|
1
19
20 package org.apache.cayenne.util;
21
22 import java.lang.reflect.Method  ;
23 import java.util.ArrayList ;
24 import java.util.Collection ;
25 import java.util.HashMap ;
26 import java.util.Map ;
27
28 import org.apache.cayenne.jpa.JpaProviderException;
29 import org.apache.cayenne.project.ProjectPath;
30
31
37 public class TraversalUtil {
38
39 static final ClassTraversalDescriptor noopDescriptor = new ClassTraversalDescriptor();
40 static final Map <String , ClassTraversalDescriptor> descriptors = new HashMap <String , ClassTraversalDescriptor>();
41
42 private static Method [] traversableGetters(Class nodeType) {
43
44 Collection <Method > getters = null;
45
46 Method [] methods = nodeType.getMethods();
47 for (int i = 0; i < methods.length; i++) {
48 if (methods[i].isAnnotationPresent(TreeNodeChild.class)
49 && !Void.TYPE.equals(methods[i].getReturnType())) {
50
51 if (getters == null) {
52 getters = new ArrayList <Method >(5);
53 }
54
55 getters.add(methods[i]);
56 }
57 }
58
59 return getters != null ? getters.toArray(new Method [getters.size()]) : null;
60 }
61
62 static synchronized ClassTraversalDescriptor getDescriptor(Class nodeType) {
63 String typeName = nodeType.getName();
64 ClassTraversalDescriptor descriptor = descriptors.get(typeName);
65 if (descriptor == null) {
66 Method [] getters = traversableGetters(nodeType);
67 descriptor = getters != null
68 ? new ClassTraversalDescriptor(getters)
69 : noopDescriptor;
70 descriptors.put(typeName, descriptor);
71 }
72
73 return descriptor;
74 }
75
76
79 public static void traverse(Object treeRoot, HierarchicalTreeVisitor visitor) {
80 traverse(treeRoot, visitor, null);
81 }
82
83 static void traverse(
84 Object node,
85 HierarchicalTreeVisitor visitor,
86 ProjectPath parentPath) {
87
88 ProjectPath path = parentPath != null
89 ? parentPath.appendToPath(node)
90 : new ProjectPath(node);
91
92 if (visitor.onStartNode(path)) {
93
94 ClassTraversalDescriptor descriptor = getDescriptor(node.getClass());
95 Class [] childTypes = descriptor.getTraversableChildTypes();
96 if (childTypes != null && childTypes.length > 0) {
97 for (int i = 0; i < childTypes.length; i++) {
98
99 HierarchicalTreeVisitor childVisitor = visitor.childVisitor(
100 path,
101 childTypes[i]);
102 if (childVisitor != null) {
103 Object child = descriptor.getTraversableChild(node, i);
104
105 if (child == null) {
106 continue;
107 }
108 else if (child instanceof Collection ) {
109 Collection children = (Collection ) child;
110
111 if (children != null && !children.isEmpty()) {
112 for (Object collectionChild : children) {
113 traverse(collectionChild, childVisitor, path);
114 }
115 }
116 }
117 else {
118 traverse(child, childVisitor, path);
119 }
120 }
121 }
122 }
123
124 visitor.onFinishNode(path);
125 }
126 }
127
128 static class ClassTraversalDescriptor {
129
130 Class [] traversableChildTypes;
131 Method [] traversableGetters;
132
133 ClassTraversalDescriptor() {
134
135 }
136
137 ClassTraversalDescriptor(Method [] traversableChildGetters) {
138 this.traversableGetters = traversableChildGetters;
139 this.traversableChildTypes = new Class [traversableChildGetters.length];
140 for (int i = 0; i < traversableChildGetters.length; i++) {
141 Class type = traversableChildGetters[i].getReturnType();
142 if (Collection .class.isAssignableFrom(type)) {
143 type = traversableChildGetters[i]
144 .getAnnotation(TreeNodeChild.class)
145 .type();
146
147 if (void.class.equals(type)) {
150 throw new JpaProviderException("No type for collection defined: "
151 + traversableChildGetters[i].getName());
152 }
153 }
154
155 traversableChildTypes[i] = type;
156 }
157 }
158
159 Class [] getTraversableChildTypes() {
160 return traversableChildTypes;
161 }
162
163 Object getTraversableChild(Object object, int childIndex) {
164
165 try {
166 return traversableGetters[childIndex].invoke(object, (Object []) null);
167 }
168 catch (Exception e) {
169 throw new JpaProviderException("Error reading traversible property", e);
170 }
171 }
172 }
173 }
174 |
Popular Tags |
Java API By Example, From Geeks To Geeks.