Grails Error Handling With Custom Http Status Code

First need to create a trait Groovy file as follows under src/groovy:

trait CustomExceptionHandler {
    /* Handle common exception */
    def handleException(Exception e) {
        handleCustomException(new CustomException(e.getMessage()))
    }

    /* Handle defined custom exception */
    def handleCustomException2(CustomException2 e) {
        handleCustomException(e)
    }

    /* Handle defined custom exception */
    def handleCustomException(CustomException e) {
        if (!CommonUtils.request) {
            // do something
        }
        else {
            CommonUtils.currentResponse.status = 220 (Custom response code)
            if(e.getStatusCode()) {
                CommonUtils.currentResponse.status = e.getStatusCode()
            }
            if (CommonUtils.request.xhr) {
                def error = [
                        type: "error",
                        message: e.getMessage()
                ]
                render error as JSON
            }
            else {
                render(view: "/error/error", model: [exception: e])
            }
        }
    }
}

Create a groovy class under src/groovy:

import org.springframework.web.context.request.RequestContextHolder
class CommonUtils {
    public static def getRequest() {
        def request = RequestContextHolder.getRequestAttributes()
        return request ? request.request : null
    }

    public static HttpServletResponse getCurrentResponse() {
        return WebUtils.retrieveGrailsWebRequest().getCurrentResponse()
    }
}

Exception Types (Reside in src/groovy):

class CustomException extends RuntimeException {

}
class CustomException2 extends CustomException {

}

How controller can use this feature:

class Controller1 implements CustomExceptionHandler {
    def index() {
        throw new Exception("Common exception")
    }

    def index2() {
        throw new CustomException("Defined custom exception")
    }

    def index3() {
        someService.index3()
    }

    def index4() {
        someService.index4()
    }
}

Exception thrown from service bahave same as from controller

class SomeService {
    def index3() {
        throw new Exception("Common exception")
    }

    def index4() {
        throw new CustomException("Defined custom exception")
    }
}

Spring MVC - Custom Exception Handling & Send Appropriate Error Code

Download full source code

Create a custom exception handler class as follows:

package com.pkm.maven.exception;

public class SpringException extends RuntimeException {
    private String exceptionMsg;
    
    public SpringException(String exceptionMsg) {
        this.exceptionMsg = exceptionMsg;
    }
    
    public String getExceptionMsg() {
        return this.exceptionMsg;
    }
    
    public void setExceptionMsg(String exceptionMsg) {
        this.exceptionMsg = exceptionMsg;
    }
}

Add following lines of code to your XXX-servlet.xml under WEB-INF

<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    <property name="exceptionMappings">
        <props>
            <prop key="com.pkm.maven.exception.SpringException">ExceptionPage</prop>
        </props>
    </property>
    <property name="defaultErrorView" value="error"/>
</bean>

Create a jsp page named 'ExceptionPage.jsp' defined in previous XXX-servlet.xml file under WEB-INF folder.

<h3 class="error">${exception.exceptionMsg}</h3>

Also create a file named 'error.jsp' under WEB-INF/jsp/ folder

<h3>General Error Page</h3>

Now time to throw custom exception

From method1 & method2 i am throwing my custom error so rendering my custom error page 'ErrorPage.jsp' & in method4, I am not throwing any exception but when invoking the line 'nullString.length()', it automatically throwing general exception, so rendering 'error.jsp' as defined in XXX-servlet.xml.

package com.pkm.maven.controller;

import com.pkm.maven.exception.SpringException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;

/**
 * Controller action would be like this
 * public (ModelAndView | Map | String | void) actionName(HttpServletRequest, HttpServletResponse [,HttpSession] [,CommandObject]);
 * @author Pritom K Mondal
 */

public class CustomerController extends MultiActionController {    
    public ModelAndView method1(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        response.setStatus( HttpServletResponse.SC_BAD_REQUEST  );
        throw new SpringException("Error from customer controller and method1() action.");
        //return new ModelAndView("CustomerPage", "msg", "method1() method"); 
    }
 
    public ModelAndView method2(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        response.setStatus( HttpServletResponse.SC_BAD_REQUEST  );
        throw new Exception("Error from customer controller and method2() action.");
        //return new ModelAndView("CustomerPage", "msg", "method2() method"); 
    }
 
    public ModelAndView method3(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        return new ModelAndView("CustomerPage", "msg", "method3() method"); 
    }
 
    public ModelAndView method4(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        String nullString = null;
        Integer length = nullString.length();
        return new ModelAndView("CustomerPage", "msg", "method4() method"); 
    }
}

Output would be like this in browser if you browse 'customer/method1' or 'customer/method2':

Output would be like this in browser if you browse 'customer/method4':