AuWriters.java :  » Ajax » zk » org » zkoss » zk » au » Java Open Source

/* AuWriters.java

  Purpose:
    
  Description:
    
  History:
    Tue Dec  4 11:20:33     2007, Created by tomyeh

Copyright (C) 2007 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
  This program is distributed under LGPL Version 3.0 in the hope that
  it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zk.au;

import java.io.Writer;
import java.io.IOException;

import org.zkoss.idom.Verifier;

import org.zkoss.zk.ui.UiException;
import org.zkoss.zk.au.http.HttpAuWriter;

/**
 * Utilities to instantiate an implmentation of {@link AuWriter}.
 *
 * @author tomyeh
 * @since 3.0.1
 */
public class AuWriters {
  /** The implementation class of {@link AuWriter}. */
  private static Class _awCls;

  /** Returns the implementation class of {@link AuWriter} that
   * will be used to generate the output to the client.
   *
   * <p>Default: {@link HttpAuWriter}.
   */
  public static Class getImplementationClass() {
    return _awCls != null ? _awCls: HttpAuWriter.class;
  }
  /** Sets the implementation class of {@link AuWriter} that
   * will be used to generate the output to the client.
   */
  public static void setImplementationClass(Class cls) {
    if (cls != null)
      if (cls.equals(HttpAuWriter.class))
        cls = null;
      else if (!AuWriter.class.isAssignableFrom(cls))
        throw new IllegalArgumentException(cls+" must implement "+AuWriter.class.getName());
    _awCls = cls;
  }
  /** Creates an instance of {@link AuWriter}.
   */
  public static AuWriter newInstance() throws UiException {
    if (_awCls != null) {
      try {
        return (AuWriter)_awCls.newInstance();
      } catch (Exception ex) {
        throw UiException.Aide.wrap(ex);
      }
    }
    return new HttpAuWriter();
  }

  /** The content type of the output.
   * @since 3.5.0
   */
  public static final String CONTENT_TYPE = "text/plain;charset=UTF-8";
}