Build servlets in Java

<x2erpc>
    <handler class="com.mindoo.rest.RestHandler" alias="/rest" />
</x2erpc>

package com.mindoo.rest;

import java.io.IOException;

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

import lotus.domino.Database;
import lotus.domino.Session;
import lotus.domino.View;

import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;

import com.mindoo.cms.tools.extlib.DefaultViewParameters;
import com.mindoo.cms.tools.extlib.RestViewNavigator;
import com.mindoo.remote.api.IRemoteEclipseConnection;
import com.mindoo.xpages2eclipse.rpc.IRPCHandler;
import com.mindoo.xpages2eclipse.tools.ServletHelper;

/**
 * RPC Handler implementation that provides a REST service to read the persons documents
 * in this database
 * 
 * @author Karsten Lehmann
 */
public class RestHandler implements IRPCHandler {

    public void serviceRPC(HttpServletRequest req, HttpServletResponse response,
            Session session, Database database, IRemoteEclipseConnection conn)
            throws ServletException, IOException {
        
        String method=req.getMethod();
        if (!"GET".equals(method)) {
            System.out.println("Unsupported http method: "+method);
            ServletHelper.sendHttpError(response, 500, "Unsupported http method: "+method, null);
            return;
        }
        
        String pathInfo=req.getPathInfo();
        if (pathInfo==null) {
            System.out.println("Missing pathinfo value");
            ServletHelper.sendHttpError(response, 500, "Missing pathinfo value", null);
            return;
        }
        
        if (pathInfo.equals("/persons")) {
            //we only support the /persons service for now
            try {
                handlePersonRequest(req, response, session, database, conn);
            } catch (Exception e) {
                e.printStackTrace();
                ServletHelper.sendHttpError(response, 500, "Could not read data from database", e);
                return;
            }
        }
        else {
            System.out.println("Unsupported pathinfo value: "+pathInfo);
            ServletHelper.sendHttpError(response, 500, "Unsupported pathinfo value: "+pathInfo, null);
            return;
        }
    }

    /**
     * Java method that handles the persons rest API request
     * 
     * @param req servlet request
     * @param response response
     * @param session current Notes session
     * @param database current Notes database
     * @param conn XPages2Eclipse connection or <code>null</code> if running on the server
     * @throws Exception
     */
    private void handlePersonRequest(HttpServletRequest req,
            HttpServletResponse response, Session session, Database database,
            IRemoteEclipseConnection conn) throws Exception {
        //read start and limit parameter sent by the Ext JS 4 grid
        int start=ServletHelper.getParamInt(req, "start", 0);
        int limit=ServletHelper.getParamInt(req, "limit", -1);
        
        //open People view in database
        View peopleView=database.getView("People");
        //autoUpdate=false needed for the accelerated ViewNavigator
        //used in the RestViewNavigatorFactory class (uses
        //new buffered mode in 8.5.2)
        peopleView.setAutoUpdate(false);
        
        //to read the view content, we are using a few classes from
        //the Domino Extension Library (Apache License) that unify
        //several different sorts of view data access
        DefaultViewParameters params=new com.mindoo.cms.tools.extlib.DefaultViewParameters();
        RestViewNavigator nav=com.mindoo.cms.tools.extlib.RestViewNavigatorFactory.createNavigator(peopleView, params);

        //send json mimetype to browser
        response.setContentType("application/json; charset=UTF-8");
        response.setHeader("Cache-Control", "no-cache");
        response.setCharacterEncoding("UTF-8");

        //instantiate Jackson library that is used to stream out the JSON code
        JsonFactory jsonFactory=new org.codehaus.jackson.JsonFactory();
        JsonGenerator jg = jsonFactory.createJsonGenerator(response.getWriter());
        
        jg.writeStartObject();
        
        //send the total number of entries as "totalCount"
        jg.writeBooleanField("success", true);
        int totalCount=nav.getTopLevelEntryCount();
        if (limit==-1)
            limit=totalCount;
        jg.writeNumberField("totalCount", totalCount);

        //now iterate through the view data and write an array entry for each row
        jg.writeArrayFieldStart("data");

        int idx=0;
        for( boolean b=nav.first(start,limit); b && idx<limit; b=nav.next(), idx++) {
            String unid=nav.getUniversalId();
            Object lastName=nav.getColumnValue("LastName");
            Object firstName=nav.getColumnValue("FirstName");
            
            jg.writeStartObject();

            jg.writeStringField("id", unid);
            jg.writeStringField("firstname", firstName==null ? null : firstName.toString());
            jg.writeStringField("lastname", lastName==null ? null : lastName.toString());
            
            jg.writeEndObject();
        }

        jg.writeEndArray();
        
        jg.writeEndObject();
        jg.flush();
        
        nav.recycle();
    }
}