varhellotag.java

J2EE 技术 源码 书籍源代码（j2ee编程技术）

/*
 * Created on 2004-5-7
 *
 * To change the template for this generated file go to
 * Window - Preferences - Java - Code Generation - Code and Comments
 */
package tag;
import java.util.ArrayList;
import java.io.IOException;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.tagext.BodyTagSupport;
/**
 * @author 郝玉龙
 *
 * To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Generation - Code and Comments
 */
public class VarHelloTag extends BodyTagSupport {
	/** List of names passed in */
	private ArrayList			names;
	private ArrayList			positions;
	/** Where we're up to in iterating over the body content */
	private int				index;
	/** Output we're building up while iterating over the body content */
	private StringBuffer	output = new StringBuffer();
	/**
	*	Getter for the names property/attribute
	*/
	public ArrayList getNames() {
		return names;
	}
	/**
	*	Setter for the names property/attribute
	*/
	public void setNames(ArrayList names) {
		this.names = names;
	}
    public int doStartTag() throws JspTagException {
    	//控制循环次数
    	if(names.size()>0){
		setLoopVariables();
		return EVAL_BODY_TAG;
    	}
    	return SKIP_BODY;
    }

	/**
	*	The JSP engine will call this method each time the body
	*	content of this tag has been processed. If it returns
	*	SKIP_BODY, the body content will have been processed for the
	*	last time. If it returns EVAL_BODY_TAG, the body will be processed
	*	and this method called at least once more.
	*	<p/>We store content in a StringBuffer, rather than write output directly.
	*/
    public int doAfterBody() throws JspTagException {
		BodyContent bodyContent = getBodyContent();
		if (bodyContent != null) {
			output.append(bodyContent.getString());
			try {
				bodyContent.clear();
			}
			catch (IOException ex) {
				throw new JspTagException("Fatal IO error");
			}
		}

		// If we still haven't got to the end of the list,
		// continue processing
		if (++index < names.size()) {
			setLoopVariables();
			return EVAL_BODY_TAG;
		}
		// If we get to here, we've finished processing the list
		return SKIP_BODY;
	}

	/**
	*	Called after processing of body content is complete.
	*	We use it to output the content we built up during processing
	*	of the body content.
	*/
	public int doEndTag() throws JspTagException {
		BodyContent bodyContent = getBodyContent();
		try {
			bodyContent.getEnclosingWriter().write(output.toString());
		}
		catch (IOException ex) {
			throw new JspTagException("Fatal IO error");
		}

		// We've finished processing.
		// Set variables for the rest of the page
		
		

		// Process the rest of the page
		return EVAL_PAGE;
	}

	/**
	*	Make variable available for each iteration
	*/
	private void setLoopVariables() {
		pageContext.setAttribute("name", names.get(index).toString());
		pageContext.setAttribute("position", positions.get(index).toString());
		pageContext.setAttribute("index", new Integer(index));
	}


	/**
	*	Method from NameContext interface required to provide context to
	*	nested tags
	*/
	public String getName() {
		return names.get(index).toString();
	}

	/**
	 * @return Returns the positions.
	 */
	public ArrayList getPositions() {
		return positions;
	}
	/**
	 * @param positions The positions to set.
	 */
	public void setPositions(ArrayList positions) {
		this.positions = positions;
	}
	
}