基于xml文件实现系统属性配置管理

package com.yanek.cfg; import java.io.*; import java.util.*; import org.dom4j.Document; import org.dom4j.Element; import org.dom4j.io.*; import org.apache.log4j.Logger; public class XMLSystemProperties implements SystemProperties { static Logger logger = Logger.getLogger(XMLSystemProperties.class.getName()); private File file; private Document doc; private Map propertyCache; private Object propLock; public XMLSystemProperties(InputStream in) throws Exception { propertyCache = new HashMap(); propLock = new Object(); Reader reader = new BufferedReader(new InputStreamReader(in)); buildDoc(reader); } public XMLSystemProperties(String fileName) throws IOException { File tempFile; boolean error=false; Reader reader; propertyCache = new HashMap(); propLock = new Object(); file = new File(fileName); if(!file.exists()) { tempFile = new File(file.getParentFile(), file.getName() + ".tmp"); if(tempFile.exists()) { logger.error("WARNING: " + fileName + " was not found, but temp file from " + "previous write operation was. Attempting automatic recovery. Please " + "check file for data consistency."); tempFile.renameTo(file); } else { throw new FileNotFoundException("XML properties file does not exist: " + fileName); } } tempFile = new File(file.getParentFile(), file.getName() + ".tmp"); if(tempFile.exists()) { logger.error("WARNING: found a temp file: " + tempFile.getName() + ". This may " + "indicate that a previous write operation failed. Attempting automatic " + "recovery. Please check file " + fileName + " for data consistency."); if (tempFile.lastModified() > file.lastModified()) { error = false; reader = null; try{ reader = new InputStreamReader(new FileInputStream(tempFile), "UTF-8"); SAXReader xmlReader = new SAXReader(); xmlReader.read(reader); }catch(Exception e){ try { reader.close(); } catch (Exception ex) {} error = true; } } } if(error) { String bakFile = tempFile.getName() + "-" + System.currentTimeMillis() + ".bak"; tempFile.renameTo(new File(tempFile.getParentFile(), bakFile)); } else { /*String bakFile = file.getName() + "-" + System.currentTimeMillis() + ".bak"; file.renameTo(new File(file.getParentFile(), bakFile)); try { Thread.sleep(100L); } catch(Exception e) { } tempFile.renameTo(file);*/ } error = false; reader = null; try{ reader = new InputStreamReader(new FileInputStream(file), "UTF-8"); SAXReader xmlReader = new SAXReader(); xmlReader.read(reader); try { reader.close(); } catch (Exception e) {} }catch(Exception e){ error = true; } if(error) { String bakFileName = file.getName() + "-" + System.currentTimeMillis() + ".bak"; File bakFile = new File(file.getParentFile(), bakFileName); file.renameTo(bakFile); try { Thread.sleep(100L); } catch(Exception e) { } tempFile.renameTo(file); } /*else { String bakFile = tempFile.getName() + "-" + System.currentTimeMillis() + ".bak"; tempFile.renameTo(new File(tempFile.getParentFile(), bakFile)); }*/ if(!file.canRead()) throw new IOException("XML properties file must be readable: " + fileName); if(!file.canWrite()) throw new IOException("XML properties file must be writable: " + fileName); reader = null; try { reader = new InputStreamReader(new FileInputStream(file), "UTF-8"); buildDoc(reader); } catch(Exception e) { logger.error("Error creating XML properties file " + fileName + ": " + e.getMessage()); throw new IOException(e.getMessage()); } finally { } try { reader.close(); } catch(Exception e) { e.printStackTrace(); } } public Object get(Object o) { String name; String value; Element element; name = (String)o; value = (String)propertyCache.get(name); if(value != null) return value; String propName[] = parsePropertyName(name); element = doc.getRootElement(); for(int i = 0; i < propName.length; i++) { element = element.element(propName[i]); if(element == null) return null; } synchronized(propLock){ value = element.getText(); if ("".equals(value)) return null; value = value.trim(); propertyCache.put(name, value); return value; } } public Collection getChildrenNames(String parent) { String propName[] = parsePropertyName(parent); Element element = doc.getRootElement(); for(int i = 0; i < propName.length; i++) { element = element.element(propName[i]); if(element == null) return Collections.EMPTY_LIST; } List children = element.elements(); int childCount = children.size(); List childrenNames = new ArrayList(childCount); for(Iterator i = children.iterator(); i.hasNext(); childrenNames.add(((Element)i.next()).getName())); return childrenNames; } public Collection getPropertyNames() { List propNames = new java.util.LinkedList(); List elements = doc.getRootElement().elements(); if(elements.size() == 0) return Collections.EMPTY_LIST; for(int i = 0; i < elements.size(); i++) { Element element = (Element)elements.get(i); getElementNames(propNames, element, element.getName()); } return propNames; } public String getAttribute(String name, String attribute) { if(name == null || attribute == null) return null; String propName[] = parsePropertyName(name); Element element = doc.getRootElement(); int i = 0; do { if(i >= propName.length) break; String child = propName[i]; element = element.element(child); if(element == null) break; i++; } while(true); if(element != null) return element.attributeValue(attribute); else return null; } private void getElementNames(List list, Element e, String name) { if(e.elements().isEmpty()) { list.add(name); } else { List children = e.elements(); for(int i = 0; i < children.size(); i++) { Ele