EventManager-JEE

Dino planner is a school project we did for the Ecole des Mines de Nantes. The aims are to use what we learned in JEE class but also to improve our ergonomic skills.

Table of contents :

• Architecture
• Router
• Flash
• CRUD database

Architecture

src/
|--main/
   |--java/
      |--fr.lidadi.jee.eventmanager/
         |--app/ (contains business part (controllers, services, daos and entity) organised by entity)
         |--conf/
            |--Router.java (Router configuration)
         |--framework/
            |--dao/ (manage database connection, and interaction)
               |--sqldsl/ (A SQL DSL used by findBy())
               |--...
            |--jsptags (custom jsp tags)
            |--router  (router core code)
            |--utils   (some util tools)
   |--resources/META-INF/persistence.xml (database information)
   |--webapp/
      |--assets/
         |--css/ (contains all CSS)
         |--js/  (contains all JavaScript)
      |--WEB-INF/
         |--jsp/    (contains all JSP of the app organized by entity)
         |--app.tld (needed to use custom tags and funtions in JSP)
         |--web.xml (define routes (not used))
   
|--test

Router

The usage of the router is very simple. The first step is to configure a route. And then, you just have to implement the method. The following example will guide you.

This is router is powerfull :

• it is able to extract parameters from URL and to check there type (UUID, STRING or INT). And then, give them to controller methods without require any cast !
• it is able to filter according to controllers needs : - HttpServletRequest is default request (no filter) - UserAwareRequest user can be logged, but it is not required. Then it is possible to get an Optional<Person> thanks to req.getUser(). - SecuredRequest user have to be logged (error if not). Then it is to possible get the logged Person thanks to req.getUser().

See examples below.

Route configuration

public class Router implements HttpRouter {

    @Override
    public Config.HttpConfig route(Config.EmptyHttpConfig config) {
        return config
                .get("/")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.welcome()")
                .get("/events")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.fetchAll()")
                .get("/events/{id}")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.fetch(UUID id)")
                .get("/events/{eventId}/group/{groupId}/members")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.test(UUID eventId, INT groupId)")
                .post("/events")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.add()")
                .put("/events")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.update()")
                .delete("/events/{id}")
                    .to("fr.lidadi.jee.eventmanager.EventServlet.delete(UUID id)");
    }
}

Controller and method definition

public class EventServlet implements HttpErrorResponse {

    public void fetchAll(HttpServlet servlet, SecuredRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ok(resp, "fetchAll");
    }

    public void welcome(HttpServlet servlet, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        okJsp(servlet, req, resp, "/welcome.jsp");
    }


    public void fetch(HttpServlet servlet, UserAwareRequest req, HttpServletResponse resp, UUID id) throws ServletException, IOException {
        ok(resp, "fetch(" + id + ")");
    }
}

Flash

Flash messages are : - set in a controller - display in view only once (the message is deleted after)

For the moment this is implemented using http sessions.

Set a message

Associate message "Wrong credentials" to key "error" :

private Flashing flashing = new Flashing();
// ...
flashing.flashing(req.getSession(), "error", "Wrong credentials");

Test if a key is defined & display a message

Get the message associated to key "error" :

<c:if test="${app:flashExist(sessionScope, \"error\")}">
    <div class="alert alert-error">${app:consumeFlash(sessionScope, "error")}</div>
</c:if>

CRUD database

In order to communicate with database, you have to :

• Create an entity that extends fr.lidadi.jee.eventmanager.framework.dao.Entity
• Create a Dao that extends fr.lidadi.jee.eventmanager.framework.dao.Dao

Then, you can use defined methods such as :

• getAll()
• get(PK id) : get an entity from it primary key (PK is the type of the primary key)
• findBy(SQLClauses sqlClauses) : equivalent to getAll with conditions
• add(T entity)
• update(T entity)
• delete(PK id)

SQL DSL

We have defined a DSL to easily request entities with conditions. The two examples below show how it works.

Where

To get all event that is today, at Nantes or at Angers :

findBy(
    where(
        and(
            equal("date", today),
            or(
                equal("location", "Nantes"),
                equal("location", "Angers"),
            )
        )
    )
)

Like (not implemented yet)

To get all event that location starts with "P".

findBy(
    like(
        equal("location", "P%")
    )
)