Examples of javax.servlet.jsp.el.ExpressionEvaluator

javax.servlet.jsp.el.ExpressionEvaluator
The abstract base class for an expression-language evaluator. Classes that implement an expression language expose their functionality via this abstract class.

An instance of the ExpressionEvaluator can be obtained via the JspContext / PageContext

The parseExpression() and evaluate() methods must be thread-safe. That is, multiple threads may call these methods on the same ExpressionEvaluator object simultaneously. Implementations should synchronize access if they depend on transient state. Implementations should not, however, assume that only one object of each ExpressionEvaluator type will be instantiated; global caching should therefore be static.

Only a single EL expression, starting with '${' and ending with '}', can be parsed or evaluated at a time. EL expressions cannot be mixed with static text. For example, attempting to parse or evaluate "abc${1+1}def${1+1}ghi" or even "${1+1}${1+1}" will cause an ELException to be thrown.

The following are examples of syntactically legal EL expressions:
- ${person.lastName}
- ${8 * 8}
- ${my:reverse('hello')}
@since 2.0 @deprecated As of JSP 2.1, replaced by javax.el.ExpressionFactory

   * @see de.odysseus.calyxo.base.conf.impl.ConfigImpl#_evaluate(de.odysseus.calyxo.base.ModuleContext)
   */
  protected void _evaluate(ModuleContext context) throws ConfigException {
    super._evaluate(context);


    ExpressionEvaluator evaluator = context.getExpressionEvaluator();
    
    if (relax != null) {
      StringBuffer s = new StringBuffer();
      s.append("${");
      s.append(relax);
      s.append("}");
      try {
        relaxExpression = evaluator.parseExpression(s.toString(), Boolean.class, this);
      } catch (Exception e) {
        throw new ConfigException("Parse error in '" + relax + "'", e);
      }
    }
    if (ignore != null) {
      StringBuffer s = new StringBuffer();
      s.append("${");
      s.append(ignore);
      s.append("}");
      try {
        ignoreExpression = evaluator.parseExpression(s.toString(), Boolean.class, this);
      } catch (Exception e) {
        throw new ConfigException("Parse error in '" + ignore + "'", e);
      }
    }
  }

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public class ParamTag extends org.apache.pluto.tags.ParamTag {


    public String getValue() throws JspException {
        String string = super.getValue();


        ExpressionEvaluator eval = pageContext.getExpressionEvaluator();


        try {
            Object evaluated = eval.evaluate(
                    string,
                    Object.class,
                    pageContext.getVariableResolver(),
                    null
            );

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public class ParamTag extends org.apache.pluto.tags.ParamTag {


    public String getValue() throws JspException {
        String string = super.getValue();


        ExpressionEvaluator eval = pageContext.getExpressionEvaluator();


        try {
            Object evaluated = eval.evaluate(
                    string,
                    Object.class,
                    pageContext.getVariableResolver(),
                    null
            );

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    private static final Object evaluate(String expression, Class expectedType, Object actionForm, HttpServletRequest request, ServletContext servletContext)
        throws ELException
    {
        // todo: can this be static / final?
        ExpressionEvaluator ee = getExpressionEvaluator();
        return ee.evaluate(expression, expectedType, getVariableResolver(actionForm, request, servletContext), null);
    }

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   *
   * @param data DOCUMENT ME!
   * @param handler DOCUMENT ME!
   */
  public void handle(String data, ContentHandler handler) {
    ExpressionEvaluator evaluator = new ExpressionEvaluatorImpl();
    Object value;


    try {
      value = evaluator.evaluate(data, Object.class, resolver, mapper);


      if (value != null) {
        char[] result = value.toString().toCharArray();
        handler.characters(result, 0, result.length);
      } else {

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        BeanVariableResolver resolver = null;


        if (validationInfo.expression() != null) {
            try {
                // Make sure we can get an evaluator
                ExpressionEvaluator evaluator = getEvaluator();
                if (evaluator == null) return;


                // If this turns out to be slow we could probably cache the parsed expression
                String expression = validationInfo.expression();
                expr = evaluator.parseExpression(expression, Boolean.class, null);
                resolver = new BeanVariableResolver(bean);
            }
            catch (ELException ele) {
                throw new StripesRuntimeException(
                        "Could not parse the EL expression being used to validate field " +

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    private static final Object evaluate(String expression, Class expectedType, Object actionForm, HttpServletRequest request, ServletContext servletContext)
        throws ELException
    {
        // todo: can this be static / final?
        ExpressionEvaluator ee = getExpressionEvaluator();
        return ee.evaluate(expression, expectedType, getVariableResolver(actionForm, request, servletContext), null);
    }

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     * rules of the Expression Language.
     */
    private Object convertToExpectedType( final Object value,
    Class expectedType )
    throws javax.servlet.jsp.el.ELException {
        ExpressionEvaluator evaluator = pageContext.getExpressionEvaluator();
        return evaluator.evaluate( "${result}", expectedType,
        new VariableResolver() {
            public Object resolveVariable( String pName )
            throws ELException {
                return value;
            }

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                throw ValidationException.required(nameText, "Please enter a name.");
            }
            if ((uriText.getText().length() == 0) && !editingDefault) {
                throw ValidationException.required(uriText, "Please enter a URL.");
            }
            ExpressionEvaluator eval = new ExpressionEvaluatorImpl();
            try {
                eval.evaluate((String) nameText.getText(), String.class, new DefaultVariables(),
                              StaticFunctionMapper.getDefault());
            } catch (Exception e) {
                throw ValidationException.invalid(nameText, "Error evaluating EL expression:\n" + e.getMessage());
            }
            try {
                eval.evaluate((String) uriText.getText(), String.class, new DefaultVariables(),
                              StaticFunctionMapper.getDefault());
            } catch (Exception e) {
                throw ValidationException.invalid(uriText, "Error evaluating EL expression:\n" + e.getMessage());
            }

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    }


    public void actionPerformed(ActionEvent ev) {
      try {
        StaticFunctionMapper functionMapper = StaticFunctionMapper.getDefault();
        ExpressionEvaluator eval = new ExpressionEvaluatorImpl();
        VariableResolver resolver = new DefaultVariables(uriText.getText(), null, null);
        resultText.setText((String) eval.evaluate(elText.getText(), String.class, resolver, functionMapper));
      } catch (ELException e) {
        ExceptionDialog.show(TestingTool.this, e);
      }
    }

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