解析 XHTML 时出错:元素的内容必须由格式正确的字符数据或标记组成 [英] Error parsing XHTML: The content of elements must consist of well-formed character data or markup

问题描述

作为这个问题的扩展，我正在尝试将 Javascript 插入 <h:commandButton/> 的 onclick 属性，因为 action 已经在呈现一个 ajax 表.

As an extension of this question, I'm trying to insert Javascript to a <h:commandButton />'s onclick property as action is already rendering an ajax table.

我想做什么:获取列表框中选定的项目并将它们转换为要在 JSF FileServlet 中使用的参数.即 para2=value1&param=value2&param=value3

What I want to do: Get the selected items in a list box and turn them into parameters to be used in a JSF FileServlet. i.e. para2=value1&param=value2&param=value3

这是我所拥有的:

<script type ="text/javascript">
function myScript() {
    var box = document.getElementbyId('myForm:box');
    var length = box.options.length;
    var paramstring = "";
    for (var i = 0; i < length; i++) {
        if (i != (length - 1) {
            if (box.options[i].selected) {
                paramstring = paramstring + "param=" + box.options[i].value + "&amp;";
            }
        } else {
            paramstring = paramstring + "param=" + box.options[i].value;
        }
    }
    if (document.getElementById('myForm:checkbox').checked) {
        window.location='fileServlet? + paramstring;
    }
}
</script>  

页面加载时我得到了什么:javax.servlet.ServletException: Error Parsing/page.xhtml: Error Traced[line:15] 元素的内容必须由格式正确的字符数据或标记组成.

What I get when page is loaded: javax.servlet.ServletException: Error Parsing /page.xhtml: Error Traced[line:15] The content of elements must consist of well-formed character data or markup.

什么不会触发异常:

<script type ="text/javascript">
function myScript() {
    var box = document.getElementbyId('myForm:box');
    var length = box.options.length;
    var paramstring = "";

    if (document.getElementById('myForm:checkbox').checked) {
        window.location='fileServlet? + paramstring;
    }
}
</script> 

只要我添加 for (var i = 0; i 甚至 for (var i = 0; i <10; i++) 页面无法加载.为什么它不喜欢 for 循环?

As soon as I add in for (var i = 0; i < length; i++) or even for (var i = 0; i < 10; i++) the page wouldn't load. Why does it not like the for loop?

推荐答案

Facelets 是一种基于 XML 的视图技术，它使用 XHTML+XML 生成 HTML 输出.XML 有五个特殊字符，它们被 XML 解析器特殊处理:

Facelets is a XML based view technology which uses XHTML+XML to generate HTML output. XML has five special characters which has special treatment by the XML parser:

• < 标签的开始.
• > 标签的结尾.
• " 属性值的开始和结束.
• ' 属性值的替代开始和结束.
• & 实体的开始(以 ; 结尾).

• < the start of a tag.
• > the end of a tag.
• " the start and end of an attribute value.
• ' the alternative start and end of an attribute value.
• & the start of an entity (which ends with ;).

在 < 的情况下，XML 解析器隐式地寻找标签名称和结束标签 >.但是，在您的特定情况下，您使用 < 作为 JavaScript 运算符，而不是作为 XML 实体.这完全解释了您遇到的 XML 解析错误:

In case of <, the XML parser is implicitly looking for the tag name and the end tag >. However, in your particular case, you were using < as a JavaScript operator, not as an XML entity. This totally explains the XML parsing error you got:

元素的内容必须由格式良好的字符数据或标记组成.

The content of elements must consist of well-formed character data or markup.

本质上，您在错误的地方编写了 JavaScript 代码，即 XML 文档而不是 JS 文件，因此您应该相应地转义所有 XML 特殊字符.< 必须转义为 <.

In essence, you're writing JavaScript code in the wrong place, a XML document instead of a JS file, so you should be escaping all XML special characters accordingly. The < must be escaped as <.

所以，本质上，

for (var i = 0; i < length; i++) {

必须成为

for (var i = 0; i < length; i++) {

使其对 XML 有效.

to make it XML-valid.

然而，这使得 JavaScript 代码更难阅读和维护.正如 Mozilla 开发者网络的优秀文档 Writing JavaScript for XHTML 所述，您应该将 JavaScript 代码放在字符数据 (CDATA) 块中.因此，在 JSF 术语中，这将是:

However, this makes the JavaScript code harder to read and maintain. As stated in Mozilla Developer Network's excellent document Writing JavaScript for XHTML, you should be placing the JavaScript code in a character data (CDATA) block. Thus, in JSF terms, that would be:

<h:outputScript>
    <![CDATA[
        // ...
    ]]>
</h:outputScript>

XML 解析器会将块的内容解释为普通的"；字符数据而不是 XML，因此将 XML 特殊字符按原样"解释.

The XML parser will interpret the block's contents as "plain vanilla" character data and not as XML and hence interpret the XML special characters "as-is".

但是，更好的是将 JS 代码放在它自己的 JS 文件中，该文件由 <script src> 包含，或者在 JSF 术语中，<h:outputScript>.

But, much better is to just put the JS code in its own JS file which you include by <script src>, or in JSF terms, the <h:outputScript>.

<h:outputScript name="functions.js" target="head" />

这样您就无需担心 JS 代码中的 XML 特殊字符.另一个好处是，这让浏览器有机会缓存​​ JS 文件，从而使平均响应大小更小.

This way you don't need to worry about XML-special characters in your JS code. Additional advantage is that this gives the browser the opportunity to cache the JS file so that average response size is smaller.

• 实体名称必须立即遵循&"在实体引用中
• 是否可以将 JSF+Facelets 与HTML 4/5?
• 如何在 Facelets 模板中引用 CSS/JS/图像资源?
• 为 XHTML 编写 JavaScript

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