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精通struts技术第二章(4)

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<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">标准<span lang=EN-US>Actions<o:p></o:p></FONT></B></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">JSP<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">标准<span lang=EN-US>Actions是预先定义的标签。这标签很容易用来封装action。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">在<span lang=EN-US>JSP中有两种类型的标准action。第一种:JavaBean,第二种:由另外的标准action组成。<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">JavaBeans有三种相应的标签设置:<useBean>, <setProperty>和<getProperty>.。<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">在定义三个标签后,我们会创建一个例子:<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><jsp:useBean><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><span style="mso-spacerun: yes"> <jsp:useBean>是 JavaBean的标准行为。它通过ID号和范围来实例化一个JavaBean 。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.4对<jsp:useBean>的属性进行说明,表2.5定义了行为的范围。<jsp:useBean>行为非常灵活如果执行到<useBean>,将去寻找是否存在相同ID和scope,如果实例不存在,它会创建一个,把命名空间和ID号关联并存储起来。语法如下:<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><jsp:useBean id="name"<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">scope="page|request|session|application" tpeSpec><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">body<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"></jsp:useBean><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">typeSpec ::=class="className" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">class="className" type="typeName" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">type="typeName" class="className" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">beanName="beanName" type="typeName" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">type="typeName" beanName="beanName" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">type="typeName"<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.4<jsp:useBean>属性:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">属性<span lang=EN-US><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">定义<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">id<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">这个键关联指定范围的实例化对象。这个键大小写敏感。这个<span lang=EN-US>id属性的键和page.getAttribute方法取得的是一样。<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">Scope<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">对象的生命周期。范围选项<span lang=EN-US>page, request, session, and application.在表2.5中定义。<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US> 2.5: <jsp:useBean>的范围值:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">值<span lang=EN-US><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">定义<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">page<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">只能在被创建的页面中使用。当前页面完成工作时,引用的对象会被释放掉。<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">request<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">只为同一个请求服务。只在请求中实例化,也包括转向请求。所有引用的对象在请求完成时被释放。<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">session<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">只处理有相同<span lang=EN-US>session的请求,引用的对象也是在session中创建的。当session终止时引用对象被释放。<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">Application<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">在相同的<span lang=EN-US>WEB应用中被使用。当JSP/Servlet容器关闭,引用对象被释放。<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><jsp:setProperty><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">用于设置<span lang=EN-US>bean属性的值。它要设置的属性所在的对象必须已经存在。<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><jsp:setProperty>语法如下:<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:setProperty name="beanName" propexpr /><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">name属性时bean的实例化名称。<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">property="*" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">property="propertyName" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">property="propertyName" param="parameterName" |<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">property="propertyName" value="propertyValue"<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.6<jsp:setProperty>的属性列表:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">属性<span lang=EN-US><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">说明<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">name<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">是通过<span lang=EN-US><jsp:useBean>实例化的bean<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">property<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">设置一个属性的值。如果你对<span lang=EN-US>propertyName设置“*“,会取出ServletRequest中所有的参数集合。匹配参数名值类型属性名和设置方法类型。并设置每一个匹配的属性的值。如果参数值为空,相关的属性是左未更改的。.<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">param<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">你要设置值的属性名称。<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">value<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">对<span lang=EN-US>bean的属性赋值<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">.<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><jsp:getProperty><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">用来获取实例化的<span lang=EN-US>bean的属性值,转换成java.lang.String类型并产生输出。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">在使用前<span lang=EN-US>bean必须被实例化。语法如下:<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:getProperty name="name" property="propertyName" /><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.7介绍了<jsp:getProperty>的属性:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">属性<span lang=EN-US><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">说明<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">name<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">获取实例化的<span lang=EN-US>bean的名称,在<jsp:useBean>中定义<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">Property<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">从实例化的<span lang=EN-US>bean中获取值的属性的名称<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">一个<span lang=EN-US>JavaBean例子<o:p></o:p></FONT></B></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">为了学习如何使用<span lang=EN-US>JavaBean,让我们创建一个例子。这个例子实现一个简单的计数器JavaBean。这个计数器有简单的int类型的count属性。它用来统计当前bean属性被访问的次数。另外它也包含了相应的设置获取属性的方法。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.11为Counter bean代码:Counter.java.<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">----------------------------------------------------------------<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">package chapter2;<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">public class Counter {<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">int count = 0;<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt">39<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">public Counter() {<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">}<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">public int getCount() {<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">count ;<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">return count;<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">}<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">public void setCount(int count) {<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">this.count = count;<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">}<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">}<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">----------------------------------------------------------<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">让我们来看访问<span lang=EN-US>JavaBean的JSP页面:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">列表<span lang=EN-US> 2.12<span style="mso-spacerun: yes">  counter.jsp.<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">-------------------------------------------------------------<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- Set the scripting language to java --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><%@ page language="java" %><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><HTML><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><HEAD><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><TITLE>Bean Example</TITLE><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"></HEAD><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><BODY><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- Instantiate the Counter bean with an id of "counter" --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:useBean id="counter" scope="session"<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">class="chapter2.Counter" /><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><%<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">// write the current value of the property count<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">out.println("Count from scriptlet code : "<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"> counter.getCount() "<BR>");<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">%><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- Get the the bean’s count property, --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- using the jsp:getProperty action. --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">Count from jsp:getProperty :<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:getProperty name="counter" property="count" /><BR><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"></BODY><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"></HTML><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">----------------------------------------------------------------------------------------------<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">Counter.jsp有四个JSP组件。第一个:告诉JSP容器脚本语言为:java<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><%@ page language="java" %><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-font-kerning: 0pt">第二步:用<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><jsp:useBean>实例化一个Counter对象,id为counter,范围为session。<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">现在我们可以在<span lang=EN-US>JSP中引用名称为counter的实例。下面的代码实例化<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">Counter:<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:useBean id="counter" scope="session" class="chapter2.Counter" /><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">有两个种方法指明如何获取当前<span lang=EN-US>bean属性的值。第一种是在JSP脚本中使用一个方法访问bean属性。它是通过访问bean的ID并调用getCount()得到的。脚本代码如下:<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><%<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">// write the current value of the property count<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">out.println("Count from scriptlet code : "<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"> counter.getCount() "<BR>");<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt">%><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">第二种是通过<span lang=EN-US><jsp:getProperty>取得当前bean属性的值。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">访问对应的属性,绑定它的属性值并输出到<span lang=EN-US>HTML中。<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- Get the bean’s count property, --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><!-- using the jsp:getProperty action. --><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt">Count from jsp:getProperty :<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:getProperty name="counter" property="count" /><BR><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">当你运行<span lang=EN-US>Counter.jsp,你会发现下一次的结果值大于前一次的。这是因为每次访问count属性都会调用getCount()方法,所以每次count的值都会增加。<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">编译<span lang=EN-US>Counter.java,把类文件复制到:<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><<i>CATALINA_HOME</i>>/wileyapp/WEB-INF/classes/chapter2/目录下,复制Counter.jsp到<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><<i>CATALINA_HOME</i>>/wileyapp/ 目录。在浏览器中输入地址:<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><span style="COLOR: windowtext; TEXT-DECORATION: none; text-underline: none">http://localhost:8080/wileyapp/counter.jsp<o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-bidi-font-family: Arial; mso-font-kerning: 0pt"><jsp:param><o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">提供参数和值。<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><jsp:include>,<o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><jsp:forward>, and <jsp:plugin><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 9.0pt; mso-font-kerning: 0pt"><jsp:param name="name" value="value"/><o:p></o:p></FONT>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt"><o:p> </FONT></o:p>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">表<span lang=EN-US>2.8说明了<jsp:param>的属性:<o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">属性<span lang=EN-US><o:p></o:p></FONT></P>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">说明<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">name<o:p></o:p></FONT>

<span style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">引用的参数名称<span lang=EN-US><o:p></o:p></FONT></P>

<span lang=EN-US style="FONT-FAMILY: 宋体; mso-bidi-font-size: 11.0pt; mso-font-kerning: 0pt">
</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

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