各位高手，有没有关于STRUTS〈logic：empty〉标签的例子啊？

----------jsp start---------><%@ page language="java" %>
<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<html>
<head>
<title>Test struts-logic Emptiness Tags</title>
</head>
<body bgcolor="white"><div align="center">
<h1>Test struts-logic Emptiness Tags</h1>
</div><jsp:useBean id="bean" scope="page" class="org.apache.struts.webapp.exercise.TestBean"/><table border="1">
  <tr>
    <th>Test Type</th>
    <th>Correct Value</th>
    <th>Test Result</th>
  </tr>
  <tr>
    <td>missing bean, no property attribute</td>
    <td>empty</td>
    <td>
      <logic:empty name="missingBean">
        empty
      </logic:empty>
      <logic:notEmpty name="missingBean">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>not-missing bean, no property attribute</td>
    <td>notEmpty</td>
    <td>
      <logic:empty name="bean">
        empty
      </logic:empty>
      <logic:notEmpty name="bean">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>  <tr>
    <td>null</td>
    <td>empty</td>
    <td>
      <logic:empty name="bean" property="nullProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="nullProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>empty string</td>
    <td>empty</td>
    <td>
      <logic:empty name="bean" property="emptyStringProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="emptyStringProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>non-empty string</td>
    <td>notEmpty</td>
    <td>
      <logic:empty name="bean" property="stringProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="stringProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>empty collection</td>
    <td>empty</td>
    <td>
      <logic:empty name="bean" property="emptyListProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="emptyListProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>non-empty collection</td>
    <td>notEmpty</td>
    <td>
      <logic:empty name="bean" property="listProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="listProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>empty map</td>
    <td>empty</td>
    <td>
      <logic:empty name="bean" property="emptyMapProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="emptyMapProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>non-empty map</td>
    <td>notEmpty</td>
    <td>
      <logic:empty name="bean" property="mapProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="mapProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
  <tr>
    <td>unsupported object</td>
    <td>notEmpty</td>
    <td>
      <logic:empty name="bean" property="intProperty">
        empty
      </logic:empty>
      <logic:notEmpty name="bean" property="intProperty">
        notEmpty
      </logic:notEmpty>
    </td>
  </tr>
</table></body>
</html>
<--------jsp end--------------
----------java start--------->
package org.apache.struts.webapp.exercise;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Vector;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.util.LabelValueBean;
/**
* General purpose test bean for Struts custom tag tests.
*
* @author Craig R. McClanahan
* @author Martin F N Cooper
* @version $Revision: 1.8 $ $Date: 2002/10/12 19:21:18 $
*/public class TestBean extends ActionForm {    /**
     * A collection property where the elements of the collection are
     * of type <code>LabelValueBean</code>.
     */
    private Collection beanCollection = null;    public Collection getBeanCollection() {
        if (beanCollection == null) {
            Vector entries = new Vector(10);            entries.add(new LabelValueBean("Label 0", "Value 0"));
            entries.add(new LabelValueBean("Label 1", "Value 1"));
            entries.add(new LabelValueBean("Label 2", "Value 2"));
            entries.add(new LabelValueBean("Label 3", "Value 3"));
            entries.add(new LabelValueBean("Label 4", "Value 4"));
            entries.add(new LabelValueBean("Label 5", "Value 5"));
            entries.add(new LabelValueBean("Label 6", "Value 6"));
            entries.add(new LabelValueBean("Label 7", "Value 7"));
            entries.add(new LabelValueBean("Label 8", "Value 8"));
            entries.add(new LabelValueBean("Label 9", "Value 9"));            beanCollection = entries;
        }        return (beanCollection);
    }    public void setBeanCollection(Collection beanCollection) {
        this.beanCollection = beanCollection;
    }
    /**
     * A multiple-String SELECT element using a bean collection.
     */
    private String[] beanCollectionSelect = { "Value 1", "Value 3",
                                              "Value 5" };    public String[] getBeanCollectionSelect() {
        return (this.beanCollectionSelect);
    }    public void setBeanCollectionSelect(String beanCollectionSelect[]) {
        this.beanCollectionSelect = beanCollectionSelect;
    }
    /**
     * A boolean property whose initial value is true.
     */
    private boolean booleanProperty = true;    public boolean getBooleanProperty() {
        return (booleanProperty);
    }    public void setBooleanProperty(boolean booleanProperty) {
        this.booleanProperty = booleanProperty;
    }
    /**
     * A multiple-String SELECT element using a collection.
     */
    private String[] collectionSelect = { "Value 2", "Value 4",
                                          "Value 6" };    public String[] getCollectionSelect() {
        return (this.collectionSelect);
    }    public void setCollectionSelect(String collectionSelect[]) {
        this.collectionSelect = collectionSelect;
    }
    /**
     * A double property.
     */
    private double doubleProperty = 321.0;    public double getDoubleProperty() {
        return (this.doubleProperty);
    }    public void setDoubleProperty(double doubleProperty) {
        this.doubleProperty = doubleProperty;
    }
    /**
     * A boolean property whose initial value is false
     */
    private boolean falseProperty = false;    public boolean getFalseProperty() {
        return (falseProperty);
    }    public void setFalseProperty(boolean falseProperty) {
        this.falseProperty = falseProperty;
    }
    /**
     * A float property.
     */
    private float floatProperty = (float) 123.0;    public float getFloatProperty() {
        return (this.floatProperty);
    }    public void setFloatProperty(float floatProperty) {
        this.floatProperty = floatProperty;
    }
/**
     * Integer arrays that are accessed as an array as well as indexed.
     */
    private int intArray[] = { 0, 10, 20, 30, 40 };    public int[] getIntArray() {
        return (this.intArray);
    }    public void setIntArray(int intArray[]) {
        this.intArray = intArray;
    }    private int intIndexed[] = { 0, 10, 20, 30, 40 };    public int getIntIndexed(int index) {
        return (intIndexed[index]);
    }    public void setIntIndexed(int index, int value) {
        intIndexed[index] = value;
    }
    private int intMultibox[] = new int[0];    public int[] getIntMultibox() {
        return (this.intMultibox);
    }    public void setIntMultibox(int intMultibox[]) {
        this.intMultibox = intMultibox;
    }    /**
     * An integer property.
     */
    private int intProperty = 123;    public int getIntProperty() {
        return (this.intProperty);
    }    public void setIntProperty(int intProperty) {
        this.intProperty = intProperty;
    }
    /**
     * A long property.
     */
    private long longProperty = 321;    public long getLongProperty() {
        return (this.longProperty);
    }    public void setLongProperty(long longProperty) {
        this.longProperty = longProperty;
    }
    /**
     * A multiple-String SELECT element.
     */
    private String[] multipleSelect = { "Multiple 3", "Multiple 5",
                                        "Multiple 7" };    public String[] getMultipleSelect() {
        return (this.multipleSelect);
    }    public void setMultipleSelect(String multipleSelect[]) {
        this.multipleSelect = multipleSelect;
    }
    /**
     * A nested reference to another test bean (populated as needed).
     */
    private TestBean nested = null;    public TestBean getNested() {
        if (nested == null)
            nested = new TestBean();
        return (nested);
    }
    /**
     * A String property with an initial value of null.
     */
    private String nullProperty = null;    public String getNullProperty() {
        return (this.nullProperty);
    }    public void setNullProperty(String nullProperty) {
        this.nullProperty = nullProperty;
    }
    /**
     * A short property.
     */
    private short shortProperty = (short) 987;    public short getShortProperty() {
        return (this.shortProperty);
    }    public void setShortProperty(short shortProperty) {
        this.shortProperty = shortProperty;
    }
    /**
     * A single-String value for a SELECT element.
     */
    private String singleSelect = "Single 5";    public String getSingleSelect() {
        return (this.singleSelect);
    }    public void setSingleSelect(String singleSelect) {
        this.singleSelect = singleSelect;
    }
    /**
     * String arrays that are accessed as an array as well as indexed.
     */
    private String stringArray[] =
    { "String 0", "String 1", "String 2", "String 3", "String 4" };    public String[] getStringArray() {
        return (this.stringArray);
    }    public void setStringArray(String stringArray[]) {
        this.stringArray = stringArray;
    }    private String stringIndexed[] =
    { "String 0", "String 1", "String 2", "String 3", "String 4" };    public String getStringIndexed(int index) {
        return (stringIndexed[index]);
    }    public void setStringIndexed(int index, String value) {
        stringIndexed[index] = value;
    }
    private String stringMultibox[] = new String[0];    public String[] getStringMultibox() {
        return (this.stringMultibox);
    }    public void setStringMultibox(String stringMultibox[]) {
        this.stringMultibox = stringMultibox;
    }    /**
     * A String property.
     */
    private String stringProperty = "This is a string";    public String getStringProperty() {
        return (this.stringProperty);
    }    public void setStringProperty(String stringProperty) {
        this.stringProperty = stringProperty;
    }    /**
     * An empty String property.
     */
    private String emptyStringProperty = "";    public String getEmptyStringProperty() {
        return (this.emptyStringProperty);
    }    public void setEmptyStringProperty(String emptyStringProperty) {
        this.emptyStringProperty = emptyStringProperty;
    }
    /**
     * A single-String value for a SELECT element based on resource strings.
     */
    private String resourcesSelect = "Resources 2";    public String getResourcesSelect() {
        return (this.resourcesSelect);
    }    public void setResourcesSelect(String resourcesSelect) {
        this.resourcesSelect = resourcesSelect;
    }
    /**
     * A property that allows a null value but is still used in a SELECT.
     */
    private String withNulls = null;    public String getWithNulls() {
        return (this.withNulls);
    }    public void setWithNulls(String withNulls) {
        this.withNulls = withNulls;
    }/**
     * A List property.
     */
    private List listProperty = null;    public List getListProperty() {
        if (listProperty == null) {
            listProperty = new ArrayList();
            listProperty.add("dummy");
        }
        return listProperty;
    }    public void setListProperty(List listProperty) {
        this.listProperty = listProperty;
    }    /**
     * An empty List property.
     */
    private List emptyListProperty = null;    public List getEmptyListProperty() {
        if (emptyListProperty == null) {
            emptyListProperty = new ArrayList();
        }
        return emptyListProperty;
    }    public void setEmptyListProperty(List emptyListProperty) {
        this.emptyListProperty = emptyListProperty;
    }
    /**
     * A Map property.
     */
    private Map mapProperty = null;    public Map getMapProperty() {
        if (mapProperty == null) {
            mapProperty = new HashMap();
            mapProperty.put("dummy", "dummy");
        }
        return mapProperty;
    }    public void setMapProperty(Map mapProperty) {
        this.mapProperty = mapProperty;
    }    /**
     * An empty Map property.
     */
    private Map emptyMapProperty = null;    public Map getEmptyMapProperty() {
        if (emptyMapProperty == null) {
            emptyMapProperty = new HashMap();
        }
        return emptyMapProperty;
    }    public void setEmptyMapProperty(Map emptyMapProperty) {
        this.emptyMapProperty = emptyMapProperty;
    }
    // --------------------------------------------------------- Public Methods
    /**
     * Reset the properties that will be received as input.
     */
    public void reset(ActionMapping mapping, HttpServletRequest request) {        booleanProperty = false;
        collectionSelect = new String[0];
        intMultibox = new int[0];
        multipleSelect = new String[0];
        stringMultibox = new String[0];
        if (nested != null)
            nested.reset(mapping, request);    }
}<--------java end--------------

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各位高手，有没有关于STRUTS〈logic：empty〉标签的例子啊？

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