gu.sql2java.excel.utils.FieldUtils Maven / Gradle / Ivy
package gu.sql2java.excel.utils;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkArgument;
import static net.gdface.utils.ConditionChecks.checkTrue;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import com.google.common.base.Strings;
public class FieldUtils {
/**
* Gets an accessible {@link Field} by name, breaking scope if requested. Superclasses/interfaces will be
* considered.
*
* @param cls
* the {@link Class} to reflect, must not be {@code null}
* @param fieldName
* the field name to obtain
* @param forceAccess
* whether to break scope restrictions using the
* {@link java.lang.reflect.AccessibleObject#setAccessible(boolean)} method. {@code false} will only
* match {@code public} fields.
* @return the Field object
* @throws IllegalArgumentException
* if the class is {@code null}, or the field name is blank or empty or is matched at multiple places
* in the inheritance hierarchy
*/
public static Field getField(final Class cls, final String fieldName, final boolean forceAccess) {
checkNotNull(cls, "The class must not be null");
checkArgument(!Strings.isNullOrEmpty(fieldName), "The field name must not be blank/empty");
// FIXME is this workaround still needed? lang requires Java 6
// Sun Java 1.3 has a bugged implementation of getField hence we write the
// code ourselves
// getField() will return the Field object with the declaring class
// set correctly to the class that declares the field. Thus requesting the
// field on a subclass will return the field from the superclass.
//
// priority order for lookup:
// searchclass private/protected/package/public
// superclass protected/package/public
// private/different package blocks access to further superclasses
// implementedinterface public
// check up the superclass hierarchy
for (Class acls = cls; acls != null; acls = acls.getSuperclass()) {
try {
final Field field = acls.getDeclaredField(fieldName);
// getDeclaredField checks for non-public scopes as well
// and it returns accurate results
if (!Modifier.isPublic(field.getModifiers())) {
if (forceAccess) {
field.setAccessible(true);
} else {
continue;
}
}
return field;
} catch (final NoSuchFieldException ex) { // NOPMD
// ignore
}
}
// check the public interface case. This must be manually searched for
// incase there is a public supersuperclass field hidden by a private/package
// superclass field.
Field match = null;
for (final Class class1 : getAllInterfaces(cls)) {
try {
final Field test = class1.getField(fieldName);
checkTrue(match == null, IllegalArgumentException.class,"Reference to field %s is ambiguous relative to %s"
+ "; a matching field exists on two or more implemented interfaces.", fieldName, cls);
match = test;
} catch (final NoSuchFieldException ex) { // NOPMD
// ignore
}
}
return match;
}
/**
* Gets a {@code List} of all interfaces implemented by the given
* class and its superclasses.
*
* The order is determined by looking through each interface in turn as
* declared in the source file and following its hierarchy up. Then each
* superclass is considered in the same way. Later duplicates are ignored,
* so the order is maintained.
*
* @param cls the class to look up, may be {@code null}
* @return the {@code List} of interfaces in order,
* {@code null} if null input
*/
public static List> getAllInterfaces(final Class cls) {
if (cls == null) {
return null;
}
final LinkedHashSet> interfacesFound = new LinkedHashSet<>();
getAllInterfaces(cls, interfacesFound);
return new ArrayList<>(interfacesFound);
}
/**
* Get the interfaces for the specified class.
*
* @param cls the class to look up, may be {@code null}
* @param interfacesFound the {@code Set} of interfaces for the class
*/
private static void getAllInterfaces(Class cls, final HashSet> interfacesFound) {
while (cls != null) {
final Class[] interfaces = cls.getInterfaces();
for (final Class i : interfaces) {
if (interfacesFound.add(i)) {
getAllInterfaces(i, interfacesFound);
}
}
cls = cls.getSuperclass();
}
}
}