Základy GWT

Google Web Toolkit

Wednesday, March 17, 2010

Google Web Toolkit
GWT


Úvod


Úvod
• GWT je javascriptový framework


Úvod
• Vývoj v JAVE (kompilátor preloží do JS)


Úvod
• silné IDE - refaktor, code completion


Úvod
• unit testovanie, moznosť TDD


Úvod
• unit testovanie, moznosť TDD
• integrácia s backendami (Spring,
Hibernate, JSF a ďalšie)


Úvod

• debug kódu v prehliadači


Úvod

• kompatibilita


Úvod

• kompatibilita
• IE 6+, FF 1.x+, Opera 8.5+, Safari 2.0.x


Hello world!
public class HelloApp implements EntryPoint {
public void onModuleLoad() {
Button b = new Button("Click me", new ClickListener() {
public void onClick(Widget sender) {
Window.alert("Hello world!");
}
}
RootPanel.get().add(b);
}
}


Widgets

Panels

Project Layout
• module base

• .client - kód ktorý sa
kompiluje do JS

• .server - java kód ktorý
nebude kompilovaný do
JS (ale bude pristupný
iba na serveri)

• .public - resources


Module
• XML súbor MyApp.gwt.xml
• source
• super source
• deferred binding
• inherited modules
• entry point

Module XML
<module>
<inherits name="com.google.gwt.user.User" />
<inherits name="com.google.gwt.user.theme.standard.Standard" />

<entry-point class="com.your.application.client.HelloApp" />

<script src=”someScript_inside_PublicFolder.js” />
<stylesheet src=”publicFolderRelativeURL_OR_HttpFullPath.css”/>

<source path=”shared” />
<super-source path=”jre” />
<module>


Module - source
• <source src=”client” />
• com.app.Module.gwt.xml
• com.app.client.* - kód ktorý sa bude
kompilovať
• com.app.other* alebo com.other.*- na
tento kód gwt neuvidí a nebude sa
kompilovať do JS


Module - super-source

• <super-source src=”jre” />
• com.app.Module.gwt.xml
• com.app.jre.java.util.UUID.java -
kompilátor to uvidí ako
java.util.UUID.java


Module - deferred

<replace-with class="com.google.gwt.user.client.ui.impl.PopupImpl">
<when-type-is class="com.google.gwt.user.client.ui.impl.PopupImpl"/>
</replace-with>


<replace-with class="com.google.gwt.user.client.ui.impl.PopupImplMozilla">
<when-type-is class="com.google.gwt.user.client.ui.impl.PopupImpl" />
<any>
<when-property-is name="user.agent" value="gecko"/>
<when-property-is name="user.agent" value="gecko1_8" />
</any>
</replace-with>

Module - deferred
PopupImpl impl = GWT.create(PopupImpl.class);
impl.callSomeMethod();
}
}


Index.html
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=UTF-8">
<title>Web Application Starter Project</title>

<script type="text/javascript" language="javascript"
src="com.your.application.client.HelloApp.nocache.js"></script>
</head>
<body>
<h1>GWT content</h1>
<div id=”gwt-main-container”></div>
<div id=”gwt-sub-container”></div>
</body>
</html>


Hello world!
Button b = new Button("Click me", new ClickListener() {
public void onClick(Widget sender) {
Window.alert("Hello world!");
}
}
RootPanel.get(“gwt-main-container”).add(b);
}
}


Index.html
<body>
<h1>GWT content</h1>
<div id=”gwt-main-container”>
<button
type=”button”
tabindex=”0”
class=”gwt-Button”>Click me</button>
</div>
<div id=”gwt-sub-container”></di
</body>


Debug


Request Response


AJAX

• AJAX (Asynchronous JavaScript and XML) mení obsah
stránky bez nutnosti znovunačítania

• RIA (desktop-like Rich Internet Application) aka WEB 2.0


AJAX v podani GWT


AJAX v podani GWT
/ some code ﬂow
/

/ GWT.create(YourService.class);
/
YourService.Util.getInstance().method(param, new AsyncCallback() {
public void onFailure(Throwable e) {
Window.alertError(“error occured”);
}

public void onSuccess(Object result) {
/ and more logic continues
/
/ process the result
/
}
});


Client Bundles

• obrázky - multi-obrázok (jeden request)
• minimalizuje chyby medzi ﬁlename-om a
konštantou

• rozširiteľný design pre nové resource typy


Client Bundles
<inherits name="com.google.gwt.resources.Resources" />

public interface MyResources extends ClientBundle {
public static final MyResources INSTANCE = GWT.create
(MyResources.class);

@Source("my.css")
public CssResource css();

@Source("config.xml")
public TextResource initialConfiguration();

@Source("manual.pdf")
public DataResource ownersManual();


Client Bundles
/ Inject the contents of the CSS ﬁle
/
MyResources.INSTANCE.css().ensureInjected();

/ Display the manual ﬁle in an iframe
/
new Frame(MyResources.INSTANCE.ownersManual().getURL());


Client Bundles
@Source("logo.png")
ImageResource logo();

@Source("arrow.png")
@ImageOptions(ﬂipRtl = true)
ImageResource pointer();

@Source("a.txt")
TextResource synchronous();

@Source("b.txt")
ExternalTextResource asynchronous();


Client Bundles
/ Using a TextResource
/
myTextArea.setInnerText(Resources.INSTANCE.synchronous().getText());

/ Using an ExternalTextResource
/
Resources.INSTANCE.asynchronous().getText(new
ResourceCallback<TextResource>() {
public void onError(ResourceException e) { ... }
public void onSuccess(TextResource r) {
myTextArea.setInnerText(r.getText());
}
});


Vlastne komponenty

• extends Widget
• setElement()
• extends Composite
• initWidget()
• extends Button, Panel, ....


JSNI

• JavaScript Native Interface
• ľahko kombinovateľný JavaScript kód do
GWT
• volanie metód z GWT v JS
• volanie metód z JS v GWT


JSNI Syntax

• /*-{ JavaScript code here }-*/;
• native void nativeJsCall()/*-{alert(“JS”);}-*/;
• $wnd - pointer na window (ale preco?)


JSNI - JS call do GWT

• [instance-expr.]@class-name::method-name
(param-signature)(arguments)

• [instance-expr.]@class-name::ﬁeld-name


[instance-expr.]@class-name::method-name(param-signature)(arguments)
/ method calls
/
this.@com.example.client.MyClass::setStringValue(Ljava/lang/String;)(s);

x.@com.example.client.MyClass::setStringValue(Ljava/lang/String;)(s);

@com.example.client.MyClass::setStaticValue(Ljava/lang/String;)(s);

/ ﬁelds
/
var val = this.@com.example.client.MyClass::valueStringFiled

x.@com.example.client.MyClass::valueStringField = val + " and stuff";


Type Signature Java Type long f (int n, String s, int[] arr);
Z boolean =
B byte (ILjava/lang/String;[I)J
C char
S short
I int
J long
F ﬂoat
D double
L class ; class
[ type type[]


JavaScript overlay types

• JS objekt ako Java objekt
• protected konštruktor - bez arg
• mžnosť písť natívne aj nenatívne metódy
• nesmie obsahovať ﬁeldy


var jsonData = [
{ "FirstName" : "Jimmy", "LastName" : "Webber" },
{ "FirstName" : "Alan", "LastName" : "Dayal" },
{ "FirstName" : "Keanu", "LastName" : "Spoon" },
{ "FirstName" : "Emily", "LastName" : "Rudnick" }
];


class Customer extends JavaScriptObject {
/ Overlay types always have protected, zero-arg ctors
/
protected Customer() { }

/ Typically, methods on overlay types are JSNI
/
public final native String getFirstName() /*-{return this.FirstName; }-*/;
public final native String getLastName() /*-{return this.LastName; }-*/;

/ Note, though, that methods aren't required to be JSNI
/
public final String getFullName() {
return getFirstName() + " " + getLastName();
}
}


class MyModuleEntryPoint implements EntryPoint {
JsArray<Customer> cs = getCustomers();
for (int i = 0, n = cs.length(); i < n; ++i) {
Window.alert("Hello, " + cs.get(i).getFullName());
}
}

/ Return the whole JSON array, as is
/
private ﬁnal native JsArray<Customer> getCustomers() /*-{
return $wnd.jsonData;
}-*/;
}


Dovidenia

Základy GWT

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