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.awt.*;
28 import javax.swing.*;
29 import javax.swing.text.*;
30 import java.beans.*;
31 import java.lang.reflect.*;
32
33 import sun.reflect.misc.MethodUtil;
34 import sun.reflect.misc.ReflectUtil;
35
36 /**
37 * Component decorator that implements the view interface
38 * for <object> elements.
39 * <p>
40 * This view will try to load the class specified by the
41 * <code>classid</code> attribute. If possible, the Classloader
42 * used to load the associated Document is used.
43 * This would typically be the same as the ClassLoader
44 * used to load the EditorKit. If the document's
45 * ClassLoader is null, <code>Class.forName</code> is used.
46 * <p>
47 * If the class can successfully be loaded, an attempt will
48 * be made to create an instance of it by calling
49 * <code>Class.newInstance</code>. An attempt will be made
50 * to narrow the instance to type <code>java.awt.Component</code>
51 * to display the object.
52 * <p>
53 * This view can also manage a set of parameters with limitations.
54 * The parameters to the <object> element are expected to
55 * be present on the associated elements attribute set as simple
56 * strings. Each bean property will be queried as a key on
57 * the AttributeSet, with the expectation that a non-null value
58 * (of type String) will be present if there was a parameter
59 * specification for the property. Reflection is used to
60 * set the parameter. Currently, this is limited to a very
61 * simple single parameter of type String.
62 * <p>
63 * A simple example HTML invocation is:
64 * <pre>
65 * <object classid="javax.swing.JLabel">
66 * <param name="text" value="sample text">
67 * </object>
68 * </pre>
69 *
70 * @author Timothy Prinzing
71 */
72 public class ObjectView extends ComponentView {
73
74 /**
75 * Creates a new ObjectView object.
76 *
77 * @param elem the element to decorate
78 */
79 public ObjectView(Element elem) {
80 super(elem);
81 }
82
83 /**
84 * Create the component. The classid is used
85 * as a specification of the classname, which
86 * we try to load.
87 */
88 protected Component createComponent() {
89 AttributeSet attr = getElement().getAttributes();
90 String classname = (String) attr.getAttribute(HTML.Attribute.CLASSID);
91 try {
92 ReflectUtil.checkPackageAccess(classname);
93 Class<?> c = Class.forName(classname, true,Thread.currentThread().
94 getContextClassLoader());
95 Object o = c.newInstance();
96 if (o instanceof Component) {
97 Component comp = (Component) o;
98 setParameters(comp, attr);
99 return comp;
100 }
101 } catch (Throwable e) {
102 // couldn't create a component... fall through to the
103 // couldn't load representation.
104 }
105
106 return getUnloadableRepresentation();
107 }
108
109 /**
110 * Fetch a component that can be used to represent the
111 * object if it can't be created.
112 */
113 Component getUnloadableRepresentation() {
114 // PENDING(prinz) get some artwork and return something
115 // interesting here.
116 Component comp = new JLabel("??");
117 comp.setForeground(Color.red);
118 return comp;
119 }
120
121 /**
122 * Initialize this component according the KEY/VALUEs passed in
123 * via the <param> elements in the corresponding
124 * <object> element.
125 */
126 private void setParameters(Component comp, AttributeSet attr) {
127 Class<?> k = comp.getClass();
128 BeanInfo bi;
129 try {
130 bi = Introspector.getBeanInfo(k);
131 } catch (IntrospectionException ex) {
132 System.err.println("introspector failed, ex: "+ex);
133 return; // quit for now
134 }
135 PropertyDescriptor props[] = bi.getPropertyDescriptors();
136 for (int i=0; i < props.length; i++) {
137 // System.err.println("checking on props[i]: "+props[i].getName());
138 Object v = attr.getAttribute(props[i].getName());
139 if (v instanceof String) {
140 // found a property parameter
141 String value = (String) v;
142 Method writer = props[i].getWriteMethod();
143 if (writer == null) {
144 // read-only property. ignore
145 return; // for now
146 }
147 Class<?>[] params = writer.getParameterTypes();
148 if (params.length != 1) {
149 // zero or more than one argument, ignore
150 return; // for now
151 }
152 Object [] args = { value };
153 try {
154 MethodUtil.invoke(writer, comp, args);
155 } catch (Exception ex) {
156 System.err.println("Invocation failed");
157 // invocation code
158 }
159 }
160 }
161 }
162
163 }