CODEWITHSUNDEEP
javajavascriptjspmarkerclusterer
Bruno Finger
Bruno Finger

Reputation: 2603

What is the best practice to manage dynamic JavaScript from Java?

I am developing a webpage in JSP which uses a big ammount of dynamically generated JavaScript code from a Java backend class. It is about Google Maps and a JS library called MarkerClusterer.

Currently this class is generating the JavaScript code by handling Strings in Java and printing it directly into the JSP page, but it's getting a little bit complicated to write JS within Java String and maintain that.

The JavaScript requires a lot of modifications all the time, as this class is being used in different projects. Ideally I would like to package this in a way it could be used as a library, not requiring further modifications, so that's the question, what is the best way to do that?

Here's a part of the code:

public class JavascriptGenerator {

    public String gerarPorRegiao(String contextPath, List<Endereco> lista, boolean infoWindowEnabled) {
        String saida = "";

        saida += "<script type=\"text/javascript\" src=\"http://maps.google.com/maps/api/js?sensor=false\"></script>"
                + "<script type=\"text/javascript\" src=\""
                + contextPath
                + "/js/markerclusterer.js\"></script>"
                + "<script type=\"text/javascript\">"
                + "var map;";
        for(Estado e: Estado.values()) {
            saida += "var mc" + e.toString() + ";";
        }
                saida += "var selecionado;"
                + "var center = new google.maps.LatLng(-11.0, -51.9);"
                + "var geocoder = new google.maps.Geocoder();"
                + "var infowindow = new google.maps.InfoWindow();"
                + "var markerContent = new Array();"
                + "function geocoderInit() {"
...

Upvotes: 3

Views: 1887

Answers (4)

Charli Lowe
Charli Lowe

Reputation: 1

When managing dynamic JavaScript from Java, it's essential to maintain separation of concerns and ensure that your Java backend cleanly generates the necessary JavaScript. Using frameworks that facilitate the integration of Java and JavaScript, such as JSP with scriptlets or JSTL, can be beneficial. For instance, you can create a Java class to handle the logic and then pass the data to your JSP, where it can be formatted into JavaScript. Additionally, consider using JSON to exchange data between Java and JavaScript, as it simplifies the data structure and enhances readability. Lastly, ensure that your JavaScript is modular and uses best practices to improve maintainability and performance.

Utilizing libraries like MarkerClusterer can enhance user experience, but always test the integration thoroughly to avoid performance bottlenecks, especially with large datasets like Google Maps markers.

Upvotes: -1

Esben Skov Pedersen
Esben Skov Pedersen

Reputation: 4517

I would say: don't.

Don't generate javascript dynamically. It will be a nightmare to maintain. Keep your js in a static file, and use ajax to fetch your data. Your data can be in the form of JSON. JSON can be auto-generated from an object hierarchy using one of many JSON libs you can download.

Upvotes: 2

isnot2bad
isnot2bad

Reputation: 24454

You could write a separate JSP file that creates the javascript. Then all static parts of the Javascript would be as usual:

var map;

<% for(Estado e: Eastado.values()) { %>
var mc<%=e.toString()%>;
<% } %>

var selecionado;
...

This JSP can then be loaded by the HTML page your other JSP creates:

<script type="text/JavaScript" src="path/to/jsp/file.jsp"></script>

If your script needs access to data, you could pass parameters via URL:

<script type="text/JavaScript" src="path/to/jsp/file.jsp?id=15"></script>

Then, in the script, in a filter or anything similar, you can directly use these parameters or use them to load data from a database or so.

Upvotes: 1

Sai Avinash
Sai Avinash

Reputation: 4753

one thing you can do is , use a string buffer and add all you java script stuff into it. Then write it a file with .js as extension. so, this makes your script maintainable

Upvotes: 1

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