Struts 2 + GWT
Struts 2 + GWT
Struts GWT Plugin is the recommended way to integrate Struts 2 and GWT.Use this tutorial if you cannot change your actions, or you just don't like the way (GWT way) that you have to implement them to be used with the plugin.
These tutorial will demonstrate how to call an Struts 2 action, using GWT to submit a form and use the returned data.
Write your action.
Example action:
"Hello.java"
{
?? "firstName" : "John",
?? "lastName"? : "Galt"
}
The "Main" action points to the "Main.jsp" page which is the page that uses GWT. The path of the result is "org.apache.struts.gwt.Main/Main.jsp". That means that the files generated by GWT must go under a folder named "org.apache.struts.gwt.Main" under the root of your application. See "Deployment structure" for more details.
Write "Main.jsp" page.
This is the page that is generated by GWT's "applicationCreator". It has been renamed to .jsp because we have modified it to be a jsp page, instead of a plain html page.
Main.jsp ?
??
We set head's tag attribute "theme" to ajax to use Dojo, don't panic, you won't have to use it directly. Note that we have changed a few things from the original html page generated by GWT, we set "content" to "org.apache.struts.gwt.Main/org.apache.struts.gwt.Main" because the GWT generated files will be under "AppRoot/org.apache.struts.gwt.Main" instead of beneath root, and we set "src" to "${pageContext.request.contextPath}/org.apache.struts.gwt.Main/gwt.js" for the same reason. Without these two changes the GWT files wouldn't be loaded.
Struts2GWTHelper
This class will take care of making the request. Why? Why do I need this class? Couple of reasons, first, there is a bug on bug on HTTPRequest.asyncPost which doesn't encode the payload properly, second, if you want to submit a form, you have to encode it yourself, and this class will help you do that. Optionally you can download a jar containing this class (with more methods) from here , add this to your GWT application file (i.e Main.gwt.xml):
<inherits name='struts2gwt.Struts2GWT'/>
and add the jar to the classpath in your compile script (i.e Main-compile.cmd) and the compile script (i.e Main-shell.cmd).
Struts2GWTHelper .java
?
?
The makeRequest() method will make a request to the "Hello" action that we created before, and will pass the fields of the form "form1" as parameters. Which will be populated on the action, and serialized back as JSON. Using JSONParser the JSON string is parsed into a JSON object. It is definitely not type safe as GWT Remoting, but it works.
Create Main.gwt.xml
Nothing new on this file, just as reference:
Main.gwt.xml
?
<module> <!-- Inherit the core Web Toolkit stuff. --> <inherits name='com.google.gwt.user.User'/> <inherits name='com.google.gwt.json.JSON'/> <!-- Specify the app entry point class. --> <entry-point class='org.apache.struts.gwt.client.Main'/> </module>
?Deployment structure
Folder????????????????????????????????????????????????????????????? Notes
AppRoot????????????????????????????????????????????????????????? The application deployment folder
AppRoot/index.html???????????????????????????????????????? Welcome Page
AppRoot/org.apache.struts.gwt.Main????????????? Content generated by GWT?????????????????????????????????????? ????????????????????????????????????????????????????????????????????? ? (usually it?gets?generated into a folder named 'www')
AppRoot/WEB-INF??????????????????????????????????????????? Regular webapp files and classes