io.undertow.server.handlers.ExceptionHandler Maven / Gradle / Ivy
package io.undertow.server.handlers;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import io.undertow.util.AttachmentKey;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
/**
* Handler that dispatches to a given handler and allows mapping exceptions
* to be handled by additional handlers. The order the exception handlers are
* added is important because of inheritance. Add all child classes before their
* parents in order to use different handlers.
*/
public class ExceptionHandler implements HttpHandler {
public static final AttachmentKey THROWABLE = AttachmentKey.create(Throwable.class);
private final HttpHandler handler;
private final List> exceptionHandlers = new CopyOnWriteArrayList<>();
public ExceptionHandler(HttpHandler handler) {
this.handler = handler;
}
@Override
public void handleRequest(HttpServerExchange exchange) throws Exception {
try {
handler.handleRequest(exchange);
} catch (Throwable throwable) {
for (ExceptionHandlerHolder holder : exceptionHandlers) {
if (holder.getClazz().isInstance(throwable)) {
exchange.putAttachment(THROWABLE, throwable);
holder.getHandler().handleRequest(exchange);
return;
}
}
throw throwable;
}
}
public ExceptionHandler addExceptionHandler(Class clazz, HttpHandler handler) {
exceptionHandlers.add(new ExceptionHandlerHolder<>(clazz, handler));
return this;
}
private static class ExceptionHandlerHolder {
private final Class clazz;
private final HttpHandler handler;
ExceptionHandlerHolder(Class clazz, HttpHandler handler) {
super();
this.clazz = clazz;
this.handler = handler;
}
public Class getClazz() {
return clazz;
}
public HttpHandler getHandler() {
return handler;
}
}
}