/*
* Copyright 2002-2009 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.expression.spel.ast;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.ExpressionInvocationTargetException;
import org.springframework.expression.MethodExecutor;
import org.springframework.expression.MethodResolver;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
/**
* @author Andy Clement
* @author Juergen Hoeller
* @since 3.0
*/
public class MethodReference extends SpelNodeImpl {
private final String name;
private final boolean nullSafe;
private volatile MethodExecutor cachedExecutor;
public MethodReference(boolean nullSafe, String methodName, int pos, SpelNodeImpl... arguments) {
super(pos,arguments);
this.name = methodName;
this.nullSafe = nullSafe;
}
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
TypedValue currentContext = state.getActiveContextObject();
Object[] arguments = new Object[getChildCount()];
for (int i = 0; i < arguments.length; i++) {
// Make the root object the active context again for evaluating the parameter
// expressions
try {
state.pushActiveContextObject(state.getRootContextObject());
arguments[i] = children[i].getValueInternal(state).getValue();
}
finally {
state.popActiveContextObject();
}
}
if (currentContext.getValue() == null) {
if (this.nullSafe) {
return TypedValue.NULL;
}
else {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.METHOD_CALL_ON_NULL_OBJECT_NOT_ALLOWED,
FormatHelper.formatMethodForMessage(name, getTypes(arguments)));
}
}
MethodExecutor executorToUse = this.cachedExecutor;
if (executorToUse != null) {
try {
return executorToUse.execute(
state.getEvaluationContext(), state.getActiveContextObject().getValue(), arguments);
}
catch (AccessException ae) {
// Two reasons this can occur:
// 1. the method invoked actually threw a real exception
// 2. the method invoked was not passed the arguments it expected and has become 'stale'
// In the first case we should not retry, in the second case we should see if there is a
// better suited method.
// To determine which situation it is, the AccessException will contain a cause.
// If the cause is an InvocationTargetException, a user exception was thrown inside the method.
// Otherwise the method could not be invoked.
throwSimpleExceptionIfPossible(state, ae);
// at this point we know it wasn't a user problem so worth a retry if a better candidate can be found
this.cachedExecutor = null;
}
}
// either there was no accessor or it no longer existed
executorToUse = findAccessorForMethod(this.name, getTypes(arguments), state);
this.cachedExecutor = executorToUse;
try {
return executorToUse.execute(
state.getEvaluationContext(), state.getActiveContextObject().getValue(), arguments);
} catch (AccessException ae) {
// Same unwrapping exception handling as above in above catch block
throwSimpleExceptionIfPossible(state, ae);
throw new SpelEvaluationException( getStartPosition(), ae, SpelMessage.EXCEPTION_DURING_METHOD_INVOCATION,
this.name, state.getActiveContextObject().getValue().getClass().getName(), ae.getMessage());
}
}
/**
* Decode the AccessException, throwing a lightweight evaluation exception or, if the cause was a RuntimeException,
* throw the RuntimeException directly.
*/
private void throwSimpleExceptionIfPossible(ExpressionState state, AccessException ae) {
if (ae.getCause() instanceof InvocationTargetException) {
Throwable rootCause = ae.getCause().getCause();
if (rootCause instanceof RuntimeException) {
throw (RuntimeException) rootCause;
}
else {
throw new ExpressionInvocationTargetException(getStartPosition(),
"A problem occurred when trying to execute method '" + this.name +
"' on object of type '" + state.getActiveContextObject().getValue().getClass().getName() + "'",
rootCause);
}
}
}
private List<TypeDescriptor> getTypes(Object... arguments) {
List<TypeDescriptor> descriptors = new ArrayList<TypeDescriptor>(arguments.length);
for (Object argument : arguments) {
descriptors.add(TypeDescriptor.forObject(argument));
}
return descriptors;
}
@Override
public String toStringAST() {
StringBuilder sb = new StringBuilder();
sb.append(name).append("(");
for (int i = 0; i < getChildCount(); i++) {
if (i > 0)
sb.append(",");
sb.append(getChild(i).toStringAST());
}
sb.append(")");
return sb.toString();
}
private MethodExecutor findAccessorForMethod(String name, List<TypeDescriptor> argumentTypes, ExpressionState state)
throws SpelEvaluationException {
TypedValue context = state.getActiveContextObject();
Object contextObject = context.getValue();
EvaluationContext eContext = state.getEvaluationContext();
List<MethodResolver> mResolvers = eContext.getMethodResolvers();
if (mResolvers != null) {
for (MethodResolver methodResolver : mResolvers) {
try {
MethodExecutor cEx = methodResolver.resolve(
state.getEvaluationContext(), contextObject, name, argumentTypes);
if (cEx != null) {
return cEx;
}
}
catch (AccessException ex) {
throw new SpelEvaluationException(getStartPosition(),ex, SpelMessage.PROBLEM_LOCATING_METHOD, name, contextObject.getClass());
}
}
}
throw new SpelEvaluationException(getStartPosition(),SpelMessage.METHOD_NOT_FOUND, FormatHelper.formatMethodForMessage(name, argumentTypes),
FormatHelper.formatClassNameForMessage(contextObject instanceof Class ? ((Class<?>) contextObject) : contextObject.getClass()));
}
}