juneau-rest/juneau-rest-server/src/main/java/org/apache/juneau/rest/RestServlet.java - juneau - Git at Google

 // ***************************************************************************************************************************
 // * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
 // * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
 // * to you 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 org.apache.juneau.rest;

 import static java.util.logging.Level.*;
 import static javax.servlet.http.HttpServletResponse.*;
 import static org.apache.juneau.internal.StringUtils.*;
 import static org.apache.juneau.internal.ClassUtils.*;

 import java.io.*;
 import java.text.*;
 import java.util.logging.*;

 import javax.servlet.*;
 import javax.servlet.http.*;

 import org.apache.juneau.reflect.*;
 import org.apache.juneau.rest.annotation.*;
 import org.apache.juneau.rest.exception.*;

 /**
  * Servlet implementation of a REST resource.
  *
  * <h5 class='section'>See Also:</h5>
  * <ul>
  * 	<li class='link'>{@doc juneau-rest-server.Instantiation.RestServlet}
  * </ul>
  */
 public abstract class RestServlet extends HttpServlet {

 	private static final long serialVersionUID = 1L;

 	private RestContextBuilder builder;
 	private volatile RestContext context;
 	private volatile Exception initException;
 	private boolean isInitialized = false;  // Should not be volatile.
 	private volatile RestResourceResolver resourceResolver;


 	@Override /* Servlet */
 	public final synchronized void init(ServletConfig servletConfig) throws ServletException {
 		try {
 			if (context != null)
 				return;
 			builder = RestContext.create(servletConfig, this.getClass(), null);
 			if (resourceResolver != null)
 				builder.resourceResolver(resourceResolver);
 			builder.init(this);
 			super.init(servletConfig);
 			builder.servletContext(this.getServletContext());
 			setContext(builder.build());
 			context.postInitChildFirst();
 		} catch (RestException e) {
 			// Thrown RestExceptions are simply caught and re-thrown on subsequent calls to service().
 			initException = e;
 			log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
 		} catch (ServletException e) {
 			initException = e;
 			log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
 			throw e;
 		} catch (Exception e) {
 			initException = e;
 			log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
 			throw new ServletException(e);
 		} catch (Throwable e) {
 			initException = new Exception(e);
 			log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
 			throw new ServletException(e);
 		}
 	}

 	/*
 	 * Bypasses the init(ServletConfig) method and just calls the super.init(ServletConfig) method directly.
 	 * Used when subclasses of RestServlet are attached as child resources.
 	 */
 	synchronized void innerInit(ServletConfig servletConfig) throws ServletException {
 		super.init(servletConfig);
 	}

 	/**
 	 * Sets the context object for this servlet.
 	 *
 	 * @param context
 	 * @throws ServletException
 	 */
 	public synchronized void setContext(RestContext context) throws ServletException {
 		this.builder = context.builder;
 		this.context = context;
 		isInitialized = true;
 		context.postInit();
 	}

 	/**
 	 * Sets the resource resolver to use for this servlet and all child servlets.
 	 * <p>
 	 * This method can be called immediately following object construction, but must be called before {@link #init(ServletConfig)} is called.
 	 * Otherwise calling this method will have no effect.
 	 *
 	 * @param resourceResolver The resolver instance.  Can be <jk>null</jk>.
 	 * @return This object (for method chaining).
 	 */
 	public synchronized RestServlet setRestResourceResolver(RestResourceResolver resourceResolver) {
 		this.resourceResolver = resourceResolver;
 		return this;
 	}

 	/**
 	 * Returns the path defined on this servlet if it's defined via {@link RestResource#path()}.
 	 *
 	 * @return The path defined on this servlet, or an empty string if not specified.
 	 */
 	public synchronized String getPath() {
 		if (context != null)
 			return context.getPath();
 		ClassInfo ci = getClassInfo(getClass());
 		for (RestResource rr : ci.getAnnotations(RestResource.class))
 			if (! rr.path().isEmpty())
 				return trimSlashes(rr.path());
 		return "";
 	}

 	@Override /* GenericServlet */
 	public synchronized RestContextBuilder getServletConfig() {
 		return builder;
 	}

 	/**
 	 * Returns the read-only context object that contains all the configuration information about this resource.
 	 *
 	 * <p>
 	 * This object is <jk>null</jk> during the call to {@link #init(ServletConfig)} but is populated by the time
 	 * {@link #init()} is called.
 	 *
 	 * <p>
 	 * Resource classes that don't extend from {@link RestServlet} can add the following method to their class to get
 	 * access to this context object:
 	 * <p class='bcode w800'>
 	 * 	<jk>public void</jk> init(RestServletContext context) <jk>throws</jk> Exception;
 	 * </p>
 	 *
 	 * @return The context information on this servlet.
 	 */
 	protected synchronized RestContext getContext() {
 		return context;
 	}


 	//-----------------------------------------------------------------------------------------------------------------
 	// Other methods
 	//-----------------------------------------------------------------------------------------------------------------

 	/**
 	 * The main service method.
 	 *
 	 * <p>
 	 * Subclasses can optionally override this method if they want to tailor the behavior of requests.
 	 */
 	@Override /* Servlet */
 	public void service(HttpServletRequest r1, HttpServletResponse r2) throws ServletException, InternalServerError, IOException {
 		try {
 			// To avoid checking the volatile field context on every call, use the non-volatile isInitialized field as a first-check check.
 			if (! isInitialized) {
 				if (initException != null) {
 					if (initException instanceof RestException)
 						throw (RestException)initException;
 					throw new InternalServerError(initException);
 				}
 				if (context == null)
 					throw new InternalServerError("Servlet {0} not initialized.  init(ServletConfig) was not called.  This can occur if you've overridden this method but didn't call super.init(RestConfig).", getClass().getName());
 				isInitialized = true;
 			}

 			context.getCallHandler().service(r1, r2);

 		} catch (RestException e) {
 			r2.sendError(SC_INTERNAL_SERVER_ERROR, e.getLocalizedMessage());
 		} catch (Throwable e) {
 			r2.sendError(SC_INTERNAL_SERVER_ERROR, e.getLocalizedMessage());
 		}
 	}

 	@Override /* GenericServlet */
 	public void log(String msg) {
 		if (context != null)
 			context.getLogger().log(INFO, msg);
 	}

 	@Override /* GenericServlet */
 	public void log(String msg, Throwable cause) {
 		if (context != null)
 			context.getLogger().log(INFO, cause, msg);
 	}

 	/**
 	 * Convenience method for calling <code>getContext().getLogger().log(level, msg, args);</code>
 	 *
 	 * @param level The log level.
 	 * @param msg The message to log.
 	 * @param args Optional {@link MessageFormat}-style arguments.
 	 */
 	public void log(Level level, String msg, Object...args) {
 		if (context != null)
 			context.getLogger().log(level, msg, args);
 	}

 	/**
 	 * Convenience method for calling <code>getContext().getLogger().logObjects(level, msg, args);</code>
 	 *
 	 * @param level The log level.
 	 * @param msg The message to log.
 	 * @param args Optional {@link MessageFormat}-style arguments.
 	 */
 	public void logObjects(Level level, String msg, Object...args) {
 		if (context != null)
 			context.getLogger().logObjects(level, msg, args);
 	}

 	/**
 	 * Convenience method for calling <code>getContext().getLogger().log(level, cause, msg, args);</code>
 	 *
 	 * @param level The log level.
 	 * @param cause The cause.
 	 * @param msg The message to log.
 	 * @param args Optional {@link MessageFormat}-style arguments.
 	 */
 	public void log(Level level, Throwable cause, String msg, Object...args) {
 		if (context != null)
 			context.getLogger().log(level, cause, msg, args);
 		else {
 			// If context failed to initialize, log to the console.
 			System.err.println(format(msg, args));
 			if (cause != null)
 				cause.printStackTrace();
 		}
 	}

 	/**
 	 * Returns the current HTTP request.
 	 *
 	 * @return The current HTTP request, or <jk>null</jk> if it wasn't created.
 	 */
 	public RestRequest getRequest() {
 		if (context == null)
 			return null;
 		return context.getRequest();
 	}

 	/**
 	 * Returns the current HTTP response.
 	 *
 	 * @return The current HTTP response, or <jk>null</jk> if it wasn't created.
 	 */
 	public RestResponse getResponse() {
 		if (context == null)
 			return null;
 		return context.getResponse();
 	}

 	@Override /* GenericServlet */
 	public synchronized void destroy() {
 		if (context != null)
 			context.destroy();
 		super.destroy();
 	}

 	/**
 	 * Convenience method for calling <code>getContext().getProperties();</code>
 	 *
 	 * @return The resource properties as an {@link RestContextProperties}.
 	 * @see RestContext#getProperties()
 	 */
 	public RestContextProperties getProperties() {
 		return getContext().getProperties();
 	}
 }
	// ***************************************************************************************************************************
	// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file *
	// * distributed with this work for additional information regarding copyright ownership. The ASF licenses this file *
	// * to you 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 org.apache.juneau.rest;

	import static java.util.logging.Level.*;
	import static javax.servlet.http.HttpServletResponse.*;
	import static org.apache.juneau.internal.StringUtils.*;
	import static org.apache.juneau.internal.ClassUtils.*;

	import java.io.*;
	import java.text.*;
	import java.util.logging.*;

	import javax.servlet.*;
	import javax.servlet.http.*;

	import org.apache.juneau.reflect.*;
	import org.apache.juneau.rest.annotation.*;
	import org.apache.juneau.rest.exception.*;

	/**
	* Servlet implementation of a REST resource.
	*
	* <h5 class='section'>See Also:</h5>
	* <ul>
	* <li class='link'>{@doc juneau-rest-server.Instantiation.RestServlet}
	* </ul>
	*/
	public abstract class RestServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	private RestContextBuilder builder;
	private volatile RestContext context;
	private volatile Exception initException;
	private boolean isInitialized = false; // Should not be volatile.
	private volatile RestResourceResolver resourceResolver;


	@Override /* Servlet */
	public final synchronized void init(ServletConfig servletConfig) throws ServletException {
	try {
	if (context != null)
	return;
	builder = RestContext.create(servletConfig, this.getClass(), null);
	if (resourceResolver != null)
	builder.resourceResolver(resourceResolver);
	builder.init(this);
	super.init(servletConfig);
	builder.servletContext(this.getServletContext());
	setContext(builder.build());
	context.postInitChildFirst();
	} catch (RestException e) {
	// Thrown RestExceptions are simply caught and re-thrown on subsequent calls to service().
	initException = e;
	log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
	} catch (ServletException e) {
	initException = e;
	log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
	throw e;
	} catch (Exception e) {
	initException = e;
	log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
	throw new ServletException(e);
	} catch (Throwable e) {
	initException = new Exception(e);
	log(SEVERE, e, "Servlet init error on class ''{0}''", getClass().getName());
	throw new ServletException(e);
	}
	}

	/*
	* Bypasses the init(ServletConfig) method and just calls the super.init(ServletConfig) method directly.
	* Used when subclasses of RestServlet are attached as child resources.
	*/
	synchronized void innerInit(ServletConfig servletConfig) throws ServletException {
	super.init(servletConfig);
	}

	/**
	* Sets the context object for this servlet.
	*
	* @param context
	* @throws ServletException
	*/
	public synchronized void setContext(RestContext context) throws ServletException {
	this.builder = context.builder;
	this.context = context;
	isInitialized = true;
	context.postInit();
	}

	/**
	* Sets the resource resolver to use for this servlet and all child servlets.
	* <p>
	* This method can be called immediately following object construction, but must be called before {@link #init(ServletConfig)} is called.
	* Otherwise calling this method will have no effect.
	*
	* @param resourceResolver The resolver instance. Can be <jk>null</jk>.
	* @return This object (for method chaining).
	*/
	public synchronized RestServlet setRestResourceResolver(RestResourceResolver resourceResolver) {
	this.resourceResolver = resourceResolver;
	return this;
	}

	/**
	* Returns the path defined on this servlet if it's defined via {@link RestResource#path()}.
	*
	* @return The path defined on this servlet, or an empty string if not specified.
	*/
	public synchronized String getPath() {
	if (context != null)
	return context.getPath();
	ClassInfo ci = getClassInfo(getClass());
	for (RestResource rr : ci.getAnnotations(RestResource.class))
	if (! rr.path().isEmpty())
	return trimSlashes(rr.path());
	return "";
	}

	@Override /* GenericServlet */
	public synchronized RestContextBuilder getServletConfig() {
	return builder;
	}

	/**
	* Returns the read-only context object that contains all the configuration information about this resource.
	*
	* <p>
	* This object is <jk>null</jk> during the call to {@link #init(ServletConfig)} but is populated by the time
	* {@link #init()} is called.
	*
	* <p>
	* Resource classes that don't extend from {@link RestServlet} can add the following method to their class to get
	* access to this context object:
	* <p class='bcode w800'>
	* <jk>public void</jk> init(RestServletContext context) <jk>throws</jk> Exception;
	* </p>
	*
	* @return The context information on this servlet.
	*/
	protected synchronized RestContext getContext() {
	return context;
	}


	//-----------------------------------------------------------------------------------------------------------------
	// Other methods
	//-----------------------------------------------------------------------------------------------------------------

	/**
	* The main service method.
	*
	* <p>
	* Subclasses can optionally override this method if they want to tailor the behavior of requests.
	*/
	@Override /* Servlet */
	public void service(HttpServletRequest r1, HttpServletResponse r2) throws ServletException, InternalServerError, IOException {
	try {
	// To avoid checking the volatile field context on every call, use the non-volatile isInitialized field as a first-check check.
	if (! isInitialized) {
	if (initException != null) {
	if (initException instanceof RestException)
	throw (RestException)initException;
	throw new InternalServerError(initException);
	}
	if (context == null)
	throw new InternalServerError("Servlet {0} not initialized. init(ServletConfig) was not called. This can occur if you've overridden this method but didn't call super.init(RestConfig).", getClass().getName());
	isInitialized = true;
	}

	context.getCallHandler().service(r1, r2);

	} catch (RestException e) {
	r2.sendError(SC_INTERNAL_SERVER_ERROR, e.getLocalizedMessage());
	} catch (Throwable e) {
	r2.sendError(SC_INTERNAL_SERVER_ERROR, e.getLocalizedMessage());
	}
	}

	@Override /* GenericServlet */
	public void log(String msg) {
	if (context != null)
	context.getLogger().log(INFO, msg);
	}

	@Override /* GenericServlet */
	public void log(String msg, Throwable cause) {
	if (context != null)
	context.getLogger().log(INFO, cause, msg);
	}

	/**
	* Convenience method for calling <code>getContext().getLogger().log(level, msg, args);</code>
	*
	* @param level The log level.
	* @param msg The message to log.
	* @param args Optional {@link MessageFormat}-style arguments.
	*/
	public void log(Level level, String msg, Object...args) {
	if (context != null)
	context.getLogger().log(level, msg, args);
	}

	/**
	* Convenience method for calling <code>getContext().getLogger().logObjects(level, msg, args);</code>
	*
	* @param level The log level.
	* @param msg The message to log.
	* @param args Optional {@link MessageFormat}-style arguments.
	*/
	public void logObjects(Level level, String msg, Object...args) {
	if (context != null)
	context.getLogger().logObjects(level, msg, args);
	}

	/**
	* Convenience method for calling <code>getContext().getLogger().log(level, cause, msg, args);</code>
	*
	* @param level The log level.
	* @param cause The cause.
	* @param msg The message to log.
	* @param args Optional {@link MessageFormat}-style arguments.
	*/
	public void log(Level level, Throwable cause, String msg, Object...args) {
	if (context != null)
	context.getLogger().log(level, cause, msg, args);
	else {
	// If context failed to initialize, log to the console.
	System.err.println(format(msg, args));
	if (cause != null)
	cause.printStackTrace();
	}
	}

	/**
	* Returns the current HTTP request.
	*
	* @return The current HTTP request, or <jk>null</jk> if it wasn't created.
	*/
	public RestRequest getRequest() {
	if (context == null)
	return null;
	return context.getRequest();
	}

	/**
	* Returns the current HTTP response.
	*
	* @return The current HTTP response, or <jk>null</jk> if it wasn't created.
	*/
	public RestResponse getResponse() {
	if (context == null)
	return null;
	return context.getResponse();
	}

	@Override /* GenericServlet */
	public synchronized void destroy() {
	if (context != null)
	context.destroy();
	super.destroy();
	}

	/**
	* Convenience method for calling <code>getContext().getProperties();</code>
	*
	* @return The resource properties as an {@link RestContextProperties}.
	* @see RestContext#getProperties()
	*/
	public RestContextProperties getProperties() {
	return getContext().getProperties();
	}
	}