/*
* Copyright (C) 2011, 2013, 2016 XStream Committers.
* All rights reserved.
*
* The software in this package is published under the terms of the BSD
* style license a copy of which has been included with this distribution in
* the LICENSE.txt file.
*
* Created on 30. July 2011 by Joerg Schaible
*/
package com.thoughtworks.xstream.converters.extended;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.ConverterLookup;
import com.thoughtworks.xstream.converters.ConverterMatcher;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.SingleValueConverter;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.DuplicateFieldException;
import com.thoughtworks.xstream.converters.reflection.ReflectionProvider;
import com.thoughtworks.xstream.core.JVM;
import com.thoughtworks.xstream.core.util.FastField;
import com.thoughtworks.xstream.core.util.HierarchicalStreams;
import com.thoughtworks.xstream.core.util.Primitives;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.mapper.Mapper;
/**
* Converter that supports the definition of one field member that will be written as value and
* all other field members are written as attributes. The converter requires that all the field
* types (expect the one with the value) are handled by a {@link SingleValueConverter}. The
* value field is defined using the name of the type that declares the field and the field name
* itself. Therefore it is possible to define an inherited field as value. It is also possible
* to provide no value field at all, so that all fields are written as attributes.
*
* @author Jörg Schaible
* @since 1.4
*/
public class ToAttributedValueConverter implements Converter {
private static final String STRUCTURE_MARKER = "";
private final Class type;
private final Mapper mapper;
private final Mapper enumMapper;
private final ReflectionProvider reflectionProvider;
private final ConverterLookup lookup;
private final Field valueField;
/**
* Creates a new ToAttributedValueConverter instance.
*
* All field elements will be attributes, the element itself will have no value.
*
* @param type the type that is handled by this converter instance
* @param mapper the mapper in use
* @param reflectionProvider the reflection provider in use
* @param lookup the converter lookup in use
* @since 1.4.9
*/
public ToAttributedValueConverter(
final Class type, final Mapper mapper, final ReflectionProvider reflectionProvider,
final ConverterLookup lookup) {
this(type, mapper, reflectionProvider, lookup, null, null);
}
/**
* Creates a new ToAttributedValueConverter instance.
*
* @param type the type that is handled by this converter instance
* @param mapper the mapper in use
* @param reflectionProvider the reflection provider in use
* @param lookup the converter lookup in use
* @param valueFieldName the field defining the tag's value (may be null)
*/
public ToAttributedValueConverter(
final Class type, final Mapper mapper, final ReflectionProvider reflectionProvider,
final ConverterLookup lookup, final String valueFieldName) {
this(type, mapper, reflectionProvider, lookup, valueFieldName, null);
}
/**
* Creates a new ToAttributedValueConverter instance.
*
* @param type the type that is handled by this converter instance
* @param mapper the mapper in use
* @param reflectionProvider the reflection provider in use
* @param lookup the converter lookup in use
* @param valueFieldName the field defining the tag's value (may be null)
* @param valueDefinedIn the type defining the field
*/
public ToAttributedValueConverter(
final Class type, final Mapper mapper, final ReflectionProvider reflectionProvider,
final ConverterLookup lookup, final String valueFieldName, Class valueDefinedIn) {
this.type = type;
this.mapper = mapper;
this.reflectionProvider = reflectionProvider;
this.lookup = lookup;
if (valueFieldName == null) {
valueField = null;
} else {
Field field = null;
try {
field = (valueDefinedIn != null ? valueDefinedIn : type)
.getDeclaredField(valueFieldName);
if (!field.isAccessible()) {
field.setAccessible(true);
}
} catch (NoSuchFieldException e) {
throw new IllegalArgumentException(e.getMessage() + ": " + valueFieldName);
}
this.valueField = field;
}
enumMapper = JVM.is15() ? UseAttributeForEnumMapper.createEnumMapper(mapper) : null;
}
public boolean canConvert(final Class type) {
return this.type == type;
}
public void marshal(final Object source, final HierarchicalStreamWriter writer,
final MarshallingContext context) {
final Class sourceType = source.getClass();
final Map defaultFieldDefinition = new HashMap();
final String[] tagValue = new String[1];
final Object[] realValue = new Object[1];
final Class[] fieldType = new Class[1];
final Class[] definingType = new Class[1];
reflectionProvider.visitSerializableFields(source, new ReflectionProvider.Visitor() {
public void visit(final String fieldName, final Class type, final Class definedIn,
final Object value) {
if (!mapper.shouldSerializeMember(definedIn, fieldName)) {
return;
}
final FastField field = new FastField(definedIn, fieldName);
final String alias = mapper.serializedMember(definedIn, fieldName);
if (!defaultFieldDefinition.containsKey(alias)) {
final Class lookupType = sourceType;
defaultFieldDefinition.put(
alias, reflectionProvider.getField(lookupType, fieldName));
} else if (!fieldIsEqual(field)) {
final ConversionException exception = new ConversionException(
"Cannot write attribute twice for object");
exception.add("alias", alias);
exception.add("type", sourceType.getName());
throw exception;
}
ConverterMatcher converter = UseAttributeForEnumMapper.isEnum(type)
? (ConverterMatcher)enumMapper.getConverterFromItemType(null, type, null)
: (ConverterMatcher)mapper.getLocalConverter(definedIn, fieldName);
if (converter == null) {
converter = lookup.lookupConverterForType(type);
}
if (value != null) {
boolean isValueField = valueField != null && fieldIsEqual(field);
if (isValueField) {
definingType[0] = definedIn;
fieldType[0] = type;
realValue[0] = value;
tagValue[0] = STRUCTURE_MARKER;
}
if (converter instanceof SingleValueConverter) {
final String str = ((SingleValueConverter)converter).toString(value);
if (isValueField) {
tagValue[0] = str;
} else {
if (str != null) {
writer.addAttribute(alias, str);
}
}
} else {
if (!isValueField) {
final ConversionException exception = new ConversionException(
"Cannot write element as attribute");
exception.add("alias", alias);
exception.add("type", sourceType.getName());
throw exception;
}
}
}
}
});
if (tagValue[0] != null) {
final Class actualType = realValue[0].getClass();
final Class defaultType = mapper.defaultImplementationOf(fieldType[0]);
if (!actualType.equals(defaultType)) {
final String serializedClassName = mapper.serializedClass(actualType);
if (!serializedClassName.equals(mapper.serializedClass(defaultType))) {
final String attributeName = mapper.aliasForSystemAttribute("class");
if (attributeName != null) {
writer.addAttribute(attributeName, serializedClassName);
}
}
}
if (tagValue[0] == STRUCTURE_MARKER) {
context.convertAnother(realValue[0]);
} else {
writer.setValue(tagValue[0]);
}
}
}
public Object unmarshal(final HierarchicalStreamReader reader,
final UnmarshallingContext context) {
final Object result = reflectionProvider.newInstance(context.getRequiredType());
final Class resultType = result.getClass();
final Set seenFields = new HashSet();
final Iterator it = reader.getAttributeNames();
final Set systemAttributes = new HashSet();
systemAttributes.add(mapper.aliasForSystemAttribute("class"));
// Process attributes before recursing into child elements.
while (it.hasNext()) {
final String attrName = (String)it.next();
if (systemAttributes.contains(attrName)) {
continue;
}
final String fieldName = mapper.realMember(resultType, attrName);
final Field field = reflectionProvider.getFieldOrNull(resultType, fieldName);
if (field != null) {
if (Modifier.isTransient(field.getModifiers())) {
continue;
}
Class type = field.getType();
final Class declaringClass = field.getDeclaringClass();
ConverterMatcher converter = UseAttributeForEnumMapper.isEnum(type)
? (ConverterMatcher)enumMapper.getConverterFromItemType(null, type, null)
: (ConverterMatcher)mapper.getLocalConverter(declaringClass, fieldName);
if (converter == null) {
converter = lookup.lookupConverterForType(type);
}
if (!(converter instanceof SingleValueConverter)) {
final ConversionException exception = new ConversionException(
"Cannot read field as a single value for object");
exception.add("field", fieldName);
exception.add("type", resultType.getName());
throw exception;
}
if (converter != null) {
final Object value = ((SingleValueConverter)converter).fromString(reader
.getAttribute(attrName));
if (type.isPrimitive()) {
type = Primitives.box(type);
}
if (value != null && !type.isAssignableFrom(value.getClass())) {
final ConversionException exception = new ConversionException(
"Cannot assign object to type");
exception.add("object type", value.getClass().getName());
exception.add("target type", type.getName());
throw exception;
}
reflectionProvider.writeField(result, fieldName, value, declaringClass);
if (!seenFields.add(new FastField(declaringClass, fieldName))) {
throw new DuplicateFieldException(fieldName
+ " ["
+ declaringClass.getName()
+ "]");
}
}
}
}
if (valueField != null) {
final Class classDefiningField = valueField.getDeclaringClass();
final String fieldName = valueField.getName();
final Field field = fieldName == null ? null : reflectionProvider.getField(
classDefiningField, fieldName);
if (fieldName == null || field == null) {
final ConversionException exception = new ConversionException(
"Cannot assign value to field of type");
exception.add("element", reader.getNodeName());
exception.add("field", fieldName);
exception.add("target type", context.getRequiredType().getName());
throw exception;
}
Class type;
final String classAttribute = HierarchicalStreams
.readClassAttribute(reader, mapper);
if (classAttribute != null) {
type = mapper.realClass(classAttribute);
} else {
type = mapper.defaultImplementationOf(reflectionProvider.getFieldType(
result, fieldName, classDefiningField));
}
final Object value = context.convertAnother(
result, type,
mapper.getLocalConverter(field.getDeclaringClass(), field.getName()));
final Class definedType = reflectionProvider.getFieldType(
result, fieldName, classDefiningField);
if (!definedType.isPrimitive()) {
type = definedType;
}
if (value != null && !type.isAssignableFrom(value.getClass())) {
final ConversionException exception = new ConversionException(
"Cannot assign object to type");
exception.add("object type", value.getClass().getName());
exception.add("target type", type.getName());
throw exception;
}
reflectionProvider.writeField(result, fieldName, value, classDefiningField);
if (!seenFields.add(new FastField(classDefiningField, fieldName))) {
throw new DuplicateFieldException(fieldName
+ " ["
+ classDefiningField.getName()
+ "]");
}
}
return result;
}
private boolean fieldIsEqual(FastField field) {
return valueField.getName().equals(field.getName())
&& valueField.getDeclaringClass().getName().equals(field.getDeclaringClass());
}
}