svn commit: r930375 - in /websites/production/tapestry/content: ./ cache/ implementing-the-hi-lo-guessing-game.data/

Mon, 24 Nov 2014 18:20:59 -0800 

Author: buildbot
Date: Tue Nov 25 02:19:37 2014
New Revision: 930375

Log:
Production update by buildbot for tapestry

Modified:
    websites/production/tapestry/content/cache/main.pageCache
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/gameover.png
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-1.png
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-target-zero.png
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-target.png
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/hilo-1.png
    
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.html

Modified: websites/production/tapestry/content/cache/main.pageCache
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/gameover.png
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-1.png
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-target-zero.png
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/guess-target.png
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.data/hilo-1.png
==============================================================================
Binary files - no diff available.

Modified: 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.html
==============================================================================
--- 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.html 
(original)
+++ 
websites/production/tapestry/content/implementing-the-hi-lo-guessing-game.html 
Tue Nov 25 02:19:37 2014
@@ -92,12 +92,12 @@ table.ScrollbarTable td.ScrollbarNextIco
 {
 }
 ]]></script>
-</div></div><p>Running the application gives us our start:</p><p><img 
class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/hilo-1.png?version=2&amp;modificationDate=1416709010000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/hilo-1.png?version=2&amp;modificationDate=1416709010000&amp;api=v2"></p><p>However,
 clicking the link doesn't do anything yet, as its just a placeholder &lt;a&gt; 
tag, not an actual Tapestry component. Let's think about what should happen 
when the user clicks that link:</p><ul><li>A random target number between 1 and 
10 should be selected</li><li>The number of guesses taken should be reset to 
0</li><li>The user should be sent to the Guess page to make a 
guess</li></ul><p>Our first step is to find out when the user clicks that 
"start guessing" link. In a typical web application framework, we might start 
thinking about URLs and handlers and maybe some sort of XML configuration 
 file. But this is Tapestry, so we're going to work with components and methods 
on our classes.</p><p>First, the component. We want to perform an action 
(selecting the number) before continuing on to the Guess page. The ActionLink 
component is just what we need; it creates a link with a URL that will trigger 
an action event in our code ... but that's getting ahead of ourselves. First 
up, convert the &lt;a&gt; tag to an ActionLink component:</p><div class="code 
panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Index.tml (partial)</b></div><div 
class="codeContent panelContent pdl">
+</div></div><p>Running the application gives us our start:</p><p><img 
class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/hilo-1.png?version=3&amp;modificationDate=1416879474954&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/hilo-1.png?version=3&amp;modificationDate=1416879474954&amp;api=v2"></p><p>However,
 clicking the link doesn't do anything yet, as its just a placeholder &lt;a&gt; 
tag, not an actual Tapestry component. Let's think about what should happen 
when the user clicks that link:</p><ul><li>A random target number between 1 and 
10 should be selected</li><li>The number of guesses taken should be reset to 
0</li><li>The user should be sent to the Guess page to make a 
guess</li></ul><p>Our first step is to find out when the user clicks that 
"start guessing" link. In a typical web application framework, we might start 
thinking about URLs and handlers and maybe some sort of XML configuration file. 
But th
 is is Tapestry, so we're going to work with components and methods on our 
classes.</p><p>First, the component. We want to perform an action (selecting 
the number) before continuing on to the Guess page. The ActionLink component is 
just what we need; it creates a link with a URL that will trigger an action 
event in our code ... but that's getting ahead of ourselves. First up, convert 
the &lt;a&gt; tag to an ActionLink component:</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Index.tml (partial)</b></div><div 
class="codeContent panelContent pdl">
 <script class="theme: Default; brush: xml; gutter: false" 
type="syntaxhighlighter"><![CDATA[    &lt;p&gt;
         &lt;t:actionlink t:id=&quot;start&quot;&gt;start 
guessing&lt;/t:actionlink&gt;
     &lt;/p&gt;
 ]]></script>
-</div></div><p>If you refresh the browser and hover your mouse over the "start 
guessing" link, you'll see that its URL is now /tutorial1/index.start, which 
identifies the name of the page ("index") and the id of the component 
("start").</p><p>If you click the link now, you'll get an error:</p><p><img 
class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/hilo-index-missing-action-error.png?version=3&amp;modificationDate=1416709525000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/hilo-index-missing-action-error.png?version=3&amp;modificationDate=1416709525000&amp;api=v2"></p><p>Tapestry
 is telling us that we need to provide some kind of event handler for that 
event. What does that look like?</p><p>An event handler is a method of the Java 
class with a special name. The name is 
<code>on</code><strong><em>Eventname</em></strong><code>From</code><strong><em>Component-id</em></strong>
 ... here we want a 
 method named <code>onActionFromStart()</code>. How do we know that "action" is 
the right event name? Because that's what ActionLink does, that's why its named 
<strong><em>Action</em></strong>Link.</p><p>Once again, Tapestry gives us 
options; if you don't like naming conventions, there's an @<a shape="rect" 
class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/OnEvent.html";>OnEvent</a>
 annotation you can place on the method instead, which restores the freedom to 
name the method as you like. Details about this approach are in the <a 
shape="rect" href="component-events.html">Tapestry Users' Guide</a>. We'll be 
sticking with the naming convention approach for the tutorial.</p><p>When 
handling a component event request (the kind of request triggered by the 
ActionLink component's URL), Tapestry will find the component and trigger a 
component event on it. This is the callback our server-side code needs to 
figure out what the user is doing o
 n the client side. Let's start with an empty event handler:</p><div 
class="code panel pdl" style="border-width: 1px;"><div class="codeHeader 
panelHeader pdl" style="border-bottom-width: 1px;"><b>Index.java</b></div><div 
class="codeContent panelContent pdl">
+</div></div><p>If you refresh the browser and hover your mouse over the "start 
guessing" link, you'll see that its URL is now /tutorial1/index.start, which 
identifies the name of the page ("index") and the id of the component 
("start").</p><p>If you click the link now, you'll get an error:</p><p><img 
class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/hilo-index-missing-action-error.png?version=3&amp;modificationDate=1416709525000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/hilo-index-missing-action-error.png?version=3&amp;modificationDate=1416709525000&amp;api=v2"></p><p>Tapestry
 is telling us that we need to provide some kind of event handler for that 
event. What does that look like?</p><p>An event handler is a method of the Java 
class with a special name. The name is 
<code>on</code><strong><em>Eventname</em></strong><code>From</code><strong><em>Component-id</em></strong>
 ... here we want a method named
  <code>onActionFromStart()</code>. How do we know that "action" is the right 
event name? Because that's what ActionLink does, that's why its named 
<strong><em>Action</em></strong>Link.</p><p>Once again, Tapestry gives us 
options; if you don't like naming conventions, there's an @<a shape="rect" 
class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/OnEvent.html";>OnEvent</a>
 annotation you can place on the method instead, which restores the freedom to 
name the method as you like. Details about this approach are in the <a 
shape="rect" href="component-events.html">Tapestry Users' Guide</a>. We'll be 
sticking with the naming convention approach for the tutorial.</p><p>When 
handling a component event request (the kind of request triggered by the 
ActionLink component's URL), Tapestry will find the component and trigger a 
component event on it. This is the callback our server-side code needs to 
figure out what the user is doing on the client
  side. Let's start with an empty event handler:</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Index.java</b></div><div 
class="codeContent panelContent pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[package com.example.tutorial.pages;
 
 public class Index
@@ -175,7 +175,7 @@ public class Index
                             <p>When creating your own applications, make sure 
that the objects stored in final variables are thread safe. It seems 
counter-intuitive, but final variables are shared across many threads. Ordinary 
instance variables are not. Fortunately, the implementation of Random is, in 
fact, thread safe.</p>
                     </div>
     </div>
-<p>So ... let's click the link and see what we get:</p><p><img 
class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-template-missing.png?version=2&amp;modificationDate=1416710821000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-template-missing.png?version=2&amp;modificationDate=1416710821000&amp;api=v2"></p><p>Ah!
 We didn't create a Guess page template. Tapestry was really expecting us to 
create one, so we better do so.</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 
1px;"><b>src/main/resources/com/example/tutorial/pages/Guess.tml</b></div><div 
class="codeContent panelContent pdl">
+<p>So ... let's click the link and see what we get:</p><p><img 
class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-template-missing.png?version=2&amp;modificationDate=1416710821000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-template-missing.png?version=2&amp;modificationDate=1416710821000&amp;api=v2"></p><p>Ah!
 We didn't create a Guess page template. Tapestry was really expecting us to 
create one, so we better do so.</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 
1px;"><b>src/main/resources/com/example/tutorial/pages/Guess.tml</b></div><div 
class="codeContent panelContent pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[&lt;html t:type=&quot;layout&quot; 
title=&quot;Guess The Number&quot;
     xmlns:t=&quot;http://tapestry.apache.org/schema/tapestry_5_3.xsd&quot;&gt;
 
@@ -185,16 +185,16 @@ public class Index
   
 &lt;/html&gt;
 ]]></script>
-</div></div><p>Hit the browser's back button, then click the "start guessing" 
link again. We're getting closer:</p><p><img class="confluence-embedded-image" 
width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-no-target-prop.png?version=2&amp;modificationDate=1416711075000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-no-target-prop.png?version=2&amp;modificationDate=1416711075000&amp;api=v2"></p><p>If
 you scroll down, you'll see the line of the Guess.tml template that has the 
error. We have a field named target, but it is private and there's no 
corresponding property, so Tapestry was unable to access it.</p><p>We just need 
to write the missing JavaBeans accessor methods <code>getTarget()</code> (and 
<code>setTarget()</code> for good measure). Or we could let Tapestry write 
those methods instead:</p><div class="code panel pdl" style="border-width: 
1px;"><div class="codeContent panelContent pdl">
+</div></div><p>Hit the browser's back button, then click the "start guessing" 
link again. We're getting closer:</p><p><img class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-no-target-prop.png?version=2&amp;modificationDate=1416711075000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-no-target-prop.png?version=2&amp;modificationDate=1416711075000&amp;api=v2"></p><p>If
 you scroll down, you'll see the line of the Guess.tml template that has the 
error. We have a field named target, but it is private and there's no 
corresponding property, so Tapestry was unable to access it.</p><p>We just need 
to write the missing JavaBeans accessor methods <code>getTarget()</code> (and 
<code>setTarget()</code> for good measure). Or we could let Tapestry write 
those methods instead:</p><div class="code panel pdl" style="border-width: 
1px;"><div class="codeContent panelContent pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[    @Property
     private int target;
 ]]></script>
-</div></div><p>The @<a shape="rect" class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/Property.html";>Property</a>
 annotation very simply directs Tapestry to write the getter and setter method 
for you. You only need to do this if you are going to reference the field from 
the template.</p><p>We are getting very close but there's one last big oddity 
to handle. Once you refresh the page you'll see that target is 0!</p><p><img 
class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-target-zero.png?version=2&amp;modificationDate=1416711323000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-target-zero.png?version=2&amp;modificationDate=1416711323000&amp;api=v2"></p><p>What
 gives? We know it was set to at least 1 ... where did the value go?</p><p>As 
noted above, Tapestry sends a redirect to the client after handling the event 
request. That mea
 ns that the rendering of the page happens in an entirely new request. 
Meanwhile, at the end of each request, Tapestry wipes out the value in each 
instance variable. So that means that target <em>was</em> a non-zero number 
during the component event request ... but by the time the new page render 
request comes up from the web browser to render the Guess page, the value of 
the target field has reverted back to its default, zero.</p><p>The solution 
here is to mark which fields have values that should persist from one request 
to the next (and next, and next ...). That's what the @<a shape="rect" 
class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/Persist.html";>Persist</a>
 annotation is for:</p><div class="code panel pdl" style="border-width: 
1px;"><div class="codeContent panelContent pdl">
+</div></div><p>The @<a shape="rect" class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/Property.html";>Property</a>
 annotation very simply directs Tapestry to write the getter and setter method 
for you. You only need to do this if you are going to reference the field from 
the template.</p><p>We are getting very close but there's one last big oddity 
to handle. Once you refresh the page you'll see that target is 0!</p><p><img 
class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-target-zero.png?version=3&amp;modificationDate=1416879255000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-target-zero.png?version=3&amp;modificationDate=1416879255000&amp;api=v2"></p><p>What
 gives? We know it was set to at least 1 ... where did the value go?</p><p>As 
noted above, Tapestry sends a redirect to the client after handling the event 
request. That means that the 
 rendering of the page happens in an entirely new request. Meanwhile, at the 
end of each request, Tapestry wipes out the value in each instance variable. So 
that means that target <em>was</em> a non-zero number during the component 
event request ... but by the time the new page render request comes up from the 
web browser to render the Guess page, the value of the target field has 
reverted back to its default, zero.</p><p>The solution here is to mark which 
fields have values that should persist from one request to the next (and next, 
and next ...). That's what the @<a shape="rect" class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/Persist.html";>Persist</a>
 annotation is for:</p><div class="code panel pdl" style="border-width: 
1px;"><div class="codeContent panelContent pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[    @Property  
     @Persist
     private int target;
 ]]></script>
-</div></div><p>This doesn't have anything to do with database persistence 
(that's coming up in a later chapter). It means that the value is stored in the 
HttpSession between requests.</p><p>Go back to the Index page and click the 
link again. Finally, we have a target number:</p><p><img 
class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-target.png?version=2&amp;modificationDate=1416711521000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-target.png?version=2&amp;modificationDate=1416711521000&amp;api=v2"></p><p>That's
 enough for us to get started. Let's build out the Guess page, and get ready to 
let the user make guesses. We'll show the count of guesses, and increment that 
count when they make them. We'll worry about high and low and actually 
selecting the correct value later.</p><p>When building Tapestry pages, you 
sometimes start with the Java code and build the template to match, a
 nd sometime start with the template and build the Java code to match. Both 
approaches are valid. Here, lets start with the markup in the template, then 
figure out what we need in the Java code to make it work.</p><div class="code 
panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Guess.tml (revised)</b></div><div 
class="codeContent panelContent pdl">
+</div></div><p>This doesn't have anything to do with database persistence 
(that's coming up in a later chapter). It means that the value is stored in the 
HttpSession between requests.</p><p>Go back to the Index page and click the 
link again. Finally, we have a target number:</p><p><img 
class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-target.png?version=3&amp;modificationDate=1416879254978&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-target.png?version=3&amp;modificationDate=1416879254978&amp;api=v2"></p><p>That's
 enough for us to get started. Let's build out the Guess page, and get ready to 
let the user make guesses. We'll show the count of guesses, and increment that 
count when they make them. We'll worry about high and low and actually 
selecting the correct value later.</p><p>When building Tapestry pages, you 
sometimes start with the Java code and build the template to match, and 
sometime 
 start with the template and build the Java code to match. Both approaches are 
valid. Here, lets start with the markup in the template, then figure out what 
we need in the Java code to make it work.</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Guess.tml (revised)</b></div><div 
class="codeContent panelContent pdl">
 <script class="theme: Default; brush: xml; gutter: false" 
type="syntaxhighlighter"><![CDATA[&lt;html t:type=&quot;layout&quot; 
title=&quot;Guess The Number&quot;
     xmlns:t=&quot;http://tapestry.apache.org/schema/tapestry_5_3.xsd&quot;
     xmlns:p=&quot;tapestry:parameter&quot;&gt;
@@ -252,7 +252,7 @@ public class Guess
 
 }
 ]]></script>
-</div></div><p>The revised version of Guess includes two new properties: 
<code>current</code> and <code>guessCount</code>. There's also a handler for 
the action event from the makeGuess ActionLink component; currently it just 
increments the count.</p><p>Notice that the 
<code>onActionFromMakeGuess()</code> method now has a parameter: the context 
value that was encoded into the URL by the ActionLink. When then user clicks 
the link, Tapestry will automatically extract the string from the URL, convert 
it to an int and pass that int value into the event handler method. More 
boilerplate code you don't have to write.</p><p>At this point, the page is 
partially operational:</p><p><img class="confluence-embedded-image" width="700" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-1.png?version=3&amp;modificationDate=1416877818995&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-1.png?version=3&amp;modificationDate=1416877818995&amp;api=v2"
 ></p><p>Our next step is to actually check the value provided by the user 
 >against the target and provide feedback: either they guessed too high, or too 
 >low, or just right. If they get it just right, we'll switch to the GameOver 
 >page.</p><p>For wrong guesses, we'll see an update such as:</p><p><img 
 >class="confluence-embedded-image" width="700" 
 >src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess_feedback.png?version=1&amp;modificationDate=1291918635000&amp;api=v2";
 > 
 >data-image-src="/confluence/download/attachments/23340505/guess_feedback.png?version=1&amp;modificationDate=1291918635000&amp;api=v2"></p><p>And
 > correct guesses will send us to the GameOver page:</p><p><img 
 >class="confluence-embedded-image" width="700" 
 >src="https://cwiki.apache.org/confluence/download/attachments/23340505/gameover.png?version=1&amp;modificationDate=1291918700000&amp;api=v2";
 > 
 >data-image-src="/confluence/download/attachments/23340505/gameover.png?version=1&amp;modificationDate=129191870
 0000&amp;api=v2"></p><p>Let's start with the Guess page; it now needs a new 
property to store the message to be displayed to the user, and needs a field 
for the injected GameOver page:</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>Guess.java (partial)</b></div><div 
class="codeContent panelContent pdl">
+</div></div><p>The revised version of Guess includes two new properties: 
<code>current</code> and <code>guessCount</code>. There's also a handler for 
the action event from the makeGuess ActionLink component; currently it just 
increments the count.</p><p>Notice that the 
<code>onActionFromMakeGuess()</code> method now has a parameter: the context 
value that was encoded into the URL by the ActionLink. When then user clicks 
the link, Tapestry will automatically extract the string from the URL, convert 
it to an int and pass that int value into the event handler method. More 
boilerplate code you don't have to write.</p><p>At this point, the page is 
partially operational:</p><p><img class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/guess-1.png?version=4&amp;modificationDate=1416879255000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/guess-1.png?version=4&amp;modificationDate=1416879255000&amp;api=v2"></p><p>Our
 
 next step is to actually check the value provided by the user against the 
target and provide feedback: either they guessed too high, or too low, or just 
right. If they get it just right, we'll switch to the GameOver page with a 
message such as "You guessed the number 5 in 2 guesses".</p><p>Let's start with 
the Guess page; it now needs a new property to store the message to be 
displayed to the user, and needs a field for the injected GameOver 
page:</p><div class="code panel pdl" style="border-width: 1px;"><div 
class="codeHeader panelHeader pdl" style="border-bottom-width: 
1px;"><b>Guess.java (partial)</b></div><div class="codeContent panelContent 
pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[    @Property
     @Persist(PersistenceConstants.FLASH)
     private String message;
@@ -286,7 +286,7 @@ public class Guess
         &lt;/p&gt;
     &lt;/t:if&gt;
 ]]></script>
-</div></div><p>This snippet uses Tapestry's <a shape="rect" 
class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/If.html";>If</a>
 component. The If component evaluates its <code>test</code> parameter and, if 
the value evaluates to true, renders its body. The property bound to 
<code>test</code> doesn't have to be a boolean; Tapestry treats 
<code>null</code> as false, it treats zero as false and non-zero as true, it 
treats an empty Collection as false ... and for Strings (such as 
<code>message</code>) it treats a blank string (one that is null, or consists 
only of whitespace) as false, and a non-blank string is true.</p><p>We can wrap 
up with the GameOver page:</p><div class="code panel pdl" style="border-width: 
1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 
1px;"><b>GameOver.java</b></div><div class="codeContent panelContent pdl">
+</div></div><p>This snippet uses Tapestry's <a shape="rect" 
class="external-link" 
href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/If.html";>If</a>
 component. The If component evaluates its <code>test</code> parameter and, if 
the value evaluates to true, renders its body. The property bound to 
<code>test</code> doesn't have to be a boolean; Tapestry treats 
<code>null</code> as false, it treats zero as false and non-zero as true, it 
treats an empty Collection as false ... and for Strings (such as 
<code>message</code>) it treats a blank string (one that is null, or consists 
only of white space) as false, and a non-blank string is true.</p><p>We can 
wrap up with the "GameOver" page:</p><div class="code panel pdl" 
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" 
style="border-bottom-width: 1px;"><b>GameOver.java</b></div><div 
class="codeContent panelContent pdl">
 <script class="theme: Default; brush: java; gutter: false" 
type="syntaxhighlighter"><![CDATA[package com.example.tutorial.pages;
 
 import org.apache.tapestry5.annotations.Persist;
@@ -297,7 +297,7 @@ public class GameOver
     @Property
     @Persist
     private int target, guessCount;
-
+       
     void setup(int target, int guessCount)
     {
         this.target = target;
@@ -320,7 +320,7 @@ public class GameOver
   
 &lt;/html&gt;
 ]]></script>
-</div></div><p>That wraps up the basics of Tapestry; we've demonstrated the 
basics of linking pages together and passing information from page to page in 
code as well as incorporating data inside URLs.</p><p>There's still more room 
to refactor this toy application; for example, making it possible to start a 
new game from the GameOver page (and doing it in a way that doesn't duplicate 
code). In addition, later we'll see other ways of sharing information between 
pages that are less cumbersome than the setup-and-persist approach shown 
here.</p><p>Next up, we'll start delving into how Tapestry handles HTML forms 
and user input.&#160;</p><style type="text/css">/*<![CDATA[*/
+</div></div><p>The result, when you guess correctly, should be 
this:</p><p><img class="confluence-embedded-image" 
src="https://cwiki.apache.org/confluence/download/attachments/23340505/gameover.png?version=4&amp;modificationDate=1416879255000&amp;api=v2";
 
data-image-src="/confluence/download/attachments/23340505/gameover.png?version=4&amp;modificationDate=1416879255000&amp;api=v2"></p><p>That
 wraps up the basics of Tapestry; we've demonstrated the basics of linking 
pages together and passing information from page to page in code as well as 
incorporating data inside URLs.</p><p>There's still more room to refactor this 
toy application; for example, making it possible to start a new game from the 
GameOver page (and doing it in a way that doesn't duplicate code). In addition, 
later we'll see other ways of sharing information between pages that are less 
cumbersome than the setup-and-persist approach shown here.</p><p>Next up, we'll 
start delving into how Tapestry handles HTML forms and us
 er input.&#160;</p><style type="text/css">/*<![CDATA[*/
 table.ScrollbarTable  {border: none;padding: 3px;width: 100%;padding: 
3px;margin: 0px;background-color: #f0f0f0}
 table.ScrollbarTable td.ScrollbarPrevIcon {text-align: center;width: 
16px;border: none;}
 table.ScrollbarTable td.ScrollbarPrevName {text-align: left;border: none;}

Reply via email to