Restlet Framework – Hello World Example

Sunil GulabaniSeptember 6th, 2013Last Updated: September 6th, 2013

2 209 2 minutes read

Restlet is a lightweight, comprehensive, open source REST framework for the Java platform. Restlet is suitable for both server and client Web applications. It supports major Internet transport, data format, and service description standards like HTTP and HTTPS, SMTP, XML, JSON, Atom, and WADL. A GWT port of the client-side library is also available. (Reference: http://en.wikipedia.org/wiki/Restlet)

Hello World Example

Project Structure

RestletApplication.java

package com.restlet.demo.application;
 
import org.restlet.Application;
import org.restlet.Restlet;
import org.restlet.routing.Router;
 
import com.restlet.demo.resource.HelloWorldResource;
 
public class RestletApplication extends Application{ 
    public synchronized Restlet createInboundRoot() {
        Router router = new Router(getContext());
        router.attach("/helloWorld",HelloWorldResource.class );
        return router;
    }
}

ResponseParseFactory.java

package com.restlet.demo.core;
 
import java.util.LinkedHashMap;
 
import org.apache.log4j.Logger;
import org.json.simple.JSONValue;
 
public class ResponseParseFactory {
 
 static Logger logger = Logger.getLogger(ResponseParseFactory.class);
 
 @SuppressWarnings({ "rawtypes", "unchecked" })
 public String getFailureJsonString(String msg){
  String jsonString = "";
  LinkedHashMap list = new LinkedHashMap();
  list.put("response_status", "false");
 
  list.put("result", msg+"");
  jsonString = JSONValue.toJSONString(list);
  logger.info(jsonString);
  return jsonString;
 }
 
 @SuppressWarnings({ "rawtypes", "unchecked" })
 public String getSuccessJsonString(String msg){
  String jsonString = "";
  LinkedHashMap list = new LinkedHashMap();
  list.put("response_status","true");
 
  list.put("result", msg);
  jsonString = JSONValue.toJSONString(list);
  logger.info(jsonString);
  return jsonString;
 }
}

BaseResource.java

package com.restlet.demo.resource;
 
import java.util.HashMap;
import java.util.Map;
 
import org.apache.log4j.Logger;
import org.json.JSONObject;
import org.json.simple.parser.JSONParser;
import org.restlet.data.Form;
import org.restlet.data.MediaType;
import org.restlet.data.Parameter;
import org.restlet.ext.json.JsonRepresentation;
import org.restlet.representation.Representation;
import org.restlet.representation.StringRepresentation;
import org.restlet.resource.Get;
import org.restlet.resource.Post;
import org.restlet.resource.ServerResource;
 
import com.restlet.demo.core.ResponseParseFactory;
 
public abstract class BaseResource extends ServerResource{
 
  protected ResponseParseFactory parseFactory = null;
  protected Logger logger = Logger.getLogger(BaseResource.class);
  String jsonString="";
 
 @SuppressWarnings("rawtypes")
 @Post("json")
 public Representation doPost(Representation entity){
  Map json =null;
  jsonString = "";
  parseFactory = new ResponseParseFactory();
  try {
   JsonRepresentation represent = new JsonRepresentation(entity);
   JSONObject jsonobject = represent.getJsonObject();
   JSONParser parser = new JSONParser();
   String jsonText = jsonobject.toString();
   json = (Map) parser.parse(jsonText);
   jsonString = processRequest(json,"post");
  } catch (Exception e) {
   e.printStackTrace();
   jsonString = parseFactory.getFailureJsonString(e.getMessage());
  }
  return new StringRepresentation(jsonString, MediaType.APPLICATION_JSON);
 }
 
 @SuppressWarnings("rawtypes")
 @Get
 public Representation doGet(){
  Map json =null;
  parseFactory = new ResponseParseFactory();
  jsonString = "";
  try {
   json = getMapFromParam(getRequest().getResourceRef().getQueryAsForm());
   parseFactory = new ResponseParseFactory();
   jsonString = processRequest(json,"get");
 
  } catch (Exception e) {
   e.printStackTrace();
   jsonString = parseFactory.getFailureJsonString(e.getMessage());
  }
  return new StringRepresentation(jsonString, MediaType.APPLICATION_JSON);
 }
 
 public abstract String processRequest(Map json,String method);
 
 public static Map<String, String> getMapFromParam(Form form) {
  Map<String, String> map = new HashMap<String, String>();
  for (Parameter parameter : form) {
   map.put(parameter.getName(), parameter.getValue());
  }
  return map;
 }
 
}

HelloWorldResource.java

package com.restlet.demo.resource;
 
import java.util.Map;
 
import com.restlet.demo.core.ResponseParseFactory;
 
public class HelloWorldResource extends BaseResource {
 
 public String processRequest(Map json, String method) {
  String returnString = "" ;
  returnString = new ResponseParseFactory().getSuccessJsonString("Hello " + json.get("user"));
  return returnString;
 }
}

log4j.properties

# -----------------------------
# Appender to write to console.
# -----------------------------
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.Target=System.out
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
log4j.appender.CONSOLE.file =${catalina.base}/logs/regularLogging.log
log4j.appender.CONSOLE.MaxFileSize=100KB
 
# ---------------------------------------------
# Appender to write to application log.
# ---------------------------------------------
log4j.appender.APPLICATIONLOG=org.apache.log4j.DailyRollingFileAppender
log4j.appender.APPLICATIONLOG.File=${catalina.base}/logs/restlet-demo.log
log4j.appender.APPLICATIONLOG.DatePattern='.'yyyy-MM-dd
#log4j.appender.APPLICATIONLOG.File=/home/devphp/public_html/restletframework/logs/APPLICATION-LOG.log
log4j.appender.APPLICATIONLOG.Encoding=UTF-8
log4j.appender.APPLICATIONLOG.layout=org.apache.log4j.PatternLayout
log4j.appender.APPLICATIONLOG.layout.ConversionPattern=%d [%5p]: %m%n
 
# Turn off root logging.
#log4j.rootLogger=info, APPLICATIONLOG
log4j.rootLogger=info, CONSOLE , APPLICATIONLOG

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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>RestletDemo</display-name>
 <servlet>
  <servlet-name>RestletServlet</servlet-name>
  <servlet-class>org.restlet.ext.servlet.ServerServlet</servlet-class>
  <init-param>
   <param-name>org.restlet.application</param-name>
   <param-value>com.restlet.demo.application.RestletApplication</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>RestletServlet</servlet-name>
  <url-pattern>/service/*</url-pattern>
 </servlet-mapping>
</web-app>