package com.ebc.servlet;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet(name = "appServlet", urlPatterns = "/app/*")

public class MyAppServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        String requestURI = req.getRequestURI();

        if (requestURI.endsWith("test")) {

            throw new RuntimeException("test exception from " + requestURI);

        } else if (requestURI.endsWith("test2")) {

            throw new ServletException("test servlet exception");

        } else {

            resp.getWriter().println("Response from appServlet at " + requestURI);

        }

    }

}

package com.ebc.servlet;

import org.springframework.boot.web.server.ErrorPage;

import org.springframework.boot.web.server.ErrorPageRegistrar;

import org.springframework.boot.web.server.ErrorPageRegistry;

import org.springframework.http.HttpStatus;

import org.springframework.stereotype.Component;

@Component

public class MyErrorPageRegistrar implements ErrorPageRegistrar {

    @Override

    public void registerErrorPages(ErrorPageRegistry registry) {

        registry.addErrorPages(

                createNotFoundErrorPage(),

                createRuntimeExceptionPage(),

                createOtherErrorPage());

    }

    private ErrorPage createNotFoundErrorPage() {

        return new ErrorPage(HttpStatus.NOT_FOUND, "/notFoundServlet");

    }

    private ErrorPage createRuntimeExceptionPage() {

        return new ErrorPage(RuntimeException.class, "/runtimeExceptionHandler");

    }

    private ErrorPage createOtherErrorPage() {

        return new ErrorPage(Throwable.class, "/WEB-INF/internal-error.jsp");

    }

}

package com.ebc.servlet;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

@WebServlet(name = "not-found-error-servlet", urlPatterns = "/notFoundServlet")

public class NotFoundServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        resp.setContentType("text/html");

        PrintWriter writer = resp.getWriter();

        writer.write("<h2>Page not found </h2>");

        String requestUri = (String) req.getAttribute("javax.servlet.error.request_uri");

        writer.write("request uri: " + requestUri);

        writer.write("<br>Response from " + this.getClass());

    }

}

package com.ebc.servlet;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

@WebServlet(name = "runtime-handler-servlet", urlPatterns = "/runtimeExceptionHandler")

public class RuntimeExceptionServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        resp.setContentType("text/html");

        PrintWriter writer = resp.getWriter();

        writer.write("<h2>RuntimeException</h2>");

        String requestUri = (String) req.getAttribute(RequestDispatcher.ERROR_REQUEST_URI);

        writer.write("request uri: " + requestUri);

        Integer code = (Integer) req.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);

        writer.write("<br>status code: " + code);

        String errorMessage = (String) req.getAttribute(RequestDispatcher.ERROR_MESSAGE);

        writer.write("<br>error message: " + errorMessage);

        writer.write("<br>Response from "+this.getClass());

    }

}

package com.ebc;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication

@ServletComponentScan

public class MyApplication {

    public static void main(String[] args) {

        SpringApplication.run(MyApplication.class, args);

    }

}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

<h3>Error on server side</h3>

<p>

    <%= request.getAttribute("javax.servlet.error.exception") %>

</p>

<p>From jsp page.</p>

</body>

</html>

<dependencies>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-web</artifactId>

    </dependency>

    <dependency>

        <groupId>org.projectlombok</groupId>

        <artifactId>lombok</artifactId>

        <optional>true</optional>

    </dependency>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-tomcat</artifactId>

        <scope>provided</scope>

    </dependency>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-test</artifactId>

        <scope>test</scope>

    </dependency>

    <dependency>

        <groupId>org.apache.tomcat.embed</groupId>

        <artifactId>tomcat-embed-jasper</artifactId>

        <scope>provided</scope>

    </dependency>

    <dependency>

        <groupId>javax.servlet</groupId>

        <artifactId>jstl</artifactId>

    </dependency>

</dependencies>