BaseExportView


1   /**
2    * Licensed under the Artistic License; you may not use this file
3    * except in compliance with the License.
4    * You may obtain a copy of the License at
5    *
6    *      http://displaytag.sourceforge.net/license.html
7    *
8    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
9    * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
10   * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
11   */
12  package org.displaytag.export;
13  
14  import java.io.IOException  ;
15  import java.io.Writer  ;
16  import java.util.Iterator  ;
17  
18  import javax.servlet.jsp.JspException  ;
19  
20  import org.apache.commons.lang.StringUtils;
21  import org.apache.commons.logging.Log;
22  import org.apache.commons.logging.LogFactory;
23  import org.displaytag.model.Column;
24  import org.displaytag.model.ColumnIterator;
25  import org.displaytag.model.HeaderCell;
26  import org.displaytag.model.Row;
27  import org.displaytag.model.RowIterator;
28  import org.displaytag.model.TableModel;
29  
30  
31  /**
32   * <p>
33   * Base abstract class for simple export views.
34   * </p>
35   * <p>
36   * A class that extends BaseExportView simply need to provide delimiters for rows and columns.
37   * </p>
38   * @author Fabrizio Giustina
39   * @version $Revision: 720 $ ($Author: fgiust $)
40   */
41  public abstract class BaseExportView implements TextExportView
42  {
43  
44      /**
45       * logger.
46       */
47      private static Log log = LogFactory.getLog(BaseExportView.class);
48  
49      /**
50       * TableModel to render.
51       */
52      private TableModel model;
53  
54      /**
55       * export full list?
56       */
57      private boolean exportFull;
58  
59      /**
60       * include header in export?
61       */
62      private boolean header;
63  
64      /**
65       * decorate export?
66       */
67      private boolean decorated;
68  
69      /**
70       * @see org.displaytag.export.ExportView#setParameters(org.displaytag.model.TableModel, boolean, boolean, boolean)
71       */
72      public void setParameters(TableModel tableModel, boolean exportFullList, boolean includeHeader,
73          boolean decorateValues)
74      {
75          this.model = tableModel;
76          this.exportFull = exportFullList;
77          this.header = includeHeader;
78          this.decorated = decorateValues;
79      }
80  
81      /**
82       * String to add before a row.
83       * @return String
84       */
85      protected String   getRowStart()
86      {
87          return null;
88      }
89  
90      /**
91       * String to add after a row.
92       * @return String
93       */
94      protected String   getRowEnd()
95      {
96          return null;
97      }
98  
99      /**
100      * String to add before a cell.
101      * @return String
102      */
103     protected String   getCellStart()
104     {
105         return null;
106     }
107 
108     /**
109      * String to add after a cell.
110      * @return String
111      */
112     protected abstract String   getCellEnd();
113 
114     /**
115      * String to add to the top of document.
116      * @return String
117      */
118     protected String   getDocumentStart()
119     {
120         return null;
121     }
122 
123     /**
124      * String to add to the end of document.
125      * @return String
126      */
127     protected String   getDocumentEnd()
128     {
129         return null;
130     }
131 
132     /**
133      * always append cell end string?
134      * @return boolean
135      */
136     protected abstract boolean getAlwaysAppendCellEnd();
137 
138     /**
139      * always append row end string?
140      * @return boolean
141      */
142     protected abstract boolean getAlwaysAppendRowEnd();
143 
144     /**
145      * can be implemented to escape values for different output.
146      * @param value original column value
147      * @return escaped column value
148      */
149     protected abstract String   escapeColumnValue(Object   value);
150 
151     /**
152      * Write table header.
153      * @return String rendered header
154      */
155     protected String   doHeaders()
156     {
157 
158         final String   ROW_START = getRowStart();
159         final String   ROW_END = getRowEnd();
160         final String   CELL_START = getCellStart();
161         final String   CELL_END = getCellEnd();
162         final boolean ALWAYS_APPEND_CELL_END = getAlwaysAppendCellEnd();
163 
164         StringBuffer   buffer = new StringBuffer  (1000);
165 
166         Iterator   iterator = this.model.getHeaderCellList().iterator();
167 
168         // start row
169         if (ROW_START != null)
170         {
171             buffer.append(ROW_START);
172         }
173 
174         while (iterator.hasNext())
175         {
176             HeaderCell headerCell = (HeaderCell) iterator.next();
177 
178             String   columnHeader = headerCell.getTitle();
179 
180             if (columnHeader == null)
181             {
182                 columnHeader = StringUtils.capitalize(headerCell.getBeanPropertyName());
183             }
184 
185             columnHeader = escapeColumnValue(columnHeader);
186 
187             if (CELL_START != null)
188             {
189                 buffer.append(CELL_START);
190             }
191 
192             if (columnHeader != null)
193             {
194                 buffer.append(columnHeader);
195             }
196 
197             if (CELL_END != null && (ALWAYS_APPEND_CELL_END || iterator.hasNext()))
198             {
199                 buffer.append(CELL_END);
200             }
201         }
202 
203         // end row
204         if (ROW_END != null)
205         {
206             buffer.append(ROW_END);
207         }
208 
209         return buffer.toString();
210 
211     }
212 
213     /**
214      * @see org.displaytag.export.TextExportView#doExport(java.io.Writer)
215      */
216     public void doExport(Writer   out) throws IOException  , JspException  
217     {
218         if (log.isDebugEnabled())
219         {
220             log.debug(getClass().getName());
221         }
222 
223         final String   DOCUMENT_START = getDocumentStart();
224         final String   DOCUMENT_END = getDocumentEnd();
225         final String   ROW_START = getRowStart();
226         final String   ROW_END = getRowEnd();
227         final String   CELL_START = getCellStart();
228         final String   CELL_END = getCellEnd();
229         final boolean ALWAYS_APPEND_CELL_END = getAlwaysAppendCellEnd();
230         final boolean ALWAYS_APPEND_ROW_END = getAlwaysAppendRowEnd();
231 
232         // document start
233         write(out, DOCUMENT_START);
234 
235         if (this.header)
236         {
237             write(out, doHeaders());
238         }
239 
240         // get the correct iterator (full or partial list according to the exportFull field)
241         RowIterator rowIterator = this.model.getRowIterator(this.exportFull);
242 
243         // iterator on rows
244         while (rowIterator.hasNext())
245         {
246             Row row = rowIterator.next();
247 
248             if (this.model.getTableDecorator() != null)
249             {
250 
251                 String   stringStartRow = this.model.getTableDecorator().startRow();
252                 write(out, stringStartRow);
253             }
254 
255             // iterator on columns
256             ColumnIterator columnIterator = row.getColumnIterator(this.model.getHeaderCellList());
257 
258             write(out, ROW_START);
259 
260             while (columnIterator.hasNext())
261             {
262                 Column column = columnIterator.nextColumn();
263 
264                 // Get the value to be displayed for the column
265                 String   value = escapeColumnValue(column.getValue(this.decorated));
266 
267                 write(out, CELL_START);
268 
269                 write(out, value);
270 
271                 if (ALWAYS_APPEND_CELL_END || columnIterator.hasNext())
272                 {
273                     write(out, CELL_END);
274                 }
275 
276             }
277             if (ALWAYS_APPEND_ROW_END || rowIterator.hasNext())
278             {
279                 write(out, ROW_END);
280             }
281         }
282 
283         // document end
284         write(out, DOCUMENT_END);
285 
286     }
287 
288     /**
289      * Write a String, checking for nulls value.
290      * @param out output writer
291      * @param string String to be written
292      * @throws IOException thrown by out.write
293      */
294     private void write(Writer   out, String   string) throws IOException  
295     {
296         if (string != null)
297         {
298             out.write(string);
299         }
300     }
301 
302     /**
303      * @see org.displaytag.export.TextExportView#outputPage()
304      */
305     public boolean outputPage()
306     {
307         return false;
308     }
309 }
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