Scsong at 23:10, 11 September 2008

2008-09-11T23:10:53Z

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==Creating a GWT Library==

In the ''GWT'' class, there is a ''GWT.log(String, Throwable)'' method but no ''GWT.log(String)'' method. Time to create a library of useful classes that other GWT applications can share!

===Create the library===

Create a new library project in <nowiki>NetBeans</nowiki> and add the GWT to the libraries under the project properties. In this example, the project will be called =gwt-util-5=.

Create the utility class:

<pre>
package edu.umiacs.gwt.util;

import com.google.gwt.core.client.GWT;

public class GWTUtil
{
public static void log(String message)
{
GWT.log(message, null);
}
}
</pre>

Create a ''ModuleName.gwt.xml'' and place it in the top-most source directory that does not contain code. In this example, the module will be called ''GWTUtil'' and it will be placed in the ''edu.umiacs.gwt'' directory. The file should contain:

<pre>
<?xml version="1.0" encoding="UTF-8"?>
<module>
<inherits name="com.google.gwt.user.User"/>
<source path="util"/>
</module>
</pre>

The source element specifies which directories contain translatable code and is relative to the location of the xml file. If not specified, it defaults to ''client''.

===Include the library===

In the hello world application, use the brand new method! Change:

<pre>
GWT.log("onModuleLoad()", null);
</pre>

to:

<pre>
edu.umiacs.gwt.util.GWTUtil.log("onModuleLoad")
</pre>

In the project properties of the hello-world project, add the gwt-util project to the libraries.

Include an inherit element in the module xml file of the hello-world project. The module xml file should now be:

<pre>
<module>
<inherits name="com.google.gwt.user.User"/>
<inherits name="edu.umiacs.gwt.GWTUtil"/>
<entry-point class="edu.umiacs.gwt.hello.client.HelloWorldApp"/>
<servlet class="edu.umiacs.gwt.hello.server.HelloWorldServiceImpl" path="/hello-service"/>
</module>
</pre>

The name is the java-ish path to the xml file, minus the ''.gwt.xml''.

Now include the gwt-util source and class directories to the ''run'' and ''-compile-to-javascript'' targets in the hello-world ''build.xml'' file:

<pre>
<target name="run" depends="init,compile">
<java classpath=
"${run.classpath}:${basedir}/build/classes:${basedir}/src:${project.gwt-util-5}/build/classes:${project.gwt-util-5}/src"
classname="com.google.gwt.dev.GWTShell"
fork="true">
<arg value="-out"/>
<arg path="${build.www.dir}/"/>
<arg value="edu.umiacs.gwt.hello.HelloWorld/HelloWorld.html"/>
</java>
</target>

<target name="-compile-to-javascript">
<echo message="Compiling Java to JavaScript"/>
<java classpath="${run.classpath}:${basedir}/src:${project.gwt-util-5}/src"
classname="com.google.gwt.dev.GWTCompiler"
fork="true">
<arg value="-out"/>
<arg path="${build.dir}/www/"/>
<arg value="${application.args}"/>
<arg value="edu.umiacs.gwt.hello.HelloWorld"/>
</java>
</target>
</pre>

For more information: [[media:gwt-tutorial-5.tar.gz|GWT Tutorial 5]]

Netbeans:NetbeansGWTLib - Revision history

Scsong at 23:10, 11 September 2008