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JFinal - Handler 处理流程

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[系统(linux) 所属分类 系统(linux) | 发布者 店小二04 | 时间 20160901 | 作者 红领巾 ] 0人收藏点击收藏
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。newFakeStaticHandler 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)。


JFinal - Handler 处理流程
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();
}
}View Cod

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);
elsereturnValue= 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 ");
}
}
JFinal - Handler 处理流程

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
* <p>
* Example:<br>
* renderJson("message", "Save successful");<br>
* renderJson("users", users);<br>
*/
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.
* <p>
* Example: renderJson(new String[]{"blogList", "user"});
*/
public void renderJson(String[] attrs) {
render= renderFactory.getJsonRender(attrs);
}

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

/**
* Render json with object.
* <p>
* 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.
* <p>
* Example: renderText("&lt;user id='5888'&gt;James&lt;/user&gt;", "application/xml");
*/
public void renderText(String text, String contentType) {
render= renderFactory.getTextRender(text, contentType);
}

/**
* Render with text and ContentType.
* <p>
* Example: renderText("&lt;html&gt;Hello James&lt;/html&gt;", 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~~

----- End -----

Jfinal学习之路---Controller使用 http://www.linuxidc.com/Linux/2014-07/104323.htm

JFinal开发8个常见问题 http://www.codesec.net/Linux/2015-02/113421.htm

JFinal的详细介绍:请点这里
JFinal的下载地址:请点这里

本文地址:http://www.codesec.net/Linux/2016-09/135257.htm


JFinal - Handler 处理流程

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