jsp中sitemesh修改tagRule技术分享

sitemesh默认提供了一些常用的rule

可以看到其实可以选择

/**
* Extracts the contents of any elements that look like
* <code><content tag=\’foo\’>…</content></code> and write the contents
* to a page property (page.foo).
*
* <p>This is a cheap and cheerful mechanism for embedding multiple components in a
* page that can be used in different places in decorators.</p>
*
* @author Joe Walnes
*/
public class ContentBlockExtractingRule extends BasicBlockRule<String> {
private final ContentProperty propertyToExport;
public ContentBlockExtractingRule(ContentProperty propertyToExport) {
this.propertyToExport = propertyToExport;
}
@Override
protected String processStart(Tag tag) throws IOException {
tagProcessorContext.pushBuffer();
return tag.getAttributeValue(\”tag\”, false);
}
@Override
protected void processEnd(Tag tag, String tagId) throws IOException {
propertyToExport.getChild(tagId).setValue(tagProcessorContext.currentBufferContents());
tagProcessorContext.popBuffer();
}
}

修改ScriptTagRuleBundle处理如下

public class ScriptTagRuleBundle implements TagRuleBundle {
@Override
public void install(State defaultState, ContentProperty contentProperty, SiteMeshContext siteMeshContext) {
defaultState.addRule(\”content\”, new ContentBlockExtractingRule(contentProperty.getChild(\”page\”)));
}
@Override
public void cleanUp(State defaultState, ContentProperty contentProperty, SiteMeshContext siteMeshContext) {
}
}

用法很简单使用content作为tag默认填上tag即可

比如

<content tag=\”reference\”>
<script type=\”text/javascript\” src=\”<%=path%>/plugins/select2/js/select2.min.js\”></script>
<script type=\”text/javascript\” src=\”<%=path%>/plugins/select2/js/i18n/zh-CN.js\”></script>
<script type=\”text/javascript\” src=\”<%=path%>/plugins/bootstrap-modal/js/bootstrap-modal.js\”></script>
<script type=\”text/javascript\” src=\”<%=path%>/plugins/bootstrap-modal/js/bootstrap-modalmanager.js\”></script>
</content>

在模板中这样

这样就可以很简单的放入到任意位置！！！

弊端

这样虽然很简单但是也存在一些问题开发如果需要增加新的content必须要要到母版页【对的其实sitemesh不就像是asp.net中的母版页么】

增加对应的sitemesh:write标签

propertyToExport.getChild(tagId).setValue(tagProcessorContext.currentBufferContents());

并且上述代码中同样存在覆盖的问题比如多处使用了同样的tagId

解决

sitemesh似乎没有提供直接用来拼接多个的tagRule

如果有需求将某块元素放入到末尾可以考虑增加tagRule

在processEnd时直接将对应的元素直接append

最终可以直接输出