Archive for 四月, 2009
struts2.0标签应用(2)–for循环的实现
Java代码
<s:bean name="org.apache.struts2.util.Counter" id="counter">
<s:param name="first" value="1" />
<s:param name="last" value="10" />
<s:iterator>
counter:<s:property value="current-1"/>
</s:iterator>
</s:bean>
其中first属性指定循环起始值，last指定循环终止值，其它相关属性可以查看org.apache.struts2.util.Counter类源码。在下面迭代器中输入循环的当前值，即：current-1
Counter类源码
/*
* $Id: Counter.java 471756 2006-11-06 15:01:43Z husted $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts2.util;
import java.io.Serializable;
/**
* A bean that can be used to keep track of a counter.
* <p/>
* Since it is an Iterator it can be used by the iterator tag
*
*/
public class Counter implements java.util.Iterator, Serializable {
private static final long serialVersionUID = 2796965884308060179L;
boolean wrap = false;
// Attributes —————————————————-
long first = 1;
long current = first;
long interval = 1;
long last = -1;
public void setAdd(long addition) {
current += addition;
}
public void setCurrent(long current) {
this.current = current;
}
public long getCurrent() {
return current;
}
public void setFirst(long first) {
this.first = first;
current = first;
}
public long getFirst() {
return first;
}
public void setInterval(long interval) {
this.interval = interval;
}
public long getInterval() {
return interval;
}
public void setLast(long last) {
this.last = last;
}
public long getLast() {
return last;
}
// Public ——————————————————–
public long getNext() {
long next = current;
current += interval;
if (wrap && (current > last)) {
current -= ((1 + last) - first);
}
return next;
}
public long getPrevious() {
current -= interval;
if (wrap && (current < first)) {
current += (last - first + 1);
}
return current;
}
public void setWrap(boolean wrap) {
this.wrap = wrap;
}
public boolean isWrap() {
return wrap;
}
public boolean hasNext() {
return ((last == -1) || wrap) ? true : (current <= last);
}
public Object next() {
return new Long(getNext());
}
public void remove() {
// Do nothing
}
}
struts2.0标签应用(1)
%{}用于计算表达式
如%{10+20}结果将输出30
如%{"a"+"b"}结果将输出"ab"
#通常强调从上下文取
如#parameters.name[0]等价于request.getParameter("name")
如#session.name等价于session.getAttribute("name")
如#request.name等价于request.getAttribute("name")
%{#}仍然用于计算表达式，只不过操作元可以是变量
如先定义一个变量
<s:set name="age" value="%{25}"/>
则%{#age}将输出25，也可以省略"#",写为%{age}
若将age加10，可这么写：
%{#age+10}，将输出30.不能省略"#"。也就说变量用于计算时不能省略"#"
