Tomcat处理Http请求和Pipeline机制

Tomcat处理HTTP请求源码分析

tomcat pipline设计模式

Pipeline的机制

tomcat对Http处理：

假设来自客户的请求为：http://localhost:8080/test/index.jsp

请求被发送到本机端口8080，被在那里侦听的Coyote HTTP/1.1 Connector获得

Connector把该请求交给它所在的Service的Engine来处理，并等待Engine的回应

Engine获得请求localhost:8080/test/index.jsp，匹配它所有虚拟主机Host

Engine匹配到名为localhost的Host（即使匹配不到也把请求交给该Host处理，因为该Host被定义为该Engine的默认主机）

localhost Host获得请求/test/index.jsp，匹配它所拥有的所有Context

Host匹配到路径为/test的Context（如果匹配不到就把该请求交给路径名为”“的Context去处理）

path=”/test”的Context获得请求/index.jsp，在它的mapping table中寻找对应的servlet

Context匹配到URL PATTERN为*.jsp的servlet，对应于JspServlet类

构造HttpServletRequest对象和HttpServletResponse对象，作为参数调用JspServlet的doGet或doPost方法

Context把执行完了之后的HttpServletResponse对象返回给Host

Host把HttpServletResponse对象返回给Engine

Engine把HttpServletResponse对象返回给Connector

Connector把HttpServletResponse对象返回给客户browser

pipeline 实现:

@Override
public void addValve(Valve valve) {

// Validate that we can add this Valve
if (valve instanceof Contained)
((Contained) valve).setContainer(this.container);

// Start the new component if necessary
if (getState().isAvailable()) {
if (valve instanceof Lifecycle) {
try {
((Lifecycle) valve).start();
} catch (LifecycleException e) {
log.error("StandardPipeline.addValve: start: ", e);
}
}
}

// basic永远最后，表示没有nextValue（）
if (first == null) {
first = valve;
valve.setNext(basic);
} else {
Valve current = first;
while (current != null) {
if (current.getNext() == basic) {
current.setNext(valve);
valve.setNext(basic);
break;
}
current = current.getNext();
}
}

container.fireContainerEvent(Container.ADD_VALVE_EVENT, valve);
}