Struts标签库详解
Struts标签库详解
在JSP页面中,使用标记库代替传统的Java代码来实现页面的显示逻辑是大势所趋,然而,由于自定义标记很容易造成重复定义和非标准的实现,于是出现了基于Java Web的JSTL和基于struts的taglib等标签库来解决这些问题。
这些标签库在实现原理上相差无几,学会一种,另一种也就很容易上手,那咱们就从Struts的标签库走起。
常用的strust标签库有<bean:write>、<logic:empty>和<logic:notEmpty>、<logic:present>和<logic:notPresent>、<logic:iterator>4种。
使用方法:
1.在strus-config.xml中配置message-resources,注意,这个标签要放在action-mappings标签后面。配置信息如下:
<message-resources parameter="MessageResources" />
2.在src目录下引入提供国际化资源文件MessageResources.properties
3.在JSP页面中引入taglib
<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
4.下面是分别是<bean:wriete>(获取字段值、JavaBean属性值)、<logic:empty>和<logic:notEmpty>(判断是否为空)、<logic:present>和<logic:notPresent>(判断是否存在)、<logic:iterator>(迭代取出集合中的数据)分别在Action和JSP页面的配置
(1)<bean:wriete>-->action
public class BeanWriteAction extends Action {
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
// 普通字符串
request.setAttribute("hello", "quwenzhe");
request.setAttribute("today", new Date());
Group group = new Group();
group.setName("提高班");
User user = new User();
user.setUsername("quwenzhe");
user.setAge("24");
user.setGroup(group);
request.setAttribute("user", user);
return mapping.findForward("success");
}
}
<bean:wriete>-->JSP
姓名:<input type="text" name="username" value="<bean:write name="user" property="username"/>"><br/>
年龄:<input type="text" name="age" value=" <bean:write name="user" property="age"/>"><br>
所属组:<input type="text" name="group" value=" <bean:write name="user" property="group.name"/>"><br/>
(2)<logic:empty>和<logic:notEmpty>、<logic:present>和<logic:notPresent>-->action
public class EmptyPresentAction extends Action {
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
request.setAttribute("attr1", null);
request.setAttribute("attr2", "");
request.setAttribute("attr3", new ArrayList());
return mapping.findForward("success");
}
}
<logic:empty>和<logic:notEmpty>、<logic:present>和<logic:notPresent>-->JSP
<p>
<logic:empty name="attr1">
attr1为空
</logic:empty>
<logic:notEmpty name="attr1">
attr1为空
</logic:notEmpty>
<logic:present name="attr1">
attr1存在
</logic:present>
<logic:notPresent name="attr1">
attr1不存在
</logic:notPresent>
</p>
<p>
<logic:empty name="attr2">
attr2为空
</logic:empty>
<logic:notEmpty name="attr2">
attr2为空
</logic:notEmpty>
<logic:present name="attr2">
attr2存在
</logic:present>
<logic:notPresent name="attr2">
attr2不存在
</logic:notPresent>
</p>
<p>
<logic:empty name="attr3">
attr3为空
</logic:empty>
<logic:notEmpty name="attr3">
attr3为空
</logic:notEmpty>
<logic:present name="attr3">
attr3存在
</logic:present>
<logic:notPresent name="attr3">
attr3不存在
</logic:notPresent>
</p>
(3)<logic:iterator>-->action
public class IteratorAction extends Action {
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
Group group = new Group();
group.setName("提高班");
List userList = new ArrayList();
for (int i = 0; i < 10; i++) {
User user = new User();
user.setUsername("quwenzhe-->" + i);
user.setAge("24-->" + i);
user.setGroup(group);
userList.add(user);
}
request.setAttribute("userList", userList);
return mapping.findForward("success");
}
}
<logic:iterator>-->JSP
<table border="1">
<tr>
<td>姓名</td>
<td>年龄</td>
<td>所属组</td>
</tr>
<logic:empty name="userList">
<tr>
<td colspan="3">没有符合条件的数据</td>
</tr>
</logic:empty>
<logic:notEmpty name="userList">
<logic:iterate id="user" name="userList">
<tr>
<td>
<bean:write name="user" property="username"/>
</td>
<td>
<bean:write name="user" property="age"/>
</td>
<td>
<bean:write name="user" property="group.name"/>
</td>
</tr>
</logic:iterate>
</logic:notEmpty>
</table>
这样我们在后台Action中通过request设置的值,在JSP页面中通过标签就能很方便的获取到,大大提高工作效率。
struts2文件上传(保存为BLOB格式)
Struts2的入门实例
Struts2实现ModelDriven接口
遇到的Struts2文件下载乱码问题
Struts2整合Spring方法及原理
Struts2 注解模式的几个知识点
Struts 的详细介绍:请点这里
Struts 的下载地址:请点这里
本文永久更新链接地址:
评论暂时关闭