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de.escalon.hypermedia.ResourceTraversal Maven / Gradle / Ivy
package de.escalon.hypermedia;
import de.escalon.hypermedia.affordance.DataType;
import org.springframework.hateoas.Resource;
import org.springframework.hateoas.ResourceSupport;
import org.springframework.hateoas.Resources;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.util.*;
/**
* Created by Dietrich on 07.05.2016.
*/
public class ResourceTraversal {
static final Set FILTER_RESOURCE_SUPPORT = new HashSet(Arrays.asList("class", "links", "id"));
static class NullValue {
}
public static final NullValue NULL_VALUE = new NullValue();
public void traverseResource(ResourceSupportVisitor visitor, Object object) {
Set filtered = FILTER_RESOURCE_SUPPORT;
if (object == null) {
return;
}
try {
// TODO: move all returns to else branch of property descriptor handling
if (object instanceof Resource) {
Resource resource = (Resource) object;
if(!visitor.visitLinks(resource.getLinks())) {
return;
}
traverseResource(visitor, resource.getContent());
return;
} else if (object instanceof Resources) {
Resources resources = (Resources) object;
if(!visitor.visitLinks(resources.getLinks())) {
return;
}
traverseResource(visitor, resources.getContent());
return;
} else if (object instanceof ResourceSupport) {
ResourceSupport resource = (ResourceSupport) object;
if(!visitor.visitLinks(resource.getLinks())) {
return;
}
// wrap object attributes below to avoid endless loop
} else if (object instanceof Collection) {
Collection collection = (Collection) object;
if(!visitor.visitEnterCollection(collection)) {
return;
}
for (Object item : collection) {
traverseResource(visitor, item);
}
if(!visitor.visitLeaveCollection(collection)) {
return;
}
return;
}
if (object instanceof Map) {
Map map = (Map) object;
for (Map.Entry entry : map.entrySet()) {
String key = entry.getKey()
.toString();
Object content = entry.getValue();
Object value = getContentAsScalarValue(content);
// UberNode entryNode = new UberNode();
// objectNode.addData(entryNode);
// entryNode.setName(key);
// if (value != null) {
// entryNode.setValue(value);
// } else {
// traverseResource(visitor, content);
// }
Class type = content != null ? content.getClass() : null;
if(!visitor.visitEnterProperty(key, type, value)) {
return;
}
if (value != null) {
// for each scalar property of a simple bean, add valuepair nodes to data
if(!visitor.visitProperty(key, type, value)) {
return;
}
} else {
traverseResource(visitor, content);
}
if(!visitor.visitLeaveProperty(key, type, value)) {
return;
}
}
} else {
Map propertyDescriptors = PropertyUtils.getPropertyDescriptors(object);
for (PropertyDescriptor propertyDescriptor : propertyDescriptors.values()) {
String name = propertyDescriptor.getName();
if (filtered.contains(name)) {
continue;
}
// UberNode propertyNode = new UberNode();
Object content = propertyDescriptor.getReadMethod()
.invoke(object);
//
// if (isEmptyCollectionOrMap(content, propertyDescriptor.getPropertyType())) {
// continue;
// }
//
Object value = getContentAsScalarValue(content);
// propertyNode.setName(name);
// objectNode.addData(propertyNode);
Class propertyType = propertyDescriptor.getPropertyType();
if(!visitor.visitEnterProperty(name, propertyType, value)) {
return;
}
if (value != null) {
// for each scalar property of a simple bean, add valuepair nodes to data
if(!visitor.visitProperty(name, propertyType, value)) {
return;
}
} else {
traverseResource(visitor, content);
}
if(!visitor.visitLeaveProperty(name, propertyType, value)) {
return;
}
}
Field[] fields = object.getClass()
.getFields();
for (Field field : fields) {
String name = field.getName();
if (!propertyDescriptors.containsKey(name)) {
Object content = field.get(object);
Class type = field.getType();
// if (isEmptyCollectionOrMap(content, type)) {
// continue;
// }
// UberNode propertyNode = new UberNode();
//
Object value = getContentAsScalarValue(content);
// propertyNode.setName(name);
// objectNode.addData(propertyNode);
// if (value != null) {
// // for each scalar property of a simple bean, add valuepair nodes to data
// propertyNode.setValue(value);
// } else {
// toUberData(propertyNode, content);
// }
if(!visitor.visitEnterProperty(name, type, value)) {
return;
}
if (value != null) {
// for each scalar property of a simple bean, add valuepair nodes to data
if(!visitor.visitProperty(name, type, value)) {
return;
}
} else {
traverseResource(visitor, content);
}
if(!visitor.visitLeaveProperty(name, type, value)) {
return;
}
}
}
}
} catch (Exception ex) {
throw new RuntimeException("failed to transform object " + object, ex);
}
}
private static Object getContentAsScalarValue(Object content) {
final Object value;
if (content == null) {
value = ResourceTraversal.NULL_VALUE;
} else if (DataType.isSingleValueType(content.getClass())) {
value = content.toString();
} else {
value = null;
}
return value;
}
}
