JFinal源码分析三：AOP触发过程

1、在全局拦截器JFinalFilter的初始化函数init中会调用JFinal的init方法，在该方法中会调用initHandler()；、

//JFinal类
boolean init(JFinalConfig jfinalConfig, ServletContext servletContext) {
this.servletContext = servletContext;
this.contextPath = servletContext.getContextPath();

initPathUtil();

Config.configJFinal(jfinalConfig);	// start plugin and init log factory in this method
constants = Config.getConstants();

initActionMapping();
initHandler();    //初始化handler，Handler 可以接管所有web请求，并对应用拥有完的控制权，可以很方便地实现更高层的功能性扩展
initRender();
initOreillyCos();
initTokenManager();

return true;
}

2、initHandler()方法中会对ActionHandler初始化

private void initHandler() {
Handler actionHandler = new ActionHandler(actionMapping, constants);    //初始化action的handler
handler = HandlerFactory.getHandler(Config.getHandlers().getHandlerList(), actionHandler);
}

3、当请求被JFinalFilter拦截时(doFilter)，会调用ActionHandler的handle()方法.

//JFinalFilter类
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)res;
request.setCharacterEncoding(encoding);

String target = request.getRequestURI();
if (contextPathLength != 0)
target = target.substring(contextPathLength);

boolean[] isHandled = {false};
try {
handler.handle(target, request, response, isHandled);   //调用handler(handler已经在第一步中初始化过)
}
catch (Exception e) {
if (log.isErrorEnabled()) {
String qs = request.getQueryString();
log.error(qs == null ? target : target + "?" + qs, e);
}
}

if (isHandled[0] == false)
chain.doFilter(request, response);
}

//ActionHandler类
public final void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
if (target.indexOf('.') != -1) {
return ;
}

isHandled[0] = true;
String[] urlPara = {null};
Action action = actionMapping.getAction(target, urlPara);    //获取请求中的action

if (action == null) {
if (log.isWarnEnabled()) {
String qs = request.getQueryString();
log.warn("404 Action Not Found: " + (qs == null ? target : target + "?" + qs));
}
renderFactory.getErrorRender(404).setContext(request, response).render();
return ;
}

try {
Controller controller = action.getControllerClass().newInstance();
controller.init(request, response, urlPara[0]);//初始化action所属的controller

if (devMode) {    //开发模式
if (ActionReporter.isReportAfterInvocation(request)) {
new Invocation(action, controller).invoke();
ActionReporter.report(controller, action);
} else {
ActionReporter.report(controller, action);
new Invocation(action, controller).invoke();
}
}
else {
new Invocation(action, controller).invoke(); //初始化Invocation
}

Render render = controller.getRender();
if (render instanceof ActionRender) {
String actionUrl = ((ActionRender)render).getActionUrl();
if (target.equals(actionUrl))
throw new RuntimeException("The forward action url is the same as before.");
else
handle(actionUrl, request, response, isHandled);
return ;
}

if (render == null)
render = renderFactory.getDefaultRender(action.getViewPath() + action.getMethodName());
render.setContext(request, response, action.getViewPath()).render();
}
catch (RenderException e) {
if (log.isErrorEnabled()) {
String qs = request.getQueryString();
log.error(qs == null ? target : target + "?" + qs, e);
}
}
catch (ActionException e) {
int errorCode = e.getErrorCode();
if (errorCode == 404 && log.isWarnEnabled()) {
String qs = request.getQueryString();
log.warn("404 Not Found: " + (qs == null ? target : target + "?" + qs));
}
else if (errorCode == 401 && log.isWarnEnabled()) {
String qs = request.getQueryString();
log.warn("401 Unauthorized: " + (qs == null ? target : target + "?" + qs));
}
else if (errorCode == 403 && log.isWarnEnabled()) {
String qs = request.getQueryString();
log.warn("403 Forbidden: " + (qs == null ? target : target + "?" + qs));
}
else if (log.isErrorEnabled()) {
String qs = request.getQueryString();
log.error(qs == null ? target : target + "?" + qs, e);
}
e.getErrorRender().setContext(request, response, action.getViewPath()).render();
}
catch (Throwable t) {
if (log.isErrorEnabled()) {
String qs = request.getQueryString();
log.error(qs == null ? target : target + "?" + qs, t);
}
renderFactory.getErrorRender(500).setContext(request, response, action.getViewPath()).render();
}
}

5、Invocation类的结构(成员变量)

private Object target;    //拦截的目标对象
private Method method;    //拦截到的目标对象中的方法
private Object[] args;    //方法的参数
private MethodProxy methodProxy;    //方法代理，
private Interceptor[] inters;    //每个方法的所有拦截器

6、Invocation类中invoke方法如下：

public void invoke() {
if (index < inters.length) {
inters[index++].intercept(this);    //执行拦截器的intercept方法，传入了Invocation对象this作为参数，在每个拦截器intercept方法中，会再次调用Invocation的invoke方法，达到遍历执行所有拦截器
}
else if (index++ == inters.length) {	// index++ ensure invoke action only one time
try {
// Invoke the action
if (action != null) {
returnValue = action.getMethod().invoke(target, args);
}
// Invoke the method
else {
// if (!Modifier.isAbstract(method.getModifiers()))
// returnValue = methodProxy.invokeSuper(target, args);
if (useInjectTarget)
returnValue = methodProxy.invoke(target, args);
else
returnValue = methodProxy.invokeSuper(target, args);
}
}
catch (InvocationTargetException e) {
Throwable t = e.getTargetException();
throw t instanceof RuntimeException ? (RuntimeException)t : new RuntimeException(e);
}
catch (RuntimeException e) {
throw e;
}
catch (Throwable t) {
throw new RuntimeException(t);
}
}
}