org.springframework.data.querydsl.SimpleEntityPathResolver Maven / Gradle / Ivy
/*
* Copyright 2011-2019 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
*
* 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.data.querydsl;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Optional;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
import com.querydsl.core.types.EntityPath;
/**
* Simple implementation of {@link EntityPathResolver} to lookup a query class by reflection and using the static field
* of the same type.
*
* @author Oliver Gierke
* @author Jens Schauder
*/
public class SimpleEntityPathResolver implements EntityPathResolver {
private static final String NO_CLASS_FOUND_TEMPLATE = "Did not find a query class %s for domain class %s!";
private static final String NO_FIELD_FOUND_TEMPLATE = "Did not find a static field of the same type in %s!";
public static final SimpleEntityPathResolver INSTANCE = new SimpleEntityPathResolver("");
private final String querySuffix;
/**
* Creates a new {@link SimpleEntityPathResolver} with the given query package suffix.
*
* @param querySuffix must not be {@literal null}.
*/
public SimpleEntityPathResolver(String querySuffix) {
Assert.notNull(querySuffix, "Query suffix must not be null!");
this.querySuffix = querySuffix;
}
/**
* Creates an {@link EntityPath} instance for the given domain class. Tries to lookup a class matching the naming
* convention (prepend Q to the simple name of the class, same package) and find a static field of the same type in
* it.
*
* @param domainClass
* @return
*/
@SuppressWarnings("unchecked")
public EntityPath createPath(Class domainClass) {
String pathClassName = getQueryClassName(domainClass);
try {
Class pathClass = ClassUtils.forName(pathClassName, domainClass.getClassLoader());
return getStaticFieldOfType(pathClass)//
.map(it -> (EntityPath) ReflectionUtils.getField(it, null))//
.orElseThrow(() -> new IllegalStateException(String.format(NO_FIELD_FOUND_TEMPLATE, pathClass)));
} catch (ClassNotFoundException e) {
throw new IllegalArgumentException(String.format(NO_CLASS_FOUND_TEMPLATE, pathClassName, domainClass.getName()),
e);
}
}
/**
* Returns the first static field of the given type inside the given type.
*
* @param type
* @return
*/
private Optional getStaticFieldOfType(Class type) {
for (Field field : type.getDeclaredFields()) {
boolean isStatic = Modifier.isStatic(field.getModifiers());
boolean hasSameType = type.equals(field.getType());
if (isStatic && hasSameType) {
return Optional.of(field);
}
}
Class superclass = type.getSuperclass();
return Object.class.equals(superclass) ? Optional.empty() : getStaticFieldOfType(superclass);
}
/**
* Returns the name of the query class for the given domain class.
*
* @param domainClass
* @return
*/
private String getQueryClassName(Class domainClass) {
String simpleClassName = ClassUtils.getShortName(domainClass);
String packageName = domainClass.getPackage().getName();
return String.format("%s%s.Q%s%s", packageName, querySuffix, getClassBase(simpleClassName),
domainClass.getSimpleName());
}
/**
* Analyzes the short class name and potentially returns the outer class.
*
* @param shortName
* @return
*/
private String getClassBase(String shortName) {
String[] parts = shortName.split("\\.");
return parts.length < 2 ? "" : parts[0] + "_";
}
}