Simple implementation of Web request dispatch mechanism

1. Web. XML definition

   <!--Spring Bean configuration--
   

   <context-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>classpath:applicationContext.xml</param-value>
   </context-param>
   <listener>
   <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
   </listener>

   <!--start, scan annotations, cache defined URLs and corresponding processing class data--
   <listener>
   <listener-class>com.util.listener.ContextLoaderListener</listener-class>
   </listener>

   <!--filtering   character encoding filtering--
     <filter>
       <filter-name>characterencodingfilter </filter-name>
       <filter-class>com.util.filter.charcodefilter</filter-class
       <init-param>
         <param-name> Characterencoding</param-name>
         <param-value>utf-8</param-value
       </init-param>
     </filter>
     <filter-mapping>
       <filter-name>characterencodingfilter</filter-name>
       < Url-pattern>/*</url-pattern>
     </filter-mapping>

   <!--request to dispatch a servlet--
   <servlet>
   <servlet-name>dispatcher</servlet-name>
   <servlet-class>com.util.dispatcher.DispatcherServlet</servlet-class>
   </servlet>
   <servlet-mapping>
   <servlet-name>dispatcher</servlet-name>
   <url-pattern>/</url-pattern>
   </servlet-mapping>
   <servlet>
   

3. 1 request dispatch, Web container startup scan URL annotations

public class Contextloaderlistener implements Servletcontextlistener {
Logger log =loggerfactory.getlogger (Contextloaderlistener.class);
@Override
public void contextdestroyed (Servletcontextevent arg0) {
TODO auto-generated Method Stub
Log.info ("context destroyed");
}
@Override
public void contextinitialized (Servletcontextevent arg0) {
try {
New Contextrootname (). Setcontextrootname (Arg0.getservletcontext (). Getcontextpath ());
Annotation Scan

New Annotationscanner (). sannclasses ();

The configuration to jump after the controller has been executed

New Analysisview (). Analysisactionviewproperties ();
} catch (ClassNotFoundException e) {
Log.error (E.getmessage ());
}
Log.info ("Context inited");
}

}

2.1.1 Annotation Scan

public class Annotationscanner {

private static list<string> packages = new arraylist<string> ();
static{
Packages.add ("Com.wqf.action.impl");
}
/** the path to be scanned */
private static list<string> paths = null;
TODO Scan to Required class method needs to be changed
public void Sannclasses () throws classnotfoundexception{
String Rootpath=getclass (). GetResource ("/"). GetFile (). toString ();
paths = Getpaths ();
for (String path:paths) {
File RootFile = new file (path);
File [] files = Rootfile.listfiles ();
String PackageName = Path.replace (RootPath, ""). Replace ('/', '. ') + ".";
for (File f:files) {
String className = F.getname (). substring (0, F.getname (). IndexOf (". Class"));
Class<?> clazz = Class.forName (packagename+classname);
Parseclass (Clazz);
}
}
}
public void Parseclass (class<?> clazz) {
String url1= "";
String url2= "";
annotation[] annotations = clazz.getannotations ();
for (Annotation annotation:annotations) {
if (Annotation.annotationtype (). Getsimplename (). Equals ("NameSpace")) {
NameSpace NameSpace = (NameSpace) annotation;
URL1 = Namespace.namespace ();
}
}
Method[] methods = Clazz.getdeclaredmethods ();
for (Method method:methods) {
annotation[] methodannotations = Method.getannotations ();
for (Annotation annotation:methodannotations) {
if (Annotation.annotationtype (). Getsimplename (). Equals ("requestmapping")) {
Requestmapping requestmapping = (requestmapping) annotation;
Url2 = Requestmapping.mapping ();
Mapclassmethodbean data = new Mapclassmethodbean ();
Data.setbean (Clazz);
Data.setm (method);
String url = modifyurl (url1 + url2);
Requestdata.setdata (URL, data);
}
}
}
}
private static string Modifyurl (string url) {
return URL;
}
TODO gets path to read from XML config file instead
Private List<string> getpaths () {
String Rootpath=getclass (). GetResource ("/"). GetFile (). toString ();
list<string> stringlist = new arraylist<string> ();
for (String scanpackage:packages) {
String Tmppath = Scanpackage.replace ('. ', '/');
Stringlist.add (RootPath + tmppath);
}
return stringlist;
}
}

2.1.2controller and jump to JSP page configuration

Firstaction/test.do = test.jsp

public class Analysisview {
Private String ViewPath = "/resource/viewnamesprop";

public void Analysisactionviewproperties () {
Properties prop = new properties ();
FileInputStream in;
try {
String Rootpath=getclass (). GetResource ("/"). GetFile (). toString ();
in = new FileInputStream (RootPath + viewPath);
Prop.load (in);
Iterator<string> it = Prop.stringpropertynames (). Iterator ();
while (It.hasnext ()) {
String Key=it.next ();
Viewnamedata.setdata (Key, Prop.getproperty (key));
}
In.close ();
} catch (FileNotFoundException e) {
E.printstacktrace ();
} catch (IOException e) {
E.printstacktrace ();
}
}
}

3. Core distribution Servlet

public class Dispatcherservlet extends HttpServlet {
/**
*
*/
Private static final long serialversionuid = 1L;
Logger log = Loggerfactory.getlogger (Dispatcherservlet.class);
Ibaseaction action = null;
Private String jsp = "JSP";
@Override
protected void Doget (HttpServletRequest req, HttpServletResponse resp) throws Servletexception, IOException {
Log.error ("No GET Request");
Return
DoPost (req, resp);
}

@Override
protected void DoPost (HttpServletRequest req, HttpServletResponse resp) throws Servletexception, IOException {

/**
* Determine the type of request to be distributed to different class
*/
String suffix = "";
if (Actionname.indexof (".")! =-1) {
suffix = actionname.substring (Actionname.indexof (".") + 1,actionname.indexof ("?") = =-1? Actionname.length (): Actionname.indexof ("?")-1);
//        }
if (jsp.equals (suffix)) {
Jspdispatcherservlet.getinstance (). DoPost (req, resp);
Return
//        }

try {//catch exception not thrown to foreground
String actionname = Req.getservletpath ();
ActionName = Actionname.indexof ("?") = =-1? ActionName:actionName.substring (0, Actionname.indexof ("?"));
/** the actual business class */
Class<?> clazz = null;
/** method of actual business */
method = null;
/** the variables passed in the foreground are uniformly encapsulated inside the context */
Context context = Contextfactory.createcontext (req, resp);
Proxyhandler handler = new Proxyhandler ();

String url = actionname.indexof (".") = =-1? actionName:actionName.substring (0, Actionname.indexof ("."));
Find the appropriate action on request
Mapclassmethodbean Classmethodbean = requestdata.getdata (URL);
if (Classmethodbean = = null) {
Log.info ("The URL is not configured");
Sendredirect (Viewnamedata.getnotfoundpage (), REQ,RESP);
Return
}
Clazz = Classmethodbean.getbean ();
method = Classmethodbean.getm ();
Cglibproxyhandler cglibproxy = new Cglibproxyhandler ();
Enhancer enhancer = new enhancer ();

Enhancer.setsuperclass (Clazz);
Enhancer.setcallback (Cglibproxy);

Object target = Clazz.cast (Ac.getbean (clazz));
Handler.settarget (target);
Object o =
Proxy.newproxyinstance (Target.getclass (). getClassLoader (),
Target.getclass (). Getinterfaces (),
handler);
Object o = enhancer.create ();
method[] Omethods = O.getclass (). Getdeclaredmethods ();
for (Method omethod:omethods) {
if (Omethod.getname (). Equals (Method.getname ())) {
try {
Omethod.invoke (o, context);
} catch (Illegalaccessexception e) {
Log.warn (E.getmessage ());
} catch (IllegalArgumentException e) {
Log.warn (E.getmessage ());
} catch (InvocationTargetException e) {
Log.warn (E.getmessage ());
}
}
}
If there is a corresponding view, the corresponding view of the jump

String viewName = Viewnamedata.getdata (ActionName);
if (viewName! = null) {
Sendredirect (VIEWNAME,REQ,RESP);
}
If there is no corresponding view
} catch (Exception E1) {
Log.error (E1.getmessage ());
Sendredirect (Viewnamedata.geterrorpage (), REQ,RESP);
}
}
private void Sendredirect (String fordardpage,httpservletrequest req, HttpServletResponse resp) throws ioexception{
String Rooturl = req.getscheme () + "://" + Req.getservername ()
+ ":" + req.getserverport ()
+ Req.getcontextpath ();
Resp.sendredirect (Rooturl + "/" + fordardpage);
}
}

Summary: When the Web container starts, listener scans the annotations of the Contrller package, forming the map<string URL, beanmethod<class controller, String method>> Data, when requested to go Dispatcherservlet, find the appropriate controller and method processing request according to the URL of the request.

If there is a corresponding JSP page configured after the request, jump to the corresponding JSP page.

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Simple implementation of Web request dispatch mechanism