Ultra simple examples of HttpServlet, DesignerFacesServlet, and AbstractXSPServlet.

com.hello.servlets.ExampleAbstractedServlet.java

package com.hello.servlets;

import java.util.Enumeration;

import javax.faces.context.FacesContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ibm.commons.util.StringUtil;

import frostillicus.xsp.servlet.AbstractXSPServlet;

/**
 * Example Servlet implementing AbstractXSPServlet,
 * from Jesse Gallagher.
 * 
 * @author Eric McCormick, @edm00se
 *
 */
public class ExampleAbstractedServlet extends AbstractXSPServlet {

	/* (non-Javadoc)
	 * @see frostillicus.xsp.servlet.AbstractXSPServlet#doService(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.faces.context.FacesContext, javax.servlet.ServletOutputStream)
	 */
	@Override
	protected void doService(HttpServletRequest req, HttpServletResponse res,
			FacesContext facesContext, ServletOutputStream out)
			throws Exception {
		
	    	res.setContentType("text/plain");
	    	
	        String reqMethod = req.getMethod();
	        
	        if( reqMethod.equals("GET") ) {
	        	
	    		out.println("doing something with GET");
				
	        } else if( reqMethod.equals("POST") ) {
	        	res.setStatus(200); // OK
	        	out.println("doing something with POST");
	        	
	        } else if( reqMethod.equals("PUT") ) {
	        	res.setStatus(200); // OK
	        	out.println("doing something with PUT");
				
	        } else if( reqMethod.equals("DELETE") ) {
	        	res.setStatus(200); // OK
	        	out.println("doing something with DELETE");
				
	        } else if( reqMethod.equals("PATCH") ) {
	        	res.setStatus(200); // OK
	        	out.println("doing something with PATCH");
	        	
	        } else {
	        	res.setStatus(405); // method not allowed
	        	out.println("what the devil are you trying to do, break the server?");
	        }
	}
	
}

com.hello.servlets.ExampleDesignerFacesServlet.java

package com.hello.servlets;

import java.io.IOException;
import java.io.PrintStream;
import java.util.Map;

import javax.faces.context.FacesContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ibm.xsp.webapp.DesignerFacesServlet;

/**
 * Example servlet showing the use of access to FacesContext.
 * This was originally blogged about by Jesse Gallagher and
 * is a near duplicate class.
 * src: https://frostillic.us/blog/posts/159496067A27FD3585257A70005E7BC1
 */
public class ExampleServlet extends DesignerFacesServlet {
	private static final long serialVersionUID = 1L;
	
	@SuppressWarnings("unchecked")
	@Override
	public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
		// Set up handy environment variables
		HttpServletRequest req = (HttpServletRequest)servletRequest;
		HttpServletResponse res = (HttpServletResponse)servletResponse;
		ServletOutputStream out = res.getOutputStream();
		FacesContext facesContext = this.getFacesContext(req, res);
		
		try {
			res.setContentType("text/plain");
			
			out.println("start");
			
			// The sessionScope is available via the ExternalContext. Resolving the variable
			//  would work as well
			Map<Object, Object> sessionScope = facesContext.getExternalContext().getSessionMap();
			// ... this is showing how we can get facesContext and *scope variables inside the servlet
			
			out.println("done");
			
		} catch(Exception e) {
			// hit an error, dump out whatever is there
			e.printStackTrace(new PrintStream(out));
		} finally {
			out.close();
			
			// It shouldn't be null if things are going well, but a check never hurt
			if(facesContext != null) {
				//complete the response and release the handle on the FacesContext instance
				facesContext.responseComplete();
				facesContext.release();
			}
		}
	}
	
	/**
	 * @return FacesContext currentInstance
	 */
	public static FacesContext getFacesContext() {
		return FacesContext.getCurrentInstance();
	}
}

com.hello.servlets.ExampleHttpServlet.java

package com.hello.servlets;

import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Example Servlet, implemented as 'vanilla'
 * HttpServlet. Many non-Domino Java Servlets
 * implement HttpServlet.
 * 
 * @author Eric McCormick, @edm00se
 *
 */
public class ExampleHttpServlet extends HttpServlet {
	
    private static final long serialVersionUID = 1L;
	
    @Override
	public void init () {
        
    }
    
    @Override
	public void destroy () {
        
    }
    
    @Override
	protected void doGet (HttpServletRequest req, HttpServletResponse res) {
        HttpServletRequest _req = req;
        HttpServletResponse _res = res;
        PrintWriter out = null;
        try{
            _res.setContentType("text/plain");
            out = _res.getWriter();
            out.println("Servlet Running");
            out.println("You executed a "+_req.getMethod().toString()+" request.");
        }catch(Exception e){
            if(out!=null){
                out.println("Sorry, an error occurred...");
            }
        }finally{
            out.close();
        }
    }
	
}

partialMethodCheck.java

String reqMethod = req.getMethod();

if( reqMethod.equals("GET") ) {
	try {
		out.println("doing something with my GET");
		} catch (Exception e) {
			e.printStackTrace();
			out.println(e.toString());
		} finally {
			facesContext.responseComplete();
			facesContext.release();
			out.close();
		}
} else if( reqMethod.equals("POST") ) {
	try {
		out.println("doing something with my POST");
		} catch (Exception e) {
			e.printStackTrace();
			out.println(e.toString());
		} finally {
			facesContext.responseComplete();
			facesContext.release();
			out.close();
		}
} //...