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How to implement own factory in Spring

I have three or more types of request that come in form of JSON data and convert to object.
Let's say that there is a request:
{
"id":1,
"type":"0",
"url":
"http://stackoverflow.com"
}
And I want to build some sort of conncetion factory that allows me to get pages like that:
Request request = new Request(json);
Response response = request.execute();
Of course the execute method has different implementation for each of the request's types.
I have a prototype that is written in plain JavaSE and I want to migrate to Spring Framework and also get some feedback about my code if it has problems. First of all I built a SimpleRequest that just obtains the page and returns the body.
class SimpleRequest implements Request{
Package requestData;
#Override
public Connection.Response execute() throws IOException {
Connection.Response response = Jsoup
.connect(requestData.getUrl())
.execute();
return response;
}
public void bind(Package requestData){
this.requestData = requestData;
}
}
This method just fetch the page. Nothing interesting.
Also I have RequestTemplate that prepare request:
class RequestTemplate{
Package requestData;
RequestFactory requestFactory = new RequestFactory();
Request request;
public RequestTemplate(Package requestData){
this.requestData = requestData;
try {
request = requestFactory.getRequestInstance(requestData.getType());
request.bind(requestData);
}catch (Exception e){
e.printStackTrace();
}
}
public Connection.Response execute(){
Connection.Response connection = null;
try{
connection = request.execute();
}catch (Exception e){
e.printStackTrace();
}
return connection;
}
}
This method obtains an object based of RequestType;
And of course I have RequestFactory that has a description of objects and create new Instances of them.
class RequestFactory{
public Request getRequestInstance(RequestType type) throws Exception {
switch (type){
case SIMPLE:
return new SimpleRequest();
default:
throw new Exception("Error");
}
}}
So we check the RequestType type matching with the enum list and return new instance.
I also what to implement something like that in my small project that are based on Spring Framework and there are two issues.
As I understand the code above is a bit messy and has some performance problems. I think that I'll use the code to serve lots of connection so that I have to optimize it somehow because of memory limit and so on.
Integration with Spring. It's a framework so I think there should be some features that could make my life easier. I've read about FactoryBean, but haven't caught how to wire it with my task. As I mentioned above that the code is a bit messy and i think that i created to much abstraction.
Thanks.

How to connect EJB, REST and Client?

I have 2 java projects in netbeans and I want to connect them. First is based on Jboss server and contains ejb and rest. EJB connects with databse and rest service packs object to xml and sends to client witch is standard swing based gui application. Problem is that I don't know what to do next, because I got null pointer exception when I try to recive any data from server. Am I doing it right way? Maybe my whole idea is wrong? Please help.
EDIT:
I figured that the fault is on server side. I don't know how to create a rest service. In class WholesaleREST in netbeans there were warning that rest is not configured. I clicked "Configure REST with Java EE6 Specification" and server can't deploy it and throws an error:
Deployment "vfs:///E:/Instalki/jboss/jboss-as-distribution-6.1.0.Final/jboss-6.1.0.Final/server/default/deploy/WholesaleApp.war" is in error due to the following reason(s): org.jboss.deployers.spi.DeploymentException: URL file:/E:/Instalki/jboss/jboss-as-distribution-6.1.0.Final/jboss-6.1.0.Final/server/default/tmp/vfs/automount6dbf7312f2f10b36/WholesaleApp.war-1ad4d6611c73bd02/ deployment failed
This error doesn't tell me anything about it and I dont know what to do. Any Ideas please?
End of added text, rest below is old.
Here is code I wrote:
EJB class:
#Stateless
public class WholesaleEJB {
#PersistenceContext(name="WholesaleAppPU")
EntityManager entityManager;
public List<Clients> getClients() {
Query q = entityManager.createQuery("select c from Clients c");
#SuppressWarnings("unchecked")
List<Clients> lista = q.getResultList();
return lista;
}
}
Rest class:
#Path("/wholesale")
#Stateless
public class WholesaleREST implements WholesaleInterface{
#EJB
WholesaleEJB bean;
#Override
#GET
#Path("/get")
public String getCars() {
List<Clients> listOfClients = bean.getClients();
StringWriter sw = new StringWriter();
ClientsContainer container = new ClientsContainer(listOfClients);
JAXB.marshal(container, sw);
return sw.toString();
}
}
Client side class with get method
public class HttpConnector {
public static String doGet(String url) {
try {
URLConnection connection = new URL(url).openConnection();
String charset = "UTF-8";
connection.setRequestProperty("Accept-Charset", charset);
return getResponse(connection);
} catch (Exception ex) {
ex.getMessage();
}
return null;
}
private static String getResponse(URLConnection connection)
throws UnsupportedEncodingException, IOException {
InputStream response = connection.getInputStream();
final char[] buffer = new char[0x10000];
StringBuilder out = new StringBuilder();
Reader in = new InputStreamReader(response, "UTF-8");
int read;
do {
read = in.read(buffer, 0, buffer.length);
if (read>0) {
out.append(buffer, 0, read);
}
} while (read>=0);
return out.toString();
}
}
And last class which access ejb methods from client side:
public class ClientRemoteAccess implements ClientInterface{
String url = "http://localhost:8080/WholesaleApp/wholesale";
#Override
public List<Clients> getClients() {
String recivedXML = HttpConnector.doGet(url+"/get");
ClientsContainer container = JAXB.unmarshal(
new StringReader(recivedXML), ClientsContainer.class);
return container.getListOfClients();
}
}

I think the architecture you want to achieve is something like this:
common-model: here you place the domain model, for example the JPA entities and the class ClientsContainer
restfull-service: depends on the common-model and contains the EJB/JPA layer that communicates with the database and the RESTful web service that exposes the data as resources.
restful-client: the swing rich client that depends on the common-model and communicates with the restfull-service via HTTP.
Note that there is no direct communication between the EJB and the client.

Java- redirecting a request

I'm writing a Servlet in Java, that basically, gets a request with a XML in the Requests body, and then changes a few things in the XML and redirect/foreword the request with The new XML to a different Servlet that's on the same server, but its on a different web app.
How do redirect/foreword the request with The new XML? can i find code example any where?
this is what i have so far:
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String body = getBody(request);
MapXml mapXml = new MapXml(body,
"C:\\Projects\\XmlMapper\\output.xml","C:\\Projects\\XmlMapper\\output\\");
String outputXml = mapXml.getOutputXml();
}
public static String getBody(HttpServletRequest request) throws IOException {
String body = null;
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try {
InputStream inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
stringBuilder.append("");
}
} catch (IOException ex) {
throw ex;
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException ex) {
throw ex;
}
}
}
body = stringBuilder.toString();
return body;
}
And i have no idea how to continue on from here. I'm new to the servlet world.. Thanks!!! Cheers:)

If both web-apps are on the same server, i.e. Tomcat
in its META-INF/context.xml set <Context crossContext="true" />
getServletContext().getContext("/app").getRequestDispatcher("f.jsp").forward(..);,
where app is the name of the other application.
Or what you maybe should do is, Use URLConnection to send request to any URL.
URLConnection connection = new URL(url + "?" + query).openConnection();
connection.setRequestProperty("Accept-Charset", charset);
InputStream response = connection.getInputStream();
// ...
About how to set XML in request, you can carry relatively larger amounts of data in POST request. You can also find the max limit of POST data.
just read the bytes that make up the XML file (using FileInputStream)
(if you dont have xml in file, use String to create ur xml)and send
them in the POST body. Make sure to set the content encoding
accordingly.
I am editing this for the 4th time, to add more details.
You can use Apache HTTP Client to post XML easily if its difficult for you to use Java's HTTP client.
String xml = "your xml";
PostMethod post = new PostMethod(strURL);
try {
StringRequestEntity requestEntity = new StringRequestEntity(xml);
post.setRequestEntity(requestEntity); ..
....
...

Because the xml will not be a small body for request,so you have to let the client post the new xml for you. or you can do:
share the same database or cache with remote web service, and forward the key of the data in database or cache.
use HttpClient to post the request for your client, with modified xml, and return the response from remote service to your client.
if you can make sure the xml body is small, you can just using GET method, forward the request to remote server

Let's rule out some possibilities first:
You cannot do response.sendRedirect("/otherapp/servlet.do") since it doesn't let you send POST data to another webapp.
You cannot use session since you're sending data across to a different webapp.
You cannot obviously pass full XML in a query string using GET.
Once those possibilities are ruled out only possible way I can think of is this:
Return to the calling page with modified XML and URL of other webapps's servelt in response
Let calling page immediately POST the modified XML to other webapps's servelt using simple Javascript

Fetching JSON object from Servlet Java

I want to create an application that will fetch a JSON object from a servlet to deserialize it, and then use its variables to do other things.
My servlet has the following code in the doPost:
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
ObjectOutputStream os;
os = new ObjectOutputStream(response.getOutputStream());
String s = new String("A String");
Gson gson = new Gson();
String gsonObject= gson.toJson(s);
os.writeObject(gsonObject);
os.close();
}
Now, while the servlet is running, I can access it via a browser, if I post same code in the doGet method, that would download a servlet file, which is not what I want.
What should I use in my second application that would connect to the servlet, fetch the object, so that I can manipulate it later?
Thanks in advance.

You need few changes in your servlet :
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String s = new String("A String");
String json = new Gson().toJson(s);
this.response.setContentType("application/json");
this.response.setCharacterEncoding("UTF-8");
Writer writer = null;
try {
writer = this.response.getWriter();
writer.write(json);
} finally {
try {
writer.close();
}
catch (IOException ex) {
}
}
}

If its downloading the servlet file instead of showing it in the browser , most probably you have not set the content type in the response. If you are writing a JSON string as the servlet response , you have to use
response.setContentType("text/html");
response.getWriter().write(json);
Please note the order , its "text/html" and not "html/text"

IfI understood the question correctly then you can use, java.net.HttpURLConnection and java.net.URL objects to create a connection to this servlet and read the JSON streamed by the above JSON servlet in your second servlet.

Proxy servlet hangs on HttpClient.execute()

I need to write a servlet that basically just proxies each incoming request to the same URL path on a different host. Here's what I came up with using Apache Commons Http Client 4.1.3:
#WebServlet("/data/*")
public class ProxyServlet extends HttpServlet {
protected void doGet (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpClient client = new DefaultHttpClient();
try {
String url = getMappedServiceUrlFromRequest(request);
HttpGet get = new HttpGet(url);
copyRequestHeaders(request, get);
HttpResponse getResp = client.execute(get);
response.setStatus(getResp.getStatusLine().getStatusCode());
copyResponseHeaders(getResp, response);
HttpEntity entity = getResp.getEntity();
if (entity != null) {
OutputStream os = response.getOutputStream();
try {
entity.writeTo(os);
} finally {
try { os.close(); } catch (Exception ignored) { }
}
}
} catch (Exception e) {
throw new ServletException(e);
} finally {
client.getConnectionManager().shutdown();
}
}
private void getMappedServiceUrlFromRequest (...)
private void copyResponseHeaders (...)
private void copyRequestHeaders (...)
}
This works just fine the first time the servlet is called. However, after the first time, the servlet hangs on the line client.execute(get).
There are plenty of Google hits for "HttpClient execute hangs", most of which suggest using an instance of ThreadSafeClientConnManager. Tried that, sadly didn't help.
I've spent several hours googling for the problem, but I haven't found anything that fixes it yet. I'd seriously appreciate any pointers as to what I am doing wrong here.

I suggest you are doing this the hard way. Just write a Filter that does the redirect.
Or even just a TCP server that listens at the port and just copies bytes back and forth. You don't really need to engage in the HTTP protocol at all in a proxy, unless you are implementing the CONNECT command, in which case that's the only piece of HTTP you need to understand, and its reply is the only HTTP response you need to know about. Everything else is just bytes.