employeedaoxml.java

对XML和DB的CURD的基本操作.使用的两个比较常用的组合设计模式：MVC模式+DAO模式。

package com.mycompany.myapp.dao.xml;

import java.io.File;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import com.mycompany.myapp.dao.EmployeeDao;
import com.mycompany.myapp.exception.XmlFileReadException;
import com.mycompany.myapp.exception.XmlFileWriteException;
import com.mycompany.myapp.model.Employee;

/**
 * the xml file implement for employeeDao
 */
public class EmployeeDaoXml implements EmployeeDao {
	private String xmlFilePos;

	private Document document;

	public EmployeeDaoXml() {
	}

	public EmployeeDaoXml(String xmlFilePos) throws XmlFileReadException,
			XmlFileWriteException {
		this.xmlFilePos = xmlFilePos;
		if (isFileExist(this.xmlFilePos) == false) {
			// Create document when file not exist
			createDocument();
			return;
		} else {
			// Get Docunent when file exist
			SAXReader reader = new SAXReader();
			try {
				document = reader.read(new File(this.xmlFilePos));
			} catch (Exception ex) {
				throw new XmlFileReadException(ex.getMessage());
			}
		}
	}

	//@Override
	public Employee get(Long id) {
		Element rootElm = document.getRootElement();
		List nodes = rootElm.elements("employee");
		for (Iterator it = nodes.iterator(); it.hasNext();) {
			Element elm = (Element) it.next();
			if (elm.attributeValue("id").equals(String.valueOf(id))) {
				Employee employee = new Employee();
				employee.setId(id);
				employee.setFirstName(elm.element("firstName").getText());
				employee.setLastName(elm.element("lastName").getText());
				employee.setPhoneNumber(elm.element("phoneNumber").getText());
				employee.setAddress(elm.element("address").getText());
				return employee;
			}
		}
		return null;
	}

	///////////////////////////@Override
	public List<Employee> getAll() {
		List<Employee> lst = new ArrayList<Employee>();
		List nodes = document.getRootElement().elements("employee");
		for (Iterator it = nodes.iterator(); it.hasNext();) {
			Element elm = (Element) it.next();
			Employee employee = new Employee();
			employee.setId(Long.valueOf(elm.attributeValue("id")));
			employee.setFirstName(elm.elementText("firstName"));
			employee.setLastName(elm.elementText("lastName"));
			employee.setPhoneNumber(elm.elementText("phoneNumber"));
			employee.setAddress(elm.elementText("address"));
			lst.add(employee);
		}
		return lst;
	}

	//@Override
	public void remove(Long id) {
		try {
			Element rootElm = document.getRootElement();
			List nodes = rootElm.elements("employee");
			for (Iterator it = nodes.iterator(); it.hasNext();) {
				Element elm = (Element) it.next();
				Employee employee = new Employee();
				employee.setId(Long.valueOf(elm.attributeValue("id")));
				employee.setFirstName(elm.elementText("firstName"));
				employee.setLastName(elm.elementText("lastName"));
				employee.setPhoneNumber(elm.elementText("phoneNumber"));
				employee.setAddress(elm.elementText("address"));
				if (employee.getId().equals(id)) {
					rootElm.remove(elm);
					break;
				}
				else{
					System.out.println("No employee with id="+id+" exist!\n");
				}
			}
			writeDocumentToFile();
		} catch (XmlFileWriteException ex) {
			System.err.println(ex.getMessage());
		}
	}

	//@Override
	public Employee insert(Employee employee) {
		try {
			Element rootElm = document.getRootElement();
			Element newEmployeeElm = rootElm.addElement("employee");
			newEmployeeElm.addAttribute("id", String.valueOf(employee.getId()));
			Element firstNameElm = newEmployeeElm.addElement("firstName");
			firstNameElm.setText(employee.getFirstName());
			Element lastNameElm = newEmployeeElm.addElement("lastName");
			lastNameElm.setText(employee.getLastName());
			Element phoneNumberElm = newEmployeeElm.addElement("phoneNumber");
			phoneNumberElm.setText(employee.getPhoneNumber());
			Element addressElm = newEmployeeElm.addElement("address");
			addressElm.setText(employee.getAddress());
			writeDocumentToFile();
		} catch (XmlFileWriteException e) {
			e.printStackTrace();
		}
		return employee;
	}

	//@Override
	public Employee update(Employee employee) {
		try {
			Element rootElm = document.getRootElement();
			List nodes = rootElm.elements("employee");
			for (Iterator it = nodes.iterator(); it.hasNext();) {
				Element elm = (Element) it.next();
				if (elm.attributeValue("id").equals(
						String.valueOf(employee.getId()))) {
					elm.element("firstName").setText(employee.getFirstName());
					elm.element("lastName").setText(employee.getLastName());
					elm.element("phoneNumber").setText(
							employee.getPhoneNumber());
					elm.element("address").setText(employee.getAddress());
					break;
				}
			}
			writeDocumentToFile();
		} catch (XmlFileWriteException e) {
			e.printStackTrace();
		}
		return employee;
	}

	private void writeDocumentToFile() throws XmlFileWriteException {
		try {
			XMLWriter writer = new XMLWriter(new FileWriter(this.xmlFilePos));
			writer.write(document);
			writer.close();
		} catch (Exception ex) {
			throw new XmlFileWriteException(ex.getMessage());
		}
	}

	private void createDocument() throws XmlFileWriteException {
		String text = "<employees></employees>";
		try {
			document = DocumentHelper.parseText(text);
			writeDocumentToFile();
		} catch (XmlFileWriteException ex) {
			throw ex;
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}

	public static boolean isFileExist(String filePath) {
		boolean exists = (new File(filePath)).exists();
		return exists;
	}
}