JSONServlet.java :  » Google-tech » amazingapis » org » webscale » json » Java Open Source

package org.webscale.json;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

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


import org.webscale.ApplicationController;



/**
 * Servlet implementation class for Servlet: JSONServlet
 *
 */
 public class JSONServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
  
   private static final Logger log = Logger.getLogger(JSONServlet.class.getName());
   private static final long serialVersionUID = -1305501839940993379L;
   private static final String SPRING_PROPERTIES_LOCATION = "spring.properties.location";
   public static final String REQUEST_ID = "json-request-id";
   public static final String JSON_REQUEST_STRING = "json-request-string";

  
  @Override
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
    String propfileLocation = config.getInitParameter(SPRING_PROPERTIES_LOCATION);
    try{
      Properties p = loadProperties(config);
      ApplicationController.instance().setStartUpParamenters(p);
      ApplicationController.instance().init();
      }catch (Exception e) {
        log.severe("JSON Servelet Init Failed");
        log.log(Level.SEVERE , e.getMessage() , e);
        //TODO: Handler this properly
        throw new ServletException(e);
      }
  }

  /* (non-Java-doc)
   * @see javax.servlet.http.HttpServlet#HttpServlet()
   */
  public JSONServlet() {
    super();
  }     
  
  /* (non-Java-doc)
   * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    processHTTPRequest(request , response);
  }    
  
  /* (non-Java-doc)
   * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    processHTTPRequest(request , response);
  }       
  
  
  protected void processHTTPRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{
    String requestID = request.getParameter(REQUEST_ID);
    
    if(requestID == null){
       showErrorPage("No Request ID" , request ,response);
       return;
    }
    
    
    //TODO: Add a layer for Authorization here
    
    JsonRequestHandler handler = JsonRequestHandler.Factory.create(requestID);
    if(handler == null){
       showErrorPage("Could Find a Handler for REQUEST="+requestID , request ,response);
       return;
    }
    
    String jsonResponse = handler.executeRequest(request.getParameter(JSON_REQUEST_STRING));
    
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println(jsonResponse);
    out.close();
    
  
      log.fine("RETURNING VALUE ***");
      log.fine(jsonResponse);
  
  }
  
  
  private void showErrorPage(String msg ,HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("<H3> Error : </H3>");
    out.println("<H4> " + msg + "</H2>");
    out.close();
    log.severe(msg);
  
  }

  private Properties loadProperties(ServletConfig config) throws IOException{
    Properties prop = new Properties();
    Enumeration e = config.getInitParameterNames();
    while(e.hasMoreElements()){
      String key = e.nextElement().toString();
      String value = config.getInitParameter(key);
      prop.put(key, value);
    }
    return prop;
  }
}