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/*
* Copyright 2002-2019 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.integration.expression;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.expression.BeanFactoryResolver;
import org.springframework.context.expression.MapAccessor;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.io.Resource;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.DataBindingPropertyAccessor;
import org.springframework.expression.spel.support.SimpleEvaluationContext;
import org.springframework.expression.spel.support.SimpleEvaluationContext.Builder;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.expression.spel.support.StandardTypeConverter;
import org.springframework.integration.context.IntegrationContextUtils;
import org.springframework.integration.support.utils.IntegrationUtils;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.util.Assert;
import org.springframework.util.ResourceUtils;
/**
* Utility class with static methods for helping with evaluation of SpEL expressions.
*
* @author Gary Russell
* @author Oleg Zhurakousky
* @author Artem Bilan
*
* @since 2.2
*/
public final class ExpressionUtils {
private static final ExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();
private static final Log LOGGER = LogFactory.getLog(ExpressionUtils.class);
private ExpressionUtils() {
super();
}
/**
* Used to create a context with no BeanFactory, usually in tests.
* @return The evaluation context.
*/
public static StandardEvaluationContext createStandardEvaluationContext() {
return (StandardEvaluationContext) doCreateContext(null, false);
}
/**
* Used to create a context with no BeanFactory, usually in tests.
* @return The evaluation context.
* @since 4.3.15
*/
public static SimpleEvaluationContext createSimpleEvaluationContext() {
return (SimpleEvaluationContext) doCreateContext(null, true);
}
/**
* Obtains the context from the beanFactory if not null; emits a warning if the beanFactory
* is null.
* @param beanFactory The bean factory.
* @return The evaluation context.
*/
public static StandardEvaluationContext createStandardEvaluationContext(@Nullable BeanFactory beanFactory) {
if (beanFactory == null) {
LOGGER.warn("Creating EvaluationContext with no beanFactory", new RuntimeException("No beanFactory"));
}
return (StandardEvaluationContext) doCreateContext(beanFactory, false);
}
/**
* Obtains the context from the beanFactory if not null; emits a warning if the beanFactory
* is null.
* @param beanFactory The bean factory.
* @return The evaluation context.
* @since 4.3.15
*/
public static SimpleEvaluationContext createSimpleEvaluationContext(@Nullable BeanFactory beanFactory) {
if (beanFactory == null) {
LOGGER.warn("Creating EvaluationContext with no beanFactory", new RuntimeException("No beanFactory"));
}
return (SimpleEvaluationContext) doCreateContext(beanFactory, true);
}
private static EvaluationContext doCreateContext(@Nullable BeanFactory beanFactory, boolean simple) {
ConversionService conversionService = null;
EvaluationContext evaluationContext = null;
if (beanFactory != null) {
evaluationContext =
simple
? IntegrationContextUtils.getSimpleEvaluationContext(beanFactory)
: IntegrationContextUtils.getEvaluationContext(beanFactory);
}
if (evaluationContext == null) {
if (beanFactory != null) {
conversionService = IntegrationUtils.getConversionService(beanFactory);
}
evaluationContext = createEvaluationContext(conversionService, beanFactory, simple);
}
return evaluationContext;
}
/**
* Create a {@link StandardEvaluationContext} with a {@link MapAccessor} in its
* property accessor property and the supplied {@link ConversionService} in its
* conversionService property.
* @param conversionService the conversion service.
* @param beanFactory the bean factory.
* @param simple true if simple.
* @return the evaluation context.
*/
private static EvaluationContext createEvaluationContext(@Nullable ConversionService conversionService,
@Nullable BeanFactory beanFactory, boolean simple) {
if (simple) {
Builder ecBuilder = SimpleEvaluationContext.forPropertyAccessors(
new MapAccessor(), DataBindingPropertyAccessor.forReadOnlyAccess())
.withInstanceMethods();
if (conversionService != null) {
ecBuilder.withConversionService(conversionService);
}
return ecBuilder.build();
}
else {
StandardEvaluationContext evaluationContext = new StandardEvaluationContext();
evaluationContext.addPropertyAccessor(new MapAccessor());
if (conversionService != null) {
evaluationContext.setTypeConverter(new StandardTypeConverter(conversionService));
}
if (beanFactory != null) {
evaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
}
return evaluationContext;
}
}
/**
* Evaluate an expression and return a {@link File} object; the expression can evaluate
* to a {@link String} or {@link File}.
* @param expression the expression.
* @param evaluationContext the evaluation context.
* @param message the message (if available).
* @param propertyName the property name the expression is evaluated for.
* @return the File.
* @since 5.0
*/
public static File expressionToFile(Expression expression, EvaluationContext evaluationContext,
@Nullable Message message, String propertyName) {
Object value =
message == null
? expression.getValue(evaluationContext)
: expression.getValue(evaluationContext, message);
Assert.state(value != null, () ->
String.format("The provided %s expression (%s) must not evaluate to null.",
propertyName, expression.getExpressionString()));
if (value instanceof File) {
return (File) value;
}
else if (value instanceof String) {
String path = (String) value;
Assert.hasText(path, String.format("Unable to resolve %s for the provided Expression '%s'.", propertyName,
expression.getExpressionString()));
try {
return ResourceUtils.getFile(path);
}
catch (FileNotFoundException ex) {
throw new IllegalStateException(
String.format("Unable to resolve %s for the provided Expression '%s'.",
propertyName, expression.getExpressionString()),
ex);
}
}
else if (value instanceof Resource) {
try {
return ((Resource) value).getFile();
}
catch (IOException ex) {
throw new IllegalStateException(
String.format("Unable to resolve %s for the provided Expression '%s'.",
propertyName, expression.getExpressionString()),
ex);
}
}
else {
throw new IllegalStateException(String.format(
"The provided %s expression (%s) must evaluate to type java.io.File, String " +
"or org.springframework.core.io.Resource, not %s.", propertyName,
expression.getExpressionString(), value.getClass().getName()));
}
}
/**
* Return a {@link ValueExpression} for a simple literal, otherwise
* a {@link org.springframework.expression.spel.standard.SpelExpression}.
* @param expression the expression string.
* @return the expression.
* @since 5.0
*/
public static Expression intExpression(String expression) {
try {
return new ValueExpression<>(Integer.parseInt(expression));
}
catch (NumberFormatException e) {
// empty
}
return EXPRESSION_PARSER.parseExpression(expression);
}
/**
* Return a {@link ValueExpression} for a simple literal, otherwise
* a {@link org.springframework.expression.spel.standard.SpelExpression}.
* @param expression the expression string.
* @return the expression.
* @since 5.0
*/
public static Expression longExpression(String expression) {
try {
return new ValueExpression<>(Long.parseLong(expression));
}
catch (NumberFormatException e) {
// empty
}
return EXPRESSION_PARSER.parseExpression(expression);
}
}
