[Optional] Spring Framework Lab

Review all the necessary steps required to create a simple web application with the Spring Framework 5.

Time: 25 minutes.

Requirements:

Java 1.8 (recommended)
Maven 3.x installed.
Tomcat 8.5.x installed.

Simple Spring Web Application with Thymeleaf

To create a simple Spring Web application, open a terminal window and execute the following statement:
```
mvn archetype:generate -DgroupId=io.pivotal.workshop -DartifactId=simple-spring-webapp -Dversion=1.0-SNAPSHOT -DinteractiveMode=false -DarchetypeArtifactId=maven-archetype-webapp
```
If you have a Maven version below 3.x, you need to use the command mvn archetype:create instead.
Create the missing Java EE structure (ex: src/main/java, src/main/webapp/WEB-INF, etc.)

Create the web controller SimpleController class in src/main/java/io/pivotal/workshop/web folder.

io.pivotal.workshop.web.SimpleController.java

package io.pivotal.workshop.web;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class SimpleController{

        Logger log = LoggerFactory.getLogger(SimpleController.class);

        @RequestMapping("/")
        public ModelAndView index(){
                log.debug("About to redirect...");
                return new ModelAndView("redirect:/showMessage");
        }

        @RequestMapping(value="/showMessage",method = RequestMethod.GET)
        public ModelAndView helloWorld(){
                final String message = "Simple Spring MVC Web App with Thymeleaf and Spring 5";
                 log.debug("Showing the Message: " + message);
                ModelAndView model = new ModelAndView("showMessage");
                model.addObject("message", message);
                return model;
        }
}

Modify the src/main/webapp/WEB-INF/web.xml file.

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Simple Spring Web Application</display-name>

  <servlet>
      <servlet-name>dispatcherServlet</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
      <servlet-name>dispatcherServlet</servlet-name>
      <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>

Create the src/main/webapp/WEB-INF/dispatcherServlet-servlet.xml file.

dispatcherServlet-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
                http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

        <!--
        DispatcherServlet creates its own WebApplicationContext and the handlers/controllers/view-resolvers are managed
        by this context.
        -->

         <context:component-scan base-package="io.pivotal.workshop.web" />

        <!-- Useful when only JSP is required. The javax.servlet.jsp:avax.servlet.jsp-api:2.3.1 dendency is necessary-->
        <!--
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                <property name="prefix" value="/WEB-INF/view/"/>
                <property name="suffix" value=".jsp"/>
        </bean>
        -->

        <!-- Thymeleaf Configuration -->
        <bean id="templateResolver" class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
                <property name="prefix" value="/WEB-INF/view/" />
                <property name="suffix" value=".html" />
                <property name="templateMode" value="HTML5" />
        </bean>

        <bean id="templateEngine" class="org.thymeleaf.spring5.SpringTemplateEngine">
                <property name="templateResolver" ref="templateResolver" />
                <property name="enableSpringELCompiler" value="true" />
        </bean>

        <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
                <property name="templateEngine" ref="templateEngine" />
</bean>

</beans>

Modify the src/main/webapp/index.html file and move it to the src/main/webapp/WEB-INF/view directory.

index.html

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">
        <head>
                <meta charset="utf-8">
                <title>Welcome</title>
        </head>
        <body>
                <p>This page never will show up</p>
        </body>
</html>

This page will never show up, because the handler will do a redirect to the showMessage.html.

Create the src/main/webapp/WEB-INF/view/showMessage.html file.

showMessage.jsp

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">
        <head>
                <meta charset="utf-8">
                <title>Welcome</title>
        </head>
        <body style="font-family: Verdana, sans-serif;">
        <h2><p th:text="${message}"/></h2>
        </body>
</html>

Create the logging configuration. Create a logback.xml file in the src/main/resources directory.

logback.xml

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="io.pivotal.workshop" level="DEBUG"/>
        <logger name="org.thymeleaf" level="OFF"/>

    <root level="INFO">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

Modify the pom.xml file. Add the necessary dependencies. See all the Spring 5 dependencies.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <groupId>io.pivotal.workshop</groupId>
        <artifactId>simple-spring-webapp</artifactId>
        <packaging>war</packaging>
        <version>1.0-SNAPSHOT</version>
        <name>simple-spring-webapp Maven Webapp</name>
        <url>http://maven.apache.org</url>
        <parent>
                <groupId>io.pivotal.education.boot</groupId>
                <artifactId>parentProject</artifactId>
                <version>1.0.a.RELEASE</version>
                <relativePath>../../</relativePath>
        </parent>
        <properties>

                <!-- Generic properties -->
                <java.version>1.8</java.version>

                <!-- Web -->
                <servlet.version>3.1.0</servlet.version>

                <!-- Spring -->
                <spring-framework.version>5.0.1.RELEASE</spring-framework.version>

                <!-- Thymeleaf -->
                <thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>

                <!--  Logging -->
                <slf4j.version>1.7.25</slf4j.version>
                <logback.version>1.2.3</logback.version>
        </properties>

        <dependencies>

                <!-- Spring MVC -->
                <dependency>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-context</artifactId>
                        <version>${spring-framework.version}</version>
                </dependency>
                <dependency>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-aop</artifactId>
                        <version>${spring-framework.version}</version>
                </dependency>
                <dependency>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-webmvc</artifactId>
                        <version>${spring-framework.version}</version>
                </dependency>
                <dependency>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-web</artifactId>
                        <version>${spring-framework.version}</version>
                </dependency>

                <dependency>
                        <groupId>org.thymeleaf</groupId>
                        <artifactId>thymeleaf</artifactId>
                        <version>${thymeleaf.version}</version>
                </dependency>
                <dependency>
                        <groupId>org.thymeleaf</groupId>
                        <artifactId>thymeleaf-spring5</artifactId>
                        <version>${thymeleaf.version}</version>
                </dependency>


                <dependency>
                        <groupId>org.slf4j</groupId>
                        <artifactId>slf4j-api</artifactId>
                        <version>${slf4j.version}</version>
                </dependency>
                <dependency>
                        <groupId>ch.qos.logback</groupId>
                        <artifactId>logback-classic</artifactId>
                        <version>${logback.version}</version>
                </dependency>

                <!-- Other Web dependencies -->
                <dependency>
                        <groupId>javax.servlet</groupId>
                        <artifactId>javax.servlet-api</artifactId>
                        <version>${servlet.version}</version>
                        <scope>provided</scope>
                </dependency>
        </dependencies>

        <build>
                <finalName>simple-spring-webapp</finalName>
        </build>
</project>

Building the Spring Web Application

To build the Spring Web application, execute the following command:

mvn clean compile package

the above command will generate the target/simple-spring-webapp.war.

Deploying the Spring Web Application

To deploy the application, install any application container that supports the Java Servlets specification.

For example, to deploy to Apache Tomcat, copy the target/simple-spring-webapp.war file into the $TOMCAT-INSTALLATION/webapps/ directory and start the container. Then, go to your browser and hit the http://localhost:8080/simple-spring-webapp/ URL.

You should see the text: Simple Spring MVC Web App with Thymeleaf and Spring 5.