ConcretePage.comStruts 2 Exception Handling with @ExceptionMapping Annotation
June 12, 2014
@ExceptionMappings({
@ExceptionMapping(exception = "java.lang.NullPointerException", result = "success",
params = {"param1", "val1"})
})
@ExceptionMappings : This is group of @ExceptionMapping
@ExceptionMapping : This defines the exception mapping
exception attribute: This is the attribute which declares the exception class.
result attribute: This plays the role to get result so that appropriate page could be redirected.
params attribute: The value defined by param is passed to result.
If we want to handle exception action wise, we can use annotation at method level as below.
@Action(value = "exception1", exceptionMappings = {
@ExceptionMapping(exception = "java.lang.NullPointerException", result = "success",
params = {"param1", "val1"})
})
Action Class for Exception Handling in Struts 2
Find the action class that is annotated with @ExceptionMappings at class level.UserAction.java
package com.concretepage.action;
import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.ExceptionMapping;
import org.apache.struts2.convention.annotation.ExceptionMappings;
import org.apache.struts2.convention.annotation.Namespace;
import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.convention.annotation.Results;
import com.opensymphony.xwork2.ActionSupport;
@Namespace("/user")
@Results({
@Result(name="success", location="/user/user.jsp"),
})
@ExceptionMappings({
@ExceptionMapping(exception = "java.lang.NullPointerException", result = "success")
})
public class UserAction extends ActionSupport{
@Action("/demo")
public String demo() {
throw new NullPointerException("Exception Occured.");
}
}
JSP page: Use of exception and exceptionStack
Find the jsp which displays the result.user.jsp
<%@ taglib prefix="s" uri="/struts-tags" %> <html> <head><title>Struts 2 Annotation Example</title> </head> <body> <h1>Struts 2 Annotation Example</h1> <s:property value="exception"/> <!--s:property value="exceptionStack"/--> </body> </html>
exception : displays short description of error.
exceptionStack : displays the stack trace of error.
web.xml Configuration for Struts 2
Find the web.xml.web.xml
<web-app>
<display-name>Struts 2 Annotation Example</display-name>
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
<init-param>
<param-name>actionPackages</param-name>
<param-value>com.concretepage.action</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
pom.xml for Struts 2
Find the maven dependencies to run the struts application.<dependencies> <dependency> <groupId>org.apache.struts</groupId> <artifactId>struts2-core</artifactId> <version>2.3.16</version> </dependency> <dependency> <groupId>org.apache.struts</groupId> <artifactId>struts2-convention-plugin</artifactId> <version>2.3.8</version> </dependency> </dependencies>
Eclipse Configuration of files for Exception Handling in Struts 2
Find the screen shot of eclipse configuration.
Exception Handling Demo Output
To run the application use the URL http://localhost:8080/Struts2Demo-1/user/demo and output will look like as below.
