simplexmldata.java

此程序都是企业级 的数据库开发程序 全面揭示了JAVA对数据库的操作

import java.sql.*;                   /* JDBC Classes */
// import COM.cloudscape.core.*;        /* Cloudscape JDBC classes */
import org.w3c.dom.*;                /* W3C Interfaces */
import org.apache.xerces.dom.*;      /* Xerces DOM Classes */
import org.apache.xml.serialize.*;   /* Xerces serializer */
import java.io.*;                    /* Java io classes for file access */

public class SimpleXMLData {

  public static final String JDBCURL = 
    "jdbc:cloudscape:c:/wrox/database/Wrox4370.db";
  public static final String JDBCDRIVER = "COM.cloudscape.core.JDBCDriver";
  public static final String SQL = "SELECT customerid, customerfirstname, " +
                                   " customerlastname " +
                                   "FROM customers";
  public static final String OUTPUTFILE = "c:\\customer.xml";


  /**
   * **************************************************************************
   * 
   * This is a simple example of how to pull data out of the database and
   * convert the output to an XML DOM. This class has purposely been written
   * as a set of static methods because at this point I want to focus on the
   * XML code and not necessarily the OO features of Java.
   * ***************************************************************************
   */

  public static void main(String args[]) {

    try {

      /**
       * ****Step 1 - Making my JDBC Connection to Cloudscape****
       */
      Class.forName(JDBCDRIVER).newInstance();
      Connection conn = DriverManager.getConnection(JDBCURL);

      /**
       * ****Step 2 - Retrieve my customer data from the database****
       */
      Statement statement = conn.createStatement();
      ResultSet customerRS = statement.executeQuery(SQL);

      /**
       * ****Step 3 - Build customer XML DOM.****
       */
      Document xmlDoc = buildCustomerXML(customerRS);

      /**
       * ****Step 4 - Writing the output to a file ****
       */
      File outputFile = new File(OUTPUTFILE);
      printDOM(xmlDoc, outputFile);

      conn.close();   /* Closing my connection */
    } catch (Exception e) {
      System.out.println("Really poor exception handling: " + e.toString());
    } 
  } 

  /**
   * ********************************************************************
   * 
   * The buildCustomerXML will build a simple xml document based on the
   * records retrieved from SQL statement defined in the SQL constant.
   * 
   * The xml document object will then be passed back to the main
   * method where it will be written to a flat file.
   * 
   * *******************************************************************
   */
  private static Document buildCustomerXML(ResultSet _customerRS) 
                          throws Exception {
    Document xmlDoc = new DocumentImpl();

    /* Creating the root element */
    Element rootElement = xmlDoc.createElement("CUSTOMERS");
    xmlDoc.appendChild(rootElement);

    while (_customerRS.next()) {
      Element customer = xmlDoc.createElement("CUSTOMER");

      /* Building the id attribute for the DOM */
      customer.setAttribute("customerid", _customerRS.getString("customerid"));

      /* Creating the elements within my customer DOM */
      Element firstName = xmlDoc.createElement("FIRSTNAME");
      Element lastName = xmlDoc.createElement("LASTNAME");

      /* Populating my customer DOM with data */
      firstName.appendChild(xmlDoc.createTextNode(
                            _customerRS.getString("customerfirstname")));

      lastName.appendChild(xmlDoc.createTextNode(
                           _customerRS.getString("customerlastname")));

      /*
       * Appending the customer elements to the customer element declared at
       * the beginning of the while loop.
       */
      customer.appendChild(firstName);
      customer.appendChild(lastName);

      /* Appending the customer to the root class */
      rootElement.appendChild(customer);
    } 

    return xmlDoc;
  } 

  /**
   * ****************************************************************************
   * 
   * The printDOM method below will write the contents of the XML document
   * passed into it out to the a file. The method will that the XML
   * document will be written out is defined by the File object passed into
   * it.
   * ***************************************************************************
   */
  private static void printDOM(Document _xmlDoc, 
                               File _outputFile) throws Exception {
    OutputFormat outputFormat = new OutputFormat("XML", "UTF-8", true);
    FileWriter fileWriter = new FileWriter(_outputFile);

    XMLSerializer xmlSerializer = new XMLSerializer(fileWriter, 
                                                    outputFormat);
    xmlSerializer.asDOMSerializer();

    xmlSerializer.serialize(_xmlDoc.getDocumentElement());
  } 
}