: SocketProcessor将会调用handler.process()将socket请求内容传入Processor.process().
AbstractHttp11Processor: AbstractHttp11Processor.process()调用CoyoAdapter.service(),
CoyoAdapter: 调用Service拥有的容器(也就是Engine)对应Pipeline的第一个Valve的invoke方法
这样Request和Response对象就进入容器。每个容器Pipeline上的最后一个Valve负责将Request和Response传入下一个容器(也就是每个容器的第一个Valve)。经过了Pipeline上所有的Valve,最后一个Valve也就是StandardWrapperValve,它的invoke方法将调用FilterChain.doFIlter(),将把设置好的Request和Response对象传入Filter链,这就进入我们熟悉的部分了,最终将被分派的正确的Servlet进行处理。
请求流程图如下:
请求流程简述:
- 接收到请求的serverSocket会被wrapper包装一下,之后放到线程池里面,由线程池分配一个线程来处理这个请求
- Http11Processor解析http的请求,生产并封装request和response对象
- 通过connector.getService()调用一系列的invoke(request,response)方法,传递request和response顺着Containter的Pipeline一直到StandardWrapperValve,在StandardWrapperValve中,创建FilterChain并执行,包括我们自己定义的,到我们的应用中,完成响应
//1.
protected class Acceptor extends AbstractEndpoint.Acceptor {
@Override
public void run() {
// Loop until we receive a shutdown command
while (running) {
// block线程,等待请求的到来
socket = serverSocketFactory.acceptSocket(serverSocket);
//接受到请求之后处理请求
if (!processSocket(socket)) {
closeSocket(socket);
}
}
}
// 调用本类的processSocket方法
//org.apache.tomcat.util.net.JIoEndpoint#processSocket
protected boolean processSocket(Socket socket) {
// Process the request from this socket
try {
// 把socket包装成SocketWrapper
SocketWrapper<Socket> wrapper = new SocketWrapper<Socket>(socket);
wrapper.setKeepAliveLeft(getMaxKeepAliveRequests());
wrapper.setSecure(isSSLEnabled());
// 从线程池中新起一个线程执行包装类
getExecutor().execute(new SocketProcessor(wrapper));
}
return true;
}
//2.
//org.apache.tomcat.util.net.JIoEndpoint.SocketProcessor#run
public void run() {
if ((state != SocketState.CLOSED)) {
if (status == null) {
// AbstractProtocol.AbstractConnectionHandler.process()
state = handler.process(socket, SocketStatus.OPEN_READ);
} else {
state = handler.process(socket,status);
}
}
}
1.处Acceptor 为JIoEndpoint的内部类, 该类监听TCP/IP请求,并将请求发送给合适的Processor.
2.处从线程池获取一个线程执行SocketProcessor. SocketProcessor 同样是内部类, 但只被用于线程池中, 当做工作线程使用(Worker), 其run方法总会调用AbstractProtocol.AbstractConnectionHandler.process()方法处理socket.
AbstractProtocol.AbstractConnectionHandler.process()方法,会根据请求的协议类型创建相应的类型处理类,协议类型的来源就是con/server.xml中connector元素的protocol属性值。我们这里配置的是HTTP/1.1,所以类型为Http11Protocol,接着调用其处理器AbstractHttp11Processor的process()方法继续处理包装socket的SocketeWrapper类,处理的目的是生成request和response对象
注意Http11Protocol 的基类是AbstractHttp11Processor, Http11Protocol 初始化的时候会创建一对request和response, 其类型分别为Corg.apache.coyote.Request,org.apache.coyote.Response, 这是最原始的tomcat使用的类,非我们web程序中的类, 构造函数源码如下:
//org.apache.coyote.AbstractProcessor#AbstractProcessor
//构造函数.
public AbstractProcessor(AbstractEndpoint endpoint) {
this.endpoint = endpoint;
asyncStateMachine = new AsyncStateMachine(this);
request = new Request();
response = new Response();
response.setHook(this);
request.setResponse(response);
}
具体process请求如下:
//org.apache.coyote.http11.AbstractHttp11Processor#process
public SocketState process(SocketWrapper<Socket> socketWrapper){
// 这个request和response是通过父类的构造方法new出来的
RequestInfo rp = request.getRequestProcessor();
// Setting up the I/O
setSocketWrapper(socketWrapper);
// Setting up filters, and parse some request headers,设置request.serverPort等
prepareRequest();
// Process the request in the adapter
adapter.service(request, response);
endRequest();
request.updateCounters();
}
org.apache.catalina.connector.CoyoteAdapter#service 源码如下
public void service(org.apache.coyote.Request req,
org.apache.coyote.Response res)
throws Exception {
Request request = (Request) req.getNote(ADAPTER_NOTES);
Response response = (Response) res.getNote(ADAPTER_NOTES);
if (request == null) {
// Create objects
request = connector.createRequest();
request.setCoyoteRequest(req);
response = connector.createResponse();
response.setCoyoteResponse(res);
// Link objects
request.setResponse(response);
response.setRequest(request);
// Set as notes
req.setNote(ADAPTER_NOTES, request);
res.setNote(ADAPTER_NOTES, response);
// Set query string encoding
req.getParameters().setQueryStringEncoding
(connector.getURIEncoding());
}
if (connector.getXpoweredBy()) {
response.addHeader("X-Powered-By", POWERED_BY);
}
boolean comet = false;
boolean async = false;
// 正式将请求转发到Container中. 正式进入Engine管道
connector.getService().getContainer().getPipeline().getFirst().invoke(request, response);
}
进入管道后的操作见本人博客:
https://blog.youkuaiyun.com/yangsnow_rain_wind/article/details/80053703
附录:
代码的异常栈可以清楚地看到请求的执行逻辑
at com.XXXX.XXXXX.core.security.SecurityAspect.execute(SecurityAspect.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:68)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:168)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.XXXX.XXXXX.pc.controller.IndexController$$EnhancerBySpringCGLIB$$10cfddca.confirm(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:522)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1096)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:760)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1480)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
Notes
- Tomcat接收到请求后创建
org.apache.coyote.Request
和org.apache.coyote.Resposne
,这两个类是轻量级的类,对象很小;这是有Tomcat内部工作线程创建的; - 将
org.apache.coyote.Request
和org.apache.coyote.Resposne
传递给用户线程,创建org.apache.catalina.connector.Request
和org.apache.catalina.connector.Resposne
,这两个对象一直整个Servlet容器直到要传给Servlet; - 创建门面类
RequestFacade
和ResponseFacade
给Servlet;
注: 部分代码引用自:
https://blog.youkuaiyun.com/mingliangniwo/article/details/54575168