struts2执行过程浅析
2013-07-20 15:38
225 查看
[size=medium]struts2的执行过程[/size]
1.首先进入StrutsPrepareAndExecuteFilter这个filter，执行doFilter方法
2.做完所有准备工作之后，初始化后的ExecuteOperations执行executeAction
3.ExecuteOperations实际上是个代理类，内部调用dispatcher的serviceAction方法
在这个方法中首先拿到当前线程（ActionContext维护一个ThreadLocal），并且得到valueStack，接着得到映射中的信息（namespace，method，name），根据这些信息创建代理对象
4.以下是具体创建代理对象和ActionInvocation的过程
DefaultActionProxyFactory(createActionProxy())
4.1.代理对象的准备工作 DefaultActionProxy(prepare())
4.2.proxy会初始化actionInvocation，其中包括上下文环境，值栈，以及拦截器
5.当所有的准备工作都做好之后，回到ExecuteOperations中，执行proxy.execute()方法，实际执行的是StrutsActionProxy的execute()方法
6.此时actionInvocation开始执行。
7.1.所有拦截器执行完之后调用invokeActionOnly
8.得到result对象并跳转到相应页面
根据字符串跳转到相应的页面 StrutsResultSupport(execute())
注：本文仅涉及struts2的执行过程，具体的细节和详细的步骤暂不讨论！
1.首先进入StrutsPrepareAndExecuteFilter这个filter，执行doFilter方法
public void doFilter(ServletRequest req,ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
try {
//设置Encoding和Locale
prepare.setEncodingAndLocale(request, response);
prepare.createActionContext(request, response);
//将dispatcher绑定到当前线程
prepare.assignDispatcherToThread();
if ( excludedPatterns != null && prepare.isUrlExcluded(request, excludedPatterns)) {
chain.doFilter(request, response);
} else {
request = prepare.wrapRequest(request);
//查找配置中是否有映射
ActionMapping mapping = prepare.findActionMapping(request, response, true);
if (mapping == null) {
boolean handled = execute.executeStaticResourceRequest(request, response);
if (!handled) {
chain.doFilter(request, response);
}
} else {
//向下执行
execute.executeAction(request, response, mapping); }
}
} finally {
prepare.cleanupRequest(request);
}
}
2.做完所有准备工作之后，初始化后的ExecuteOperations执行executeAction
public void executeAction(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping) throws ServletException {
dispatcher.serviceAction(request, response, servletContext, mapping);}
3.ExecuteOperations实际上是个代理类，内部调用dispatcher的serviceAction方法
在这个方法中首先拿到当前线程（ActionContext维护一个ThreadLocal），并且得到valueStack，接着得到映射中的信息（namespace，method，name），根据这些信息创建代理对象
public void serviceAction(HttpServletRequest request, HttpServletResponse response, ServletContext context,
ActionMapping mapping) throws ServletException {
Map<String, Object> extraContext = createContextMap(request, response, mapping, context);
ValueStack stack = (ValueStack) request.getAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY);
boolean nullStack = stack == null;
if (nullStack) {
//得到当前线程的ActionContext
ActionContext ctx = ActionContext.getContext();
if (ctx != null) {
//得到ValueStack
stack = ctx.getValueStack();
}
}
if (stack != null) {
extraContext.put(ActionContext.VALUE_STACK, valueStackFactory.createValueStack(stack));
}
String timerKey = "Handling request from Dispatcher";
try {
UtilTimerStack.push(timerKey);
//得到映射中的信息
String namespace = mapping.getNamespace();
String name = mapping.getName();
String method = mapping.getMethod();
Configuration config = configurationManager.getConfiguration();
//创建一个代理对象
ActionProxy proxy = config.getContainer().getInstance(ActionProxyFactory.class).createActionProxy(
namespace, name, method, extraContext, true, false);request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, proxy.getInvocation().getStack());
if (mapping.getResult() != null) {
Result result = mapping.getResult();
result.execute(proxy.getInvocation());
} else {
//开始执行
proxy.execute();
}
if (!nullStack) {
request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, stack);
}
} catch (ConfigurationException e) {
if(devMode) {
String reqStr = request.getRequestURI();
if (request.getQueryString() != null) {
reqStr = reqStr + "?" + request.getQueryString();
}
LOG.error("Could not find action or result\n" + reqStr, e);
}
else {
if (LOG.isWarnEnabled()) {
LOG.warn("Could not find action or result", e);
}
}
sendError(request, response, context, HttpServletResponse.SC_NOT_FOUND, e);
} catch (Exception e) {
sendError(request, response, context, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);
} finally {
UtilTimerStack.pop(timerKey);
}
}
4.以下是具体创建代理对象和ActionInvocation的过程
DefaultActionProxyFactory(createActionProxy())
public ActionProxy createActionProxy(String namespace, String actionName, String methodName, Map<String, Object> extraContext, boolean executeResult, boolean cleanupContext) {
//创建ActionInvocation
ActionInvocation inv = new DefaultActionInvocation(extraContext, true);
container.inject(inv);
return createActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext);
}
public ActionProxy createActionProxy(ActionInvocation inv, String namespace, String actionName, String methodName, boolean executeResult, boolean cleanupContext) {
//创建proxy
StrutsActionProxy proxy = new StrutsActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext);
container.inject(proxy);
proxy.prepare();
return proxy;
}
4.1.代理对象的准备工作 DefaultActionProxy(prepare())
protected void prepare() {
String profileKey = "create DefaultActionProxy: ";
try {
UtilTimerStack.push(profileKey);
config = configuration.getRuntimeConfiguration().getActionConfig(namespace, actionName);
if (config == null && unknownHandlerManager.hasUnknownHandlers()) {
config = unknownHandlerManager.handleUnknownAction(namespace, actionName);
}
if (config == null) {
throw new ConfigurationException(getErrorMessage());
}
resolveMethod();
if (!config.isAllowedMethod(method)) {
throw new ConfigurationException("Invalid method: " + method + " for action " + actionName);
}
//actionInvocation的初始化
invocation.init(this);
} finally {
UtilTimerStack.pop(profileKey);
}
}
4.2.proxy会初始化actionInvocation，其中包括上下文环境，值栈，以及拦截器
DefaultActionInvocation(init())
public void init(ActionProxy proxy) {
this.proxy = proxy;
Map<String, Object> contextMap = createContextMap();
ActionContext actionContext = ActionContext.getContext();
if (actionContext != null) {
//将actionInvocation放入上下文环境中
actionContext.setActionInvocation(this);
}
createAction(contextMap);
if (pushAction) {
//将action置于valueStack中
stack.push(action);
contextMap.put("action", action);
}
//创建invocationContext上下文
invocationContext = new ActionContext(contextMap);
invocationContext.setName(proxy.getActionName());
//初始化拦截器
List<InterceptorMapping> interceptorList = new ArrayList<InterceptorMapping>(proxy.getConfig().getInterceptors());
interceptors = interceptorList.iterator();
}
5.当所有的准备工作都做好之后，回到ExecuteOperations中，执行proxy.execute()方法，实际执行的是StrutsActionProxy的execute()方法
public String execute() throws Exception {
ActionContext previous = ActionContext.getContext();
ActionContext.setContext(invocation.getInvocationContext());
try {
//生成的actionInvocation开始执行
return invocation.invoke();
} finally {
if (cleanupContext)
ActionContext.setContext(previous);
}
}
6.此时actionInvocation开始执行。
public String invoke() throws Exception {
String profileKey = "invoke: ";
try {
UtilTimerStack.push(profileKey);
if (executed) {
throw new IllegalStateException("Action has already executed");
}
//依次执行每个拦截器 actionInvocation相当于一个中转站，每个拦截器执
//行完，又返回actionInvocation执行
if (interceptors.hasNext()) {
final InterceptorMapping interceptor = (InterceptorMapping) interceptors.next();
String interceptorMsg = "interceptor: " + interceptor.getName();
UtilTimerStack.push(interceptorMsg);
try {
resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this);
}
finally {
UtilTimerStack.pop(interceptorMsg);
}
} else {
//所有拦截器执行完之后调用invokeActionOnly方法
resultCode = invokeActionOnly();
}
if (!executed) {
if (preResultListeners != null) {
for (Object preResultListener : preResultListeners) {
PreResultListener listener = (PreResultListener) preResultListener;
String _profileKey = "preResultListener: ";
try {
UtilTimerStack.push(_profileKey);
listener.beforeResult(this, resultCode);
}
finally {
UtilTimerStack.pop(_profileKey);
}
}
}
if (proxy.getExecuteResult()) {
//根据得到的字符串跳转到对应的页面
executeResult();
}
executed = true;
}
return resultCode;
}
finally {
UtilTimerStack.pop(profileKey);
}
}
7.1.所有拦截器执行完之后调用invokeActionOnly
public String invokeActionOnly() throws Exception {
return invokeAction(getAction(), proxy.getConfig());
}
protected String invokeAction(Object action, ActionConfig actionConfig) throws Exception {
//得到action类中调用方法的名称
String methodName = proxy.getMethod();
if (LOG.isDebugEnabled()) {
LOG.debug("Executing action method = " + actionConfig.getMethodName());
}
String timerKey = "invokeAction: " + proxy.getActionName();
try {
UtilTimerStack.push(timerKey);
boolean methodCalled = false;
Object methodResult = null;
Method method = null;
try {
method = getAction().getClass().getMethod(methodName, EMPTY_CLASS_ARRAY);
} catch (NoSuchMethodException e) {
try {
String altMethodName = "do" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1);
//构成Method对象
method = getAction().getClass().getMethod(altMethodName, EMPTY_CLASS_ARRAY);
} catch (NoSuchMethodException e1) {
if (unknownHandlerManager.hasUnknownHandlers()) {
try {
methodResult = unknownHandlerManager.handleUnknownMethod(action, methodName);
methodCalled = true;
} catch (NoSuchMethodException e2) {
throw e;
}
} else {
throw e;
}
}
}
if (!methodCalled) {
//执行方法得到返回对对象（实际是字符串）
methodResult = method.invoke(action, EMPTY_OBJECT_ARRAY);
}
return saveResult(actionConfig, methodResult);
} catch (NoSuchMethodException e) {
throw new IllegalArgumentException("The " + methodName + "() is not defined in action " + getAction().getClass() + "");
} catch (InvocationTargetException e) {
Throwable t = e.getTargetException();
if (actionEventListener != null) {
String result = actionEventListener.handleException(t, getStack());
if (result != null) {
return result;
}
}
if (t instanceof Exception) {
throw (Exception) t;
} else {
throw e;
}
} finally {
UtilTimerStack.pop(timerKey);
}
}
//保存后面要用到的字符串，否则返回
protected String saveResult(ActionConfig actionConfig, Object methodResult) {
if (methodResult instanceof Result) {
this.explicitResult = (Result) methodResult;
container.inject(explicitResult);
return null;
} else {
return (String) methodResult;
}
}
8.得到result对象并跳转到相应页面
private void executeResult() throws Exception {
result = createResult();
String timerKey = "executeResult: " + getResultCode();
try {
UtilTimerStack.push(timerKey);
if (result != null) {
//封装的result执行
result.execute(this);
} else if (resultCode != null && !Action.NONE.equals(resultCode)) {
throw new ConfigurationException("No result defined for action " + getAction().getClass().getName()
+ " and result " + getResultCode(), proxy.getConfig());
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("No result returned for action " + getAction().getClass().getName() + " at " + proxy.getConfig().getLocation());
}
}
} finally {
UtilTimerStack.pop(timerKey);
}
}
根据字符串跳转到相应的页面 StrutsResultSupport(execute())
public void execute(ActionInvocation invocation) throws Exception {
lastFinalLocation = conditionalParse(location, invocation);
doExecute(lastFinalLocation, invocation);
}
ServletDispatcherResult(doExecute())
public void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
if (LOG.isDebugEnabled()) {
LOG.debug("Forwarding to location " + finalLocation);
}
PageContext pageContext = ServletActionContext.getPageContext();
if (pageContext != null) {
pageContext.include(finalLocation);
} else {
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
RequestDispatcher dispatcher = request.getRequestDispatcher(finalLocation);
if (StringUtils.isNotEmpty(finalLocation) && finalLocation.indexOf("?") > 0) {
String queryString = finalLocation.substring(finalLocation.indexOf("?") + 1);
Map<String, Object> parameters = getParameters(invocation);
Map<String, Object> queryParams = urlHelper.parseQueryString(queryString, true);
if (queryParams != null && !queryParams.isEmpty())
parameters.putAll(queryParams);
}
if (dispatcher == null) {
response.sendError(404, "result '" + finalLocation + "' not found");
return;
}
Boolean insideActionTag = (Boolean) ObjectUtils.defaultIfNull(request.getAttribute(StrutsStatics.STRUTS_ACTION_TAG_INVOCATION), Boolean.FALSE);
if (!insideActionTag && !response.isCommitted() && (request.getAttribute("javax.servlet.include.servlet_path") == null)) {
request.setAttribute("struts.view_uri", finalLocation);
request.setAttribute("struts.request_uri", request.getRequestURI());
dispatcher.forward(request, response);
} else {
dispatcher.include(request, response);
}
}
}
注：本文仅涉及struts2的执行过程，具体的细节和详细的步骤暂不讨论！
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
相关文章推荐
- Struts2的执行过程和内部的执行过程
- 浅析magento执行sql文件夹下install-version.php下过程
- struts2 代替servlet 执行过程
- SQL Server性能调优之执行计划深度剖析 第一节 浅析SQL执行的过程
- 最新浅析java源代码转换为机器码的编译执行过程
- SQL Server性能调优之执行计划深度剖析 第一节 浅析SQL执行的过程
- Struts2内部执行过程
- SQL Server性能调优之执行计划深度剖析 第一节 浅析SQL执行的过程
- [转载]：SQL Server性能调优之执行计划深度剖析 第一节 浅析SQL执行的过程
- Struts2 REST 插件 XStream 远程代码执行漏洞 S2-052 复现过程
- Spring MVC 执行过程浅析
- SQL Server性能调优之执行计划深度剖析 第一节 浅析SQL执行的过程
- struts2的简单执行过程
- Struts2基本的执行过程
- Struts2执行过程
- struts2_day01_03_struts2入门案例（一）（二）_05_struts2基本执行过程
- 浅析java程序的执行过程
- SpringMVC的执行过程浅析
- struts2实例执行过程，以及原理
- Struts2执行过程解析