ELProcessor.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 jakarta.el;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashSet;
import java.util.Set;
/**
* @since EL 3.0
*/
public class ELProcessor {
private static final Set<String> PRIMITIVES = new HashSet<>();
static {
PRIMITIVES.add("boolean");
PRIMITIVES.add("byte");
PRIMITIVES.add("char");
PRIMITIVES.add("double");
PRIMITIVES.add("float");
PRIMITIVES.add("int");
PRIMITIVES.add("long");
PRIMITIVES.add("short");
}
private static final String[] EMPTY_STRING_ARRAY = new String[0];
private final ELManager manager = new ELManager();
private final ELContext context = manager.getELContext();
private final ExpressionFactory factory = ELManager.getExpressionFactory();
public ELManager getELManager() {
return manager;
}
public <T> T eval(String expression) {
@SuppressWarnings("unchecked")
T result = (T) getValue(expression, Object.class);
return result;
}
public <T> T getValue(String expression, Class<T> expectedType) {
ValueExpression ve = factory.createValueExpression(context, bracket(expression), expectedType);
return ve.getValue(context);
}
public void setValue(String expression, Object value) {
ValueExpression ve = factory.createValueExpression(context, bracket(expression), Object.class);
ve.setValue(context, value);
}
public void setVariable(String variable, String expression) {
if (expression == null) {
manager.setVariable(variable, null);
} else {
ValueExpression ve = factory.createValueExpression(context, bracket(expression), Object.class);
manager.setVariable(variable, ve);
}
}
public void defineFunction(String prefix, String function, String className, String methodName)
throws ClassNotFoundException, NoSuchMethodException {
if (prefix == null || function == null || className == null || methodName == null) {
throw new NullPointerException(Util.message(context, "elProcessor.defineFunctionNullParams"));
}
// Check the imports
Class<?> clazz = context.getImportHandler().resolveClass(className);
if (clazz == null) {
clazz = Class.forName(className, true, Util.getContextClassLoader());
}
if (!Modifier.isPublic(clazz.getModifiers())) {
throw new ClassNotFoundException(
Util.message(context, "elProcessor.defineFunctionInvalidClass", className));
}
MethodSignature sig = new MethodSignature(context, methodName, className);
if (function.length() == 0) {
function = sig.getName();
}
// Only returns public methods. Module access is checked below.
Method methods[] = clazz.getMethods();
for (Method method : methods) {
if (!Modifier.isStatic(method.getModifiers())) {
continue;
}
if (!Util.canAccess(null, method)) {
continue;
}
if (method.getName().equals(sig.getName())) {
if (sig.getParamTypeNames() == null) {
// Only a name provided, no signature so map the first
// method declared
manager.mapFunction(prefix, function, method);
return;
}
if (sig.getParamTypeNames().length != method.getParameterTypes().length) {
continue;
}
if (sig.getParamTypeNames().length == 0) {
manager.mapFunction(prefix, function, method);
return;
} else {
Class<?>[] types = method.getParameterTypes();
String[] typeNames = sig.getParamTypeNames();
if (types.length == typeNames.length) {
boolean match = true;
for (int i = 0; i < types.length; i++) {
if (i == types.length - 1 && method.isVarArgs()) {
String typeName = typeNames[i];
if (typeName.endsWith("...")) {
typeName = typeName.substring(0, typeName.length() - 3);
if (!typeName.equals(types[i].getName())) {
match = false;
}
} else {
match = false;
}
} else if (!types[i].getName().equals(typeNames[i])) {
match = false;
break;
}
}
if (match) {
manager.mapFunction(prefix, function, method);
return;
}
}
}
}
}
throw new NoSuchMethodException(
Util.message(context, "elProcessor.defineFunctionNoMethod", methodName, className));
}
/**
* Map a method to a function name.
*
* @param prefix Function prefix
* @param function Function name
* @param method Method
*
* @throws NullPointerException If any of the arguments are null
* @throws NoSuchMethodException If the method is not static
*/
public void defineFunction(String prefix, String function, Method method) throws NoSuchMethodException {
if (prefix == null || function == null || method == null) {
throw new NullPointerException(Util.message(context, "elProcessor.defineFunctionNullParams"));
}
int modifiers = method.getModifiers();
// Check for static, public method and module access
if (!Modifier.isStatic(modifiers) || !Util.canAccess(null, method)) {
throw new NoSuchMethodException(Util.message(context, "elProcessor.defineFunctionInvalidMethod",
method.getName(), method.getDeclaringClass().getName()));
}
manager.mapFunction(prefix, function, method);
}
public void defineBean(String name, Object bean) {
manager.defineBean(name, bean);
}
private static String bracket(String expression) {
return "${" + expression + "}";
}
private static class MethodSignature {
private final String name;
private final String[] parameterTypeNames;
MethodSignature(ELContext context, String methodName, String className) throws NoSuchMethodException {
int paramIndex = methodName.indexOf('(');
if (paramIndex == -1) {
name = methodName.trim();
parameterTypeNames = null;
} else {
String returnTypeAndName = methodName.substring(0, paramIndex).trim();
// Assume that the return type and the name are separated by
// whitespace. Given the use of trim() above, there should only
// be one sequence of whitespace characters.
int wsPos = -1;
for (int i = 0; i < returnTypeAndName.length(); i++) {
if (Character.isWhitespace(returnTypeAndName.charAt(i))) {
wsPos = i;
break;
}
}
if (wsPos == -1) {
throw new NoSuchMethodException();
}
name = returnTypeAndName.substring(wsPos).trim();
String paramString = methodName.substring(paramIndex).trim();
// We know the params start with '(', check they end with ')'
if (!paramString.endsWith(")")) {
throw new NoSuchMethodException(Util.message(context,
"elProcessor.defineFunctionInvalidParameterList", paramString, methodName, className));
}
// Trim '(' and ')'
paramString = paramString.substring(1, paramString.length() - 1).trim();
if (paramString.length() == 0) {
parameterTypeNames = EMPTY_STRING_ARRAY;
} else {
parameterTypeNames = paramString.split(",");
ImportHandler importHandler = context.getImportHandler();
for (int i = 0; i < parameterTypeNames.length; i++) {
String parameterTypeName = parameterTypeNames[i].trim();
int dimension = 0;
int bracketPos = parameterTypeName.indexOf('[');
if (bracketPos > -1) {
String parameterTypeNameOnly = parameterTypeName.substring(0, bracketPos).trim();
while (bracketPos > -1) {
dimension++;
bracketPos = parameterTypeName.indexOf('[', bracketPos + 1);
}
parameterTypeName = parameterTypeNameOnly;
}
boolean varArgs = false;
if (parameterTypeName.endsWith("...")) {
varArgs = true;
dimension = 1;
parameterTypeName = parameterTypeName.substring(0, parameterTypeName.length() - 3).trim();
}
boolean isPrimitive = PRIMITIVES.contains(parameterTypeName);
if (isPrimitive && dimension > 0) {
// When in an array, class name changes for primitive
switch (parameterTypeName) {
case "boolean":
parameterTypeName = "Z";
break;
case "byte":
parameterTypeName = "B";
break;
case "char":
parameterTypeName = "C";
break;
case "double":
parameterTypeName = "D";
break;
case "float":
parameterTypeName = "F";
break;
case "int":
parameterTypeName = "I";
break;
case "long":
parameterTypeName = "J";
break;
case "short":
parameterTypeName = "S";
break;
default:
// Should never happen
break;
}
} else if (!isPrimitive && !parameterTypeName.contains(".")) {
Class<?> clazz = importHandler.resolveClass(parameterTypeName);
if (clazz == null) {
throw new NoSuchMethodException(
Util.message(context, "elProcessor.defineFunctionInvalidParameterTypeName",
parameterTypeNames[i], methodName, className));
}
parameterTypeName = clazz.getName();
}
if (dimension > 0) {
// Convert to array form of class name
StringBuilder sb = new StringBuilder();
for (int j = 0; j < dimension; j++) {
sb.append('[');
}
if (!isPrimitive) {
sb.append('L');
}
sb.append(parameterTypeName);
if (!isPrimitive) {
sb.append(';');
}
parameterTypeName = sb.toString();
}
if (varArgs) {
parameterTypeName += "...";
}
parameterTypeNames[i] = parameterTypeName;
}
}
}
}
public String getName() {
return name;
}
/**
* @return <code>null</code> if just the method name was specified, an empty List if an empty parameter list was
* specified - i.e. () - otherwise an ordered list of parameter type names
*/
public String[] getParamTypeNames() {
return parameterTypeNames;
}
}
}