I want to do a project using Vaadin and am facing some issues. Here's what I did.
I downloaded Eclipse and installed the Vaadin for Eclipse plugin. Then, I created a new Vaadin 7 project. It downloaded some Ivy dependencies but then, when I pressed Run, I get this error: java.lang.NoClassDefFoundError:com/vaadin/server/VaadinServlet.
I searched a bit on the Internet but to no avail. One thing is that in the web-app's WEB-INF/lib folder, there are no jars. I have attached a screenshot of the error and also web.xml and ivy.xml.
ivy.xml:
<?xml version="1.0"?>
<!DOCTYPE ivy-module [
<!ENTITY vaadin.version "7.1.7">
]>
<ivy-module version="2.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ant.apache.org/ivy/schemas/ivy.xsd">
<info organisation="com.example" module="v7proj" />
<configurations>
<!-- The default configuration, which should be deployed to the server -->
<conf name="default" />
<!-- A configuration only needed when compiling the widget set. Should
not be deployed to the server -->
<conf name="widgetset-compile" />
<!-- A configuration used in compilation of server side classes only.
Should be deployed to the server -->
<conf name="nodeploy" />
</configurations>
<dependencies defaultconf="default" defaultconfmapping="default->default">
<!-- The core server part of Vaadin -->
<dependency org="com.vaadin" name="vaadin-server" rev="&vaadin.version;" />
<!-- Vaadin themes -->
<dependency org="com.vaadin" name="vaadin-themes" rev="&vaadin.version;" />
<!-- Push support -->
<dependency org="com.vaadin" name="vaadin-push" rev="&vaadin.version;" />
<!-- Servlet 3.0 API -->
<dependency org="javax.servlet" name="javax.servlet-api" rev="3.0.1" conf="nodeploy->default" />
<!-- Precompiled DefaultWidgetSet -->
<dependency org="com.vaadin" name="vaadin-client-compiled"
rev="&vaadin.version;" />
<!-- Vaadin client side, needed for widget set compilation -->
<dependency org="com.vaadin" name="vaadin-client" rev="&vaadin.version;"
conf="widgetset-compile->default" />
<!-- Compiler for custom widget sets. Should not be deployed -->
<dependency org="com.vaadin" name="vaadin-client-compiler"
rev="&vaadin.version;" conf="widgetset-compile->default" />
</dependencies>
</ivy-module>
ivysettings.xml:
<?xml version="1.0" encoding="UTF-8"?>
<ivysettings>
<settings defaultResolver="default" />
<resolvers>
<chain name="default">
<!-- Public Maven repository -->
<ibiblio name="public" m2compatible="true" />
<!-- Vaadin Add-on repository -->
<ibiblio name="vaadin-addons" usepoms="true" m2compatible="true"
root="http://maven.vaadin.com/vaadin-addons" />
<!-- Vaadin snapshots repository -->
<ibiblio name="vaadin-snapshots" usepoms="true" m2compatible="true"
root="https://oss.sonatype.org/content/repositories/vaadin-snapshots" />
<!-- Repository used for Vaadin modified smartsprites library -->
<dual name="custom-smartsprites">
<filesystem name="smartsprites-ivy">
<ivy pattern="${basedir}/ivymodule/[module]-ivy-[revision].xml" />
</filesystem>
<url name="smartsprites-artifact">
<artifact
pattern="http://dev.vaadin.com/svn/versions/6.8/build/smartsprites/lib/[artifact](-[revision]).[ext]" />
</url>
</dual>
</chain>
</resolvers>
<modules>
<!-- Vaadin patched SmartSprites -->
<module organisation="com.carrotsearch" name="smartsprites"
revision="0.2.3-itmill" resolver="custom-smartsprites" />
</modules>
</ivysettings>
web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>ScanAir</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>
Please help. I am basically stuck without even starting to code. I am on Windows 8.1 Pro x64 with Java 7u45, Eclipse Kepler SR1 and Vaadin 7.1.7
On stackoverflow there are many questions and more answers about this error exception.
Have a look at this good webpage: http://javareferencegv.blogspot.ch/2013/10/debugging-javalangnoclassdeffounderror.html
One thing is that in the web-app's WEB-INF/lib folder, there are no jars.
This is a good point to start.
In eclipse have a look at your project properties. There is a point called "Deployment Assembly" which should contain at least these two entries:
/src -> WEB-INF/classes
/WebContent -> /
Moreover you must add your project to the tomcat server instance.
https://vaadin.com/forum/message/2534863
What you can do is
1) Right-Click the project and Select properties 2) Select Deployment Assembly 3) Click Add 4) Choose the Java Build Path Entries 5) Adde the ivy library.
来源：https://stackoverflow.com/questions/19626808/getting-a-noclassdeffounderror-after-installing-vaadin