使Struts<select>标签的headerValue属性值支持嵌套jsp表达式实战

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难题：struts 的 select 标签的 headerValue 属性值不支持使用jsp表达式

org.apache.jasper.JasperException: /service/service_manager.jsp(42,7) According to TLD or attribute directive in tag file, attribute headerValue does not accept any expressions
	at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
	at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
	at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:148)
	at org.apache.jasper.compiler.Validator$ValidateVisitor.checkXmlAttributes(Validator.java:1172)
	at org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:819)
	at org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1507)
	at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2338)
	at org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2388)
	at org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2394)
	at org.apache.jasper.compiler.Node$Root.accept(Node.java:489)
	at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2338)
	at org.apache.jasper.compiler.Validator.validate(Validator.java:1737)
	at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:178)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:306)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:273)
	at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:566)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:316)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

解决方案：暴力修改jboss的jsp编译检验过程，使struts<s:select headerValue>支持jsp表达式<%=%>

实战过程：
到http://nchc.dl.sourceforge.net/project/jboss/JBoss/JBoss-4.2.3.GA/jboss-4.2.3.GA-src.tar.gz下载源码

主要的源文件是Japser的/Japser/src/org/apache/jasper/compiler/Validator.java

} else {
    // Attribute does not accept any expressions.
    // Make sure its value does not contain any.

    if (expression) {
        err.jspError(n, "jsp.error.attribute.custom.non_rt_with_expr",
            tldAttrs[j].getName());
    }
    jspAttrs[i] = new Node.JspAttribute(tldAttrs[j],
        attrs.getQName(i), attrs.getURI(i), attrs
        .getLocalName(i),
    attrs.getValue(i), false, null, false);
}

修改为：

} else {
    // Attribute does not accept any expressions.
    // Make sure its value does not contain any.

    if (expression) {
		String value = attrs.getValue(i);
            if("headerValue".equals(attrs.getQName(i))&&value.startsWith("<%=")&&value.endsWith("%>")){
            jspAttrs[i] = getJspAttribute(tldAttrs[j],
            attrs.getQName(i), attrs.getURI(i),                                
			attrs.getLocalName(i), attrs
            .getValue(i), String.class, n,
            false);
            found = true;
            break;
        }
        err.jspError(n, "jsp.error.attribute.custom.non_rt_with_expr",
            tldAttrs[j].getName());
    }
    jspAttrs[i] = new Node.JspAttribute(tldAttrs[j],
        attrs.getQName(i), attrs.getURI(i), attrs
        .getLocalName(i),
    attrs.getValue(i), false, null, false);
}

把Japser项目，编译后替换\server\default\deploy\jboss-web.deployer目录下jbossweb.jar文件即可