从零开始手写Tomcat的教程12节----StandardContext
- StandardContext的配置
- StandardContext类的构造函数
- 启动StandardContext类的实例
- invoke方法
- StandardContextMapper类
- 对重载的支持
- backgroundProcess()方法
- 小结
StandardContext的配置
StandardContext类的构造函数
代码语言：javascript复制 /**
* Create a new StandardContext component with the default basic Valve.
*/
public StandardContext() {
super();
pipeline.setBasic(new org.apache.catalina.core.StandardContextValve());
namingResources.setContainer(this);
}
启动StandardContext类的实例
/**
* Start this Context component.
*
* @exception LifecycleException if a startup error occurs
*/
public synchronized void start() throws LifecycleException {
//防止重复启动
if (started)
throw new LifecycleException
(sm.getString("containerBase.alreadyStarted", logName()));
if (debug >= 1)
log("Starting");
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);
if (debug >= 1)
log("Processing start(), current available=" getAvailable());
setAvailable(false);
setConfigured(false);
boolean ok = true;
//设置资源
// Add missing components as necessary
if (getResources() == null) { // (1) Required by Loader
if (debug >= 1)
log("Configuring default Resources");
try {
//当前应用程序是一个war包还是一个目录---联想tomcat会自动解压webapp下面的war包
if ((docBase != null) && (docBase.endsWith(".war")))
setResources(new WARDirContext());
else
setResources(new FileDirContext());
} catch (IllegalArgumentException e) {
log("Error initializing resources: " e.getMessage());
ok = false;
}
}
if (ok && (resources instanceof ProxyDirContext)) {
DirContext dirContext =
((ProxyDirContext) resources).getDirContext();
if ((dirContext != null)
&& (dirContext instanceof BaseDirContext)) {
((BaseDirContext) dirContext).setDocBase(getBasePath());
((BaseDirContext) dirContext).allocate();
}
}
//设置加载器
if (getLoader() == null) { // (2) Required by Manager
if (getPrivileged()) {
if (debug >= 1)
log("Configuring privileged default Loader");
//该方法会设置载入器，然后发出firePropertyChange事件
setLoader(new WebappLoader(this.getClass().getClassLoader()));
} else {
if (debug >= 1)
log("Configuring non-privileged default Loader");
setLoader(new WebappLoader(getParentClassLoader()));
}
}
//设置session管理器
if (getManager() == null) { // (3) After prerequisites
if (debug >= 1)
log("Configuring default Manager");
//该方法会设置session管理器，然后发出firePropertyChange事件
setManager(new StandardManager());
}
//初始化字符集映射器
// Initialize character set mapper
getCharsetMapper();
// Post work directory
postWorkDirectory();
// Reading the "catalina.useNaming" environment variable
String useNamingProperty = System.getProperty("catalina.useNaming");
if ((useNamingProperty != null)
&& (useNamingProperty.equals("false"))) {
useNaming = false;
}
if (ok && isUseNaming()) {
if (namingContextListener == null) {
namingContextListener = new NamingContextListener();
namingContextListener.setDebug(getDebug());
namingContextListener.setName(getNamingContextName());
addLifecycleListener(namingContextListener);
}
}
// Binding thread
ClassLoader oldCCL = bindThread();
// Standard container startup
if (debug >= 1)
log("Processing standard container startup");
if (ok) {
try {
//添加默认映射器
addDefaultMapper(this.mapperClass);
started = true;
//下面是启动与该Context容器相关联的组件
// Start our subordinate components, if any
//启动载入器组件
if ((loader != null) && (loader instanceof Lifecycle))
((Lifecycle) loader).start();
if ((logger != null) && (logger instanceof Lifecycle))
((Lifecycle) logger).start();
// Unbinding thread
unbindThread(oldCCL);
// Binding thread
oldCCL = bindThread();
//启动相关组件
if ((cluster != null) && (cluster instanceof Lifecycle))
((Lifecycle) cluster).start();
if ((realm != null) && (realm instanceof Lifecycle))
((Lifecycle) realm).start();
if ((resources != null) && (resources instanceof Lifecycle))
((Lifecycle) resources).start();
//启动相关映射器
// Start our Mappers, if any
Mapper mappers[] = findMappers();
for (int i = 0; i < mappers.length; i ) {
if (mappers[i] instanceof Lifecycle)
((Lifecycle) mappers[i]).start();
}
//启动子容器
// Start our child containers, if any
Container children[] = findChildren();
for (int i = 0; i < children.length; i ) {
if (children[i] instanceof Lifecycle)
((Lifecycle) children[i]).start();
}
// Start the Valves in our pipeline (including the basic),
// if any
//启动管道对象
if (pipeline instanceof Lifecycle)
((Lifecycle) pipeline).start();
//释放启动事件信号----这里ContextConfig接收并响应该事件
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(START_EVENT, null);
//启动session管理器
if ((manager != null) && (manager instanceof Lifecycle))
((Lifecycle) manager).start();
} finally {
// Unbinding thread
unbindThread(oldCCL);
}
}
//是否配置好了
if (!getConfigured())
ok = false;
// We put the resources into the servlet context
if (ok)
getServletContext().setAttribute
(Globals.RESOURCES_ATTR, getResources());
// Binding thread
oldCCL = bindThread();
// Create context attributes that will be required
if (ok) {
if (debug >= 1)
log("Posting standard context attributes");
postWelcomeFiles();
}
// Configure and call application event listeners and filters
if (ok) {
if (!listenerStart())
ok = false;
}
if (ok) {
if (!filterStart())
ok = false;
}
// Load and initialize all "load on startup" servlets
if (ok)
//调用下面的方法来载入哪些需要在启动就载入的子容器，例如Wrapper实例
loadOnStartup(findChildren());
// Unbinding thread
unbindThread(oldCCL);
// Set available status depending upon startup success
if (ok) {
if (debug >= 1)
log("Starting completed");
setAvailable(true);
} else {
log(sm.getString("standardContext.startFailed"));
try {
stop();
} catch (Throwable t) {
log(sm.getString("standardContext.startCleanup"), t);
}
setAvailable(false);
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}
上面在13处有问题，应该是调用loadOnStartup方法
代码语言：javascript复制 /**
* Load and initialize all servlets marked "load on startup" in the
* web application deployment descriptor.
*
* @param children Array of wrappers for all currently defined
* servlets (including those not declared load on startup)
*/
public void loadOnStartup(Container children[]) {
// Collect "load on startup" servlets that need to be initialized
TreeMap map = new TreeMap();
for (int i = 0; i < children.length; i ) {
Wrapper wrapper = (Wrapper) children[i];
int loadOnStartup = wrapper.getLoadOnStartup();
if (loadOnStartup < 0)
continue;
if (loadOnStartup == 0) // Arbitrarily put them last
loadOnStartup = Integer.MAX_VALUE;
Integer key = new Integer(loadOnStartup);
ArrayList list = (ArrayList) map.get(key);
if (list == null) {
list = new ArrayList();
map.put(key, list);
}
list.add(wrapper);
}
// Load the collected "load on startup" servlets
Iterator keys = map.keySet().iterator();
while (keys.hasNext()) {
Integer key = (Integer) keys.next();
ArrayList list = (ArrayList) map.get(key);
Iterator wrappers = list.iterator();
while (wrappers.hasNext()) {
Wrapper wrapper = (Wrapper) wrappers.next();
try {
wrapper.load();
} catch (ServletException e) {
log(sm.getString("standardWrapper.loadException",
getName()), e);
// NOTE: load errors (including a servlet that throws
// UnavailableException from tht init() method) are NOT
// fatal to application startup
}
}
}
}从零开始手写Tomcat的教程11节----StandardWrapper
wrapper的load方法会去调用loadServelt方法生成并返回一个与当前wrapper关联的servlet对象
invoke方法
/**
* Process the specified Request, and generate the corresponding Response,
* according to the design of this particular Container.
*
* @param request Request to be processed
* @param response Response to be produced
*
* @exception IOException if an input/output error occurred while
* processing
* @exception ServletException if a ServletException was thrown
* while processing this request
*/
public void invoke(Request request, Response response)
throws IOException, ServletException {
// Wait if we are reloading
while (getPaused()) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
;
}
}
// Normal request processing
if (swallowOutput) {
try {
SystemLogHandler.startCapture();
super.invoke(request, response);
} finally {
String log = SystemLogHandler.stopCapture();
if (log != null && log.length() > 0) {
log(log);
}
}
} else {
super.invoke(request, response);
}
}
父类ContainerBase的invoke方法:
代码语言：javascript复制 /**
* Process the specified Request, to produce the corresponding Response,
* by invoking the first Valve in our pipeline (if any), or the basic
* Valve otherwise.
*
* @param request Request to be processed
* @param response Response to be produced
*
* @exception IllegalStateException if neither a pipeline or a basic
* Valve have been configured for this Container
* @exception IOException if an input/output error occurred while
* processing
* @exception ServletException if a ServletException was thrown
* while processing this request
*/
public void invoke(Request request, Response response)
throws IOException, ServletException {
pipeline.invoke(request, response);
}ContainerBase的成员变量:
代码语言：javascript复制 /**
* The Pipeline object with which this Container is associated.
*/
protected Pipeline pipeline = new org.apache.catalina.core.StandardPipeline(this);最终调用的是StandardPipeline的invoke方法:
代码语言：javascript复制 public void invoke(Request request, Response response)
throws IOException, ServletException {
// Invoke the first Valve in this pipeline for this request
(new StandardPipelineValveContext()).invokeNext(request, response);
}StandardPipelineValveContext是StandardPipeline的一个内部类,可以访问StandardPipeline的成员属性:
代码语言：javascript复制 protected class StandardPipelineValveContext
implements ValveContext {
protected int stage = 0;
public void invokeNext(Request request, Response response)
throws IOException, ServletException {
int subscript = stage;
stage = stage 1;
// Invoke the requested Valve for the current request thread
if (subscript < valves.length) {
valves[subscript].invoke(request, response, this);
} else if ((subscript == valves.length) && (basic != null)) {
basic.invoke(request, response, this);
} else {
throw new ServletException
(sm.getString("standardPipeline.noValve"));
}
}
}
这是11节末尾画的图，大家可以回顾一下:
StandardContextMapper类
/**
* Add the specified Mapper associated with this Container.
*/
public void addMapper(Mapper mapper) {
synchronized(mappers) {
if (mappers.get(mapper.getProtocol()) != null)
throw new IllegalArgumentException("addMapper: Protocol '"
mapper.getProtocol()
"' is not unique");
//设置映射器关联的容器对象
mapper.setContainer((Container) this); // May throw IAE
//如果是容器启动后才放入的映射器，则需要调用其start方法进行启动
if (started && (mapper instanceof Lifecycle)) {
try {
((Lifecycle) mapper).start();
} catch (LifecycleException e) {
log("ContainerBase.addMapper: start: ", e);
throw new IllegalStateException
("ContainerBase.addMapper: start: " e);
}
}
//放入映射器集合中
mappers.put(mapper.getProtocol(), mapper);
if (mappers.size() == 1)
this.mapper = mapper;
else
this.mapper = null;
//释放事件
fireContainerEvent(ADD_MAPPER_EVENT, mapper);
}
}
addDefaultMapper(this.mapperClass);
/**
* The Java class name of the default Mapper class for this Container.
*/
private String mapperClass =
"org.apache.catalina.core.StandardContextMapper";
public void setContainer(Container container) {
if (!(container instanceof StandardContext))
throw new IllegalArgumentException
(sm.getString("httpContextMapper.container"));
context = (StandardContext) container;
}
public Container map(Request request, boolean update);
public Container map(Request request, boolean update) {
// Select the Mapper we will use
Mapper mapper = findMapper(request.getRequest().getProtocol());
if (mapper == null)
return (null);
// Use this Mapper to perform this mapping
return (mapper.map(request, update));
}
public Container map(Request request, boolean update) {
int debug = context.getDebug();
// Has this request already been mapped?
if (update && (request.getWrapper() != null))
return (request.getWrapper());
// Identify the context-relative URI to be mapped
//1.标识出相对于Context的URI
String contextPath =
((HttpServletRequest) request.getRequest()).getContextPath();
String requestURI = ((HttpRequest) request).getDecodedRequestURI();
String relativeURI = requestURI.substring(contextPath.length());
if (debug >= 1)
context.log("Mapping contextPath='" contextPath
"' with requestURI='" requestURI
"' and relativeURI='" relativeURI "'");
// Apply the standard request URI mapping rules from the specification
Wrapper wrapper = null;
String servletPath = relativeURI;
String pathInfo = null;
String name = null;
//下面有这几种匹配规则
// Rule 1 -- Exact Match ---精确匹配
if (wrapper == null) {
if (debug >= 2)
context.log(" Trying exact match");
if (!(relativeURI.equals("/")))
//利用匹配规则找到一个当前请求URI对应的wrapper的name
name = context.findServletMapping(relativeURI);
if (name != null)
//从context的子容器中找个找个wrapper实例
wrapper = (Wrapper) context.findChild(name);
if (wrapper != null) {
servletPath = relativeURI;
pathInfo = null;
}
}
// Rule 2 -- Prefix Match --- 前缀匹配
if (wrapper == null) {
if (debug >= 2)
context.log(" Trying prefix match");
servletPath = relativeURI;
while (true) {
name = context.findServletMapping(servletPath "/*");
if (name != null)
wrapper = (Wrapper) context.findChild(name);
if (wrapper != null) {
pathInfo = relativeURI.substring(servletPath.length());
if (pathInfo.length() == 0)
pathInfo = null;
break;
}
int slash = servletPath.lastIndexOf('/');
if (slash < 0)
break;
servletPath = servletPath.substring(0, slash);
}
}
// Rule 3 -- Extension Match ----扩展匹配规则
if (wrapper == null) {
if (debug >= 2)
context.log(" Trying extension match");
int slash = relativeURI.lastIndexOf('/');
if (slash >= 0) {
String last = relativeURI.substring(slash);
int period = last.lastIndexOf('.');
if (period >= 0) {
String pattern = "*" last.substring(period);
name = context.findServletMapping(pattern);
if (name != null)
wrapper = (Wrapper) context.findChild(name);
if (wrapper != null) {
servletPath = relativeURI;
pathInfo = null;
}
}
}
}
// Rule 4 -- Default Match ----默认匹配
if (wrapper == null) {
if (debug >= 2)
context.log(" Trying default match");
name = context.findServletMapping("/");
if (name != null)
wrapper = (Wrapper) context.findChild(name);
if (wrapper != null) {
servletPath = relativeURI;
pathInfo = null;
}
}
// Update the Request (if requested) and return this Wrapper
if ((debug >= 1) && (wrapper != null))
context.log(" Mapped to servlet '" wrapper.getName()
"' with servlet path '" servletPath
"' and path info '" pathInfo
"' and update=" update);
//将查询到的wrapper对象设置给当然request对象
if (update) {
request.setWrapper(wrapper);
((HttpRequest) request).setServletPath(servletPath);
((HttpRequest) request).setPathInfo(pathInfo);
}
return (wrapper);
}
对重载的支持
/**
* Set the Container with which this Logger has been associated.
*
* @param container The associated Container
*/
public void setContainer(Container container) {
// Deregister from the old Container (if any)
if ((this.container != null) && (this.container instanceof Context))
((Context) this.container).removePropertyChangeListener(this);
// Process this property change
Container oldContainer = this.container;
this.container = container;
support.firePropertyChange("container", oldContainer, this.container);
// Register with the new Container (if any)
if ((this.container != null) && (this.container instanceof Context)) {
setReloadable( ((Context) this.container).getReloadable() );
((Context) this.container).addPropertyChangeListener(this);
}
}
/**
* Set the reloadable flag for this Loader.
*
* @param reloadable The new reloadable flag
*/
public void setReloadable(boolean reloadable) {
// Process this property change
boolean oldReloadable = this.reloadable;
this.reloadable = reloadable;
support.firePropertyChange("reloadable",
new Boolean(oldReloadable),
new Boolean(this.reloadable));
// Start or stop our background thread if required
if (!started)
return;
if (!oldReloadable && this.reloadable)
threadStart();
else if (oldReloadable && !this.reloadable)
threadStop();
}
backgroundProcess()方法
小结
这里的源码分析针对的是tomcat4版本的
这里我先对StandardContext容器的start方法调用链做个总结:
ContainerBase的start方法:
代码语言：javascript复制 @Override
public synchronized void start() throws LifecycleException {
// Validate and update our current component state
if (started)
throw new LifecycleException
(sm.getString("containerBase.alreadyStarted", logName()));
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);
addDefaultMapper(this.mapperClass);
started = true;
// Start our subordinate components, if any
if ((loader != null) && (loader instanceof Lifecycle))
((Lifecycle) loader).start();
if ((logger != null) && (logger instanceof Lifecycle))
((Lifecycle) logger).start();
if ((manager != null) && (manager instanceof Lifecycle))
((Lifecycle) manager).start();
if ((cluster != null) && (cluster instanceof Lifecycle))
((Lifecycle) cluster).start();
if ((realm != null) && (realm instanceof Lifecycle))
((Lifecycle) realm).start();
if ((resources != null) && (resources instanceof Lifecycle))
((Lifecycle) resources).start();
// Start our Mappers, if any
Mapper mappers[] = findMappers();
for (int i = 0; i < mappers.length; i ) {
if (mappers[i] instanceof Lifecycle)
((Lifecycle) mappers[i]).start();
}
// Start our child containers, if any
Container children[] = findChildren();
for (int i = 0; i < children.length; i ) {
if (children[i] instanceof Lifecycle)
((Lifecycle) children[i]).start();
}
// Start the Valves in our pipeline (including the basic), if any
if (pipeline instanceof Lifecycle)
((Lifecycle) pipeline).start();
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(START_EVENT, null);
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}StandardContext后面的start方法调用干了啥子，就是上面讲的过程了，这里没有调用其父类ContainerBase的start方法了注意
