/*
* Copyright 2002-2016 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
*
* 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.springframework.integration.file;
import java.io.File;
import org.springframework.expression.Expression;
import org.springframework.integration.util.AbstractExpressionEvaluator;
import org.springframework.messaging.Message;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* Default implementation of the filename generator strategy. It evaluates an
* expression against the Message in order to generate the file name. Either
* the 'expression' property can be set directly, or for a simple header name
* to be used as the filename, there is also a {@link #setHeaderName(String)}
* method for convenience. If neither a header name nor custom expression is set,
* the default header name is defined by the constant {@link FileHeaders#FILENAME}.
* If no String-typed value is returned from the expression evaluation (or
* associated with the header if no expression has been provided), it checks if
* the Message payload is a File instance, and if so, it uses the same name.
* Finally, it falls back to the Message ID and adds the suffix '.msg'.
*
* @author Mark Fisher
* @author Gary Russell
* @author Artem Bilan
*/
public class DefaultFileNameGenerator extends AbstractExpressionEvaluator implements FileNameGenerator {
private volatile Expression expression =
EXPRESSION_PARSER.parseExpression("headers['" + FileHeaders.FILENAME + "']");
/**
* Specify an expression to be evaluated against the Message
* in order to generate a file name.
* @param expression The expression.
*/
public void setExpression(String expression) {
Assert.hasText(expression, "expression must not be empty");
this.expression = EXPRESSION_PARSER.parseExpression(expression);
}
/**
* Specify a custom header name to check for the file name.
* The default is defined by {@link FileHeaders#FILENAME}.
* @param headerName The header name.
*/
public void setHeaderName(String headerName) {
Assert.notNull(headerName, "'headerName' must not be null");
this.expression = EXPRESSION_PARSER.parseExpression("headers['" + headerName + "']");
}
@Override
public String generateFileName(Message<?> message) {
Object filename = this.evaluateExpression(this.expression, message);
if (filename instanceof String && StringUtils.hasText((String) filename)) {
return (String) filename;
}
if (message.getPayload() instanceof File) {
return ((File) message.getPayload()).getName();
}
return message.getHeaders().getId() + ".msg";
}
}