JFinal - Handler 处理步骤

发布时间：2021-12-10 15:30:41 所属栏目：教程来源：互联网

导读：Handler 处理流程 doFilter - Handler 链中每个 handler.handle(...) 容器初始化时访问 web.xml 配置的 JFinalFilter.doFilter。沿着 Handler 链，每个 handler 调用 handle 方法进行处理，然后交给下一个 handler。 public void doFilter(ServletRequest re

Handler 处理流程
doFilter - Handler 链中每个 handler.handle(...)
容器初始化时访问 web.xml 配置的 JFinalFilter.doFilter。沿着 Handler 链，每个 handler 调用 handle 方法进行处理，然后交给下一个 handler。

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

 // 获取 request、response，设置编码
 HttpServletRequest request = (HttpServletRequest)req;
 HttpServletResponse response = (HttpServletResponse)res;
 request.setCharacterEncoding(encoding);

 // 初始化的时候可以看出 contextPathLength 为 0 或者为项目名称的长度
 // 比如 target = webapp/xx/yy/zz，则截取后的 target = /xx/yy/zz
 String target = request.getRequestURI();
 if (contextPathLength != 0)
 target = target.substring(contextPathLength);

 // 在调用了 ActionHandler的 handle 方法之后，isHandled[0] 才会被置为 true。
 boolean[] isHandled = {false};
 try {
 // 重头戏，handler 链首到链尾 ActionHandler 依次进行处理
 handler.handle(target, request, response, isHandled);
 }
 catch (Exception e) {
 if (log.isErrorEnabled()) {
 String qs = request.getQueryString();
 log.error(qs == null ? target : target + "?" + qs, e);
 }
 }

 // 若最后 isHandled[0] = false，会执行下一个 Filter。
 if (isHandled[0] == false)
 chain.doFilter(request, response);
}
JFinal 初始化过程中可以 add JFinal 库中的Handler 或自定义的 Handler。

例如：ContextPathHandler，JFinal 自身扩展的 Handler。

访问项目时就会走过 handler 方法设置 contextPath。这样在前端就可以通过 ${CONTEXT_PATH} 得到项目根路径。

public class ContextPathHandler extends Handler {

 private String contextPathName;

 public ContextPathHandler() {
 contextPathName = "CONTEXT_PATH";
 }

 public ContextPathHandler(String contextPathName) {
 if (StrKit.isBlank(contextPathName))
 throw new IllegalArgumentException("contextPathName can not be blank.");
 this.contextPathName = contextPathName;
 }

 public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
 request.setAttribute(contextPathName, request.getContextPath());
 System.out.println("哈哈哈");
 next.handle(target, request, response, isHandled);
 }
}
FakeStaticHandler，也是 JFinal 自身扩展的 Handler。new FakeStaticHandler 时可定义后缀，访问路径 target 必须是以这个后缀结尾才可以进行下去。

public class FakeStaticHandler extends Handler {private String viewPostfix;

 public FakeStaticHandler() {
 viewPostfix= ".html";
 }

 public FakeStaticHandler(String viewPostfix) {
 if (StrKit.isBlank(viewPostfix))
 throw new IllegalArgumentException("viewPostfix can not be blank.");
 this.viewPostfix = viewPostfix;
 }

 public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
 if ("/".equals(target)) {
 next.handle(target, request, response, isHandled);
 return;
 }

 if (target.indexOf('.') == -1) {
 HandlerKit.renderError404(request, response, isHandled);
 return ;
 }

 int index = target.lastIndexOf(viewPostfix);
 if (index != -1)
 target= target.substring(0, index);
 next.handle(target, request, response, isHandled);
 }
}

到达 Handler 链尾 ActionHandler 处理
访问交给 Handler 链尾 ActionHandler，调用 handle 方法进行处理：根据访问路径 target 得到 Action，由 Action 得到 Controller。接着 new Invocation(action, controller).invoke() 进入责任链，反射机制调用 Controller 的方法处理（此方法可根据 Action 得到）。

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

 isHandled[0] = true;
 String[] urlPara= {null};

 // actionMapping 根据 target 得到对应的 action
 Action action = actionMapping.getAction(target, urlPara);

 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 {
 // 由 action 得到对应的 Controller
 Controller controller = action.getControllerClass().newInstance();

 // Controller 初始化
 controller.init(request, response, urlPara[0]);

 if (devMode) {
 if (ActionReporter.isReportAfterInvocation(request)) {
 new Invocation(action, controller).invoke();
 ActionReporter.report(controller, action);
 }else {
 ActionReporter.report(controller, action);
 new Invocation(action, controller).invoke();
 }
 }
 else {
 // 调用 Controller 相应的处理方法
 new Invocation(action, controller).invoke();
 }

 // 获取对应的 Render，如果是一个 ActionRender，就再交给 handler 处理；如果 Render == null会按照默认Render处理；
 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());

 // 调用 Render 实现类讲数据写入页面
 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();
 }
}
下面看看拦截器链如何处理

public class Invocation {

 private Action action;
 private static final Object[] NULL_ARGS = new Object[0]; // Prevent new Object[0] by jvm for paras of action invocation.

 boolean useInjectTarget;
 private Object target;
 private Method method;
 private Object[] args;
 private MethodProxy methodProxy;
 private Interceptor[] inters;
 private Object returnValue = null;

 private int index = 0;

 // InvocationWrapper need this constructor
 protected Invocation() {
 this.action = null;
 }

 public Invocation(Action action, Controller controller) {
 this.action = action;
 this.inters = action.getInterceptors();
 this.target = controller;
 this.args = NULL_ARGS;
 }

 public Invocation(Object target, Method method, Object[] args, MethodProxy methodProxy, Interceptor[] inters) {
 this.action = null;
 this.target = target;
 this.method = method;
 this.args = args;
 this.methodProxy = methodProxy;
 this.inters = inters;
 }

 public void invoke() {
 if (index < inters.length) {
 inters[index++].intercept(this);
 }
 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);
 }
 }
 }

 // ... many sets and gets
}

public class AInterceptor implements Interceptor {
 public void intercept(Invocation inv) {
 System.out.println("Before invoking ");
 inv.invoke();
 System.out.println("After invoking ");
 }
}

public class BInterceptor implements Interceptor {
 public void intercept(Invocation inv) {
 System.out.println("Before invoking ");
 inv.invoke();
 System.out.println("After invoking ");
 }
}

public class BInterceptor implements Interceptor {
 public void intercept(Invocation inv) {
 System.out.println("Before invoking ");
 inv.invoke();
 System.out.println("After invoking ");
 }
}
复制代码

new Invocation(action, controller).invoke()，由 action 得到拦截器数组，如果数组为空，就可以利用反射机制进入 Controller 的方法进行处理的了；

如果拦截器数组不为空，就会遇到拦截器1 的拦截 - inters[0].intercept(this)，数组下标 +1，拦截器1 继续调用这个 Invocation 实例的 invoke() 方法，并且会在前后加上一些目的性操作；

若下标未越界，接着会遇到拦截器2 的拦截 - inters[1].intercept(this)，数组下标 +1，拦截器2 继续调用这个 Invocation 实例的 invoke() 方法，并且会在前面加上一些目的性操作；

如此继续直到下标越界，接着反射机制进入 Controller 的方法进行处理。

render(...)
接着上面 ActionHandler.handle 继续，在 Controller 方法处理的最后，往往要调用 render 方法来实例化 render 变量。例如，我自定义的一个 IndexController，在最后一步调用 render("next.html")。

public class IndexController extends Controller {
 public void index() {
 // ...
 render("next.html");
 }
}
用到父类 Controller 的 render 方法，通过 renderFactory.getRender 得到 render 实例。

public abstract class Controller {

 // ...
 // render below ---
 private static final RenderFactory renderFactory = RenderFactory.me();

 /**
 * Hold Render object when invoke renderXxx(...)
 */
 private Render render;

 public Render getRender() {
 return render;
 }

 /**
 * Render with any Render which extends Render
 */
 public void render(Render render) {
 this.render = render;
 }

 /**
 * Render with view use default type Render configured in JFinalConfig
 */
 public void render(String view) {
 render= renderFactory.getRender(view);
 }

 /**
 * Render with jsp view
 */
 public void renderJsp(String view) {
 render= renderFactory.getJspRender(view);
 }

 /**
 * Render with freemarker view
 */
 public void renderFreeMarker(String view) {
 render= renderFactory.getFreeMarkerRender(view);
 }

 /**
 * Render with velocity view
 */
 public void renderVelocity(String view) {
 render= renderFactory.getVelocityRender(view);
 }

 /**
 * Render with json
 * 
 * Example: 
 * renderJson("message", "Save successful"); 
 * renderJson("users", users); 
 */
 public void renderJson(String key, Object value) {
 render= renderFactory.getJsonRender(key, value);
 }

 /**
 * Render with json
 */
 public void renderJson() {
 render= renderFactory.getJsonRender();
 }

 /**
 * Render with attributes set by setAttr(...) before.
 * 
 * Example: renderJson(new String[]{"blogList", "user"});
 */
 public void renderJson(String[] attrs) {
 render= renderFactory.getJsonRender(attrs);
 }

 /**
 * Render with json text.
 * 
 * Example: renderJson("{"message":"Please input password!"}");
 */
 public void renderJson(String jsonText) {
 render= renderFactory.getJsonRender(jsonText);
 }

 /**
 * Render json with object.
 * 
 * Example: renderJson(new User().set("name", "JFinal").set("age", 18));
 */
 public void renderJson(Object object) {
 render= object instanceof JsonRender ? (JsonRender)object : renderFactory.getJsonRender(object);
 }

 /**
 * Render with text. The contentType is: "text/plain".
 */
 public void renderText(String text) {
 render= renderFactory.getTextRender(text);
 }

 /**
 * Render with text and content type.
 * 
 * Example: renderText("<user id='5888'>James</user>", "application/xml");
 */
 public void renderText(String text, String contentType) {
 render= renderFactory.getTextRender(text, contentType);
 }

 /**
 * Render with text and ContentType.
 * 
 * Example: renderText("<html>Hello James</html>", ContentType.HTML);
 */
 public void renderText(String text, ContentType contentType) {
 render= renderFactory.getTextRender(text, contentType);
 }

 /**
 * Forward to an action
 */
 public void forwardAction(String actionUrl) {
 render= new ActionRender(actionUrl);
 }

 /**
 * Render with file
 */
 public void renderFile(String fileName) {
 render= renderFactory.getFileRender(fileName);
 }

 /**
 * Render with file
 */
 public void renderFile(File file) {
 render= renderFactory.getFileRender(file);
 }

 /**
 * Redirect to url
 */
 public void redirect(String url) {
 render= renderFactory.getRedirectRender(url);
 }

 /**
 * Redirect to url
 */
 public void redirect(String url, boolean withQueryString) {
 render= renderFactory.getRedirectRender(url, withQueryString);
 }

 /**
 * Render with view and status use default type Render configured in JFinalConfig
 */
 public void render(String view, int status) {
 render= renderFactory.getRender(view);
 response.setStatus(status);
 }

 /**
 * Render with url and 301 status
 */
 public void redirect301(String url) {
 render= renderFactory.getRedirect301Render(url);
 }

 /**
 * Render with url and 301 status
 */
 public void redirect301(String url, boolean withQueryString) {
 render= renderFactory.getRedirect301Render(url, withQueryString);
 }

 /**
 * Render with view and errorCode status
 */
 public void renderError(int errorCode, String view) {
 throw new ActionException(errorCode, renderFactory.getErrorRender(errorCode, view));
 }

 /**
 * Render with render and errorCode status
 */
 public void renderError(int errorCode, Render render) {
 throw new ActionException(errorCode, render);
 }

 /**
 * Render with view and errorCode status configured in JFinalConfig
 */
 public void renderError(int errorCode) {
 throw new ActionException(errorCode, renderFactory.getErrorRender(errorCode));
 }

 /**
 * Render nothing, no response to browser
 */
 public void renderNull() {
 render= renderFactory.getNullRender();
 }

 /**
 * Render with javascript text. The contentType is: "text/javascript".
 */
 public void renderJavascript(String javascriptText) {
 render= renderFactory.getJavascriptRender(javascriptText);
 }

 /**
 * Render with html text. The contentType is: "text/html".
 */
 public void renderHtml(String htmlText) {
 render= renderFactory.getHtmlRender(htmlText);
 }

 /**
 * Render with xml view using freemarker.
 */
 public void renderXml(String view) {
 render= renderFactory.getXmlRender(view);
 }

 public void renderCaptcha() {
 render= renderFactory.getCaptchaRender();
 }
}
根据 Controller 可以看出还能使用 renderJosn、renderText 等多种方法，这里一笔带过。

就先写到这里吧~~

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