XML文件要有根标签（Extra content at the end of the document in file 错误）

转自：http://bioinfo.ustc.edu.cn/seagven/?p=769

今天在使用php解析XML时出现错误：

DOMDocument::load() [domdocument.load]: Extra content at the end of the document in file *****

使用的xml文档如下

<?xml version="1.0" encoding="UTF-8"?>
  <SearchConstraints>
    <Begin>glucose</Begin>
    <End>Ethanol</End>
    <Interface>name</Interface>
    <IntermediatesInclude number="0"></IntermediatesInclude>
    <IntermediatesExclude> number="0"></IntermediatesExclude>
    <Organisms type="all"></Organisms>
    <KShort>10</KShort>
  </SearchConstraints>
  <StoPList>
    <StoP>
      <Source id="glucose"></Source>
      <Target id="Ethanol"></Target>
      <RouteList>
      </RouteList>
    </StoP>
  </StoPList>

问题所在： 没有加根标签呀！ XML文件只能有一个根标签！
把xml改成下面这样就ok了，也就是 加一个Document标签，将先前的两个根标签SearchConstraints和StoPList都放到Document标签的下面，从而整个XML文件只有一个根标签。

<?xml version="1.0" encoding="UTF-8"?>
<Document>
  <SearchConstraints>
    <Begin>glucose</Begin>
    <End>Ethanol</End>
    <Interface>name</Interface>
    <IntermediatesInclude number="0"></IntermediatesInclude>
    <IntermediatesExclude> number="0"></IntermediatesExclude>
    <Organisms type="all"></Organisms>
    <KShort>10</KShort>
  </SearchConstraints>
  <StoPList>
    <StoP>
      <Source id="glucose"></Source>
      <Target id="Ethanol"></Target>
      <RouteList>
      </RouteList>
    </StoP>
  </StoPList>
</Document>