TransformStep


1   /*
2    * $Id: TransformStep.java,v 1.4 2003/04/12 06:10:51 lhoriman Exp $
3    * $Source: /cvsroot/mav/maverick/src/java/org/infohazard/maverick/flow/TransformStep.java,v $
4    */
5   
6   package org.infohazard.maverick.flow;
7   
8   import java.io.IOException  ;
9   import java.io.Writer  ;
10  import java.io.Reader  ;
11  import javax.servlet.ServletException  ;
12  import javax.servlet.http.HttpServletResponse  ;
13  import javax.xml.transform.Source  ;
14  import org.xml.sax.ContentHandler  ;
15  
16  /**
17   * The TransformStep defines a transformation step in a single request.  It
18   * is used and then disposed of.  It provides convenient facades for most
19   * of the usual output mechanisms that views and previous transforms might
20   * want.
21   *
22   * Unlike a Transform, a TransformStep is used in a single request and
23   * then thrown away.
24   */
25  public interface TransformStep
26  {
27      /**
28       * Your steps should always return false.  The last step, which
29       * is not really a step at all - it's the real output stream,
30       * will return true.
31       */
32      public boolean isLast();
33      
34      /**
35       * This method allows content-type information to be passed into the
36       * subsequent step.  It is equivalent to getResponse().setContentType(),
37       * however it can be used for all the other output methods (which
38       * do not provide a HttpServletResponse interface.  Calling this method
39       * is optional but recommended so that prematurely halted transformations
40       * can have an intelligently set content-type.
41       */
42      public void setContentType(String   contentType);
43      
44      /**
45       * Must call done() when finished.
46       */
47      public ContentHandler   getSAXHandler() throws IOException  , ServletException  ;
48      
49      /**
50       * Must call done() when finished.
51       */
52      public HttpServletResponse   getResponse() throws IOException  , ServletException  ;
53  
54      /**
55       * Must call done() when finished.
56       */
57      public Writer   getWriter() throws IOException  , ServletException  ;
58      
59      /**
60       * This should be called after writing is complete.
61       */
62      public void done() throws IOException  , ServletException  ;
63  
64      //
65      //
66      // OR one of the below methods can be called.  Note that these
67      // do not require the use of done(), although it doesn't hurt.
68      //
69      //
70  
71      /**
72       * This is available if it is more convenient.
73       */
74      public void go(Source   input) throws IOException  , ServletException  ;
75  
76      /**
77       * This is available if it is more convenient.
78       */
79      public void go(Reader   input) throws IOException  , ServletException  ;
80      
81      /**
82       * This is available if it is more convenient.
83       */
84      public void go(String   input) throws IOException  , ServletException  ;
85  }
86
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