/*
* Copyright 2010 Jeff McHugh (Segue Development LLC)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.googlecode.gwtrpccommlayer.server;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.googlecode.gwtrpccommlayer.shared.GwtRpcCommLayerPojoConstants;
import com.googlecode.gwtrpccommlayer.shared.GwtRpcCommLayerPojoRequest;
import com.googlecode.gwtrpccommlayer.shared.GwtRpcCommLayerPojoResponse;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.LinkedList;
/**
* This class can either sit above your servlet (i.e. your servlet extends this) or it can wrap
* your servlet (i.e. it will receive the calls and delegate it to the respective methods
* @author jeff mchugh
*
*/
public abstract class AbstractGwtRpcCommLayerServlet extends RemoteServiceServlet
{
private static final long serialVersionUID = -8829760243946113688L;
Object servletInstance = null;
public AbstractGwtRpcCommLayerServlet() { }
//@Inject
//Can be extended and injected Guice
public AbstractGwtRpcCommLayerServlet(Object servletImplementation)
{
this.servletInstance = servletImplementation;
//this.servletImplementation = servletImplementation;
}
/**
* Initializes the servlet
*/
public void init(ServletConfig config) throws ServletException
{
super.init(config);
/*
* The default is to assume this instance is the selected servlet
*/
servletInstance = this;
/*
* Check to see another servlet should be the target
*/
//todo: this is currently configured using an init param in web.xml. We need to change this to use something guice-friendly!
//maybe use @Inject(optional=true) @Named("CommLayerImplClass") String strImplmentationClass;
String servletImplClassName = config.getInitParameter(GwtRpcCommLayerPojoConstants.GWT_RPC_COMM_LAYER_SERVLET_IMPL_CLASS);
//Use guice injected name instead of init parameter
//if ( servletImplementation != null)
if ( servletImplClassName != null && !servletImplClassName.trim().equals(""))
{
try
{
Class clzz = Class.forName(servletImplClassName);
servletInstance = clzz.newInstance();
}
catch(Throwable t)
{
throw new ServletException(t);
}
}
}
/**
* any servlet that extends can opt to deny these request
* either explicitly or using web.xml
* @return
*/
protected boolean allowGwtRpcPojoRequest()
{
return true;
}
protected void initalizePerRequestPerResponseIfNeeded()
{
if ( super.perThreadRequest == null )
{
super.perThreadRequest = new ThreadLocal<HttpServletRequest>();
}
if ( super.perThreadResponse == null )
{
super.perThreadResponse = new ThreadLocal<HttpServletResponse>();
}
}
/**
* Override the main service call and implement the special handling here
*/
public void service(ServletRequest req, ServletResponse resp) throws ServletException, IOException
{
//need some function intercept <ServletRequest,Boolean>
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
/*
* If the GwtRpcCommLayerClient has made this request, this header should be provided
*/
String gwtClientUserAgent = request.getHeader(GwtRpcCommLayerPojoConstants.GWT_RPC_COMM_LAYER_CLIENT_KEY);
/*
* Only execute this block if:
* - allowGwtRpcPojoRequest() is true
* - is POST
* - gwtClientUserAgent = 'GwtRpcCommLayerPojoRequest'
*/
if ( allowGwtRpcPojoRequest()
&& request.getMethod().equals("POST")
&& gwtClientUserAgent != null
&& gwtClientUserAgent.equalsIgnoreCase(GwtRpcCommLayerPojoConstants.GWT_RPC_COMM_LAYER_POJO_CLIENT))
{
try
{
/*
* This might not be initialized.
* So do it if needed
*/
initalizePerRequestPerResponseIfNeeded();
super.perThreadRequest.set(request);
super.perThreadResponse.set(response);
doServicePojoRequest(request,response);
}
finally
{
super.perThreadRequest.set(null);
super.perThreadResponse.set(null);
}
}
else
{
/*
* Call up the chain and allow one of the implementations handle the request accordingly.
* For an
*/
super.service(req, resp);
}
}
/**
* Reads the request's InputStream and cast it to the correct Object type(s)
* @param req
* @param resp
* @throws javax.servlet.ServletException
* @throws java.io.IOException
*/
protected abstract void doServicePojoRequest(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException;
protected Object getImplementation() {
return this.servletInstance;
}
/**
* Execute the actual method within the GwtRpc servlet
* @param pojoRequest
* @param req
* @param resp
* @throws Throwable
*/
public void executePojoRequest(GwtRpcCommLayerPojoRequest pojoRequest,HttpServletRequest req, HttpServletResponse resp) throws Throwable
{
try
{
/*
* extract the appropriate method
*/
Method method = getMethod(pojoRequest);
/*
* invoke the method
*/
Object returnedInstance = invokeMethod(pojoRequest, method);
/*
* wrap response within a response object
*/
GwtRpcCommLayerPojoResponse pojoResp = new GwtRpcCommLayerPojoResponse();
pojoResp.setResponseInstance( (Serializable) returnedInstance);
/*
* send back the result as a stream set of bytes
*/
serializeResponse(req,resp,pojoRequest,pojoResp);
}
catch(NoSuchMethodException e)
{
log("Method does not found.", e);
resp.sendError(500, e.toString() );
}
catch(InvocationTargetException e)
{
log("Error executing method.", e.getCause());
resp.sendError(500, e.toString() );
}
catch(IllegalAccessException e)
{
log("Error accessing method.", e);
resp.sendError(500, e.toString() );
}
}
/**
* Write the appropriate response
* @param req
* @param resp
* @param pojoRequest
* @param pojoResp
* @throws java.io.IOException
*/
protected void serializeResponse(HttpServletRequest req, HttpServletResponse resp, GwtRpcCommLayerPojoRequest pojoRequest, GwtRpcCommLayerPojoResponse pojoResp) throws IOException
{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream objOut = new ObjectOutputStream(bos);
objOut.writeObject(pojoResp);
objOut.flush();
objOut.close();
resp.setContentType("binary/octet-stream");
resp.setContentLength(bos.toByteArray().length);
OutputStream out = resp.getOutputStream();
out.write(bos.toByteArray());
out.flush();
}
/**
*
* @param stressTestRequest
* @return
* @throws NoSuchMethodException
*/
protected Method getMethod(GwtRpcCommLayerPojoRequest stressTestRequest) throws NoSuchMethodException, ClassNotFoundException {
int count = 0;
Class<?> paramClasses[] = new Class[stressTestRequest.getMethodParameters().size()];
LinkedList<Class<?>> lstParameterClasses = new LinkedList<Class<?>>();
for (String methodName: stressTestRequest.getParameterClassNames()) {
lstParameterClasses.add(Class.forName(methodName));
}
Class[] arrParameterClasses = lstParameterClasses.toArray(new Class[0]);
return getClass().getMethod(stressTestRequest.getMethodName(), arrParameterClasses);
}
/**
*
* @param stressTestRequest
* @param method
* @return
* @throws java.lang.reflect.InvocationTargetException
* @throws IllegalAccessException
*/
protected Object invokeMethod(GwtRpcCommLayerPojoRequest stressTestRequest, Method method) throws InvocationTargetException, IllegalAccessException
{
//todo: call toArray with correct size Object Array
Object paramsAsObjects[] = stressTestRequest.getMethodParameters().toArray( new Object[0]);
Object instance = method.invoke(servletInstance, paramsAsObjects);
return instance;
}
}