001 package edu.nrao.sss.webapp.faces.component;
002
003 import javax.faces.context.FacesContext;
004 import javax.faces.context.ResponseWriter;
005 import javax.faces.el.ValueBinding;
006
007 import java.io.IOException;
008
009 import java.util.Map;
010
011 /**
012 * This component extends the FloatingDialogUIComponent to provide both a
013 * serverside and clientside check for unsaved data when the exit button is
014 * hit. This component relies on 1 java script method being available in the
015 * rendered page:
016 *
017 * <p>
018 * <code>getClientSideChangesExist()</code>: returns true if changes have occured
019 * that have not yet been submitted. This method is <em>not</em> rendered by
020 * this component and must be provided by the application!
021 * </p>
022 * <p>
023 * TODO: Need to rewrite this and the FloatingDialogUIComponent to break up the
024 * rendering of the link/button into a separate method that's more easily
025 * overridden.
026 * </p>
027 * <p>
028 * NOTE: There is one outstanding problem with this safety mechanism, and that
029 * is, if a user changes a field, doesn't submit the form, but instead reloads
030 * the page for some reason, the form will still hold the new values they typed
031 * in (thanks to their trusty web browser) but neither the server, nor the java
032 * script will know that there have been changes. In this case, the user may
033 * loose data. It's rare enough that I don't think it's necessary to try and
034 * fix it. At least not yet.
035 * </p>
036 */
037 public class ExitDialogUIComponent extends FloatingDialogUIComponent
038 {
039 private static final String javaScriptBegin = "var elementStyle = document.getElementById('";
040 private static final String javaScriptEnd = "').style;" +
041 "elementStyle.display='block'; return false;";
042 protected static final String RENDERED_SCRIPT_KEY =
043 "edu.nrao.sss.webapp.faces.component.ExitDialogUIComponent.JavaScriptRendered";
044
045 private Boolean submittedChanges = null;
046
047 /**
048 * Override the encodeBegin method to make it output a button instead of a
049 * link and to write out fancier java script to handle the clientside
050 * changes flag.
051 */
052 public void encodeBegin(FacesContext context)
053 throws IOException
054 {
055 if (!isRendered())
056 return;
057
058 String id = getClientId(context);
059 encodeJavascriptMethods(context, id);
060
061 String linkStyleClass = (String)getAttributes().get("linkStyleClass");
062 String dialogStyleClass = (String)getAttributes().get("dialogStyleClass");
063 String styleClass = (String)getAttributes().get("styleClass");
064
065 String dialogId = id + ":popup";
066
067 ResponseWriter writer = context.getResponseWriter();
068 writer.write('\n');
069 writer.write('\n');
070
071 //Start a wrapper div with position: relative so the popup can be
072 //positioned relative to it.
073 writer.startElement("div", this);
074 writer.writeAttribute("id", id, null);
075
076 if (styleClass != null)
077 writer.writeAttribute("class", styleClass, null);
078
079 writer.write('\n');
080
081 //This is our button section.
082 writer.startElement("input", this);
083 writer.writeAttribute("value", "Exit", null);
084 writer.writeAttribute("type", "submit", null);
085 writer.writeAttribute("id", "LOGOUT", null);
086 writer.writeAttribute("name", "LOGOUT", null);
087
088 String title = getTitle();
089 if (title != null)
090 writer.writeAttribute("title", title, null);
091
092 if (linkStyleClass != null)
093 writer.writeAttribute("class", linkStyleClass, null);
094
095 String onclick = javaScriptBegin + dialogId + javaScriptEnd;
096
097 //If we don't have server side changes, we have to check if we client side
098 //changes in the javascript.
099 if (!getHasSubmittedChanges())
100 {
101 onclick = "if (getClientSideChangesExist()) { " +
102 onclick + "} else {return true;}";
103 }
104
105 writer.writeAttribute("onclick", onclick, null);
106
107 writer.endElement("input");
108 writer.write('\n');
109
110 //This is our popupDialog
111 writer.startElement("div", this);
112 writer.writeAttribute("id", dialogId, null);
113 writer.writeAttribute("style", "display:none;", null);
114
115 if (dialogStyleClass != null)
116 writer.writeAttribute("class", dialogStyleClass, null);
117
118 writer.write('\n');
119
120 //render our children as the contents of our dialog in the encodeChildren
121 //method.
122 }
123
124 /**
125 * Overridden to output the necessary javascript for this component. If the
126 * javascript has already be rendered for this response, nothing is done.
127 */
128 @SuppressWarnings("unchecked")
129 public void encodeJavascriptMethods(FacesContext context, String id)
130 throws IOException
131 {
132 Map requestMap = context.getExternalContext().getRequestMap();
133 Boolean scriptRendered = (Boolean)requestMap.get(RENDERED_SCRIPT_KEY);
134
135 if (scriptRendered != Boolean.TRUE)
136 {
137 requestMap.put(RENDERED_SCRIPT_KEY, Boolean.TRUE);
138 ResponseWriter writer = context.getResponseWriter();
139
140 writer.startElement("script", this);
141 writer.writeAttribute("type", "text/javascript", null);
142
143 StringBuilder sb = new StringBuilder();
144 sb.append("function getClientSideChangesExist() {\n");
145 sb.append("\tform = document.getElementById('" + id + "');\n");
146 sb.append("\tif (!form.clientSideChangesExist) {\n");
147 sb.append("\t\tform.clientSideChangesExist = false;\n");
148 sb.append("\t}\n");
149 sb.append("\treturn form.clientSideChangesExist;\n");
150 sb.append("}\n");
151 sb.append("\n");
152 sb.append("function setClientSideChangesExist(changed) {\n");
153 sb.append("\tform = document.getElementById('" + id + "');\n");
154 sb.append("\tform.clientSideChangesExist = changed;\n");
155 sb.append("}\n");
156
157 sb.append("var myrules = {\n");
158 sb.append("'input' : function(el) {\n");
159 sb.append("\tel.oldOnChange = el.onchange;\n");
160 sb.append("\tel.onchange = function(e) {\n");
161 sb.append("\tif (this.type != 'submit' && this.type != 'button') {\n");
162 sb.append("\tsetClientSideChangesExist(true);\n");
163 sb.append("\tif (this.oldOnChange) {\n");
164 sb.append("\tthis.oldOnChange(e);\n");
165 sb.append("\t}\n");
166 sb.append("\t}\n");
167 sb.append("\t};\n");
168 sb.append("},\n");
169 sb.append("'select' : function(el) {\n");
170 sb.append("\tel.oldOnChange = el.onchange;\n");
171 sb.append("\tel.onchange = function(e) {\n");
172 sb.append("\tsetClientSideChangesExist(true);\n");
173 sb.append("\tif (this.oldOnChange) {\n");
174 sb.append("\tthis.oldOnChange(e);\n");
175 sb.append("\t}\n");
176 sb.append("\t};\n");
177 sb.append("},\n");
178 sb.append("'textarea' : function(el) {\n");
179 sb.append("\tel.oldOnKeyPress = el.onkeypress;\n");
180 sb.append("\tel.onkeypress = function(e) {\n");
181 sb.append("\tsetClientSideChangesExist(true);\n");
182 sb.append("\tif (this.oldOnKeyPress) {\n");
183 sb.append("\tthis.oldOnKeyPress(e);\n");
184 sb.append("\t}\n");
185 sb.append("\t};\n");
186 sb.append("\t}\n");
187 sb.append("}\n");
188 sb.append("Behaviour.register(myrules);\n");
189
190
191 writer.write(sb.toString());
192 writer.endElement("script");
193 }
194 }
195
196 public Boolean getHasSubmittedChanges()
197 {
198 if (this.submittedChanges != null)
199 return this.submittedChanges;
200
201 ValueBinding vb = getValueBinding("submittedChanges");
202 if (vb != null)
203 {
204 Object val = vb.getValue(getFacesContext());
205
206 if (val instanceof Boolean && val != null)
207 return (Boolean)val;
208 }
209
210 //else
211 return Boolean.FALSE;
212 }
213
214 public void setHasSubmittedChanges(Boolean e)
215 {
216 this.submittedChanges = e;
217 }
218
219 public Object saveState(FacesContext context)
220 {
221 Object[] state = new Object[2];
222 state[0] = super.saveState(context);
223 state[1] = this.submittedChanges;
224
225 return state;
226 }
227
228 public void restoreState(FacesContext context, Object state)
229 {
230 Object[] myState = (Object[])state;
231 super.restoreState(context, myState[0]);
232 setHasSubmittedChanges((Boolean)myState[1]);
233 }
234 }