othercontent.java

google gdata API 很好用的API

/* Copyright (c) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package com.google.gdata.data;

import com.google.gdata.util.common.util.Base64;
import com.google.gdata.util.common.util.Base64DecoderException;
import com.google.gdata.util.common.xml.XmlWriter;
import com.google.gdata.util.ContentType;
import com.google.gdata.util.Namespaces;
import com.google.gdata.util.ParseException;
import com.google.gdata.util.XmlBlob;
import com.google.gdata.util.XmlParser;

import org.xml.sax.Attributes;

import java.io.IOException;
import java.util.ArrayList;


/**
 * Variant of {@link Content} for entries containing miscellaneous
 * inlined content types.
 *
 * 
 */
public class OtherContent extends Content {


  /** @return the type of this content */
  public int getType() {
    if (xml != null) {
      return Content.Type.OTHER_XML;
    } else if (text != null) {
      return Content.Type.OTHER_TEXT;
    } else {
      return Content.Type.OTHER_BINARY;
    }
  }


  /** MIME type. */
  protected ContentType mimeType;
  /** @return the MIME type */
  public ContentType getMimeType() { return mimeType; }
  /** Specifies the MIME type. */
  public void setMimeType(ContentType v) { mimeType = v; }


  /**
   * Language. Derived from the current state of {@code xml:lang}.
   * Applies to inline text and binary types only.
   */
  protected String lang;
  /** @return  the human language that this content is written in */
  public String getLang() { return lang; }
  /** Specifies the human language that this content is written in. */
  public void setLang(String v) { lang = v; }


  /** XML contents. Valid only for XML types (ending with "+xml" or "/xml"). */
  protected XmlBlob xml;
  /** @return the XML contents */
  public XmlBlob getXml() { return xml; }
  /** Specifies the XML contents. */
  public void setXml(XmlBlob v) {
    xml = v;
    text = null;
    bytes = null;
  }


  /** Text contents. Valid only for text types (starting with "text/"). */
  protected String text;
  /** @return the plain text contents */
  public String getText() { return text; }
  /** Specifies the plain-text contents. */
  public void setText(String v) {
    xml = null;
    text = v;
    bytes = null;
  }


  /** Binary Contents. Valid if neither XML nor text contents are valid. */
  protected byte[] bytes;
  /** @return the binary contents */
  public byte[] getBytes() { return bytes; }
  /** Specifies the binary contents. */
  public void setBytes(byte[] v) {
    xml = null;
    bytes = v;
    text = null;
  }


  /**
   * Generates XML in the Atom format.
   *
   * @param   w
   *            output writer
   *
   * @throws  IOException
   */
  public void generateAtom(XmlWriter w) throws IOException {

    ArrayList<XmlWriter.Attribute> attrs =
      new ArrayList<XmlWriter.Attribute>(2);

    if (mimeType != null) {
      attrs.add(new XmlWriter.Attribute("type", mimeType.getMediaType()));
    }

    if (xml == null) {

      String value;

      if (text != null) {
        value = text;
        if (lang != null) {
          attrs.add(new XmlWriter.Attribute("xml:lang", lang));
        }
      } else if (bytes != null) {
        value = Base64.encode(bytes);
        if (lang != null) {
          attrs.add(new XmlWriter.Attribute("xml:lang", lang));
        }
      } else {
        value = null;
      }

      w.simpleElement(Namespaces.atomNs, "content", attrs, value);

    } else {
      XmlBlob.startElement(w, Namespaces.atomNs, "content", xml, attrs, null);
      XmlBlob.endElement(w, Namespaces.atomNs, "content", xml);
    }
  }


  /**
   * Generates XML in the RSS format.
   *
   * @param   w
   *            output writer
   *
   * @throws  IOException
   */
  public void generateRss(XmlWriter w) throws IOException {

    // If content has a link instead of a body, generate a <link> element.
    if (getType() == Content.Type.OTHER_TEXT) {
      w.simpleElement(Namespaces.rssNs, "description", null, text);
    } else {
      // RSS doesn't support non-text content, so we use the Atom type.
      generateAtom(w);
    }
  }


  /** Parses XML in the Atom format. */
  public class AtomHandler extends XmlParser.ElementHandler {


    private final int type;


    /**
     * Class constructor specifying attributes.
     *
     * @throws   IOException
     */
    AtomHandler(Attributes attrs) throws IOException {

      String typeAttr = attrs.getValue("", "type");

      if (typeAttr.endsWith("+xml") || typeAttr.endsWith("/xml")) {
        type = Content.Type.OTHER_XML;
        xml = new XmlBlob();
        initializeXmlBlob(xml, true, true);
      } else if (typeAttr.startsWith("text/")) {
        type = Content.Type.OTHER_TEXT;
      } else {
        type = Content.Type.OTHER_BINARY;
      }
    }


    /**
     * Processes attributes.
     *
     * @throws   ParseException
     */
    public void processAttribute(String namespace,
                                 String localName,
                                 String value)
        throws ParseException {

      if (namespace.equals("")) {
        if (localName.equals("type")) {
          mimeType = new ContentType(value);
        }
      }
    }


    /**
     * Processes this element; overrides inherited method.
     */
    public void processEndElement() throws ParseException {

      switch (type) {

      case Content.Type.OTHER_XML:
        // XML contents are processed through initializeXmlBlob() above.
        break;

      case Content.Type.OTHER_TEXT:
        text = value;
        lang = xmlLang;
        break;

      case Content.Type.OTHER_BINARY:
        if (value != null) {
          try {
            bytes = Base64.decode(value);
          } catch (Base64DecoderException e) {
            throw new ParseException("Expected Base-64 content.");
          }
        }

        lang = xmlLang;
        break;

      default:
        assert false;
      }
    }
  }
}