xpathfind.java

一个查找java程序里bug的程序的源代码,该程序本身也是java写的,对提高java编程水平很有用

/*
 * Evaluate XPath expressions on an XML file
 * Copyright (C) 2004, University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.xml;

import java.util.Iterator;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

/**
 * Find nodes in a dom4j tree that match a particular
 * XPath expression.  The main() driver prints out information
 * about matching nodes in an XML document.
 *
 * <p> For example, to find the list of non-disabled detectors
 * in a FindBugs plugin descriptor, you can use the expression
 * <blockquote>
 * <code>/FindbugsPlugin/Detector[boolean(@disabled)=false()]/@class</code>
 * </blockquote>
 *
 * @author David Hovemeyer
 */
public abstract class XPathFind {
	private Document document;

	public XPathFind(Document document) {
		this.document = document;
	}

	public void find(String xpath) {
		for (Iterator i = document.selectNodes(xpath).iterator(); i.hasNext(); ) {
			match((Node) i.next());
		}
	}

	protected abstract void match(Node node);

	public static void main(String[] argv) throws Exception {
		if (argv.length != 2) {
			System.err.println("Usage: " + XPathFind.class.getName() +
				": <filename> <xpath expression>");
			System.exit(1);
		}

		String fileName = argv[0];
		String xpath = argv[1];

		SAXReader reader = new SAXReader();
		Document document = reader.read(fileName);

		XPathFind finder = new XPathFind(document) {
			protected void match(Node node) {
				//System.out.println(node.toString());
				if (node instanceof Element) {
					Element element = (Element) node;
					System.out.println("Element: " + element.getQualifiedName());
					System.out.println("\tText: " + element.getText());
					System.out.println("\tAttributes:");
					for (Iterator i = element.attributeIterator(); i.hasNext(); ) {
						Attribute attribute = (Attribute) i.next();
						System.out.println("\t\t" + attribute.getName() + "=" + attribute.getValue());
					}
				} else if (node instanceof Attribute) {
					Attribute attribute = (Attribute) node;
					System.out.println("Attribute: " + attribute.getName() + "=" + attribute.getValue());
				}
			}
		};

		finder.find(xpath);
	}
}

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