spring ConstructorReference 源码
spring ConstructorReference 代码
文件路径：/spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java
/*
* Copyright 2002-2022 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.expression.spel.ast;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import org.springframework.asm.MethodVisitor;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.AccessException;
import org.springframework.expression.ConstructorExecutor;
import org.springframework.expression.ConstructorResolver;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypeConverter;
import org.springframework.expression.TypedValue;
import org.springframework.expression.common.ExpressionUtils;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.SpelNode;
import org.springframework.expression.spel.support.ReflectiveConstructorExecutor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Represents the invocation of a constructor. Either a constructor on a regular type or
* construction of an array. When an array is constructed, an initializer can be specified.
*
* <p>Examples:<br>
* new String('hello world')<br>
* new int[]{1,2,3,4}<br>
* new int[3] new int[3]{1,2,3}
*
* @author Andy Clement
* @author Juergen Hoeller
* @author Sam Brannen
* @since 3.0
*/
public class ConstructorReference extends SpelNodeImpl {
/**
* Maximum number of elements permitted in an array declaration, applying
* to one-dimensional as well as multi-dimensional arrays.
* @since 5.3.17
*/
private static final int MAX_ARRAY_ELEMENTS = 256 * 1024; // 256K
private final boolean isArrayConstructor;
@Nullable
private SpelNodeImpl[] dimensions;
// TODO is this caching safe - passing the expression around will mean this executor is also being passed around
/** The cached executor that may be reused on subsequent evaluations. */
@Nullable
private volatile ConstructorExecutor cachedExecutor;
/**
* Create a constructor reference. The first argument is the type, the rest are the parameters to the constructor
* call
*/
public ConstructorReference(int startPos, int endPos, SpelNodeImpl... arguments) {
super(startPos, endPos, arguments);
this.isArrayConstructor = false;
}
/**
* Create a constructor reference. The first argument is the type, the rest are the parameters to the constructor
* call
*/
public ConstructorReference(int startPos, int endPos, SpelNodeImpl[] dimensions, SpelNodeImpl... arguments) {
super(startPos, endPos, arguments);
this.isArrayConstructor = true;
this.dimensions = dimensions;
}
/**
* Implements getValue() - delegating to the code for building an array or a simple type.
*/
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
if (this.isArrayConstructor) {
return createArray(state);
}
else {
return createNewInstance(state);
}
}
/**
* Create a new ordinary object and return it.
* @param state the expression state within which this expression is being evaluated
* @return the new object
* @throws EvaluationException if there is a problem creating the object
*/
private TypedValue createNewInstance(ExpressionState state) throws EvaluationException {
Object[] arguments = new Object[getChildCount() - 1];
List<TypeDescriptor> argumentTypes = new ArrayList<>(getChildCount() - 1);
for (int i = 0; i < arguments.length; i++) {
TypedValue childValue = this.children[i + 1].getValueInternal(state);
Object value = childValue.getValue();
arguments[i] = value;
argumentTypes.add(TypeDescriptor.forObject(value));
}
ConstructorExecutor executorToUse = this.cachedExecutor;
if (executorToUse != null) {
try {
return executorToUse.execute(state.getEvaluationContext(), arguments);
}
catch (AccessException ex) {
// 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 constructor.
// Otherwise, the constructor could not be invoked.
if (ex.getCause() instanceof InvocationTargetException) {
// User exception was the root cause - exit now
Throwable rootCause = ex.getCause().getCause();
if (rootCause instanceof RuntimeException runtimeException) {
throw runtimeException;
}
else {
String typeName = (String) this.children[0].getValueInternal(state).getValue();
throw new SpelEvaluationException(getStartPosition(), rootCause,
SpelMessage.CONSTRUCTOR_INVOCATION_PROBLEM, typeName,
FormatHelper.formatMethodForMessage("", argumentTypes));
}
}
// 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 exists
String typeName = (String) this.children[0].getValueInternal(state).getValue();
Assert.state(typeName != null, "No type name");
executorToUse = findExecutorForConstructor(typeName, argumentTypes, state);
try {
this.cachedExecutor = executorToUse;
if (executorToUse instanceof ReflectiveConstructorExecutor reflectiveConstructorExecutor) {
this.exitTypeDescriptor = CodeFlow.toDescriptor(
reflectiveConstructorExecutor.getConstructor().getDeclaringClass());
}
return executorToUse.execute(state.getEvaluationContext(), arguments);
}
catch (AccessException ex) {
throw new SpelEvaluationException(getStartPosition(), ex,
SpelMessage.CONSTRUCTOR_INVOCATION_PROBLEM, typeName,
FormatHelper.formatMethodForMessage("", argumentTypes));
}
}
/**
* Go through the list of registered constructor resolvers and see if any can find a
* constructor that takes the specified set of arguments.
* @param typeName the type trying to be constructed
* @param argumentTypes the types of the arguments supplied that the constructor must take
* @param state the current state of the expression
* @return a reusable ConstructorExecutor that can be invoked to run the constructor or null
* @throws SpelEvaluationException if there is a problem locating the constructor
*/
private ConstructorExecutor findExecutorForConstructor(String typeName,
List<TypeDescriptor> argumentTypes, ExpressionState state) throws SpelEvaluationException {
EvaluationContext evalContext = state.getEvaluationContext();
List<ConstructorResolver> ctorResolvers = evalContext.getConstructorResolvers();
for (ConstructorResolver ctorResolver : ctorResolvers) {
try {
ConstructorExecutor ce = ctorResolver.resolve(state.getEvaluationContext(), typeName, argumentTypes);
if (ce != null) {
return ce;
}
}
catch (AccessException ex) {
throw new SpelEvaluationException(getStartPosition(), ex,
SpelMessage.CONSTRUCTOR_INVOCATION_PROBLEM, typeName,
FormatHelper.formatMethodForMessage("", argumentTypes));
}
}
throw new SpelEvaluationException(getStartPosition(), SpelMessage.CONSTRUCTOR_NOT_FOUND, typeName,
FormatHelper.formatMethodForMessage("", argumentTypes));
}
@Override
public String toStringAST() {
StringBuilder sb = new StringBuilder("new ");
int index = 0;
sb.append(getChild(index++).toStringAST());
sb.append('(');
for (int i = index; i < getChildCount(); i++) {
if (i > index) {
sb.append(',');
}
sb.append(getChild(i).toStringAST());
}
sb.append(')');
return sb.toString();
}
/**
* Create an array and return it.
* @param state the expression state within which this expression is being evaluated
* @return the new array
* @throws EvaluationException if there is a problem creating the array
*/
private TypedValue createArray(ExpressionState state) throws EvaluationException {
// First child gives us the array type which will either be a primitive or reference type
Object intendedArrayType = getChild(0).getValue(state);
if (!(intendedArrayType instanceof String type)) {
throw new SpelEvaluationException(getChild(0).getStartPosition(),
SpelMessage.TYPE_NAME_EXPECTED_FOR_ARRAY_CONSTRUCTION,
FormatHelper.formatClassNameForMessage(
intendedArrayType != null ? intendedArrayType.getClass() : null));
}
Class<?> componentType;
TypeCode arrayTypeCode = TypeCode.forName(type);
if (arrayTypeCode == TypeCode.OBJECT) {
componentType = state.findType(type);
}
else {
componentType = arrayTypeCode.getType();
}
Object newArray = null;
if (!hasInitializer()) {
// Confirm all dimensions were specified (for example [3][][5] is missing the 2nd dimension)
if (this.dimensions != null) {
for (SpelNodeImpl dimension : this.dimensions) {
if (dimension == null) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.MISSING_ARRAY_DIMENSION);
}
}
TypeConverter typeConverter = state.getEvaluationContext().getTypeConverter();
if (this.dimensions.length == 1) {
// Shortcut for 1-dimensional
TypedValue o = this.dimensions[0].getTypedValue(state);
int arraySize = ExpressionUtils.toInt(typeConverter, o);
checkNumElements(arraySize);
newArray = Array.newInstance(componentType, arraySize);
}
else {
// Multidimensional - hold onto your hat!
int[] dims = new int[this.dimensions.length];
long numElements = 1;
for (int d = 0; d < this.dimensions.length; d++) {
TypedValue o = this.dimensions[d].getTypedValue(state);
int arraySize = ExpressionUtils.toInt(typeConverter, o);
dims[d] = arraySize;
numElements *= arraySize;
checkNumElements(numElements);
}
newArray = Array.newInstance(componentType, dims);
}
}
}
else {
// There is an initializer
if (this.dimensions == null || this.dimensions.length > 1) {
// There is an initializer but this is a multidimensional array (e.g. new int[][]{{1,2},{3,4}})
// - this is not currently supported
throw new SpelEvaluationException(getStartPosition(),
SpelMessage.MULTIDIM_ARRAY_INITIALIZER_NOT_SUPPORTED);
}
TypeConverter typeConverter = state.getEvaluationContext().getTypeConverter();
InlineList initializer = (InlineList) getChild(1);
// If a dimension was specified, check it matches the initializer length
if (this.dimensions[0] != null) {
TypedValue dValue = this.dimensions[0].getTypedValue(state);
int i = ExpressionUtils.toInt(typeConverter, dValue);
if (i != initializer.getChildCount()) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.INITIALIZER_LENGTH_INCORRECT);
}
}
// Build the array and populate it
int arraySize = initializer.getChildCount();
newArray = Array.newInstance(componentType, arraySize);
if (arrayTypeCode == TypeCode.OBJECT) {
populateReferenceTypeArray(state, newArray, typeConverter, initializer, componentType);
}
else if (arrayTypeCode == TypeCode.BOOLEAN) {
populateBooleanArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.BYTE) {
populateByteArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.CHAR) {
populateCharArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.DOUBLE) {
populateDoubleArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.FLOAT) {
populateFloatArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.INT) {
populateIntArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.LONG) {
populateLongArray(state, newArray, typeConverter, initializer);
}
else if (arrayTypeCode == TypeCode.SHORT) {
populateShortArray(state, newArray, typeConverter, initializer);
}
else {
throw new IllegalStateException(arrayTypeCode.name());
}
}
return new TypedValue(newArray);
}
private void checkNumElements(long numElements) {
if (numElements >= MAX_ARRAY_ELEMENTS) {
throw new SpelEvaluationException(getStartPosition(),
SpelMessage.MAX_ARRAY_ELEMENTS_THRESHOLD_EXCEEDED, MAX_ARRAY_ELEMENTS);
}
}
private void populateReferenceTypeArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer, Class<?> componentType) {
TypeDescriptor toTypeDescriptor = TypeDescriptor.valueOf(componentType);
Object[] newObjectArray = (Object[]) newArray;
for (int i = 0; i < newObjectArray.length; i++) {
SpelNode elementNode = initializer.getChild(i);
Object arrayEntry = elementNode.getValue(state);
newObjectArray[i] = typeConverter.convertValue(arrayEntry,
TypeDescriptor.forObject(arrayEntry), toTypeDescriptor);
}
}
private void populateByteArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
byte[] newByteArray = (byte[]) newArray;
for (int i = 0; i < newByteArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newByteArray[i] = ExpressionUtils.toByte(typeConverter, typedValue);
}
}
private void populateFloatArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
float[] newFloatArray = (float[]) newArray;
for (int i = 0; i < newFloatArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newFloatArray[i] = ExpressionUtils.toFloat(typeConverter, typedValue);
}
}
private void populateDoubleArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
double[] newDoubleArray = (double[]) newArray;
for (int i = 0; i < newDoubleArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newDoubleArray[i] = ExpressionUtils.toDouble(typeConverter, typedValue);
}
}
private void populateShortArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
short[] newShortArray = (short[]) newArray;
for (int i = 0; i < newShortArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newShortArray[i] = ExpressionUtils.toShort(typeConverter, typedValue);
}
}
private void populateLongArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
long[] newLongArray = (long[]) newArray;
for (int i = 0; i < newLongArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newLongArray[i] = ExpressionUtils.toLong(typeConverter, typedValue);
}
}
private void populateCharArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
char[] newCharArray = (char[]) newArray;
for (int i = 0; i < newCharArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newCharArray[i] = ExpressionUtils.toChar(typeConverter, typedValue);
}
}
private void populateBooleanArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
boolean[] newBooleanArray = (boolean[]) newArray;
for (int i = 0; i < newBooleanArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newBooleanArray[i] = ExpressionUtils.toBoolean(typeConverter, typedValue);
}
}
private void populateIntArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
InlineList initializer) {
int[] newIntArray = (int[]) newArray;
for (int i = 0; i < newIntArray.length; i++) {
TypedValue typedValue = initializer.getChild(i).getTypedValue(state);
newIntArray[i] = ExpressionUtils.toInt(typeConverter, typedValue);
}
}
private boolean hasInitializer() {
return (getChildCount() > 1);
}
@Override
public boolean isCompilable() {
if (!(this.cachedExecutor instanceof ReflectiveConstructorExecutor) ||
this.exitTypeDescriptor == null) {
return false;
}
if (getChildCount() > 1) {
for (int c = 1, max = getChildCount();c < max; c++) {
if (!this.children[c].isCompilable()) {
return false;
}
}
}
ReflectiveConstructorExecutor executor = (ReflectiveConstructorExecutor) this.cachedExecutor;
if (executor == null) {
return false;
}
Constructor<?> constructor = executor.getConstructor();
return (Modifier.isPublic(constructor.getModifiers()) &&
Modifier.isPublic(constructor.getDeclaringClass().getModifiers()));
}
@Override
public void generateCode(MethodVisitor mv, CodeFlow cf) {
ReflectiveConstructorExecutor executor = ((ReflectiveConstructorExecutor) this.cachedExecutor);
Assert.state(executor != null, "No cached executor");
Constructor<?> constructor = executor.getConstructor();
String classDesc = constructor.getDeclaringClass().getName().replace('.', '/');
mv.visitTypeInsn(NEW, classDesc);
mv.visitInsn(DUP);
// children[0] is the type of the constructor, don't want to include that in argument processing
SpelNodeImpl[] arguments = new SpelNodeImpl[this.children.length - 1];
System.arraycopy(this.children, 1, arguments, 0, this.children.length - 1);
generateCodeForArguments(mv, cf, constructor, arguments);
mv.visitMethodInsn(INVOKESPECIAL, classDesc, "<init>", CodeFlow.createSignatureDescriptor(constructor), false);
cf.pushDescriptor(this.exitTypeDescriptor);
}
}
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