2012-03-19 13:45:15.0|分类: struts|浏览量: 1732
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1、<%@ taglib uri="/struts-layout-tags" prefix="layout"%>中struts-layout-tags类 <tag>
<name>yield</name>
<tag-class>com.fangdo.core.view.YieldTag</tag-class>
<body-content>JSP</body-content>
<description><![CDATA[Include a servlet's output (result of servlet or a JSP page)]]></description>
<attribute>
<name>id</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
<description><![CDATA[id for referencing element. For UI and form tags it will be used as HTML id attribute]]></description>
</attribute>
<attribute>
<name>value</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
<description><![CDATA[The jsp/servlet output to include]]></description>
</attribute>
</tag>
2、yieldTag类
继承ComponentTagSupport类是为了获得JSP页面中用户自定义的标签中设置的属性值，并包装成Component对象。
Component:
继承Component类是为了从Struts2中的ValueStack中获得相对应的值。 public class YieldTag extends ComponentTagSupport {
protected String value;
public Component getBean(ValueStack stack, HttpServletRequest req, HttpServletResponse res) {
return new Yield(stack, req, res);
}
//protected void populateParams()此方法是用来将JSP页面传来的属性值赋给基本类。这里是继承来的，所以首先调用super的相应方法。 protected void populateParams() {
super.populateParams();
((Yield) component).setValue(value);
}
public void setValue(String value) {
this.value = value;
}
}
3、Yield类 重写start，end等方法即可。 public class Yield extends Component {
private static boolean encodingDefined = true;
private static String encoding;
private static String defaultEncoding;
private String value;
private HttpServletRequest req;
private HttpServletResponse res;
public Yield(ValueStack stack,HttpServletRequest req,HttpServletResponse res){
super(stack);
this.req = req;
this.res = res;
}
@Inject(StrutsConstants.STRUTS_I18N_ENCODING)
public static void setDefaultEncoding(String encoding) {
defaultEncoding = encoding;
}
private static String getEncoding() {
if (encodingDefined) {
try {
encoding = defaultEncoding;
} catch (IllegalArgumentException e) {
encoding = System.getProperty("file.encoding");
encodingDefined = false;
}
}
return encoding;
}
@Override
public boolean end(Writer writer, String body) {
String name = StringUtils.isBlank(value) ? "content_for_layout" : "content_for_" + value;
FastByteArrayOutputStream content = (FastByteArrayOutputStream) req.getAttribute(name);
if(content !=null){
String encoding = getEncoding();
try{
if (encoding != null) {
content.writeTo(writer, encoding);
} else {
content.writeTo(writer,null);
}
} catch(IOException e) {
LogFactory.getLog(getClass()).warn("Exception thrown during ", e);
}
}
return super.end(writer, body);
}
public void setValue(String value) {
this.value = value;
}
}
4、jsp中 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="/struts-layout-tags" prefix="layout"%> <% String rootPath = request.getContextPath(); %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title><layout:yield value="title"/></title> <script type="text/javascript" src="<%= rootPath %>/js/jquery.js"></script> 。。。 <link rel="stylesheet" type="text/css" href="<%= rootPath %>/css/easyui/icon.css"/> <link rel="stylesheet" type="text/css" href="<%= rootPath %>/css/easyui/default/easyui.css"> <script type="text/javascript" src="<%= rootPath %>/js/jquery.easyui.min.js"></script> </head> <body class="easyui-layout"> <div region="north" border="false" style="height:60px;background:#B3DFDA;"> <jsp:include page="../layout/top.jsp"></jsp:include> </div> <div region="west" split="true" title="导航" style="width:200px;padding:10px;"> <jsp:include page="../user/_left_menu.jsp"></jsp:include> </div> <div region="south" border="false" style="height:50px;background:#A9FACD;padding:10px;">south region</div> <div region="center" title="Main Title"> <div id="page"> <jsp:include page="../web/_message.jsp"></jsp:include> <div class="workspace"> <layout:yield /> </div> </div>> </div> </body> </html>
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