loadingtag.java

本平台是以web2.0为基本的标准

package com.common.util;

/*
 * $Header:
 * $Revision: 1.0beta $
 * $Date: 2002/01/23 01:19:00 $
 */

import  javax.servlet.jsp.tagext.TagSupport;
import  java.io.IOException;
import  javax.servlet.jsp.JspException;
import  javax.servlet.jsp.JspWriter;
import  javax.servlet.jsp.PageContext;

/** LoadingTag
 *
 * @author <a href="mailto:[e-mail]">Emmanuel Boudrant</a>
 *
 * LoadingTag: Simple tag used to display a loading message during an long, long ... and long operation.<br>
 * <br>
 * <b>Use:</b><br>
 * &lt;code&gt;<br>
 *  &lt;tag:loading message="please wait..."&gt;<br>
 *    LONG OPERATION !<br>
 *  &lt;/tag:loading&gt;<br>
 * &lt;code&gt;<br>
 *
 * Not Working on Netscape.
 *
 * @author Emmanuel Boudrant
 * @version $Revision: 1.0beta $ $Date: 2002/01/23 01:19:00 $
 *
 * <i>
 * -----------------------------------------------------------------------------------<br>
 * Based on Macromedia Dreamweaver javascript/layer.<br>
 * Macromedia, Dreamweaver are trademarks or registered trademarks of Macromedia, Inc.<br>
 * -----------------------------------------------------------------------------------<br>
 * </i>
 */
public class LoadingTag extends TagSupport {

    // ----------------------------------------------------- Instance Variables

    /**
     * Layer name, internal use only.
     */
    private String name=null;

    /**
     * Your message (note: can be HTML code).
     */
    private String message = "Loading...";
    public String getMessage () {
        return  message;
    }
    public void setMessage (String message) {

        // Compute an unique layer name.
        name = System.currentTimeMillis() + "_" + Math.abs(message.hashCode());
        this.message = message;
    }

    /**
     * Layer position style.
     */
    private String position = "absolute";
    public String getPosition () {
        return  position;
    }
    public void setPosition (String position) {
        this.position = position;
    }

    /**
     * Layer X coord.
     */
    private int left = 44;
    public String getLeft () {
        return  left+"";
    }
    public void setLeft (String left) {
        this.left = Integer.parseInt(left);
    }

    /**
     * Layer Y coord.
     */
    private int top = 115;
    public String getTop () {
        return  top+"";
    }
    public void setTop (String top) {
        this.top = Integer.parseInt(top);
    }

    /**
     * Layer Widht.
     */
    private int width = 300;
    public String getWidth () {
        return  width+"";
    }
    public void setWidth (String width) {
        this.width = Integer.parseInt(width);
    }

    /**
     * Layer Height.
     */
    private int height = 300;
    public String getHeight () {
        return  height+"";
    }
    public void setHeight (String height) {
        this.height = Integer.parseInt(height);
    }

    /**
     * Layer Z position.
     */
    private int zIndex = 1;
    public String getZIndex () {
        return  zIndex+"";
    }
    public void setZIndex (String zIndex) {
        this.zIndex = Integer.parseInt(zIndex);
    }

    /**
     * Layer tag (div,span,layer...).
     */
    private String tag = "div";
    public String getTag () {
        return  tag;
    }
    public void setTag (String tag) {
        this.tag = tag;
    }

    // --------------------------------------------------------- Public Methods


    /**
     * Generate the layer message and flush output.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag () throws JspException {

        StringBuffer results = new StringBuffer();

        boolean functionExist = Boolean.valueOf((String)pageContext.getAttribute("functionExist",pageContext.REQUEST_SCOPE)).booleanValue();
        results.append("<!-- { LoadingTag.StartTag -->\n");
        // Do not overwrite the JavaScript function.
        if ( !functionExist ) {
          results.append("<script language=\"JavaScript\">\n");
          results.append("<!--\n");
          results.append("function _find_(n, d) { //v4.0\n");
          results.append("  var p,i,x;  if(!d) d=document; if((p=n.indexOf(\"?\"))>0&&parent.frames.length) {\n");
          results.append("    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}\n");
          results.append("  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];\n");
          results.append("  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=_find_(n,d.layers[i].document);\n");
          results.append("  if(!x && document.getElementById) x=document.getElementById(n); return x;\n");
          results.append("}\n");

          results.append("function _hide_() { //v3.0\n");
          results.append("  var i,p,v,obj,args=_hide_.arguments;\n");
          results.append("  for (i=0; i<(args.length-2); i+=3) if ((obj=_find_(args[i]))!=null) { v=args[i+2];\n");
          results.append("    if (obj.style) { obj=obj.style; v=(v=='show')?'visible':(v='hide')?'hidden':v; }\n");
          results.append("    obj.visibility=v; }\n");
          results.append("}\n");
          results.append("//-->\n");
          results.append("</script>\n");

          pageContext.setAttribute("functionExist","true",pageContext.REQUEST_SCOPE);

        }

        results.append("<"+tag+" id=\""+name+"\" style=\"position:"+position+"; width:"+width+"px; height:"+height+"px; z-index:"+zIndex+"; left: "+left+"px; top: "+top+"px\">\n");
        results.append(message+"\n");
        results.append("</"+tag+">\n");
        results.append("<!-- LoadingTag.StartTag  } -->\n");


        // Print this value to our output writer
        JspWriter writer = pageContext.getOut();
        try {
            writer.print(results.toString());
            writer.flush();
        } catch (IOException e) {
            throw  new JspException("Print/Flush in LoadingTag tag error:" + e);
        }
        // Continue processing this page
        return  (EVAL_BODY_INCLUDE);
    }

    /**
     * Generate the javascript who hide the layer message.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doEndTag () throws JspException {

        StringBuffer results = new StringBuffer();

        results.append("<!-- { LoadingTag.EndTag -->\n");
        results.append("<script language=\"JavaScript\">\n");
        results.append("_hide_('"+name+"','','hide')\n");
        results.append("</script>\n");
        results.append("<!-- LoadingTag.EndTag } -->\n");

        // Print this value to our output writer
        JspWriter writer = pageContext.getOut();
        try {
            writer.print(results.toString());
        } catch (IOException e) {
            throw  new JspException("Print/Flush in LoadingTag tag error:" + e);
        }

        return  (EVAL_PAGE);
    }

    /**
     * Release any acquired resources.
     */
    public void release() {

	super.release();
	message = null;
	name = null;
	position = null;

    }

}