TemplateExceptionHandler


1   /*
2    * Copyright (c) 2003 The Visigoth Software Society. All rights
3    * reserved.
4    *
5    * Redistribution and use in source and binary forms, with or without
6    * modification, are permitted provided that the following conditions
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8    *
9    * 1. Redistributions of source code must retain the above copyright
10   *    notice, this list of conditions and the following disclaimer.
11   *
12   * 2. Redistributions in binary form must reproduce the above copyright
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14   *    the documentation and/or other materials provided with the
15   *    distribution.
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17   * 3. The end-user documentation included with the redistribution, if
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19   *       "This product includes software developed by the
20   *        Visigoth Software Society (http://www.visigoths.org/)."
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22   *    if and wherever such third-party acknowledgements normally appear.
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51   */
52  
53  package freemarker.template;
54  
55  import java.io.Writer  ;
56  import java.io.PrintWriter  ;
57  import freemarker.core.Environment;
58  
59  /**
60   * An API for objects that handle exceptions that are thrown during
61   * template rendering.
62   * @author <a HREF="mailto:jon@revusky.com">Jonathan Revusky</a>
63   */
64  
65  public interface TemplateExceptionHandler {
66      
67      /**
68        * handle the exception.
69        * @param te the exception that occurred.
70        * @param env The environment object that represents the rendering context
71        * @param out the character output stream to output to.
72        */
73      void handleTemplateException(TemplateException te, Environment env, Writer   out) 
74          throws TemplateException;
75              
76              
77           /**
78             * This is a TemplateExceptionHandler which simply skips errors. It does nothing
79             * to handle the event. Note that the exception is still logged in any case, before
80             * being passed to the handler.
81             */
82      TemplateExceptionHandler IGNORE_HANDLER = new TemplateExceptionHandler() {
83          public void handleTemplateException(TemplateException te, Environment env, Writer   out) {
84          }
85      };
86          
87           /**
88             * This is a TemplateExceptionHandler that simply rethrows the exception.
89             * Note that the exception is logged before being rethrown.
90             */
91      TemplateExceptionHandler RETHROW_HANDLER =new TemplateExceptionHandler() {
92          public void handleTemplateException(TemplateException te, Environment env, Writer   out) 
93                      throws TemplateException  
94                  {
95                      throw te;
96          }
97      };
98          
99          /**
100           * This is a TemplateExceptionHandler used when you develop the templates. This handler
101           * outputs the stack trace information to the client and then rethrows the exception.
102           */
103     TemplateExceptionHandler DEBUG_HANDLER =new TemplateExceptionHandler() {
104         public void handleTemplateException(TemplateException te, Environment env, Writer   out) 
105                     throws TemplateException  
106                 {
107                     PrintWriter   pw = (out instanceof PrintWriter  ) 
108                                  ? (PrintWriter  ) out 
109                                  : new PrintWriter  (out);
110                     te.printStackTrace(pw);
111                     pw.flush();
112                     throw te;
113         }
114     }; 
115 
116         /**
117           * This is a TemplateExceptionHandler used when you develop HTML templates. This handler
118           * outputs the stack trace information to the client and then rethrows the exception, and
119           * surrounds it with tags to make the error message readable with the browser.
120           */
121     TemplateExceptionHandler HTML_DEBUG_HANDLER =new TemplateExceptionHandler() {
122         public void handleTemplateException(TemplateException te, Environment env, Writer   out) 
123                     throws TemplateException  
124                 {
125                     PrintWriter   pw = (out instanceof PrintWriter  ) 
126                                  ? (PrintWriter  ) out 
127                                  : new PrintWriter  (out);
128                     pw.println("<!-- FREEMARKER ERROR MESSAGE STARTS HERE -->"
129                             + "<script language=javascript>//\"></script>"
130                             + "<script language=javascript>//\'></script>"
131                             + "<script language=javascript>//\"></script>"
132                             + "<script language=javascript>//\'></script>"
133                             + "</title></xmp></script></noscript></style></object>"
134                             + "</head></pre></table>"
135                             + "</form></table></table></table></a></u></i></b>"
136                             + "<div align=left "
137                             + "style='background-color:#FFFF00; color:#FF0000; "
138                             + "display:block; border-top:double; padding:2pt; "
139                             + "font-size:medium; font-family:Arial,sans-serif; "
140                             + "font-style: normal; font-variant: normal; "
141                             + "font-weight: normal; text-decoration: none; "
142                             + "text-transform: none'>"
143                             + "<b style='font-size:medium'>FreeMarker template error!</b>"
144                             + "<pre><xmp>");
145                     te.printStackTrace(pw);
146                     pw.println("</xmp></pre></div></html>");
147                     pw.flush();
148                     throw te;
149         }
150     }; 
151 }
152
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