1
考虑片断
loop.jsp自定义标签迭代通过JSP
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib uri="mypredefinedtaglibrary" prefix="my" %>
<html>
<head>
</head>
<body>
<my:looping end="5" start="1">
<p>My Name is Khan</p><br/>
</my:looping>
</body>
</html>
MyTagHandlerForLoop.java
public class MyTagHandlerForLoop extends TagSupport {
private static final long serialVersionUID = 1L;
private int start = 0;
private int end = 0;
public void setStart(int start) {
this.start = start;
}
public void setEnd(int end) {
this.end = end;
}
@Override
public int doAfterBody() throws JspException {
if (start < end) {
start++;
return EVAL_BODY_AGAIN;
} else {
return SKIP_BODY;
}
}
@Override
public int doStartTag() throws JspException {
return EVAL_BODY_INCLUDE;
}
}
mytags.tld
<tag>
<name>looping</name>
<tag-class>org.customtags.MyTagHandlerForLoop</tag-class>
<body-content>scriptless</body-content>
<attribute>
<name>start</name>
<required>true</required>
</attribute>
<attribute>
<name>end</name>
<required>true</required>
</attribute>
</tag>
内部web.xml配置
<jsp-config>
<taglib>
<taglib-uri>mypredefinedtaglibrary</taglib-uri>
<taglib-location>/WEB-INF/tags/mytags.tld</taglib-location>
</taglib>
</jsp-config>
的O/P为反映:
My Name is Khan
My Name is Khan
My Name is Khan
My Name is Khan
My Name is Khan
当我在调试模式的第一运行,对象全部被创建, 那么setter是c/d,导致
start = 1
end = 5
if (start < end) {
start++;
return EVAL_BODY_AGAIN;
该循环过程执行4次。
那么,为什么我的名字是汗输出5次。不应该是4次。
注释掉'doAfterBody()'中的所有内容。现在打印多少次? 1,对吗?因为'doStartTag()'正在打印一次。至少这就是我所猜测的。 – developerwjk 2014-12-05 22:37:31