别人/公司已经做好了tag和处理部分,打好了包 我们需要做的只是在我们的jsp中去应用.
但是当我们自己做个taglib时, 就需要编写这部分tag handler了.
这里只针对上面文件里提到的insert tag，其他的为了避免重复，就不一一说明了
==================== InsertTag.java==============================
/*
* $Id: InsertTag.java,v 1.13 2000/03/04 02:54:57 brydon Exp $
* Copyright 1999 Sun Microsystems, Inc. All rights reserved.
* Copyright 1999 Sun Microsystems, Inc. Tous droits réservés.
*/
package com.sun.estore.taglib;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.TagSupport;
import com.sun.estore.util.Debug;
/**
* This class is an easy interface to the JSP template or other
* text that needs to be inserted.
* @author Greg Murray
*/
public class InsertTag extends TagSupport {
private boolean directInclude = false;
private String parameter = null;
private String templateName = null;
private Template template = null;
private TemplateParameter templateParam = null;
/**
* default constructor
*/
public InsertTag() {
super();
}
public void setTemplate(String templateName){
this.templateName = templateName;
}
public void setParameter(String parameter){
this.parameter = parameter;
}
public int doStartTag() {
try{
if (templateName != null){
template = (Template)pageContext.getRequest().getAttribute("template");
}
} catch (NullPointerException e){
Debug.println("Error extracting template from session: " + e);
}
if (parameter != null && template != null) templateParam = (TemplateParameter)template.getParam(parameter);
if (templateParam != null) directInclude = templateParam.isDirect();
return SKIP_BODY;
}
public int doEndTag() throws JspTagException {
try{
pageContext.getOut().flush();
} catch (Exception e){
// do nothing
}
try {
if (directInclude && templateParam != null) {
pageContext.getOut().println(templateParam.getValue());
} else if (templateParam != null) {
if (templateParam.getValue() != null) pageContext.getRequest().getRequestDispatcher(templateParam.getValue()).include(pageContext.getRequest(), pageContext.getResponse());
}
} catch (Throwable ex) {
ex.printStackTrace();
}
return EVAL_PAGE;
}
}
可以看到。InsertTag.java继承了javax.servlet.jsp.tagext.TagSupport类. 因为在TagSupport中定义了一些接口.
延伸阅读
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