org.springframework.core.Conventions Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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.core;
import java.io.Externalizable;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Provides methods to support various naming and other conventions used
* throughout the framework. Mainly for internal use within the framework.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class Conventions {
/**
* Suffix added to names when using arrays.
*/
private static final String PLURAL_SUFFIX = "List";
/**
* Set of interfaces that are supposed to be ignored
* when searching for the 'primary' interface of a proxy.
*/
private static final Set> IGNORED_INTERFACES;
static {
IGNORED_INTERFACES = Collections.unmodifiableSet(new HashSet>(
Arrays.>asList(Serializable.class, Externalizable.class, Cloneable.class, Comparable.class)));
}
/**
* Determine the conventional variable name for the supplied
* {@code Object} based on its concrete type. The convention
* used is to return the uncapitalized short name of the {@code Class},
* according to JavaBeans property naming rules: So,
* {@code com.myapp.Product} becomes {@code product};
* {@code com.myapp.MyProduct} becomes {@code myProduct};
* {@code com.myapp.UKProduct} becomes {@code UKProduct}.
* For arrays, we use the pluralized version of the array component type.
* For {@code Collection}s we attempt to 'peek ahead' in the
* {@code Collection} to determine the component type and
* return the pluralized version of that component type.
* @param value the value to generate a variable name for
* @return the generated variable name
*/
public static String getVariableName(Object value) {
Assert.notNull(value, "Value must not be null");
Class valueClass;
boolean pluralize = false;
if (value.getClass().isArray()) {
valueClass = value.getClass().getComponentType();
pluralize = true;
}
else if (value instanceof Collection) {
Collection collection = (Collection) value;
if (collection.isEmpty()) {
throw new IllegalArgumentException("Cannot generate variable name for an empty Collection");
}
Object valueToCheck = peekAhead(collection);
valueClass = getClassForValue(valueToCheck);
pluralize = true;
}
else {
valueClass = getClassForValue(value);
}
String name = ClassUtils.getShortNameAsProperty(valueClass);
return (pluralize ? pluralize(name) : name);
}
/**
* Determine the conventional variable name for the supplied parameter,
* taking the generic collection type (if any) into account.
* @param parameter the method or constructor parameter to generate a variable name for
* @return the generated variable name
*/
public static String getVariableNameForParameter(MethodParameter parameter) {
Assert.notNull(parameter, "MethodParameter must not be null");
Class valueClass;
boolean pluralize = false;
if (parameter.getParameterType().isArray()) {
valueClass = parameter.getParameterType().getComponentType();
pluralize = true;
}
else if (Collection.class.isAssignableFrom(parameter.getParameterType())) {
valueClass = ResolvableType.forMethodParameter(parameter).asCollection().resolveGeneric();
if (valueClass == null) {
throw new IllegalArgumentException(
"Cannot generate variable name for non-typed Collection parameter type");
}
pluralize = true;
}
else {
valueClass = parameter.getParameterType();
}
String name = ClassUtils.getShortNameAsProperty(valueClass);
return (pluralize ? pluralize(name) : name);
}
/**
* Determine the conventional variable name for the return type of the supplied method,
* taking the generic collection type (if any) into account.
* @param method the method to generate a variable name for
* @return the generated variable name
*/
public static String getVariableNameForReturnType(Method method) {
return getVariableNameForReturnType(method, method.getReturnType(), null);
}
/**
* Determine the conventional variable name for the return type of the supplied method,
* taking the generic collection type (if any) into account, falling back to the
* given return value if the method declaration is not specific enough (i.e. in case of
* the return type being declared as {@code Object} or as untyped collection).
* @param method the method to generate a variable name for
* @param value the return value (may be {@code null} if not available)
* @return the generated variable name
*/
public static String getVariableNameForReturnType(Method method, Object value) {
return getVariableNameForReturnType(method, method.getReturnType(), value);
}
/**
* Determine the conventional variable name for the return type of the supplied method,
* taking the generic collection type (if any) into account, falling back to the
* given return value if the method declaration is not specific enough (i.e. in case of
* the return type being declared as {@code Object} or as untyped collection).
* @param method the method to generate a variable name for
* @param resolvedType the resolved return type of the method
* @param value the return value (may be {@code null} if not available)
* @return the generated variable name
*/
public static String getVariableNameForReturnType(Method method, Class resolvedType, Object value) {
Assert.notNull(method, "Method must not be null");
if (Object.class == resolvedType) {
if (value == null) {
throw new IllegalArgumentException("Cannot generate variable name for an Object return type with null value");
}
return getVariableName(value);
}
Class valueClass;
boolean pluralize = false;
if (resolvedType.isArray()) {
valueClass = resolvedType.getComponentType();
pluralize = true;
}
else if (Collection.class.isAssignableFrom(resolvedType)) {
valueClass = ResolvableType.forMethodReturnType(method).asCollection().resolveGeneric();
if (valueClass == null) {
if (!(value instanceof Collection)) {
throw new IllegalArgumentException(
"Cannot generate variable name for non-typed Collection return type and a non-Collection value");
}
Collection collection = (Collection) value;
if (collection.isEmpty()) {
throw new IllegalArgumentException(
"Cannot generate variable name for non-typed Collection return type and an empty Collection value");
}
Object valueToCheck = peekAhead(collection);
valueClass = getClassForValue(valueToCheck);
}
pluralize = true;
}
else {
valueClass = resolvedType;
}
String name = ClassUtils.getShortNameAsProperty(valueClass);
return (pluralize ? pluralize(name) : name);
}
/**
* Convert {@code String}s in attribute name format (lowercase, hyphens separating words)
* into property name format (camel-cased). For example, {@code transaction-manager} is
* converted into {@code transactionManager}.
*/
public static String attributeNameToPropertyName(String attributeName) {
Assert.notNull(attributeName, "'attributeName' must not be null");
if (!attributeName.contains("-")) {
return attributeName;
}
char[] chars = attributeName.toCharArray();
char[] result = new char[chars.length -1]; // not completely accurate but good guess
int currPos = 0;
boolean upperCaseNext = false;
for (char c : chars) {
if (c == '-') {
upperCaseNext = true;
}
else if (upperCaseNext) {
result[currPos++] = Character.toUpperCase(c);
upperCaseNext = false;
}
else {
result[currPos++] = c;
}
}
return new String(result, 0, currPos);
}
/**
* Return an attribute name qualified by the supplied enclosing {@link Class}. For example,
* the attribute name '{@code foo}' qualified by {@link Class} '{@code com.myapp.SomeClass}'
* would be '{@code com.myapp.SomeClass.foo}'
*/
public static String getQualifiedAttributeName(Class enclosingClass, String attributeName) {
Assert.notNull(enclosingClass, "'enclosingClass' must not be null");
Assert.notNull(attributeName, "'attributeName' must not be null");
return enclosingClass.getName() + '.' + attributeName;
}
/**
* Determines the class to use for naming a variable that contains
* the given value.
*
Will return the class of the given value, except when
* encountering a JDK proxy, in which case it will determine
* the 'primary' interface implemented by that proxy.
* @param value the value to check
* @return the class to use for naming a variable
*/
private static Class getClassForValue(Object value) {
Class valueClass = value.getClass();
if (Proxy.isProxyClass(valueClass)) {
Class[] ifcs = valueClass.getInterfaces();
for (Class ifc : ifcs) {
if (!IGNORED_INTERFACES.contains(ifc)) {
return ifc;
}
}
}
else if (valueClass.getName().lastIndexOf('$') != -1 && valueClass.getDeclaringClass() == null) {
// '$' in the class name but no inner class -
// assuming it's a special subclass (e.g. by OpenJPA)
valueClass = valueClass.getSuperclass();
}
return valueClass;
}
/**
* Pluralize the given name.
*/
private static String pluralize(String name) {
return name + PLURAL_SUFFIX;
}
/**
* Retrieves the {@code Class} of an element in the {@code Collection}.
* The exact element for which the {@code Class} is retrieved will depend
* on the concrete {@code Collection} implementation.
*/
private static E peekAhead(Collection collection) {
Iterator it = collection.iterator();
if (!it.hasNext()) {
throw new IllegalStateException(
"Unable to peek ahead in non-empty collection - no element found");
}
E value = it.next();
if (value == null) {
throw new IllegalStateException(
"Unable to peek ahead in non-empty collection - only null element found");
}
return value;
}
}