xmlwriter.java

pastry的java实现的2.0b版

/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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This software is provided by RICE and the contributors on an "as is"
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********************************************************************************/

package rice.p2p.util;

import java.io.*;
import org.xmlpull.v1.*;

/**
 * XMLWriter is a utility class used by XMLObjectOutputStream to perform the
 * actual XML writing. This writing is based on the XML Pull-Parsing API,
 * available online at http://www.xmlpull.org. Any of the provided serializer
 * implementations will work with this reader.
 *
 * @version $Id: XMLWriter.java 2324 2005-03-14 23:00:27Z amislove $
 * @author Alan Mislove
 */
public class XMLWriter {

  /**
   * The actual XML serializer, which does the writing
   */
  protected XmlSerializer serializer;

  /**
   * The underlying writer which the serializer uses
   */
  protected Writer writer;

  /**
   * Constructor which takes the provided writer and builds a new XML writier to
   * read XML from the writier.
   *
   * @param out The writer to base this XML writer off of
   * @exception IOException DESCRIBE THE EXCEPTION
   * @throws IOException If an error occurs
   */
  public XMLWriter(OutputStream out) throws IOException {
    try {
      this.writer = new BufferedWriter(new OutputStreamWriter(out));
      XmlPullParserFactory factory = XmlPullParserFactory.newInstance(System.getProperty(XmlPullParserFactory.PROPERTY_NAME), null);
      serializer = factory.newSerializer();

      serializer.setOutput(this.writer);
      serializer.setProperty("http://xmlpull.org/v1/doc/properties.html#serializer-indentation", " ");
      serializer.setProperty("http://xmlpull.org/v1/doc/properties.html#serializer-line-separator", "\n");
      serializer.setFeature("http://xmlpull.org/v1/doc/features.html#serializer-attvalue-use-apostrophe", true);
    } catch (XmlPullParserException e) {
      throw new IOException("XML Exception thrown: " + e);
    }
  }

  /**
   * Method which flushes all buffered data to the underlying writer
   *
   * @throws IOException If an error occurs
   */
  public void flush() throws IOException {
    serializer.flush();
  }

  /**
   * Method which flushes and closes the underlying writer, which will cause
   * future writer attempts to throw an IOException.
   *
   * @throws IOException If an error occurs
   */
  public void close() throws IOException {
    serializer.text("\n");
    serializer.flush();
    writer.close();
  }

  /**
   * Method which writes a sequence of base64 encoded bytes to the output stream
   *
   * @param bytes The bytes to write
   * @param off DESCRIBE THE PARAMETER
   * @param len DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public void writeBase64(byte[] bytes, int off, int len) throws IOException {
    flush();
    writer.write(Base64.encodeBytes(bytes, off, len));
  }

  /**
   * Method which writes the XML header to the writer.
   *
   * @throws IOException If an error occurs
   */
  public void writeHeader() throws IOException {
    serializer.startDocument(null, null);
    serializer.text("\n\n");
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, int value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, double value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, float value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, long value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, char value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, boolean value) throws IOException {
    attribute(name, String.valueOf(value));
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  public void attribute(String name, Object value) throws IOException {
    if (value == null) {
      return;
    }

    attribute(name, value.toString());
  }

  /**
   * Method which writes an attribute to the XML document.
   *
   * @param name The name of the attribute to write
   * @param value The value to write
   * @throws IOException If an error occurs
   */
  protected void attribute(String name, String value) throws IOException {
    serializer.attribute(null, name, value);
  }

  /**
   * Method which starts the given tag name
   *
   * @param name The name of the tag to start
   * @throws IOException If an error occurs
   */
  public void start(String name) throws IOException {
    serializer.startTag(null, name);
  }

  /**
   * Method which ends the given tag name
   *
   * @param name The name of the tag to end
   * @throws IOException If an error occurs
   */
  public void end(String name) throws IOException {
    serializer.endTag(null, name);
  }
}