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22 package org.apache.struts2.views.freemarker;
23
24 import java.util.Map;
25 import java.util.Set;
26
27 import freemarker.core.CollectionAndSequence;
28 import freemarker.ext.beans.BeansWrapper;
29 import freemarker.ext.beans.MapModel;
30 import freemarker.ext.util.ModelFactory;
31 import freemarker.template.ObjectWrapper;
32 import freemarker.template.SimpleSequence;
33 import freemarker.template.TemplateBooleanModel;
34 import freemarker.template.TemplateCollectionModel;
35 import freemarker.template.TemplateHashModelEx;
36 import freemarker.template.TemplateModel;
37 import freemarker.template.TemplateModelException;
38
39 /***
40 * <!-- START SNIPPET: javadoc -->
41 *
42 * The StrutsBeanWrapper extends the default FreeMarker BeansWrapper and provides almost no change in functionality,
43 * <b>except</b> for how it handles maps. Normally, FreeMarker has two modes of operation: either support for friendly
44 * map built-ins (?keys, ?values, etc) but only support for String keys; OR no special built-in support (ie: ?keys
45 * returns the methods on the map instead of the keys) but support for String and non-String keys alike. Struts
46 * provides an alternative implementation that gives us the best of both worlds.
47 *
48 * <p/> It is possible that this special behavior may be confusing or can cause problems. Therefore, you can set the
49 * <b>struts.freemarker.wrapper.altMap</b> property in struts.properties to false, allowing the normal BeansWrapper
50 * logic to take place instead.
51 *
52 * <!-- END SNIPPET: javadoc -->
53 */
54 public class StrutsBeanWrapper extends BeansWrapper {
55 private boolean altMapWrapper;
56
57 StrutsBeanWrapper(boolean altMapWrapper) {
58 this.altMapWrapper = altMapWrapper;
59 }
60
61 public TemplateModel wrap(Object object) throws TemplateModelException {
62 if (object instanceof TemplateBooleanModel) {
63 return super.wrap(object);
64 }
65
66
67 if (altMapWrapper && object instanceof Map) {
68 return getInstance(object, FriendlyMapModel.FACTORY);
69 }
70
71 return super.wrap(object);
72 }
73
74 /***
75 * Attempting to get the best of both worlds of FM's MapModel and SimpleMapModel, by reimplementing the isEmpty(),
76 * keySet() and values() methods. ?keys and ?values built-ins are thus available, just as well as plain Map
77 * methods.
78 */
79 private final static class FriendlyMapModel extends MapModel implements TemplateHashModelEx {
80 static final ModelFactory FACTORY = new ModelFactory() {
81 public TemplateModel create(Object object, ObjectWrapper wrapper) {
82 return new FriendlyMapModel((Map) object, (BeansWrapper) wrapper);
83 }
84 };
85
86 public FriendlyMapModel(Map map, BeansWrapper wrapper) {
87 super(map, wrapper);
88 }
89
90 public boolean isEmpty() {
91 return ((Map) object).isEmpty();
92 }
93
94 protected Set keySet() {
95 return ((Map) object).keySet();
96 }
97
98 public TemplateCollectionModel values() {
99 return new CollectionAndSequence(new SimpleSequence(((Map) object).values(), wrapper));
100 }
101 }
102 }