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Commons Digester example source code file (OverlappingCallMethodRuleTestCase.java)

This example Commons Digester source code file (OverlappingCallMethodRuleTestCase.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 - Commons Digester tags/keywords

a1, b1, box, c1, digester, digester, io, ioexception, ioexception, sax, saxexception, string, stringbuffer, stringbuffer, test, test

The Commons Digester OverlappingCallMethodRuleTestCase.java source code

/* $Id: OverlappingCallMethodRuleTestCase.java 992060 2010-09-02 19:09:47Z simonetripodi $
 *
 * 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.commons.digester;


import static org.junit.Assert.assertEquals;

import java.io.IOException;
import java.io.StringReader;

import org.junit.Test;
import org.xml.sax.SAXException;

/**
 * <p>Tests for situations where CallMethodRule instances and their
 * parameters overlap each other.</p>
 */
public class OverlappingCallMethodRuleTestCase {


    // --------------------------------------------------- Overall Test Methods

    String itemId;
    String itemName;
    
    public void setItemId(String id) { itemId = id; }
    public void setItemName(String name) { itemName = name; }
    
    // ------------------------------------------------ Individual Test Methods

    @Test
    public void testItem1() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<root>");
        input.append(" <item id='1'>anitem");
        input.append("</root>");

        Digester digester = new Digester();
        
        digester.addCallMethod("root/item", "setItemId", 1);
        digester.addCallParam("root/item", 0, "id");
        digester.addCallMethod("root/item", "setItemName", 1);
        digester.addCallParam("root/item", 0);

        this.itemId = null;
        this.itemName = null;
        digester.push(this);
        digester.parse(new StringReader(input.toString()));

        assertEquals("1", this.itemId);
        assertEquals("anitem", this.itemName);
    }

    @Test
    public void testItem2() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<root>");
        input.append(" <item id='1'>anitem");
        input.append("</root>");

        Digester digester = new Digester();

        digester.addCallMethod("root/item", "setItemName", 1);
        digester.addCallParam("root/item", 0);
        digester.addCallMethod("root/item", "setItemId", 1);
        digester.addCallParam("root/item", 0, "id");

        this.itemId = null;
        this.itemName = null;
        digester.push(this);
        digester.parse(new StringReader(input.toString()));

        assertEquals("1", this.itemId);
        assertEquals("anitem", this.itemName);
    }

    @Test
    public void testItem3() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<root>");
        input.append(" <item>1");
        input.append("</root>");

        Digester digester = new Digester();

        digester.addCallMethod("root/item", "setItemId", 1);
        digester.addCallParam("root/item", 0);
        digester.addCallMethod("root/item", "setItemName", 1);
        digester.addCallParam("root/item", 0);

        this.itemId = null;
        this.itemName = null;
        digester.push(this);
        digester.parse(new StringReader(input.toString()));

        assertEquals("1", this.itemId);
        assertEquals("1", this.itemName);
    }

    /**
     * This is an "anti-test" that demonstrates how digester can <i>fails 
     * to produce the correct results, due to a design flaw (or at least
     * limitation) in the way that CallMethodRule and CallParamRule work. 
     * <p>
     * The following sequence always fails:
     * <ul>
     * <li>CallMethodRule A fires (pushing params array)
     * <li>CallMethodRule B fires (pushing params array)
     * <li>params rule for A fires --> writes to params of method B!
     * <li>params rule for B fires --> overwrites params for method B
     * </ul>
     * The result is that method "b" appears to work ok, but method "a"
     * loses its input parameters.
     * <p>
     * One solution is for CallParamRule objects to know which CallMethodRule
     * they are associated with. Even this might fail in corner cases where
     * the same rule is associated with multiple patterns, or with wildcard
     * patterns which cause a rule to fire in a "recursive" manner. However
     * implementing this is not possible with the current digester design.
     */
    @Test
    public void testItem4() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<root>");
        input.append(" <item>");
        input.append("  <id value='1'/>");
        input.append("  <name value='name'/>");
        input.append(" </item>");
        input.append("</root>");

        Digester digester = new Digester();

        digester.addCallMethod("root/item", "setItemId", 1);
        digester.addCallParam("root/item/id", 0, "value");
        digester.addCallMethod("root/item", "setItemName", 1);
        digester.addCallParam("root/item/name", 0, "value");

        this.itemId = null;
        this.itemName = null;
        digester.push(this);
        digester.parse(new StringReader(input.toString()));

        // These are the "correct" results
        //assertEquals("1", this.itemId);
        //assertEquals("name", this.itemName);

        // These are what actually happens
        assertEquals(null, this.itemId);
        assertEquals("name", this.itemName);
    }

    /**
     * This test checks that CallParamRule instances which fetch data
     * from xml attributes work ok when invoked "recursively",
     * ie a rule instances' methods gets called in the order
     * begin[1]/begin[2]/body[2]/end[2]/body[1]/end[1]
     */
    @Test
    public void testWildcard1() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<box id='A1'>");
        input.append(" <box id='B1'>");
        input.append("  <box id='C1'/>");
        input.append("  <box id='C2'/>");
        input.append(" </box>");
        input.append("</box>");

        Digester digester = new Digester();

        digester.addObjectCreate("*/box", Box.class);
        digester.addCallMethod("*/box", "setId", 1);
        digester.addCallParam("*/box", 0, "id");
        digester.addSetNext("*/box", "addChild");

        Box root = new Box();
        root.setId("root");
        digester.push(root);
        digester.parse(new StringReader(input.toString()));

        // walk the object tree, concatenating the id strings
        String ids = root.getIds();
        assertEquals("root A1 B1 C1 C2", ids);
    }

    /**
     * This test checks that CallParamRule instances which fetch data
     * from the xml element body work ok when invoked "recursively",
     * ie a rule instances' methods gets called in the order
     * begin[1]/begin[2]/body[2]/end[2]/body[1]/end[1]
     */
    @Test
    public void testWildcard2() throws SAXException, IOException {
        StringBuffer input = new StringBuffer();
        input.append("<box>A1");
        input.append(" <box>B1");
        input.append("  <box>C1");
        input.append("  <box>C2");
        input.append(" </box>");
        input.append("</box>");

        Digester digester = new Digester();

        digester.addObjectCreate("*/box", Box.class);
        digester.addCallMethod("*/box", "setId", 1);
        digester.addCallParam("*/box", 0);
        digester.addSetNext("*/box", "addChild");

        Box root = new Box();
        root.setId("root");
        digester.push(root);
        digester.parse(new StringReader(input.toString()));

        // walk the object tree, concatenating the id strings
        String ids = root.getIds();
        assertEquals("root A1 B1 C1 C2", ids);
    }
}

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