public class IfTag extends BodyTagSupport{

	public IfTag() {
        super();
        init();
    }

	@Override
    public void release() {
        super.release();
        init();
    }
    
    @Override
    public int doStartTag() throws JspException {
    	if(test){
    		this.succeeded();
    	}
		return EVAL_BODY_BUFFERED;
    }

    @Override
    public int doEndTag() throws JspException {
    	try {
    		if(subtagSucceeded)
    			pageContext.getOut().write(getBody());
		} catch (IOException e) {
			throw new JspException("IOError while writing the body: " + e.getMessage(), e);
		}
    	
		init();
    	return super.doEndTag();
    }
	
    private String body = null;		//	用于存放成功条件后的内容
    public void setBody(){
    	if(body == null){
    		body = bodyContent.getString().trim();
    	}
    }
    
    private String getBody(){
    	if(body == null)
    		return bodyContent.getString().trim();
    	else
    		return body;
    }
    
    /**
     * 判断if 或者 子 else if是否提交成功
     */
    private boolean subtagSucceeded;
    
    /**
     * 子条件判断成功
     */
    public void succeeded(){
    	subtagSucceeded = true;
    }
    /**
     * 是否已经执行完毕
     * @return
     */
    public boolean isSucceeded(){
    	return subtagSucceeded;
    }
    
    private void init() {
        test = false;
        subtagSucceeded = false;
        body = null;
    }
    
    private boolean test;  
    
    public void setTest(boolean test) {
        this.test = test;
    }
}

public class ElseIfTag extends BodyTagSupport{

	public ElseIfTag() {
        super();
        init();
    }

	@Override
	public int doStartTag() throws JspException {
	    Tag parent = getParent();

    	if(parent==null || !(parent instanceof IfTag)){
            throw new JspTagException("else tag must inside if tag");
    	}
    	
    	IfTag ifTag = (IfTag)parent;
    	if(ifTag.isSucceeded()){
    		// 已经有执行成功的条件，保存之前的html
    		ifTag.setBody();
    	}else if(test){		// 当前条件为true,之前无条件为true
    		ifTag.succeeded();
    		// 则清除之前的输出
    		ifTag.getBodyContent().clearBody();
    	}
    		
		return EVAL_BODY_BUFFERED;
    }
	 
	@Override
    public void release() {
        super.release();
        init();
    }
	
	private void init() {
        test = false;
    }
    
    private boolean test;  
    
    public void setTest(boolean test) {
        this.test = test;
    }
}

public class ElseTag extends BodyTagSupport{

	public void release() {
        super.release();
    }
    
    public int doStartTag() throws JspException {
    	Tag parent = getParent();

    	if(parent==null || !(parent instanceof IfTag)){
            throw new JspTagException("else tag must inside if tag");
    	}
    	
    	IfTag ifTag = (IfTag)parent;
    	if(ifTag.isSucceeded()){
    		// 已经有执行成功的条件，保存之前的html
    		ifTag.setBody();
    	}else{
    		// 之前没有的判断没有成功条件,则清除之前的输出
    		ifTag.getBodyContent().clearBody();
    		ifTag.succeeded();
    	}
    		
		return EVAL_BODY_BUFFERED;
    }
    
}