Struts example source code file (Property.java)

This example Struts source code file (Property.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

boolean, boolean, csv, deprecated, html, io, ioexception, print, property, string, string, strutstagattribute, strutstagattribute, whether, whether

The Struts Property.java source code

/*
 * $Id: Property.java 1076544 2011-03-03 07:19:37Z lukaszlenart $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.struts2.components;

import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.struts2.views.annotations.StrutsTag;
import org.apache.struts2.views.annotations.StrutsTagAttribute;

import java.io.IOException;
import java.io.Writer;

/**
 * <!-- START SNIPPET: javadoc -->
 *
 * Used to get the property of a <i>value, which will default to the top of
 * the stack if none is specified.
 *
 * <!-- END SNIPPET: javadoc -->
 *
 * <p/>
 *
 *
 * <!-- START SNIPPET: params -->
 *
 * <ul>
 *      <li>default (String) - The default value to be used if value attribute is null
 *      <li>escape (Boolean) - Escape HTML. Default to true
 *      <li>value (Object) - value to be displayed
 * </ul>
 *
 * <!-- END SNIPPET: params -->
 *
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 *
 * <s:push value="myBean">
 *     <!-- Example 1: -->
 *     <s:property value="myBeanProperty" />
 *
 *     <!-- Example 2: -->TextUtils
 *     <s:property value="myBeanProperty" default="a default value" />
 * </s:push>
 *
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * <pre>
 * <!-- START SNIPPET: exampledescription -->
 *
 * Example 1 prints the result of myBean's getMyBeanProperty() method.
 * Example 2 prints the result of myBean's getMyBeanProperty() method and if it is null, print 'a default value' instead.
 *
 * <!-- END SNIPPET: exampledescription -->
 * </pre>
 *
 *
 * <pre>
 * <!-- START SNIPPET: i18nExample -->
 *
 * <s:property value="getText('some.key')" />
 *
 * <!-- END SNIPPET: i18nExample -->
 * </pre>
 *
 */
@StrutsTag(name="property", tldBodyContent="empty", tldTagClass="org.apache.struts2.views.jsp.PropertyTag",
    description="Print out expression which evaluates against the stack")
public class Property extends Component {
    private static final Logger LOG = LoggerFactory.getLogger(Property.class);

    public Property(ValueStack stack) {
        super(stack);
    }

    private String defaultValue;
    private String value;
    private boolean escapeHtml = true;
    private boolean escapeJavaScript = false;
    private boolean escapeXml = false;
    private boolean escapeCsv = false;

    @StrutsTagAttribute(description="The default value to be used if <u>value attribute is null")
    public void setDefault(String defaultValue) {
        this.defaultValue = defaultValue;
    }

    @StrutsTagAttribute(description="Deprecated. Use 'escapeHtml'. Whether to escape HTML", type="Boolean", defaultValue="true")
    public void setEscape(boolean escape) {
        this.escapeHtml = escape;
    }

    @StrutsTagAttribute(description="Whether to escape HTML", type="Boolean", defaultValue="true")
    public void setEscapeHtml(boolean escape) {
        this.escapeHtml = escape;
    }

    @StrutsTagAttribute(description="Whether to escape Javascript", type="Boolean", defaultValue="false")
    public void setEscapeJavaScript(boolean escapeJavaScript) {
        this.escapeJavaScript = escapeJavaScript;
    }

    @StrutsTagAttribute(description="Value to be displayed", type="Object", defaultValue="<top of stack>")
    public void setValue(String value) {
        this.value = value;
    }

    public void setDefaultValue(String defaultValue) {
        this.defaultValue = defaultValue;
    }

    @StrutsTagAttribute(description="Whether to escape CSV (useful to escape a value for a column)", type="Boolean", defaultValue="false")
    public void setEscapeCsv(boolean escapeCsv) {
        this.escapeCsv = escapeCsv;
    }

    @StrutsTagAttribute(description="Whether to escape XML", type="Boolean", defaultValue="false")
    public void setEscapeXml(boolean escapeXml) {
        this.escapeXml = escapeXml;
    }

    public boolean start(Writer writer) {
        boolean result = super.start(writer);

        String actualValue = null;

        if (value == null) {
            value = "top";
        }
        else {
        	value = stripExpressionIfAltSyntax(value);
        }

        // exception: don't call findString(), since we don't want the
        //            expression parsed in this one case. it really
        //            doesn't make sense, in fact.
        actualValue = (String) getStack().findValue(value, String.class, throwExceptionOnELFailure);

        try {
            if (actualValue != null) {
                writer.write(prepare(actualValue));
            } else if (defaultValue != null) {
                writer.write(prepare(defaultValue));
            }
        } catch (IOException e) {
            LOG.info("Could not print out value '" + value + "'", e);
        }

        return result;
    }

    private String prepare(String value) {
    	String result = value;
        if (escapeHtml) {
        	result = StringEscapeUtils.escapeHtml(result);
        }
        if (escapeJavaScript) {
        	result = StringEscapeUtils.escapeJavaScript(result);
        }
        if (escapeXml) {
        	result = StringEscapeUtils.escapeXml(result);
        }
        if (escapeCsv) {
            result = StringEscapeUtils.escapeCsv(result);
        }

        return result;
    }
}