formatdatetag.java

来自「jakarta-taglibs」· Java 代码 · 共 168 行

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 

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

import java.util.Date;

import javax.servlet.jsp.JspException;

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

/**
 * <p>A handler for &lt;formatDate&gt; that accepts attributes as Strings
 * and evaluates them as expressions at runtime.</p>
 *
 * @author Jan Luehe
 */

public class FormatDateTag extends FormatDateSupport {

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

    private String value_;                       // stores EL-based property
    private String type_;                        // stores EL-based property
    private String dateStyle_;		         // stores EL-based property
    private String timeStyle_;		         // stores EL-based property
    private String pattern_;		         // stores EL-based property
    private String timeZone_;		         // stores EL-based property


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

    /**
     * Constructs a new FormatDateTag.  As with TagSupport, subclasses
     * should not provide other constructors and are expected to call
     * the superclass constructor
     */
    public FormatDateTag() {
        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 setType(String type_) {
        this.type_ = type_;
    }

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

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

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

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


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

    // (re)initializes state (during release() or construction)
    private void init() {
        // null implies "no expression"
	value_ = type_ = dateStyle_ = timeStyle_ = pattern_ = timeZone_ = null;
    }

    // Evaluates expressions as necessary
    private void evaluateExpressions() throws JspException {
        /* 
         * Note: we don't check for type mismatches here; we assume
         * the expression evaluator will return the expected type
         * (by virtue of knowledge we give it about what that type is).
         * A ClassCastException here is truly unexpected, so we let it
         * propagate up.
         */

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

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

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

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

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

	// 'timeZone' attribute
	if (timeZone_ != null) {
	    timeZone = ExpressionEvaluatorManager.evaluate(
	        "timeZone", timeZone_, Object.class, this, pageContext);
	}
    }
}