Struts example source code file (ListUIBean.java)

This example Struts source code file (ListUIBean.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

collection, collection, http, httpservletresponse, if, listuibean, map, map, object, object, property, reflection, request, response, servlet, string, string, strutstagattribute, uibean, util

The Struts ListUIBean.java source code

/*
 * $Id: ListUIBean.java 726715 2008-12-15 15:39:15Z musachy $
 *
 * 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 java.lang.reflect.Array;
import java.util.Collection;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.views.annotations.StrutsTagAttribute;
import org.apache.struts2.util.ContainUtil;
import org.apache.struts2.util.MakeIterator;

import com.opensymphony.xwork2.util.ValueStack;

/**
 * DoubleListUIBean is the standard superclass of all Struts list handling components.
 *
 * <p/>
 *
 * <!-- START SNIPPET: javadoc -->
 *
 * Note that the listkey and listvalue attribute will default to "key" and "value"
 * respectively only when the list attribute is evaluated to a Map or its decendant.
 * Everything else will result in listkey and listvalue to be null and not used.
 *
 * <!-- END SNIPPET: javadoc -->
 *
 */
public abstract class ListUIBean extends UIBean {
    protected Object list;
    protected String listKey;
    protected String listValue;

    // indicate if an exception is to be thrown when value attribute is null
    protected boolean throwExceptionOnNullValueAttribute = false;

    protected ListUIBean(ValueStack stack, HttpServletRequest request, HttpServletResponse response) {
        super(stack, request, response);
    }

    public void evaluateExtraParams() {
        Object value = null;

        if (list == null) {
            list = parameters.get("list");
        }

        if (list instanceof String) {
            value = findValue((String) list);
        } else if (list instanceof Collection) {
            value = list;
        } else if (MakeIterator.isIterable(list)) {
            value = MakeIterator.convert(list);
        }
        if (value == null) {
            if (throwExceptionOnNullValueAttribute) {
                // will throw an exception if not found
                value = findValue((list == null) ? (String) list : list.toString(), "list",
                    "The requested list key '" + list + "' could not be resolved as a collection/array/map/enumeration/iterator type. " +
                    "Example: people or people.{name}");
            }
            else {
                // ww-1010, allows value with null value to be compatible with ww
                // 2.1.7 behaviour
                value = findValue((list == null)?(String) list:list.toString());
            }
        }

        if (value instanceof Collection) {
            addParameter("list", value);
        } else {
            addParameter("list", MakeIterator.convert(value));
        }

        if (value instanceof Collection) {
            addParameter("listSize", Integer.valueOf(((Collection) value).size()));
        } else if (value instanceof Map) {
            addParameter("listSize", Integer.valueOf(((Map) value).size()));
        } else if (value != null && value.getClass().isArray()) {
            addParameter("listSize", Integer.valueOf(Array.getLength(value)));
        }

        if (listKey != null) {
        	listKey = stripExpressionIfAltSyntax(listKey);
            addParameter("listKey", listKey);
        } else if (value instanceof Map) {
            addParameter("listKey", "key");
        }

        if (listValue != null) {
        	listValue = stripExpressionIfAltSyntax(listValue);
            addParameter("listValue", listValue);
        } else if (value instanceof Map) {
            addParameter("listValue", "value");
        }
    }

    public boolean contains(Object obj1, Object obj2) {
        return ContainUtil.contains(obj1, obj2);
    }

    protected Class getValueClassType() {
        return null; // don't convert nameValue to anything, we need the raw value
    }

    @StrutsTagAttribute(description="Iterable source to populate from. If the list is a Map (key, value), the Map key will become the option 'value'" +
                " parameter and the Map value will become the option body.", required=true)
    public void setList(Object list) {
        this.list = list;
    }

    @StrutsTagAttribute(description=" Property of list objects to get field value from")
    public void setListKey(String listKey) {
        this.listKey = listKey;
    }

    @StrutsTagAttribute(description="Property of list objects to get field content from")
    public void setListValue(String listValue) {
        this.listValue = listValue;
    }


    public void setThrowExceptionOnNullValueAttribute(boolean throwExceptionOnNullValueAttribute) {
        this.throwExceptionOnNullValueAttribute = throwExceptionOnNullValueAttribute;
    }
}