javanus.com

Using database gives an application the dynamic content. Without database an application could be compared to Sahara, everything is static, sand everywhere, no waves. The goal is to bring Nile to Sahara desert.

In my previous blog http://javanus.com/blogs/?p=24 I described how to build your first web service.

Today I will try to connect a servlet to the database. I will use mysql database. What a great achivement If I will succeed?!;) I would be very happy.

1.I create a new web project in Netbeans. I add jar mysql-connector-java-5.0.7-bin.jar to the project library. You could have different mysql connector version.

2.I create a new class.

package mypackage;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DriverManager;
import javax.jws.WebService;
/**
 *
 * @http://www.javanus.com/blogs

 */
@WebService()
public class DatabaseExample {

    public String getName(String pUrl, Integer pId, String pUser, String pPass) {
    String ls_name = “”;
    try
     {
        //connect to database
        Class.forName(“com.mysql.jdbc.Driver”);
        Connection con = DriverManager.getConnection(pUrl, pUser, pPass);
        // query database using SQL
        Statement s = con.createStatement();
        String query = “SELECT name FROM test WHERE id = ” + pId;
        ResultSet rs = s.executeQuery(query);

        while(rs.next())
        {
           ls_name = rs.getString(“name”);
        }
        // close connection
        con.close ( );
     }
     catch (Exception e)
     {
        return “Exception ” + e.toString()+”..”+e.getMessage();
     }       
        return “Name for id ” + pId + ” is ” + ls_name + “!”;
    }
}

I build a project and deploy it to the Tomcat Web Application Server.

3.I create another project in Netbeans as Java application type.

Right click project->New->Web service client. I select WSDL radio button and put WSDL url. See the picture below.

4.In the Main Class I add a call to the webservice. See the example below.

/**
 *
 * @author http://www.javanus.com/blogs
 */
public class NewClass {
    public NewClass() {
    }
    public static void main(String[] args) {
        try { // Call Web Service Operation
            mypackage.DatabaseExampleService service = new mypackage.DatabaseExampleService();
            mypackage.DatabaseExample port = service.getDatabaseExamplePort();
            java.lang.String arg0 = “jdbc:mysql://localhost/database_name”;
            java.lang.Integer arg1 = Integer.valueOf(1);
            java.lang.String arg2 = “db_username”;
            java.lang.String arg3 = “db_password”;
            java.lang.String result = port.getName(arg0, arg1, arg2, arg3);
            System.out.println(“Result = “+result);
        } catch (Exception ex) {
        }
    }
}

5.Is the position of the stars = true? Does it work?

Yes, the position of the stars is in the harmony with my brain processes.