1 /*
2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package javax.swing.text.html;
26
27 import java.util.Enumeration;
28 import java.awt.*;
29 import javax.swing.*;
30 import javax.swing.text.*;
31 import java.beans.*;
32 import java.lang.reflect.*;
33
34 import sun.reflect.misc.MethodUtil;
35 import sun.reflect.misc.ReflectUtil;
36
37 /**
38 * Component decorator that implements the view interface
39 * for <object> elements.
40 * <p>
41 * This view will try to load the class specified by the
42 * <code>classid</code> attribute. If possible, the Classloader
43 * used to load the associated Document is used.
44 * This would typically be the same as the ClassLoader
45 * used to load the EditorKit. If the document's
46 * ClassLoader is null, <code>Class.forName</code> is used.
47 * <p>
48 * If the class can successfully be loaded, an attempt will
49 * be made to create an instance of it by calling
50 * <code>Class.newInstance</code>. An attempt will be made
51 * to narrow the instance to type <code>java.awt.Component</code>
52 * to display the object.
53 * <p>
54 * This view can also manage a set of parameters with limitations.
55 * The parameters to the <object> element are expected to
56 * be present on the associated elements attribute set as simple
57 * strings. Each bean property will be queried as a key on
58 * the AttributeSet, with the expectation that a non-null value
59 * (of type String) will be present if there was a parameter
60 * specification for the property. Reflection is used to
61 * set the parameter. Currently, this is limited to a very
62 * simple single parameter of type String.
63 * <p>
64 * A simple example HTML invocation is:
65 * <pre>
66 * <object classid="javax.swing.JLabel">
67 * <param name="text" value="sample text">
68 * </object>
69 * </pre>
70 *
71 * @author Timothy Prinzing
72 */
73 public class ObjectView extends ComponentView {
74
75 /**
76 * Creates a new ObjectView object.
77 *
78 * @param elem the element to decorate
79 */
80 public ObjectView(Element elem) {
81 super(elem);
82 }
83
84 /**
85 * Create the component. The classid is used
86 * as a specification of the classname, which
87 * we try to load.
88 */
89 protected Component createComponent() {
90 AttributeSet attr = getElement().getAttributes();
91 String classname = (String) attr.getAttribute(HTML.Attribute.CLASSID);
92 try {
93 ReflectUtil.checkPackageAccess(classname);
94 Class c = Class.forName(classname, true,Thread.currentThread().
95 getContextClassLoader());
96 Object o = c.newInstance();
97 if (o instanceof Component) {
98 Component comp = (Component) o;
99 setParameters(comp, attr);
100 return comp;
101 }
102 } catch (Throwable e) {
103 // couldn't create a component... fall through to the
104 // couldn't load representation.
105 }
106
107 return getUnloadableRepresentation();
108 }
109
110 /**
111 * Fetch a component that can be used to represent the
112 * object if it can't be created.
113 */
114 Component getUnloadableRepresentation() {
115 // PENDING(prinz) get some artwork and return something
116 // interesting here.
117 Component comp = new JLabel("??");
118 comp.setForeground(Color.red);
119 return comp;
120 }
121
122 /**
123 * Initialize this component according the KEY/VALUEs passed in
124 * via the <param> elements in the corresponding
125 * <object> element.
126 */
127 private void setParameters(Component comp, AttributeSet attr) {
128 Class k = comp.getClass();
129 BeanInfo bi;
130 try {
131 bi = Introspector.getBeanInfo(k);
132 } catch (IntrospectionException ex) {
133 System.err.println("introspector failed, ex: "+ex);
134 return; // quit for now
135 }
136 PropertyDescriptor props[] = bi.getPropertyDescriptors();
137 for (int i=0; i < props.length; i++) {
138 // System.err.println("checking on props[i]: "+props[i].getName());
139 Object v = attr.getAttribute(props[i].getName());
140 if (v instanceof String) {
141 // found a property parameter
142 String value = (String) v;
143 Method writer = props[i].getWriteMethod();
144 if (writer == null) {
145 // read-only property. ignore
146 return; // for now
147 }
148 Class[] params = writer.getParameterTypes();
149 if (params.length != 1) {
150 // zero or more than one argument, ignore
151 return; // for now
152 }
153 Object [] args = { value };
154 try {
155 MethodUtil.invoke(writer, comp, args);
156 } catch (Exception ex) {
157 System.err.println("Invocation failed");
158 // invocation code
159 }
160 }
161 }
162 }
163
164 }