Get request for 1 specific user from mysql in java

Question

I have a MySQL database (called database) with tables: event, gebruiker and situatie. Now I need to write code in Java (using netbeans) to test my restful webservice. I'm able to retrieve all users (=gebruikers, dutch), but when I want to retrieve one specific user by searching on it's primary key 'Username', I get this 500-error when testing the restful webservice. please help! this is my code in java:

@Stateless
@Path("gebruikers")
public class GebruikerService {

@Resource(name = "jdbc/socialebuurt")
private DataSource source;

/*
 * Request all users.
 */

@GET
@Produces(MediaType.APPLICATION_JSON)
public List<Gebruiker> getGebruikers() {
    try (Connection conn = source.getConnection()) {
        try (PreparedStatement stat = conn.prepareStatement("SELECT * FROM gebruiker")) {
            try (ResultSet rs = stat.executeQuery()) {
                List<Gebruiker> results = new ArrayList<>();
                while (rs.next()) {
                    Gebruiker g = new Gebruiker();
                    g.setUsername(rs.getString("Username"));
                    g.setNaam(rs.getString("Naam"));
                    g.setVoornaam(rs.getString("Voornaam"));
                    g.setStraat(rs.getString("Straat"));
                    g.setHuisNr(rs.getInt("huisnr"));
                    g.setPostcode(rs.getInt("postcode"));
                    g.setGemeente(rs.getString("gemeente"));
                    g.setWachtwoord(rs.getString("wachtwoord"));
                    results.add(g);
                }
                return results;
            }
        }
    } catch (SQLException ex) {
        throw new WebApplicationException(ex);
    }
}


/*
 * Request one specific user.
 */

@Path("{username}")
@GET
@Produces(MediaType.APPLICATION_JSON)
public Gebruiker getGebruiker(@PathParam("username") String username) {
    try (Connection conn = source.getConnection()) {
        try (PreparedStatement stat = conn.prepareStatement("SELECT * FROM gebruiker WHERE username = ?")) {
            stat.setString(1,"");
            try (ResultSet rs = stat.executeQuery()) {
                if (rs.next()) {
                    Gebruiker ge = new Gebruiker();
                    ge.setUsername(rs.getString("Username"));
                    ge.setNaam(rs.getString("Naam"));
                    ge.setVoornaam(rs.getString("Voornaam"));
                    ge.setStraat(rs.getString("Straat"));
                    ge.setHuisNr(rs.getInt("huisnr"));
                    ge.setPostcode(rs.getInt("postcode"));
                    ge.setGemeente(rs.getString("gemeente"));
                    ge.setWachtwoord(rs.getString("wachtwoord"));
                    return ge;
                } else {
                    throw new WebApplicationException(Status.NOT_FOUND);
                }
            }
        }
    } catch (SQLException ex) {
        throw new WebApplicationException(ex);
    }
}
}

Table 'gebruiker' has following attributes: username (primary key, varchar(26)), naam (text), voornaam (text), straat (text), huisNr (int(11)), postcode (int(4)), gemeente (text), wachtwoord (text). If more info is needed, please ask. Thanks to all!

Answer 1

您需要在语句中包含WHERE子句，如下所示：

"SELECT * FROM gebruiker WHERE username =" + username;