Java tutorial
/** * Copyright (C) 2010-16 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 com.github.rvesse.airline; import com.github.rvesse.airline.parser.ParserUtil; import com.github.rvesse.airline.parser.errors.ParseException; import com.github.rvesse.airline.utils.AirlineUtils; import java.lang.annotation.Annotation; import java.lang.reflect.Field; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.lang.reflect.TypeVariable; import java.util.ArrayList; import java.util.Collection; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.Set; import java.util.SortedSet; import java.util.TreeSet; import org.apache.commons.collections4.CollectionUtils; import org.apache.commons.collections4.IteratorUtils; import org.apache.commons.collections4.ListUtils; public class Accessor { private final String name; private final Class<?> javaType; private final List<Field> path; private boolean multiValued; public Accessor(Field... path) { this(AirlineUtils.arrayToList(path)); } public Accessor(Iterable<Field> path) { this(path.iterator()); } public Accessor(Iterator<Field> path) { this(IteratorUtils.toList(path)); } public Accessor(List<Field> path) { if (path == null) throw new NullPointerException("path is null"); if (path.size() == 0) throw new IllegalArgumentException("path is empty"); this.path = ListUtils.unmodifiableList(path); StringBuilder nameBuilder = new StringBuilder(); // Build the name for the accessor nameBuilder.append(this.path.get(0).getDeclaringClass().getSimpleName()); for (Field field : this.path) { nameBuilder.append('.').append(field.getName()); } this.name = nameBuilder.toString(); Field field = this.path.get(this.path.size() - 1); multiValued = Collection.class.isAssignableFrom(field.getType()); javaType = getItemType(name, field.getGenericType()); } public String getName() { return name; } public Class<?> getJavaType() { return javaType; } public boolean isMultiValued() { return multiValued; } public Object getValue(Object instance) { StringBuilder pathName = new StringBuilder(); for (Field intermediateField : path.subList(0, path.size() - 1)) { if (pathName.length() != 0) { pathName.append("."); } pathName.append(intermediateField.getName()); try { Object nextInstance = intermediateField.get(instance); if (nextInstance == null) { nextInstance = ParserUtil.createInstance(intermediateField.getType()); intermediateField.set(instance, nextInstance); } instance = nextInstance; } catch (Exception e) { throw new ParseException(e, "Error getting value of %s", pathName); } } return instance; } public <T extends Annotation> T getAnnotation(Class<T> annotationCls) { Field lastField = path.get(path.size() - 1); return lastField.getAnnotation(annotationCls); } public void addValues(Object commandInstance, Iterable<?> values) { if (!values.iterator().hasNext()) { return; } // get the actual instance Object instance = getValue(commandInstance); Field field = path.get(path.size() - 1); field.setAccessible(true); if (Collection.class.isAssignableFrom(field.getType())) { Collection<Object> collection = getOrCreateCollectionField(name, instance, field); CollectionUtils.addAll(collection, values); } else { try { field.set(instance, AirlineUtils.last(values)); } catch (Exception e) { throw new ParseException(e, "Error setting %s for argument %s", field.getName(), name); } } } @Override public boolean equals(Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } Accessor accessor = (Accessor) o; if (!path.equals(accessor.path)) { return false; } return true; } @Override public int hashCode() { return path.hashCode(); } @Override public String toString() { return name; } // // Private reflection helper methods // @SuppressWarnings({ "unchecked", "rawtypes" }) private static Collection<Object> newCollection(Class<?> type) { if (Collection.class.equals(type) || List.class.equals(type)) { return new ArrayList<Object>(); } if (Set.class.equals(type)) { return new HashSet<Object>(); } if (SortedSet.class.equals(type)) { return new TreeSet(); } try { return (Collection<Object>) type.getConstructor().newInstance(); } catch (Exception ignored) { } throw new ParseException( "Parameters of Collection type '%s' are not supported. Please use List or Set instead.", type.getSimpleName()); } @SuppressWarnings("unchecked") private static Collection<Object> getOrCreateCollectionField(String name, Object object, Field field) { Collection<Object> collection; try { collection = (Collection<Object>) field.get(object); } catch (Exception e) { throw new ParseException(e, "Error getting collection field %s for argument %s", field.getName(), name); } if (collection == null) { collection = newCollection(field.getType()); try { field.set(object, collection); } catch (Exception e) { throw new ParseException(e, "Error setting collection field %s for argument %s", field.getName(), name); } } return collection; } private static Class<?> getItemType(String name, Type type) { Class<?> rawClass = getRawType(type); if (rawClass == null) { throw new ParseException("Type of option %s be an exact type", name); } if (!Collection.class.isAssignableFrom(rawClass)) { return rawClass; } Type[] types = getTypeParameters(Collection.class, type); if ((types == null) || (types.length != 1)) { throw new ParseException("Unable to get item type of Collection option %s", name); } Type itemType = types[0]; if (!(itemType instanceof Class)) { throw new ParseException("Collection type option %s must be an exact type", name); } return (Class<?>) itemType; } private static Class<?> getRawType(Type type) { if (type instanceof Class) { return (Class<?>) type; } if (type instanceof ParameterizedType) { ParameterizedType parameterizedType = (ParameterizedType) type; return getRawType(parameterizedType.getRawType()); } return null; } private static Type[] getTypeParameters(Class<?> desiredType, Type type) { if (type instanceof Class) { Class<?> rawClass = (Class<?>) type; // if this is the collection class we're done if (desiredType.equals(type)) { return null; } for (Type iface : rawClass.getGenericInterfaces()) { Type[] collectionType = getTypeParameters(desiredType, iface); if (collectionType != null) { return collectionType; } } return getTypeParameters(desiredType, rawClass.getGenericSuperclass()); } if (type instanceof ParameterizedType) { ParameterizedType parameterizedType = (ParameterizedType) type; Type rawType = parameterizedType.getRawType(); if (desiredType.equals(rawType)) { return parameterizedType.getActualTypeArguments(); } Type[] collectionTypes = getTypeParameters(desiredType, rawType); if (collectionTypes != null) { for (int i = 0; i < collectionTypes.length; i++) { if (collectionTypes[i] instanceof TypeVariable) { TypeVariable<?> typeVariable = (TypeVariable<?>) collectionTypes[i]; TypeVariable<?>[] rawTypeParams = ((Class<?>) rawType).getTypeParameters(); for (int j = 0; j < rawTypeParams.length; j++) { if (typeVariable.getName().equals(rawTypeParams[j].getName())) { collectionTypes[i] = parameterizedType.getActualTypeArguments()[j]; } } } } } return collectionTypes; } return null; } }