Micro Java Web Framework

It's an open source (Apache License) micro web framework in Java, with minimal dependencies and a quick learning curve.
The goal of this project is to create a micro web framework in Java that should be easy to use and hack.
The size of pippo-core is only 140 KB and the size of pippo-controller (optional) is only 45 KB.

Sample code

1. Routes approach

First we must create an Application and add some routes:

public class BasicApplication extends Application {

    @Override
    protected void onInit() {
        // send 'Hello World' as response
        GET("/", routeContext -> routeContext.send("Hello World"));

        // send a file as response
        GET("/file", routeContext -> routeContext.send(new File("pom.xml")));

        // send a json as response
        GET("/json", routeContext -> {
            Contact contact = createContact();
            routeContext.json().send(contact);
        });

        // send xml as response
        GET("/xml", routeContext -> {
            Contact contact = createContact();
            routeContext.xml().send(contact);
        });

        // send an object and negotiate the Response content-type, default to XML
        GET("/negotiate", routeContext -> {
            Contact contact = createContact();
            routeContext.xml().negotiateContentType().send(contact);
        });

        // send a template with name "hello" as response
        GET("/template", routeContext -> {
            routeContext.setLocal("greeting", "Hello");
            routeContext.render("hello");
        });
    }

    private Contact createContact() {
        return new Contact()
            .setId(12345)
            .setName("John")
            .setPhone("0733434435")
            .setAddress("Sunflower Street, No. 6");
    }

}

where Contact is a simple POJO:

public class Contact  {

    private int id;
    private String name;
    private String phone;
    private String address;

    // getters and setters

}

The second step is to choose your favorite server, template engine and content type engine.
For example, I will choose Jetty as server, Freemarker as template engine, Jackson as JSON engine and JAXB as XML engine.
My Maven pom.xml looks like:

<dependency>
    <groupId>ro.pippo</groupId>
    <artifactId>pippo-core</artifactId>
    <version>${pippo.version}</version>
</dependency>

<dependency>
    <groupId>ro.pippo</groupId>
    <artifactId>pippo-jetty</artifactId>
    <version>${pippo.version}</version>
</dependency>

<dependency>
    <groupId>ro.pippo</groupId>
    <artifactId>pippo-freemarker</artifactId>
    <version>${pippo.version}</version>
</dependency>

<dependency>
    <groupId>ro.pippo</groupId>
    <artifactId>pippo-jackson</artifactId>
    <version>${pippo.version}</version>
</dependency>

The last step it's to start Pippo with your application as parameter:

public class BasicDemo {

    public static void main(String[] args) {
        Pippo pippo = new Pippo(new BasicApplication());
        pippo.start();
    }

}

Pippo launches the embedded web server (found in your classpath) and makes the application available on port 8338 (default value). Open your internet browser and check the routes declared in Application:

http://localhost:8338
http://localhost:8338/file
http://localhost:8338/json
http://localhost:8338/xml
http://localhost:8338/negotiate
http://localhost:8338/template

2. Controllers approach

Define controller(s):

@Path("/contacts")
@Logging
public class ContactsController extends Controller {

    private ContactService contactService;

    public ContactsController() {
        contactService = new InMemoryContactService();
    }

    @GET
    @Named("index")
//    @Produces(Produces.HTML)
    @Metered
    @Logging
    public void index() {
        // inject "user" attribute in session
        getRouteContext().setSession("user", "decebal");

        // send a template with name "contacts" as response
        getResponse()
            .bind("contacts", contactService.getContacts())
            .render("contacts");
    }

    @GET("/uriFor/{id: [0-9]+}")
    @Named("uriFor")
    @Produces(Produces.TEXT)
    @Timed
    public String uriFor(@Param int id, @Header String host, @Session String user) {
        System.out.println("id = " + id);
        System.out.println("host = " + host);
        System.out.println("user = " + user);

        Map<String, Object> parameters = new HashMap<>();
        parameters.put("id", id);

        String uri = getApplication().getRouter().uriFor("api.get", parameters);

        return "id = " + id + "; uri = " + uri;
    }

    @GET("/api")
    @Named("api.getAll")
    @Produces(Produces.JSON)
    @NoCache
    public List<Contact> getAll() {
        return contactService.getContacts();
    }

    @GET("/api/{id: [0-9]+}")
    @Named("api.get")
    @Produces(Produces.JSON)
    public Contact get(@Param int id) {
        return contactService.getContact(id);
    }

}

@Path("/files")
public class FilesController extends Controller {

    @GET
    public void index() {
        // send a template with name "files" as response
        getRouteContext().render("files");
    }

    @GET("/download")
    public File download() {
        // send a file as response
        return new File("pom.xml");
    }

    @POST("/upload")
    @Produces(Produces.TEXT)
    public String upload(FileItem file) {
        // send a text (the info about uploaded file) as response
//        return file.toString();
        return new StringBuilder()
            .append(file.getName()).append("\n")
            .append(file.getSubmittedFileName()).append("\n")
            .append(file.getSize()).append("\n")
            .append(file.getContentType())
            .toString();
    }

}

Add controller(s) in your application:

public class BasicApplication extends ControllerApplication {

    @Override
    protected void onInit() {
        addControllers(ContactsController.class); // one instance for EACH request
        // OR
        addControllers(new ContactsController()); // one instance for ALL requests

        addControllers(FilesController.class);
    }

}