Examples of javax.servlet.jsp.JspWriter

javax.servlet.jsp.JspWriter
The actions and template data in a JSP page is written using the JspWriter object that is referenced by the implicit variable out which is initialized automatically using methods in the PageContext object.
This abstract class emulates some of the functionality found in the java.io.BufferedWriter and java.io.PrintWriter classes, however it differs in that it throws java.io.IOException from the print methods while PrintWriter does not.
Buffering
The initial JspWriter object is associated with the PrintWriter object of the ServletResponse in a way that depends on whether the page is or is not buffered. If the page is not buffered, output written to this JspWriter object will be written through to the PrintWriter directly, which will be created if necessary by invoking the getWriter() method on the response object. But if the page is buffered, the PrintWriter object will not be created until the buffer is flushed and operations like setContentType() are legal. Since this flexibility simplifies programming substantially, buffering is the default for JSP pages.
Buffering raises the issue of what to do when the buffer is exceeded. Two approaches can be taken:
- Exceeding the buffer is not a fatal error; when the buffer is exceeded, just flush the output.
- Exceeding the buffer is a fatal error; when the buffer is exceeded, raise an exception.
Both approaches are valid, and thus both are supported in the JSP technology. The behavior of a page is controlled by the autoFlush attribute, which defaults to true. In general, JSP pages that need to be sure that correct and complete data has been sent to their client may want to set autoFlush to false, with a typical case being that where the client is an application itself. On the other hand, JSP pages that send data that is meaningful even when partially constructed may want to set autoFlush to true; such as when the data is sent for immediate display through a browser. Each application will need to consider their specific needs.
An alternative considered was to make the buffer size unbounded; but, this had the disadvantage that runaway computations would consume an unbounded amount of resources.
The "out" implicit variable of a JSP implementation class is of this type. If the page directive selects autoflush="true" then all the I/O operations on this class shall automatically flush the contents of the buffer if an overflow condition would result if the current operation were performed without a flush. If autoflush="false" then all the I/O operations on this class shall throw an IOException if performing the current operation would result in a buffer overflow condition. @see java.io.Writer @see java.io.BufferedWriter @see java.io.PrintWriter

            {
                return SKIP_BODY;
            }
        }


        JspWriter out = pageContext.getOut();
        String url;
        String linkclass;


        if( isattachment )
        {
            url = m_wikiContext.getURL(WikiContext.ATTACH,pageName,
                                       (getVersion() != null) ? "version="+getVersion() : null );
            linkclass = "attachment";
        }
        else
        {
            StringBuffer params = new StringBuffer();
            if( getVersion() != null ) params.append( "version="+getVersion() );
            if( getTemplate() != null ) params.append( (params.length()>0?"&amp;":"") + "skin="+getTemplate() );


            url = m_wikiContext.getURL( WikiContext.VIEW, pageName,
                                        params.toString() );
            linkclass = "wikipage";
        }


        switch( m_format )
        {
          case ANCHOR:
            out.print("<a class=\""+linkclass+"\" href=\""+url+"\" accesskey=\"" 
                          + m_accesskey + "\" title=\"" + m_title + "\">");
            break;
          case URL:
            out.print( url );
            break;
        }


        return EVAL_BODY_INCLUDE;
    }

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            // FIXME: Do version setting later.
            // page.setVersion( WikiProvider.LATEST_VERSION );


            log.debug("Inserting page "+insertedPage);


            JspWriter out = pageContext.getOut();


            WikiPage oldPage = m_wikiContext.setRealPage( insertedPage );
            
            switch( m_mode )
            {
              case HTML:
                out.print( engine.getHTML( m_wikiContext, insertedPage ) );
                break;
              case PLAIN:
                out.print( engine.getText( m_wikiContext, insertedPage ) );
                break;
            }
            
            m_wikiContext.setRealPage( oldPage );
        }

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        //
        //  Finally, print out the correct link, according to what
        //  user commanded.
        //
        JspWriter out = pageContext.getOut();


        switch( m_format )
        {
            case ANCHOR:
                out.print("<a href=\""+getCommentURL(pageName)+"\">");
                break;


            case URL:
                out.print( getCommentURL(pageName) );
                break;
                
            default:
                throw new InternalWikiException("Impossible format "+m_format);

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    {
        if( bodyContent != null )
        {
            try
            {
                JspWriter out = getPreviousOut();
                out.print(bodyContent.getString());
                bodyContent.clearBody();
            }
            catch( IOException e )
            {
                log.error("Unable to get inner tag text", e);

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    public final int doWikiStartTag()
        throws JspException,
               IOException
    {
        WikiEngine engine   = m_wikiContext.getEngine();
        JspWriter out = pageContext.getOut();
        String msg = null;
        String value = null;


        try
        {
            value = engine.getVariableManager().getValue( m_wikiContext,
                                                          getVar() );
        }
        catch( NoSuchVariableException e )
        {
            msg = "No such variable: "+e.getMessage();
        }
        catch( IllegalArgumentException e )
        {
            msg = "Incorrect variable name: "+e.getMessage();
        }


        if( value == null )
        {
            value = m_default;
        }


        if( value == null )
        {
            value = msg;
        }
        out.write( TextUtil.replaceEntities(value) );
        return SKIP_BODY;
    }

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            {
                return SKIP_BODY;
            }
        }


        JspWriter out = pageContext.getOut();


        int r1 = 0;
        int r2 = 0;


        //
        //  In case the page does not exist, we fail silently.
        //
        if(!engine.pageExists(pageName))
        {
            return SKIP_BODY;
        }


        if( VER_LATEST.equals(getVersion()) )
        {
            WikiPage latest = engine.getPage( pageName, 
                                              WikiProvider.LATEST_VERSION );


            if( latest == null )
            {
                // This may occur if matchEnglishPlurals is on, and we access the wrong page name
                return SKIP_BODY;
            }
            r1 = latest.getVersion();
        }
        else if( VER_PREVIOUS.equals(getVersion()) )
        {
            r1 = m_wikiContext.getPage().getVersion() - 1;
            r1 = (r1 < 1 ) ? 1 : r1;
        }
        else if( VER_CURRENT.equals(getVersion()) )
        {
            r1 = m_wikiContext.getPage().getVersion();
        }
        else
        {
            r1 = Integer.parseInt( getVersion() );
        }


        if( VER_LATEST.equals(getNewVersion()) )
        {
            WikiPage latest = engine.getPage( pageName,
                                              WikiProvider.LATEST_VERSION );


            r2 = latest.getVersion();
        }
        else if( VER_PREVIOUS.equals(getNewVersion()) )
        {
            r2 = m_wikiContext.getPage().getVersion() - 1;
            r2 = (r2 < 1 ) ? 1 : r2;
        }
        else if( VER_CURRENT.equals(getNewVersion()) )
        {
            r2 = m_wikiContext.getPage().getVersion();
        }
        else
        {
            r2 = Integer.parseInt( getNewVersion() );
        }


        String url = m_wikiContext.getURL( WikiContext.DIFF,
                                           pageName,
                                           "r1="+r1+"&amp;r2="+r2 );
        switch( m_format )
        {
          case ANCHOR:
            out.print("<a href=\""+url+"\">");


            break;


          case URL:
            out.print( url );
            break;
        }


        return EVAL_BODY_INCLUDE;
    }

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    @Override
    public final int doWikiStartTag()
        throws IOException
    {
        WikiEngine engine = m_wikiContext.getEngine();
        JspWriter out = pageContext.getOut();
        ResourceBundle rb = Preferences.getBundle( m_wikiContext, InternationalizationManager.CORE_BUNDLE );


        if( engine.getRSSGenerator() != null && engine.getRSSGenerator().isEnabled() )
        {
            if( RSSGenerator.MODE_FULL.equals(m_mode) )
            {
                String rssURL = engine.getGlobalRSSURL();


                if( rssURL != null )
                {
                    out.print("<a class=\"feed\" href=\""+rssURL+"\">&nbsp;</a>");
                }
            }
            else
            {
                String page = m_pageName != null ? m_pageName : m_wikiContext.getPage().getName();
            
                String params = "page="+page+"&mode="+m_mode;
                out.print( "<a href='"+m_wikiContext.getURL( WikiContext.NONE, "rss.jsp", params ));
                out.print( "' class='feed'" );
                out.print( " title='"+MessageFormat.format( rb.getString( "rss.title" ), page )+"'>" );
                out.print( "&nbsp;</a> ");
            }
        }
        
        return SKIP_BODY;
    }

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    public final int doWikiStartTag()
        throws IOException,
               ProviderException
    {
        WikiEngine       engine   = m_wikiContext.getEngine();
        JspWriter        out      = pageContext.getOut();
        Calendar         cal      = Calendar.getInstance();
        Calendar         prevCal  = Calendar.getInstance();
        Calendar         nextCal  = Calendar.getInstance();


        //
        //  Check if there is a parameter in the request to set the date.
        //
        String calendarDate = pageContext.getRequest().getParameter( "calendar.date" );
        if( calendarDate == null )
        {
            calendarDate = pageContext.getRequest().getParameter( "weblog.startDate" );
        }
        
        if( calendarDate != null )
        {
            try
            {
                Date d = m_dateFormat.parse( calendarDate );
                cal.setTime( d );
                prevCal.setTime( d );
                nextCal.setTime( d );
            }
            catch( ParseException e )
            {
                log.warn( "date format wrong: "+calendarDate );
            }
        }


        cal.set( Calendar.DATE, 1 );     // First, set to first day of month
        prevCal.set( Calendar.DATE, 1 );
        nextCal.set( Calendar.DATE, 1 );


        prevCal.add(Calendar.MONTH, -1); // Now move to first day of previous month
        nextCal.add(Calendar.MONTH, 1);  // Now move to first day of next month


        out.write( "<table class=\"calendar\">\n" );


        HttpServletRequest httpServletRequest = m_wikiContext.getHttpRequest();
        String queryString = engine.safeGetQueryString( httpServletRequest );
        out.write( "<tr>"+
                   getMonthNaviLink(prevCal,"&lt;&lt;", queryString)+
                   "<td colspan=5 class=\"month\">"+
                   getMonthLink( cal )+
                   "</td>"+
                   getMonthNaviLink(nextCal,"&gt;&gt;", queryString)+ 
                   "</tr>\n"
                 );


        int month = cal.get( Calendar.MONTH );
        cal.set( Calendar.DAY_OF_WEEK, Calendar.MONDAY ); // Then, find the first day of the week.


        out.write( "<tr><td class=\"weekdays\">Mon</td>"+
                   "<td class=\"weekdays\">Tue</td>"+
                   "<td class=\"weekdays\">Wed</td>"+
                   "<td class=\"weekdays\">Thu</td>"+
                   "<td class=\"weekdays\">Fri</td>"+
                   "<td class=\"weekdays\">Sat</td>"+
                   "<td class=\"weekdays\">Sun</td></tr>\n" );


        boolean noMoreDates = false;
        while( !noMoreDates )
        {
            out.write( "<tr>" );
            
            for( int i = 0; i < 7; i++ )
            {
                int mth = cal.get( Calendar.MONTH );


                if( mth != month )
                {
                    out.write("<td class=\"othermonth\">"+cal.get(Calendar.DATE)+"</td>");
                }
                else
                {
                    out.write( getDayLink(cal) );
                }


                cal.add( Calendar.DATE, 1 );
            }


            if( cal.get( Calendar.MONTH ) != month )
            {
                noMoreDates = true;
            }


            out.write( "</tr>\n" );
        }


        out.write( "</table>\n" );


        return EVAL_BODY_INCLUDE;
    }

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            {
                return SKIP_BODY;
            }
        }


        JspWriter out = pageContext.getOut();


        String url = m_wikiContext.getURL( WikiContext.UPLOAD,
                                           pageName );


        switch( m_format )
        {
          case ANCHOR:
            out.print("<a target=\"_new\" class=\"uploadlink\" href=\""+url+"\">");
            break;
          case URL:
            out.print( url );
            break;
        }


        return EVAL_BODY_INCLUDE;
    }

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                // TODO: see WikiContext.getURL(); this check needs to be specified somewhere.
                WikiEngine engine = m_wikiContext.getEngine();
                m_absolute = "absolute".equals( engine.getWikiProperties().getProperty( WikiEngine.PROP_REFSTYLE ) );
            }


            JspWriter out = pageContext.getOut();
            String url = figureOutURL();


            StringBuffer sb = new StringBuffer( 20 );


            sb.append( (m_class != null)   ? "class=\""+m_class+"\" " : "" );
            sb.append( (m_style != null)   ? "style=\""+m_style+"\" " : "" );
            sb.append( (m_target != null ) ? "target=\""+m_target+"\" " : "" );
            sb.append( (m_title != null )  ? "title=\""+m_title+"\" " : "" );
            sb.append( (m_rel != null )    ? "rel=\""+m_rel+"\" " : "" );
            sb.append( (m_accesskey != null) ? "accesskey=\""+m_accesskey+"\" " : "" );


            switch( m_format )
            {
              case URL:
                out.print( url );
                break;
              default:
              case ANCHOR:
                out.print("<a "+sb.toString()+" href=\""+url+"\">");
                break;
            }


            // Add any explicit body content. This is not the intended use
            // of LinkTag, but happens to be the way it has worked previously.
            if( m_bodyContent != null )
            {
                String linktext = m_bodyContent.getString().trim();
                out.write( linktext );
            }


            //  Finish off by closing opened anchor
            if( m_format == ANCHOR ) out.print("</a>");
        }
        catch( Exception e )
        {
            // Yes, we want to catch all exceptions here, including RuntimeExceptions
            log.error( "Tag failed", e );

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