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ExpressionEvaluationUtils (Spring Framework) - Spring Framework 1.2.9 API 文档英文版

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org.springframework.web.util
Class ExpressionEvaluationUtils

java.lang.Object
  org.springframework.web.util.ExpressionEvaluationUtils

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public abstract class ExpressionEvaluationUtils
extends Object

Convenience methods for easy access to the JSP 2.0 ExpressionEvaluator or the ExpressionEvaluatorManager of Jakarta's JSTL implementation.

Automatically detects JSP 2.0 or Jakarta JSTL, preferring the JSP 2.0 mechanism if available. Falls back to throwing an exception on actual EL expressions if none of the two is available.

The evaluation methods check if the value contains "${" before invoking the EL evaluator, treating the value as "normal" expression (that is, a conventional String) else.

Note: The evaluation methods do not have a runtime dependency on JSP 2.0 or on Jakarta's JSTL implementation, as long as they don't receive actual EL expressions.

Since:

11.07.2003

Author:

Juergen Hoeller, Alef Arendsen

See Also:

ExpressionEvaluator, ExpressionEvaluatorManager

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Constructor Summary
ExpressionEvaluationUtils()

 

Method Summary
static Object	evaluate(String attrName, String attrValue, Class resultClass, PageContext pageContext)           Evaluate the given expression to an Object, be it EL or a conventional String.
static Object	evaluate(String attrName, String attrValue, PageContext pageContext)           Evaluate the given expression (be it EL or a literal String value) to an Object.
static boolean	evaluateBoolean(String attrName, String attrValue, PageContext pageContext)           Evaluate the given expression (be it EL or a literal String value) to a boolean.
static int	evaluateInteger(String attrName, String attrValue, PageContext pageContext)           Evaluate the given expression (be it EL or a literal String value) to an integer.
static String	evaluateString(String attrName, String attrValue, PageContext pageContext)           Evaluate the given expression (be it EL or a literal String value) to a String.
static boolean	isExpressionLanguage(String value)           Check if the given expression value is an EL expression.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

ExpressionEvaluationUtils

public ExpressionEvaluationUtils()

Method Detail

isExpressionLanguage

public static boolean isExpressionLanguage(String value)

Check if the given expression value is an EL expression.

Parameters:

value - the expression to check

Returns:

true if the expression is an EL expression, false otherwise

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evaluate

public static Object evaluate(String attrName,
                              String attrValue,
                              Class resultClass,
                              PageContext pageContext)
                       throws JspException

Evaluate the given expression to an Object, be it EL or a conventional String.

Parameters:

attrName - name of the attribute (typically a JSP tag attribute)

attrValue - value of the attribute

resultClass - class that the result should have (String, Integer, Boolean)

pageContext - current JSP PageContext

Returns:

the result of the evaluation

Throws:

JspException - in case of parsing errors

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evaluate

public static Object evaluate(String attrName,
                              String attrValue,
                              PageContext pageContext)
                       throws JspException

Evaluate the given expression (be it EL or a literal String value) to an Object.

Parameters:

attrName - name of the attribute (typically a JSP tag attribute)

attrValue - value of the attribute

pageContext - current JSP PageContext

Returns:

the result of the evaluation

Throws:

JspException - in case of parsing errors

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evaluateString

public static String evaluateString(String attrName,
                                    String attrValue,
                                    PageContext pageContext)
                             throws JspException

Evaluate the given expression (be it EL or a literal String value) to a String.

Parameters:

attrName - name of the attribute (typically a JSP tag attribute)

attrValue - value of the attribute

pageContext - current JSP PageContext

Returns:

the result of the evaluation

Throws:

JspException - in case of parsing errors

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evaluateInteger

public static int evaluateInteger(String attrName,
                                  String attrValue,
                                  PageContext pageContext)
                           throws JspException

Evaluate the given expression (be it EL or a literal String value) to an integer.

Parameters:

attrName - name of the attribute (typically a JSP tag attribute)

attrValue - value of the attribute

pageContext - current JSP PageContext

Returns:

the result of the evaluation

Throws:

JspException - in case of parsing errors

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evaluateBoolean

public static boolean evaluateBoolean(String attrName,
                                      String attrValue,
                                      PageContext pageContext)
                               throws JspException

Evaluate the given expression (be it EL or a literal String value) to a boolean.

Parameters:

attrName - name of the attribute (typically a JSP tag attribute)

attrValue - value of the attribute

pageContext - current JSP PageContext

Returns:

the result of the evaluation

Throws:

JspException - in case of parsing errors

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