001 package edu.nrao.sss.webapp.faces.component;
002
003 import edu.nrao.sss.webapp.faces.renderer.RendererUtils;
004
005 import javax.faces.component.UIData;
006 import javax.faces.component.UIComponent;
007 import javax.faces.context.ResponseWriter;
008 import javax.faces.context.FacesContext;
009
010 import java.io.IOException;
011 import java.io.StringWriter;
012 import java.util.List;
013 import java.util.Iterator;
014
015 /**
016 * This class implements a ForEach loop tag by partially overriding the default
017 * table renderer. By partially, I mean those parts of the rendering that dealt
018 * solely with rendering UIColumns are overridden or replaced to deal with all
019 * child elements and no table tags are written. This allows us to borrow the
020 * default renderer's handling of child id's and the data model and all that.
021 */
022 public class ForEach extends UIData
023 {
024 private static final int PROCESS_DECODES = 1;
025 private static final int PROCESS_VALIDATORS = 2;
026 private static final int PROCESS_UPDATES = 3;
027
028 /** empty constructor */
029 public ForEach()
030 {
031 }
032
033 /**
034 * This method is overridden to prevent the default renderer from writing
035 * out table tags. This is done by temporarily replacing the ResponseWriter
036 * in context, calling super (because super must be called to correctly
037 * handle some model interaction), and then putting the real writer back.
038 */
039 public void encodeBegin(FacesContext context) throws IOException
040 {
041 // Ensure that the "current row" is set to "no row", so that the
042 // correct clientId is set for this component etc. User code may
043 // have left this in some other state before rendering began...
044 setRowIndex(-1);
045
046 ResponseWriter realWriter = context.getResponseWriter();
047 ResponseWriter fake = realWriter.cloneWithWriter(new StringWriter());
048
049 context.setResponseWriter(fake);
050 super.encodeBegin(context);
051 context.setResponseWriter(realWriter);
052 }
053
054 /**
055 * Overridden to prevent end table tag output
056 */
057 public void encodeEnd(FacesContext context) throws IOException
058 {
059 }
060
061 /**
062 * Overridden to render our child UI components even though they are not
063 * UIColumns.
064 */
065 public void encodeChildren(FacesContext context) throws IOException
066 {
067 int first = getFirst();
068 int rows = getRows();
069 int last;
070 if (rows <= 0)
071 {
072 last = getRowCount();
073 }
074 else
075 {
076 last = first + rows;
077 }
078 for (int rowIndex = first; last==-1 || rowIndex < last; rowIndex++)
079 {
080 setRowIndex(rowIndex);
081
082 //scrolled past the last row
083 if (!isRowAvailable())
084 break;
085
086 List children = getChildren();
087 for (int j = 0, size = getChildCount(); j < size; j++)
088 {
089 UIComponent child = (UIComponent) children.get(j);
090 RendererUtils.renderChild(context, child);
091 }
092 }
093 }
094
095 /**
096 * Overridden to properly decode our child components
097 */
098 public void processDecodes(FacesContext context)
099 {
100 if (context == null)
101 throw new NullPointerException("context");
102 if (!isRendered())
103 return;
104 setRowIndex(-1);
105 processChildren(context, PROCESS_DECODES);
106 setRowIndex(-1);
107 try
108 {
109 decode(context);
110 }
111 catch (RuntimeException e)
112 {
113 context.renderResponse();
114 throw e;
115 }
116 }
117
118 /**
119 * Overridden to properly decode our child components
120 */
121 public void processValidators(FacesContext context)
122 {
123 if (context == null)
124 throw new NullPointerException("context");
125 if (!isRendered())
126 return;
127 setRowIndex(-1);
128 processChildren(context, PROCESS_VALIDATORS);
129 setRowIndex(-1);
130
131 //We have no uicolumns, but we need to run super.processValidators()
132 //anyway so that the correct model actions will take place when data is not
133 //valid.
134 super.processValidators(context);
135 }
136
137 /**
138 * Overridden to properly decode our child components
139 */
140 public void processUpdates(FacesContext context)
141 {
142 if (context == null)
143 throw new NullPointerException("context");
144 if (!isRendered())
145 return;
146 setRowIndex(-1);
147 processChildren(context, PROCESS_UPDATES);
148 setRowIndex(-1);
149
150 //We have no uicolumns, but we need to run super.processUpdates()
151 //anyway so that the correct model actions will take place when data is not
152 //valid.
153 super.processUpdates(context);
154 }
155
156 /**
157 * Helper method to process our children
158 */
159 private void processChildren(FacesContext context, int processAction)
160 {
161 int first = getFirst();
162 int rows = getRows();
163 int last;
164 if (rows == 0)
165 {
166 last = getRowCount();
167 }
168 else
169 {
170 last = first + rows;
171 }
172
173 for (int rowIndex = first; last==-1 || rowIndex < last; rowIndex++)
174 {
175 setRowIndex(rowIndex);
176
177 //scrolled past the last row
178 if (!isRowAvailable())
179 break;
180
181 for (Iterator childIter = getChildren().iterator(); childIter.hasNext();)
182 {
183 UIComponent child = (UIComponent)childIter.next();
184 process(context, child, processAction);
185 }
186 }
187 }
188
189 /**
190 * Helper method to process our children
191 */
192 private void process(FacesContext context, UIComponent component, int processAction)
193 {
194 switch (processAction)
195 {
196 case PROCESS_DECODES:
197 component.processDecodes(context);
198 break;
199 case PROCESS_VALIDATORS:
200 component.processValidators(context);
201 break;
202 case PROCESS_UPDATES:
203 component.processUpdates(context);
204 break;
205 }
206 }
207 }