Init method not firing JSP Servlet - servlets

Question

I am using Eclipse IDE, a simple HelloServlet.java file and a simple index.jsp file. When I run the local server, the program starts but the following code does not execute:
/**
* #see Servlet#init(ServletConfig)
*/
public void init(ServletConfig config) throws ServletException {
// TODO Auto-generated method stub
System.out.println("Init Firing: ");
}
I have the Console tab open, and the last statement I receive is: INFO: Server startup in 1442 ms. What might I do to get the init method to fire?

Answer 1

The container will only call the init() method of the servlet when it's called, not on the container startup.
If you want to start things on container startup, you can use the ContextListener as suggested here call method on server startup
This code works for me
package mine;
import java.io.IOException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MySL extends HttpServlet {
private static final long serialVersionUID = 1L;
public void init(ServletConfig config) throws ServletException {
System.out.println("xyz="+config.getInitParameter("xyz"));
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("doGet");
}
}
and web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
<display-name>jsp</display-name>
<servlet>
<servlet-name>mySL</servlet-name>
<servlet-class>mine.MySL</servlet-class>
<init-param>
<param-name>xyz</param-name>
<param-value>123</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>mySL</servlet-name>
<url-pattern>/MySL</url-pattern>
</servlet-mapping>
</web-app>
When the server starts, nothing happens, because the init() method is called when the servlet is called.
On the first servlet call (e.g. opening in your browser something like http://myserver.mydomain:8080/myapp/MySL), you'll get
xyz=123
doGet
On the second servlet call, you'll get
doGet
Please notice that this is the "old way" of declaring things. Nowadays, Servlets configuration can be made using annotations. Careful to not mix annotations with XML declarations for the same servlet.
Servlets with annotations look like this
package mine;
import java.io.IOException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
#WebServlet(urlPatterns = { "/OtherSL" }, initParams = { #WebInitParam(name = "abc", value = "456", description = "some parameter") })
public class OtherSL extends HttpServlet {
private static final long serialVersionUID = 1L;
public void init(ServletConfig config) throws ServletException {
System.out.println("abc=" + config.getInitParameter("abc"));
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("doGet");
}
}