obtain information from a Java servlet on a web page

Question

obtain information from a Java servlet on a web page

I am working on a webpage that displays various coordinates (longitude, latitude), and I need to create a Java class to sort these coordinates.

My plan is to send the coordinates to a Java servlet before displaying them on the webpage. The servlet will then sort them and send them back to the webpage for display.

To achieve this without refreshing the webpage, I believe I need to use Ajax to call the servlet. While I have a basic understanding of how to do this, I'm not sure how to receive data in Java from a webpage.

In the past, I have created servlets that called Java functions using JavaScript. However, one drawback of this approach is that the web browser navigates to a different page (a JSP with Java calls).

While I don't have the specific code for sorting coordinates yet, I am experimenting with the following:

package sorting;

public class SortCoordinates {

    public static String sort(String unsortedString) {
        String sortedString;
        
        // Sorting logic goes here
        sortedString = unsortedString;
        return sortedString;
    }
}

I know how to call a Java function from JavaScript using JSP, but I'm unsure about how to do it from other webpages on different servers or without refreshing the webpage.

Does anyone have any suggestions on how I should proceed? Or could you recommend any resources for further reading?

java javascript ajax servlets

Answer 1

Answer №1

If you're looking to deepen your understanding beyond the basics, consider diving into these resources:

How do you send an array as part of an (jquery) ajax request

Once you've grasped the concepts from those resources, remember to implement them by using a POST method instead of GET in the following structure:

var valSend = "aSingleParam";

var url = "/yourApplicationWebContext?paramPassed="+valSend;
console.log(url);
$.ajax({
    url: url,
    type: "GET",
    dataType: "json",
    success: function(data) {
    console.log("Data returned : " + data);

        if (typeof data == 'object') {

                }

        },
    error: function(jqXHR, textStatus, errorThrown) {
        console.log("jqXHR : "+jqXHR + " text status : " + textStatus + " error : " + errorThrown);
        }
    });

On the Java Servlet side, ensure that your web.xml includes a servlet and corresponding mapping:

//Your Java Servlet class

package com.xyz;

public class ServlvetClassName extends HttpServlet {

//The type: "GET" in the ajax call will trigger a "get" which the doGet will handle

protected void doGet(HttpServletRequest req, HttpServletResponse response)
        throws ServletException, IOException {

        if(null!= req.getParameter("paramPassed")){
         // get and use your parameter, which "is paramPassed"..... 

        }


        }

//The type: "POST" in the ajax call will trigger a "post" which the doPost will handle

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {

    this.doGet(req, resp);
}

}

Answer 2

If you're looking to deepen your understanding beyond the basics, consider diving into these resources:

How do you send an array as part of an (jquery) ajax request

Once you've grasped the concepts from those resources, remember to implement them by using a POST method instead of GET in the following structure:

var valSend = "aSingleParam";

var url = "/yourApplicationWebContext?paramPassed="+valSend;
console.log(url);
$.ajax({
    url: url,
    type: "GET",
    dataType: "json",
    success: function(data) {
    console.log("Data returned : " + data);

        if (typeof data == 'object') {

                }

        },
    error: function(jqXHR, textStatus, errorThrown) {
        console.log("jqXHR : "+jqXHR + " text status : " + textStatus + " error : " + errorThrown);
        }
    });

On the Java Servlet side, ensure that your web.xml includes a servlet and corresponding mapping:

//Your Java Servlet class

package com.xyz;

public class ServlvetClassName extends HttpServlet {

//The type: "GET" in the ajax call will trigger a "get" which the doGet will handle

protected void doGet(HttpServletRequest req, HttpServletResponse response)
        throws ServletException, IOException {

        if(null!= req.getParameter("paramPassed")){
         // get and use your parameter, which "is paramPassed"..... 

        }


        }

//The type: "POST" in the ajax call will trigger a "post" which the doPost will handle

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {

    this.doGet(req, resp);
}

}

obtain information from a Java servlet on a web page

Answer №1

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