Spring 4 + Embedded Tomcat 7

I try to build a web app using Spring Web MVC 4.3.2 and embedded Tomcat 7.0.64.

I did not manage to write the correct main method to start embedded Tomcat. It works for Spring Controller sending @ResponseBody content (JSON) but failed for JSP views.

public static void main(String[] args) throws Exception {

    String appBase = ".";// What to put here ?

    Tomcat tomcat = new Tomcat();
    String contextPath = "";
    String port = System.getProperty("server.port");
    tomcat.setPort(port == null ? 8080 : Integer.valueOf(port));

    tomcat.getHost().setAppBase(appBase);
    Context context = tomcat.addWebapp(contextPath, appBase);

    // So that it works when in it's launched from IntelliJ or Eclipse
    // Also need that a folder named "META-INF" exists in build/classes/main
    // https://bz.apache.org/bugzilla/show_bug.cgi?id=52853#c19
    ((StandardJarScanner) context.getJarScanner()).setScanAllDirectories(true);

    tomcat.start();
    tomcat.getServer().await();
}

For JSP view it says : The requested resource is not available (WEB-INF/views/home.jsp) HTTP 404

If I set the appBase variable to the absolute path where the JSPs are, it works. But, of course, it is not a solution as it would not work on another machine. I need a relative path.

If I set appBase varibale to "src/main/webapp", then Tomcat fails to start with the following error : java.lang.IllegalArgumentException: Document base C:\blabla\spring-jsp-embedded-tomcat\tomcat.8080\src\main\webapp\src\main\webapp does not exist or is not a readable directory.

Morevover, the jar that is built with Gradle fat jar technique does not contain the WEB-INF dir.

How can I do to make a simple Spring MVC app working with an embedded Tomcat and JSPs (to be launched with java -cp path/to/my/jar com.app.Launcher) ?

build.gradle :

apply plugin: 'java'

sourceCompatibility = 1.7
version = '1.0'

jar {
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
}

repositories {
    maven { url "http://repo1.maven.org/maven2" }
}

dependencies {

    compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.6.2'
    compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.6.2'
    compile group: 'org.apache.logging.log4j', name: 'log4j-slf4j-impl', version: '2.6.2'

    compile 'org.springframework:spring-webmvc:4.3.2.RELEASE'

    compile 'com.fasterxml.jackson.core:jackson-databind:2.7.0'

    compile 'javax.servlet:javax.servlet-api:3.0.1'
    compile 'javax.servlet.jsp:jsp-api:2.2'
    compile 'javax.servlet:jstl:1.2'

    // Embedded Tomcat
    // 2 mandatory libs
    compile 'org.apache.tomcat.embed:tomcat-embed-core:7.0.64'
    compile 'org.apache.tomcat.embed:tomcat-embed-logging-juli:7.0.64'
    // To enable JSPs
    compile 'org.apache.tomcat.embed:tomcat-embed-jasper:7.0.64'

    testCompile group: 'junit', name: 'junit', version: '4.+'

}

Tomcat launcher :

public class Launcher {

    public static void main(String[] args) throws Exception {
        String contextPath = "";
        // String appBase = "C:/absolute/path/to/webapp/dir"; // It works but of course I need a relative path
        // String appBase = "."; // Works only for Controller sending back ResponseBody (JSON) but fail to find jsp files
        String appBase = "src/main/webapp"; // Tomcat does not start properly

        Tomcat tomcat = new Tomcat();

        String port = System.getProperty("server.port");
        tomcat.setPort(port == null ? 8080 : Integer.valueOf(port));

        tomcat.getHost().setAppBase(appBase);
        Context context = tomcat.addWebapp(contextPath, appBase);

        // So that it works when in it's launched from IntelliJ or Eclipse
        // Also need that a folder named "META-INF" exists in build/classes/main
        // https://bz.apache.org/bugzilla/show_bug.cgi?id=52853#c19
        ((StandardJarScanner) context.getJarScanner()).setScanAllDirectories(true);

        tomcat.start();
        tomcat.getServer().await();
    }

}

Spring web app initializer :

public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class<?>[] { RootConfig.class };
    }
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class<?>[] { WebConfig.class };
    }

}

WebConfig :

@Configuration
@EnableWebMvc
@ComponentScan("com.app")
public class WebConfig extends WebMvcConfigurerAdapter {

    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        resolver.setExposeContextBeansAsAttributes(true);
        return resolver;
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

}

Folder structure :

Apparently, embedded Tomcat expects static resources to be in a META-INF/resources directory. I followed this : tutorial and I checked how the final jar was structured.

So I modified the Gradle build script to put the JSPs there.

sourceSets {
    main {
        resources.srcDirs = ["src/main/webapp"]
        output.resourcesDir = "$buildDir/classes/main/META-INF/resources"
    }
}

And now it works. However, I have the feeling that it's a makeshift job. If someone has a more satisfying and educational answer, I would be pleased to get it.