org.apache.juneau.rest.servlet.RestServlet Maven / Gradle / Ivy
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// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance *
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// * *
// * 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.servlet;
import static java.util.logging.Level.*;
import static jakarta.servlet.http.HttpServletResponse.*;
import static org.apache.juneau.common.internal.StringUtils.*;
import static org.apache.juneau.internal.ClassUtils.*;
import java.io.*;
import java.text.*;
import java.util.concurrent.atomic.*;
import java.util.function.*;
import java.util.logging.*;
import jakarta.servlet.*;
import jakarta.servlet.http.*;
import org.apache.juneau.reflect.*;
import org.apache.juneau.rest.*;
import org.apache.juneau.rest.annotation.*;
import org.apache.juneau.*;
import org.apache.juneau.common.internal.*;
import org.apache.juneau.http.response.*;
/**
* Servlet implementation of a REST resource.
*
*
* The {@link RestServlet} class is the entry point for your REST resources.
* It extends directly from HttpServlet and is deployed like any other servlet.
*
*
* When the servlet init() method is called, it triggers the code to find and process the @Rest
* annotations on that class and all child classes.
* These get constructed into a {@link RestContext} object that holds all the configuration
* information about your resource in a read-only object.
*
*
* Notes:
* -
* Users will typically extend from {@link BasicRestServlet} or {@link BasicRestServletGroup}
* instead of this class directly.
*
*
* See Also:
*
* @serial exclude
*/
public abstract class RestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private AtomicReference context = new AtomicReference<>();
private AtomicReference initException = new AtomicReference<>();
@Override /* Servlet */
public synchronized void init(ServletConfig servletConfig) throws ServletException {
try {
if (context.get() != null)
return;
super.init(servletConfig);
context.set(RestContext.create(this.getClass(), null, servletConfig).init(()->this).build());
context.get().postInit();
context.get().postInitChildFirst();
} catch (ServletException e) {
initException.set(e);
log(SEVERE, e, "Servlet init error on class ''{0}''", className(this));
throw e;
} catch (BasicHttpException e) {
initException.set(e);
log(SEVERE, e, "Servlet init error on class ''{0}''", className(this));
} catch (Throwable e) {
initException.set(new InternalServerError(e));
log(SEVERE, e, "Servlet init error on class ''{0}''", className(this));
}
}
/**
* Sets the context object for this servlet.
*
*
* This method is effectively a no-op if {@link #init(ServletConfig)} has already been called.
*
* @param context Sets the context object on this servlet.
* @throws ServletException If error occurred during initialization.
*/
protected void setContext(RestContext context) throws ServletException {
if (this.context.get() == null) {
super.init(context.getBuilder());
this.context.set(context);
}
}
/**
* Returns the path for this resource as defined by the @Rest(path) annotation or RestContext.Builder.path(String) method
* concatenated with those on all parent classes.
*
* @return The path defined on this servlet, or an empty string if not specified.
*/
public synchronized String getPath() {
RestContext context = this.context.get();
if (context != null)
return context.getFullPath();
ClassInfo ci = ClassInfo.of(getClass());
Value path = Value.empty();
ci.forEachAnnotation(Rest.class, x -> isNotEmpty(x.path()), x -> path.set(trimSlashes(x.path())));
return path.orElse("");
}
//-----------------------------------------------------------------------------------------------------------------
// Lifecycle methods
//-----------------------------------------------------------------------------------------------------------------
/**
* The main service method.
*
*
* 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 {
if (initException.get() != null)
throw initException.get();
if (context.get() == 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).", className(this));
getContext().execute(this, r1, r2);
} catch (Throwable e) {
r2.sendError(SC_INTERNAL_SERVER_ERROR, e.getLocalizedMessage());
}
}
@Override /* GenericServlet */
public synchronized void destroy() {
if (context.get() != null)
context.get().destroy();
super.destroy();
}
//-----------------------------------------------------------------------------------------------------------------
// Context methods.
//-----------------------------------------------------------------------------------------------------------------
/**
* Returns the read-only context object that contains all the configuration information about this resource.
*
*
* This object is null during the call to {@link #init(ServletConfig)} but is populated by the time
* {@link #init()} is called.
*
*
* Resource classes that don't extend from {@link RestServlet} can add the following method to their class to get
* access to this context object:
*
* public void init(RestServletContext context ) throws Exception;
*
*
* @return The context information on this servlet.
*/
public synchronized RestContext getContext() {
RestContext rc = context.get();
if (rc == null)
throw new InternalServerError("RestContext object not set on resource.");
return rc;
}
//-----------------------------------------------------------------------------------------------------------------
// Convenience logger methods
//-----------------------------------------------------------------------------------------------------------------
/**
* Log a message.
*
*
* Subclasses can intercept the handling of these messages by overriding {@link #doLog(Level, Throwable, Supplier)}.
*
* @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) {
doLog(level, null, () -> StringUtils.format(msg, args));
}
/**
* Log a message.
*
*
* Subclasses can intercept the handling of these messages by overriding {@link #doLog(Level, Throwable, Supplier)}.
*
* @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) {
doLog(level, cause, () -> StringUtils.format(msg, args));
}
/**
* Main logger method.
*
*
* The default behavior logs a message to the Java logger of the class name.
*
*
* Subclasses can override this method to implement their own logger handling.
*
* @param level The log level.
* @param cause Optional throwable.
* @param msg The message to log.
*/
protected void doLog(Level level, Throwable cause, Supplier msg) {
RestContext c = context.get();
Logger logger = c == null ? null : c.getLogger();
if (logger == null)
logger = Logger.getLogger(className(this));
logger.log(level, cause, msg);
}
//-----------------------------------------------------------------------------------------------------------------
// Other methods
//-----------------------------------------------------------------------------------------------------------------
/**
* Returns the current thread-local HTTP request.
*
* @return The current thread-local HTTP request, or null if it wasn't created.
*/
public synchronized RestRequest getRequest() {
return getContext().getLocalSession().getOpSession().getRequest();
}
/**
* Returns the current thread-local HTTP response.
*
* @return The current thread-local HTTP response, or null if it wasn't created.
*/
public synchronized RestResponse getResponse() {
return getContext().getLocalSession().getOpSession().getResponse();
}
}