Struts example source code file (ObjectToHTMLWriter.java)

This example Struts source code file (ObjectToHTMLWriter.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

bean, class, collection, io, iterator, javabean, list, map, map, object, object, objecttohtmlwriter, prettyprintwriter, set, set, string, string, util

The Struts ObjectToHTMLWriter.java source code

/*
 * $Id: ObjectToHTMLWriter.java 651946 2008-04-27 13:41:38Z apetrelli $
 *
 * 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.interceptor.debugging;

import java.beans.IntrospectionException;
import java.io.Writer;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.opensymphony.xwork2.util.reflection.ReflectionException;
import com.opensymphony.xwork2.util.reflection.ReflectionProvider;

/**
 * Writes an object as a table, where each field can be expanded if it is an Object/Collection/Array
 *
 */
class ObjectToHTMLWriter {
    private PrettyPrintWriter prettyWriter;

    ObjectToHTMLWriter(Writer writer) {
        this.prettyWriter = new PrettyPrintWriter(writer);
        this.prettyWriter.setEscape(false);
    }

    @SuppressWarnings("unchecked")
    public void write(ReflectionProvider reflectionProvider, Object root, String expr) throws IntrospectionException,
        ReflectionException {
        prettyWriter.startNode("table");
        prettyWriter.addAttribute("class", "debugTable");

        if (root instanceof Map) {
            for (Iterator iterator = ((Map) root).entrySet().iterator(); iterator
                .hasNext();) {
                Map.Entry property = (Map.Entry) iterator.next();
                String key = property.getKey().toString();
                Object value = property.getValue();
                writeProperty(key, value, expr);
            }
        } else if (root instanceof List) {
            List list = (List) root;
            for (int i = 0; i < list.size(); i++) {
                Object element = list.get(i);
                writeProperty(String.valueOf(i), element, expr);
            }
        } else if (root instanceof Set) {
            Set set = (Set) root;
            for (Iterator iterator = set.iterator(); iterator.hasNext();) {
                writeProperty("", iterator.next(), expr);
            }
        } else if (root.getClass().isArray()) {
            Object[] objects = (Object[]) root;
            for (int i = 0; i < objects.length; i++) {
                writeProperty(String.valueOf(i), objects[i], expr);
            }
        } else {
            //print properties
            Map<String, Object> properties = reflectionProvider.getBeanMap(root);
            for (Map.Entry<String, Object> property : properties.entrySet()) {
                String name = property.getKey();
                Object value = property.getValue();

                if ("class".equals(name))
                    continue;

                writeProperty(name, value, expr);
            }
        }

        prettyWriter.endNode();
    }

    private void writeProperty(String name, Object value, String expr) {
        prettyWriter.startNode("tr");

        //name cell
        prettyWriter.startNode("td");
        prettyWriter.addAttribute("class", "nameColumn");
        prettyWriter.setValue(name);
        prettyWriter.endNode();

        //value cell
        prettyWriter.startNode("td");
        if (value != null) {
            //if is is an empty collection or array, don't write a link
            if (value != null &&
                (isEmptyCollection(value) || isEmptyMap(value) || (value.getClass()
                    .isArray() && ((Object[]) value).length == 0))) {
                prettyWriter.addAttribute("class", "emptyCollection");
                prettyWriter.setValue("empty");
            } else {
                prettyWriter.addAttribute("class", "valueColumn");
                writeValue(name, value, expr);
            }
        } else {
            prettyWriter.addAttribute("class", "nullValue");
            prettyWriter.setValue("null");
        }
        prettyWriter.endNode();

        //type cell
        prettyWriter.startNode("td");
        if (value != null) {
            prettyWriter.addAttribute("class", "typeColumn");
            Class clazz = value.getClass();
            prettyWriter.setValue(clazz.getName());
        } else {
            prettyWriter.addAttribute("class", "nullValue");
            prettyWriter.setValue("unknown");
        }
        prettyWriter.endNode();

        //close tr
        prettyWriter.endNode();
    }

    /**
     * Some maps, like AttributeMap will throw an exception when isEmpty() is called
     */
    private boolean isEmptyMap(Object value) {
        try {
            return value instanceof Map && ((Map) value).isEmpty();
        } catch (Exception e) {
            return true;
        }
    }

    /**
     * Some collections might throw an exception when isEmpty() is called
     */
    private boolean isEmptyCollection(Object value) {
        try {
            return value instanceof Collection && ((Collection) value).isEmpty();
        } catch (Exception e) {
            return true;
        }
    }

    private void writeValue(String name, Object value, String expr) {
        Class clazz = value.getClass();
        if (clazz.isPrimitive() || Number.class.isAssignableFrom(clazz) ||
            clazz.equals(String.class) || Boolean.class.equals(clazz)) {
            prettyWriter.setValue(String.valueOf(value));
        } else {
            prettyWriter.startNode("a");
            String path = expr.replaceAll("#", "%23") + "[\"" +
                name.replaceAll("#", "%23") + "\"]";
            prettyWriter.addAttribute("onclick", "expand(this, '" + path + "')");
            prettyWriter.addAttribute("href", "javascript://nop/");
            prettyWriter.setValue("Expand");
            prettyWriter.endNode();
        }
    }
}