org.apache.taglibs.standard.tag.el.fmt.SetLocaleTag Maven / Gradle / Ivy

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package org.apache.taglibs.standard.tag.el.fmt;

import javax.servlet.jsp.JspException;

import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
import org.apache.taglibs.standard.tag.common.fmt.SetLocaleSupport;

/**
 * A handler for <setLocale> that accepts attributes as Strings
 * and evaluates them as expressions at runtime.
 *
 * @author Jan Luehe
 */

public class SetLocaleTag extends SetLocaleSupport {

    //*********************************************************************
    // 'Private' state (implementation details)

    private String value_;                      // stores EL-based property
    private String variant_;                    // stores EL-based property


    //*********************************************************************
    // Constructor

    /**
     * Constructs a new LocaleTag.  As with TagSupport, subclasses
     * should not provide other constructors and are expected to call
     * the superclass constructor
     */
    public SetLocaleTag() {
        super();
        init();
    }


    //*********************************************************************
    // Tag logic

    // evaluates expression and chains to parent
    public int doStartTag() throws JspException {

        // evaluate any expressions we were passed, once per invocation
        evaluateExpressions();

	// chain to the parent implementation
	return super.doStartTag();
    }

    // Releases any resources we may have (or inherit)
    public void release() {
        super.release();
        init();
    }


    //*********************************************************************
    // Accessor methods

    // for EL-based attribute
    public void setValue(String value_) {
        this.value_ = value_;
    }

    // for EL-based attribute
    public void setVariant(String variant_) {
        this.variant_ = variant_;
    }


    //*********************************************************************
    // Private (utility) methods

    // (re)initializes state (during release() or construction)
    private void init() {
        // null implies "no expression"
	value_ = variant_ = null;
    }

    // Evaluates expressions as necessary
    private void evaluateExpressions() throws JspException {

	// 'value' attribute (mandatory)
	value = ExpressionEvaluatorManager.evaluate(
	    "value", value_, Object.class, this, pageContext);

	// 'variant' attribute (optional)
	if (variant_ != null) {
	    variant = (String) ExpressionEvaluatorManager.evaluate(
	        "variant", variant_, String.class, this, pageContext);
	}
    }
}