How to Pass the hashmap value from a java file to Javascript

Question

I am trying to retrieve the value from DataBase using Java File and storing it to HashMap. Please find the below code (Sample.java):

import java.sql.*;
import java.util.HashMap;

public class Sample {

 static Connection conn;
 static PreparedStatement stmt;
 static ResultSet rs;
 String sql;
 static String project="Project1";
 public static HashMap< String, String> map = new HashMap< String, String>();
public static void main(String[] args) {

    try{  

        Class.forName("com.mysql.jdbc.Driver");
        conn=DriverManager.getConnection("jdbc:mysql://localhost:3309/graphvalue","root","root");
        stmt=conn.prepareStatement("select * from TestCase where ProjectName= ?");
        stmt.setString(1,project);
        rs=stmt.executeQuery();
        while(rs.next())
        {
            System.out.println(rs.getString(1)+"  "+rs.getInt(2)+"  "+rs.getInt(3)+" "+rs.getInt(4)+" "+rs.getInt(5));
        map.put("ProjectName", rs.getString(1));
        map.put("Total TestCase", String.valueOf(rs.getInt(2)));
        map.put("TestCase Executed", String.valueOf(rs.getInt(3)));
        map.put("Failed TestCase", String.valueOf(rs.getInt(4)));
        map.put("TestCase Not Executed", String.valueOf(rs.getInt(5)));
        System.out.println("ProjectName  "+map.get("ProjectName"));

        }
        conn.close();
        }
    catch(Exception e)
        { System.out.println(e);}
}

}

Please find the below data which I am retrieving from the databse:

ProjectName TotalTestCase TestCaseExecuted TestCaseFailed TestCaseNotExecuted    
 Project1       50              30              8                20

I want to pass this value to Javascript and so that I am able to draw a chart using these values. Please find my HTML/Javascript code below (test.html):

<html>
<head>
</head>
<body>
<select id="ChartType" name="ChartType" onchange="drawChart()">
<option value = "PieChart">Select Chart Type
 <option value="PieChart">PieChart
 <option value="Histogram">Histogram
 <option value="LineChart">LineChart
 <option value="BarChart">BarChart
</select>
<div id="chart_div" style="border: solid 2px #000000;"></div>
<p id="demo"></p>
<p id="demo1"></p>

<script type="text/javascript" src="https://www.google.com/jsapi"></script>

<script type="text/javascript">
var row = [];
var temp;
var stri;
google.load('visualization', '1.0', {'packages':['corechart']});
google.setOnLoadCallback(getValues);
     function getValues() {
    var xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        stri = xmlhttp.responseText;
            drawChart();
        }
    };
    xmlhttp.open("GET", "sample.java", true);
    xmlhttp.send();
    }

    function drawChart() {
    var data = new google.visualization.DataTable();
    str = stri.split(",");

        // How to call the value from java file so that I will be able to draw the below graph by passing the value.

    data.addRows(row);
    var a = document.getElementById("ChartType").value;
    document.getElementById("demo1").innerHTML = "You selected: " + a;
    var options = {'title':'How Much Pizza I Ate Last Night',
                   'width':400,
                   'height':300
                   };
    var chart = new google.visualization[document.getElementById("ChartType").value](document.getElementById('chart_div'));
    chart.draw(data, options);
    }
</script>
</body>
</html>

Please let me know how to proceed or if anyone have any other example. Please share it with me. Thank you

score 4 · Answer 1 · edited May 23 '17 at 12:01

You can convert your map to JSON. Instead of this HelloWorld class, you can convert it into a service that returns this `JSON

import java.sql.*;
import java.util.HashMap;

public class Sample {
    static Connection conn;
    static PreparedStatement stmt;
    static ResultSet rs;
    String sql;
    static String project = "Project1";
    public static HashMap < String, String > map = new HashMap < String, String > ();

    //Notice how your main class is now converted into a service
    public static String getProjects() {

        try {

            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3309/graphvalue", "root", "root");
            stmt = conn.prepareStatement("select * from TestCase where ProjectName= ?");
            stmt.setString(1, project);
            rs = stmt.executeQuery();
            while (rs.next()) {
                System.out.println(rs.getString(1) + "  " + rs.getInt(2) + "  " + rs.getInt(3) + " " + rs.getInt(4) + " " +
                    rs.getInt(5));
                map.put("ProjectName", rs.getString(1));
                map.put("Total TestCase", String.valueOf(rs.getInt(2)));
                map.put("TestCase Executed", String.valueOf(rs.getInt(3)));
                map.put("Failed TestCase", String.valueOf(rs.getInt(4)));
                map.put("TestCase Not Executed", String.valueOf(rs.getInt(5)));
                System.out.println("ProjectName  " + map.get("ProjectName"));

                /*______________ NEW CODE ______________*/
                JSONObject resultMap = new JSONObject(map);
                return resultMap.toString();
            }

        } catch (Exception e) {
            System.out.println(e);
        } finally {
            conn.close();
        }
        return "";
    }

}

Now convert your test.html to test.jsp and call that service that we've created in previous step and output the resultant JSON into a javascript variable.

test.jsp

<%@page import="com.path.to.Sample"%>
<html>
    <head>
        <script>
            <!-- call that service and output that json into a javascript variable -->
            var resultantJSON = <%= Sample.getProjects() %>

            <!-- Now all that's left is to parse that json  -->
            var projects = JSON.parse(resultantJSON);

        </script>
    </head>
    <body>
        ...
        ...
    </body>
</html>

Now all your results that you fetched from your database are in projects variable in Test.jsp. You can use them like conventional javascript object in your jsp file.

score 0 · Answer 2 · answered Sep 02 '16 at 08:14

You have to make the Java code accessable via http. There are several ways to do this. You can implement a servlet which retrieves the http request and can send data back as httpresponse. Search for a tutorial on java servlet, e.g. like this http://www.tutorialspoint.com/servlets/servlets-first-example.htm

You could also use a java rest service to supply the information. Search for java rest tutorial, e.g. like this http://www.vogella.com/tutorials/REST/article.html

How to Pass the hashmap value from a java file to Javascript

2 Answers2