Java tutorial
/* * Copyright 2002-2017 the original author or authors. * * 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 * * https://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.springframework.messaging.support; import java.util.Map; import org.springframework.lang.Nullable; import org.springframework.messaging.Message; import org.springframework.messaging.MessageHeaders; /** * A {@link GenericMessage} with a {@link Throwable} payload. * * <p>The payload is typically a {@link org.springframework.messaging.MessagingException} * with the message at the point of failure in its {@code failedMessage} property. * An optional {@code originalMessage} may be provided, which represents the message * that existed at the point in the stack where the error message is created. * * <p>Consider some code that starts with a message, invokes some process that performs * transformation on that message and then fails for some reason, throwing the exception. * The exception is caught and an error message produced that contains both the original * message, and the transformed message that failed. * * @author Mark Fisher * @author Oleg Zhurakousky * @author Gary Russell * @since 4.0 * @see MessageBuilder */ public class ErrorMessage extends GenericMessage<Throwable> { private static final long serialVersionUID = -5470210965279837728L; @Nullable private final Message<?> originalMessage; /** * Create a new message with the given payload. * @param payload the message payload (never {@code null}) */ public ErrorMessage(Throwable payload) { super(payload); this.originalMessage = null; } /** * Create a new message with the given payload and headers. * The content of the given header map is copied. * @param payload the message payload (never {@code null}) * @param headers message headers to use for initialization */ public ErrorMessage(Throwable payload, Map<String, Object> headers) { super(payload, headers); this.originalMessage = null; } /** * A constructor with the {@link MessageHeaders} instance to use. * <p><strong>Note:</strong> the given {@code MessageHeaders} instance * is used directly in the new message, i.e. it is not copied. * @param payload the message payload (never {@code null}) * @param headers message headers */ public ErrorMessage(Throwable payload, MessageHeaders headers) { super(payload, headers); this.originalMessage = null; } /** * Create a new message with the given payload and original message. * @param payload the message payload (never {@code null}) * @param originalMessage the original message (if present) at the point * in the stack where the ErrorMessage was created * @since 5.0 */ public ErrorMessage(Throwable payload, Message<?> originalMessage) { super(payload); this.originalMessage = originalMessage; } /** * Create a new message with the given payload, headers and original message. * The content of the given header map is copied. * @param payload the message payload (never {@code null}) * @param headers message headers to use for initialization * @param originalMessage the original message (if present) at the point * in the stack where the ErrorMessage was created * @since 5.0 */ public ErrorMessage(Throwable payload, Map<String, Object> headers, Message<?> originalMessage) { super(payload, headers); this.originalMessage = originalMessage; } /** * Create a new message with the payload, {@link MessageHeaders} and original message. * <p><strong>Note:</strong> the given {@code MessageHeaders} instance * is used directly in the new message, i.e. it is not copied. * @param payload the message payload (never {@code null}) * @param headers message headers * @param originalMessage the original message (if present) at the point * in the stack where the ErrorMessage was created * @since 5.0 */ public ErrorMessage(Throwable payload, MessageHeaders headers, Message<?> originalMessage) { super(payload, headers); this.originalMessage = originalMessage; } /** * Return the original message (if available) at the point in the stack * where the ErrorMessage was created. * @since 5.0 */ @Nullable public Message<?> getOriginalMessage() { return this.originalMessage; } @Override public String toString() { if (this.originalMessage == null) { return super.toString(); } return super.toString() + " for original " + this.originalMessage; } }