Netzwerkprogrammierung mit Java Part2

Transkript

1 1 Netzwerkprogrammierung mit Java Part2 HTML (ultra Kurzfassung) <html> <head> <META HTTP_EQUIV= content-type CONTENT= text/html;charset=iso > <title> Titel der </title> </head> <body gbcolor = #FFCCFF > <h1> gross geschriebener Text </h1> <! -- einzeiliger Kommentar -- > normaler Text <br> nach Zeilenumbruch geht s weiter <p> neuer Abschnitt <! -- mehrzeiliger Kommentar //-- > <a href= das isch en Link </a> <form method= get action= /cgi-bin/search.pl > Suche: <input type= text name= name size= 35 maxlength= 35 value > <br> <select name= zone > <option value= All selected>all</option> <option value= section >Section</option> </select><br> <input type= submit value=search > <input type= reset value= Reset > </body> </html> Cascading Style Sheets (CSS) <style type= text/css > H1 color:blue; don t-style:bold H2 color:red; url( </style> Javascript <SCRIPT LANGUAGE= JavaScript ><! -- document.write( hello world ); // Einzeiliger Kommentar /* ausdokumentieren von Code function display_time_in_status_line () var d = new Date(); var t = d.gethours() + : + d.getminutes(); defaultstatus = t; //time in status line settimeout ( display_time_in_status_line (), 10000); //update every 10 seconds */ // - - > </SCRIPT> <body onload= display_time_in_status_line(); > Schlüsselwörter break false in this void continue for new true while delete function null typeof with else if return var Datentypen Number String boolean Function Object Array null undefined

2 2 Array var a = new Object(); a[0] = 10; a[2] = Hello ; a[100] = true; var a2 = new Array(1, hello, true); Assoziativarray var a= new Object(); a[ height ] = 10; a[ width ] = 20; s1 = a.join // join wandelt alle Elemente in Strings um // reverse kehr den Inhalt eines Arrays um //sort, sortiert Alphabetisch Kontrollanweisungen if( boolean) else while(boolean) for(initialize; test; action) break continue with((object) function funcname([arg_1 [, arg_n]]) return [ expression] for(variable in object) EventHandler Link onclick() onmouseout() onmouseover() Button onblur() onclick() onfocus() Objekt window Membervariablen: Methoden: self,window //aktuelles Fenster defaultstatus //Inhalt der Statusbar document //angezeigtes Dokument //z.b document.write(); document.writeln(); location //angezeigte URL //.appcodename, appname, appversion navigatior //Browser-Objekt status //Statuszeile alert() confirm() prompt() open() close() //Meldung in Dialogfenster //OK/Cancel Dialog //fragt Benutzer nach String //öffnet neues Fenster //schliesst das aktuelle Fenster Webserver und CGI (Common Gateway Interface) Standard-Konfiguration ServerType standalone ServerRoot d:/apache Port 80 #User nobody #Group nobody Server Admin sschneid@suvi.org #ServerName DocumentRoot f:/apache&htdocs DirectoryIndex index.html index.htm AccessFileName.htacces HeaderName HEADER ReadmeName README IndexIgnore.???* ~ # HEADER* README* RCS CVS *,v *,t <VirtualHost ServerAdmin webmaster@hello.com DocumentRoot f:/apache/hello.com/htdocs ServerName ErrorLog d:/apache/logs/hello.com.error_log TransferLog d:/apache/logs/hello.com/transfer_log </VirtualHost>

3 3 Introduction to Perl Beispiel Hello World #!/usr/bin/perl w # -w compiler switch to turn warnings on # # comment if ($#ARGV >= 0) who = else $who = World ; print Hello, $who!\n ; >Hello World // oder Hello $ARGV Arrays ( Sun, Mon, Tue, Wed, Thu, Fri, Sat ) (13,14,15,16,17,18,19) equivalent to (13..19) (13,14,15,16,17,18,19)[2..4] equivalent to (15,16,17) Associative = (31,28,31,30,31,30,31,31,30,31,30,31); # A list whith 12 elements. $#days # Last index 11 for above list $#days = 7 # shortens of lengthens to 8 # ($days[0], # = a, c # same as ($days a, $days c ) %days # (key1, value1, key2, value2, ) Expressions $a = 5; $a++; # $a is now 6; we added 1 to it. $a += 10; # Now it's 16; we added 10. $a /= 2; # And divided it by 2, so it's 8. Search and replace $pet = "I love my cat.\n"; $pet =~ s/cat/dog/; print $pet; Variable $_ $_,$1,$2,$3 sind implizite variablen mit spezieller Bedeutung. <STDIN>; print; = split; assigns a record from filehandle STDIN to $_ print the current value of $_ removes the last character from $_ parses $_ into white-spaces delimited words, which become successive elements of Subroutines and functions sub square return $_[0] ** 2; print 5 squared is, &square(5); // Funktionen werden mit & angesprochen Loops while ( $a < 100 )... do... until ( $a > 99 ) for ( $x = 0; $x < 10 ; $x++ ) print $x\n ;

4 4 Java Servlets Ein Servlet wird vom Server geladen und initialisiert init() Das Servlet brarbeitet eine unbestimte Anzahl Anfragen service() Der Server entfernt das Servlet aus dem Server destroy() //z.b Nach Zeitlimit 30min import javax.servlet import javax.servlet.http import java.io.* ; // Gernerelles Servlet-API // Spezifische API für Servlets, die über das HTTP-Protokoll angesprochen werden public class SimpleServlet extends HttpServlet //Handel the HTTP GET method by building a simple web page public void doget (HtttpServletRequest request, HTTPServletResponse response) throws ServletException, IOException PrintWriter out; String title = Simple Servlet Output ; //set content type and other response header fields first response.setcontenttype( text/html ); //out = response.getwriter(); out.println( <HTML><HEAD><TITLE> ); out.println(title); out.println( </TITLE></HEAD><BODY> ); out.println( <H1> + title + </H1> ); out.println( <P> This is output from SimpleServlet. ); out.println( </BODY></HTML> ); out.close; Session Tracking public HttpSession getsession(boolean create); doget (.) //Get the user s session and shopping cart HttpSession session = request.getsession(true); ShoppingCart cart = (ShoppingCart)session.getAttribute( examples.bookstore.cart ); //If the user has no cart, create a new one (if cart == null) cart = new ShoppingCart(); session.setattribute( examples.bookstore.cart, cart); URL-Rewriting out.println( <a href=\ + response.encodeurl( /servlet/bookdetails?bookid= + bookid) -+ \ > + book.gettitle() + </a href> ); Cookie erstellen 1. Cookie erzeugen Cokkie thebook = new Cookie( Buy, bookid); 2. Setzen von Attributen thebook.setcomment( User wants to buy book + bookid); thebook.setmaxage(0); // mit 0 wird Cookie auf Client gelöscht 3. Cookie versenden response.addcookie(getbook);

5 5 Cookies auslesen 1. Alle Cookies eines Requests holen Cokkie [ ] cookies = request.getcookies(); 2. Anhand von Namen das gewünschte Cookie heraussuchen for (int i = 0; i< cookies.length; i++) if (cookies[i].equals( Buy )).. 3. Wert aus Cookie lessen Cookies[i].getValue(); Servlet-Kommunikation Verwenden von andere Ressourcen auf dem Server RequestDispatcher dispatcher = getservletcontext().getrequestdispatcher( /bookstore/bookstore.html ); if (dispatcher == null) response.senderror(response.sc_no_content); Weiterleiten eines Requests dispatcher.forward(request, response); Web-Applikationen Director-Struktur: /WEB-INF/web.xml /WEB-INF/classes/* /WEB-INF/lib/*.jar - Der Deployment descriptor - Directory für Servlets und Hilfsklassen - Direcotry für Bibliotheken on Form von Java ARchives JavaServer Pages (JSP) <HTML> <%@ page language= java import= java.util.* %> <H1>Welcome</H1> <P>Today is </P> <jsp: usebean id= clock scope= session class= calendar.jspcalendar /> <%! int a,b; double c; %> <!--JSP-Deklaration -- > <UL> <LI>Day: <% clock.getdayofmonth() %> <LI>Year: <%= clock.getyear() %> </UL> <%-- Check for AM or PM --, JSP Comment %> <%! int time = Calendar.getInstance.get(Clendar.AM_PM); %> <% if (time == Calendar.AM) %> Good Morning <% else %> Good Afternoon <% %> <%@ include file= copyright.html %> </HTML> Die Page Direktive <% page language= %> beschreibt Sprache, Imports, ntyp Mit der Include Directive <%@ include file= info.html %> wird ein File statisch eingebunden. Mit <jsp:include page= form.jsp flush= true /> wird ein File dynamisch eingebunden Taglibs <@ taglib uri=/tld/service.tld prefix= menu %> erweitert die Menge der Tags. Objekte <jsp:usebean id= farbtopf class= tools.colorpot /> <jsp:setproperty name= farbtopf property= color value= blue /> //ruft farbtop.setcolor( blue ) auf Weiterleiten eines Client-Requests <jsp:forward page= sorry.jsp />

6 6 Tag Libraries für JSP Tag Libraries mussen im Tag Library Descriptor File.tld eingetragen werden. javax.servlet.jsp.tagext.tag javax.servlet.jsp.tagext.tagsupport javax.servlet.jsp.tagext.bodytagsupport Tag Handler ohne Body mit Body import java.io.*; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; public class HelloTag implements Tag private PageContext pagecontext; private Tag parent ; public HelloTag( ) super( ) public void setpagecontext(final PageContext pagecontext) this.pagecontext = pagecontext; public void setparent(final Tag parent) this.parent=parent; public Tag getparent return parent; public int dostarttag( ) throws JspTagException return SKIP_BODY; // oder EVAL_BODY_INCLUDE public int doendtag( ) throws JspTagException try pagecontext.getout.write( Hello, Tag! ) catch(ioexception e) throw new JspTagException( IO Error: + e.getmessage( ) ); return EVAL_PAGE; // oder SKIP_PAGE public void release( ) Verwendung <%@ taglib uri= ttl prefix ttl %> <ttl: HelloTag /> JSP-ErrorPages <@ page iserrorpage= true %> <%= exception.tostring( ) %>