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

    throws JspException
  {
    try {
      PageContextImpl pc = (PageContextImpl) pageContext;
      
      JspWriter out = pc.getOut();


      if (_value == null) {
        if (_var != null)
          CoreSetTag.setValue(pageContext, _var, _scope, null);
      
        return EVAL_PAGE;
      }


      long time = _value.getTime();
      
      DateFormat format = null;


      Locale locale = pc.getLocale();


      int dateStyle = DateFormat.DEFAULT;
      if (_dateStyle != null)
        dateStyle = getDateStyle(_dateStyle);


      int timeStyle = DateFormat.DEFAULT;
      if (_timeStyle != null)
        timeStyle = getDateStyle(_timeStyle);


      if (locale != null) {
        if (_type == null || _type.equals("date"))
          format = DateFormat.getDateInstance(dateStyle, locale);
        else if (_type.equals("both"))
          format = DateFormat.getDateTimeInstance(dateStyle,
                                                  timeStyle,
                                                  locale);
        else if (_type.equals("time"))
          format = DateFormat.getTimeInstance(timeStyle, locale);
        else
          throw new JspException(L.l("illegal type `{0}'", _type));
      }
      else {
        if (_type == null || _type.equals("date"))
          format = DateFormat.getDateInstance(dateStyle);
        else if (_type.equals("both"))
          format = DateFormat.getDateTimeInstance(dateStyle, timeStyle);
        else if (_type.equals("time"))
          format = DateFormat.getTimeInstance(timeStyle);
        else
          throw new JspException(L.l("illegal type `{0}'", _type));
      }


      if (format != null && _pattern != null) {
        try {
          ((SimpleDateFormat) format).applyPattern(_pattern);
        } catch (ClassCastException e) {
          format = new SimpleDateFormat(_pattern, locale);
        }
      }


      if (format != null) {
        TimeZone timeZone = getTimeZone(_timeZone);


        if (timeZone == null)
          timeZone = (TimeZone) pageContext.getAttribute("com.caucho.time-zone");
        
        if (timeZone == null)
          timeZone = getTimeZone(Config.find(pageContext, Config.FMT_TIME_ZONE));


        if (timeZone != null)
          format.setTimeZone(timeZone);
      }


      Object value = _value;
      if (format != null)
        value = format.format(new Date(time));


      if (_var == null) {
        if (_scope != null)
          throw new JspException(L.l("fmt:formatDate var must not be null when scope '{0}' is set.",
                                     _scope));
        
        out.print(value);
      }
      else
        CoreSetTag.setValue(pageContext, _var, _scope, value);
    } catch (IOException e) {
    }

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    throws JspException
  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      
      JspWriter out = pageContext.getOut();


      String string;


      if (_valueExpr != null)
        string = _valueExpr.evalString(pageContext.getELContext());
      else
        string = bodyContent.getString().trim();
      
      DateFormat format = getFormat();


      Object value = format.parse(string);


      if (_var == null)
        out.print(value);
      else
        CoreSetTag.setValue(pageContext, _var, _scope, value);
    } catch (IOException e) {
    } catch (ParseException e) {
      throw new JspException(e);

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    throws JspException
  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;


      JspWriter out = pageContext.getOut();


      boolean doEscape = (_escapeXml == null ||
                          _escapeXml.evalBoolean(pageContext.getELContext()));


      toStream(out, pageContext, _select, doEscape);

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  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      ELContext env = pageContext.getELContext();
      
      JspWriter out = pageContext.getOut();


      double number;


      BodyContentImpl body = (BodyContentImpl) getBodyContent();


      if (_valueExpr != null)
        number = _valueExpr.evalDouble(env);
      else if (body != null) {
        String value = body.getTrimString();


        if (! value.equals(""))
          number = Double.parseDouble(value);
        else
          number = 0.0;
      }
      else
        number = 0.0;
      
      if (Double.isNaN(number))
        number = 0;
      
      NumberFormat format = getFormat();


      String value;
      if (format != null)
        value = format.format(number);
      else
        value = String.valueOf(number);


      if (_var == null)
        out.print(value);
      else
        CoreSetTag.setValue(pageContext, _var, _scope, value);
    } catch (Exception e) {
      throw new JspException(e);
    }

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  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      ELContext env = pageContext.getELContext();
      
      JspWriter out = pageContext.getOut();


      boolean doEscape = (_escapeXml == null || _escapeXml.evalBoolean(env));
      
      if (! _value.print(out, env, doEscape)) {
      }

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  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      ELContext env = pageContext.getELContext();
      
      JspWriter out = pageContext.getOut();
      
      BodyContentImpl body = (BodyContentImpl) getBodyContent();


      if (body != null) {
        boolean doEscape = (_escapeXml == null || _escapeXml.evalBoolean(env));


        String s = body.getString().trim();


        if (doEscape)
          Expr.toStreamEscaped(out, s);
        else
          out.print(s);
      }
    } catch (Exception e) {
    }


    return EVAL_PAGE;

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  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      ELContext env = pageContext.getELContext();
      
      JspWriter out = pageContext.getOut();


      TransformerFactory factory = TransformerFactory.newInstance();


      Source source = getSource(_xslt, _xsltSystemId);

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    throws JspException
  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      
      JspWriter out = pageContext.getOut();


      NumberFormat format = getFormat();


      String string;


      if (_valueExpr != null)
        string = _valueExpr.evalString(pageContext.getELContext());
      else
        string = bodyContent.getString().trim();


      Number value = format.parse(string);


      if (_var == null)
        out.print(value);
      else
        CoreSetTag.setValue(pageContext, _var, _scope, value);
    } catch (IOException e) {
    } catch (ParseException e) {
      throw new JspException(e);

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    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      ELContext env = pageContext.getELContext();
      
      JspWriter out = pageContext.getOut();


      String key;


      if (_keyExpr != null)
        key = _keyExpr.evalString(env);
      else
        key = getBodyContent().getString().trim();


      String msg;
      
      if (_bundleExpr != null) {
        Object bundleObject = _bundleExpr.evalObject(env);


        msg = pageContext.getLocalizedMessage(bundleObject, key, args, null);
      }
      else {
        LocalizationContext lc;
        lc = (LocalizationContext) pageContext.getAttribute("caucho.bundle");


        if (lc == null)
          msg = pageContext.getLocalizedMessage(key, args, null);
        else
          msg = pageContext.getLocalizedMessage(lc, key, args, null);
      }


      if (_var != null)
        CoreSetTag.setValue(pageContext, _var, _scope, msg);
      else
        out.print(msg);
    } catch (Exception e) {
      throw new JspException(e);
    }


    return EVAL_PAGE;

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    throws JspException
  {
    try {
      PageContextImpl pageContext = (PageContextImpl) this.pageContext;
      
      JspWriter out = pageContext.getOut();


      Object value = _valueExpr.evalObject(pageContext.getELContext());


      if (value == null) {
        if (_var != null)
          CoreSetTag.setValue(pageContext, _var, _scope, null);
      
        return EVAL_PAGE;
      }


      long time = 0;


      if (value instanceof Number)
        time = ((Number) value).longValue();
      else if (value instanceof Date)
        time = ((Date) value).getTime();
      
      DateFormat format = null;


      Locale locale = pageContext.getLocale();


      String type = null;


      ELContext env = pageContext.getELContext();


      if (_typeExpr != null)
        type = _typeExpr.evalString(env);


      int dateStyle = DateFormat.DEFAULT;
      if (_dateStyleExpr != null)
        dateStyle = getDateStyle(_dateStyleExpr.evalString(env));


      int timeStyle = DateFormat.DEFAULT;
      if (_timeStyleExpr != null)
        timeStyle = getDateStyle(_timeStyleExpr.evalString(env));


      if (locale != null) {
        if (type == null || type.equals("date"))
          format = DateFormat.getDateInstance(dateStyle, locale);
        else if (type.equals("both"))
          format = DateFormat.getDateTimeInstance(dateStyle,
                                                  timeStyle,
                                                  locale);
        else if (type.equals("time"))
          format = DateFormat.getTimeInstance(timeStyle, locale);
        else
          throw new JspException(L.l("illegal type `{0}'", type));
      }
      else {
        if (type == null || type.equals("date"))
          format = DateFormat.getDateInstance(dateStyle);
        else if (type.equals("both"))
          format = DateFormat.getDateTimeInstance(dateStyle, timeStyle);
        else if (type.equals("time"))
          format = DateFormat.getTimeInstance(timeStyle);
        else
          throw new JspException(L.l("illegal type `{0}'", type));
      }


      if (format != null && _patternExpr != null) {
        String pattern = _patternExpr.evalString(env);
        try {
          ((SimpleDateFormat) format).applyPattern(pattern);
        } catch (ClassCastException e) {
          format = new SimpleDateFormat(pattern, locale);
        }
      }


      if (format != null) {
        TimeZone timeZone = getTimeZone();


        if (timeZone != null)
          format.setTimeZone(timeZone);


        value = format.format(new Date(time));
      }


      if (_var == null)
        out.print(value);
      else
        CoreSetTag.setValue(pageContext, _var, _scope, value);
    } catch (Exception e) {
      throw new JspException(e);
    }

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