resolveext.html

来自「java类库详细讲解」· HTML 代码 · 共 154 行

HTML
154 行
字号 
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>Intercepting All Accesses to External Entities During XML SAX Parsing
(Java Developers Almanac Example)
</TITLE>
<META CONTENT="Patrick Chan" NAME="AUTHOR">
<META CONTENT="Code Examples from The Java Developers Almanac 1.4" NAME="DESCRIPTION">
<META CONTENT="Addison-Wesley/Patrick Chan" NAME="OWNER">
<META CONTENT="3/20/02" NAME="revision">
<STYLE TYPE="text/css">
<!--     BODY CODE  {font-family: Courier, Monospace;           font-size: 11pt}    TABLE, BODY          {font-family: Verdana, Arial, Helvetica, sans-serif;           font-size: 10pt}    PRE   {font-family: Courier, Monospace;           font-size: 10pt}    H3    {font-family: Verdana, Arial, Helvetica, sans-serif;           font-size: 11pt}    A.eglink {text-decoration: none}    A:hover.eglink {text-decoration: underline}    -->
</STYLE>
</HEAD>
<BODY>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD rowspan="3"><A HREF="/?l=ex"><IMG BORDER="0" ALIGN="BOTTOM" HSPACE="10" SRC="/egs/almanac14a.jpg"></A></TD><TD VALIGN="top"><font face="Times" size="6"><b>The Java Developers Almanac 1.4</b></font>
<br>
        Order this book from <a href="/cgi-bin/scripts/redirect.pl?l=ex&url=http://www.amazon.com/exec/obidos/ASIN/0201752808/xeo">Amazon</a>.
    </TD>
</TR>
<TR>
<TD align="right" valign="bottom">
<FORM method="get" action="/cgi-bin/search/find.pl">
<INPUT size="25" name="words" type="text"><INPUT value="Search" type="submit">
</FORM>
</TD>
</TR>
</TABLE>
<HR color="#6666cc">
<DIV ALIGN="LEFT">
<A HREF="/">Home</A>
    &gt;
    <A HREF="../index.html">List of Packages</A>
    &gt;
    <B><A HREF="../org.xml.sax/pkg.html">org.xml.sax</A></B><font color="#666666" SIZE="-2">
        &nbsp;[3 examples]
        </font>
</DIV><P>
  <h3>
    e553.  
    Intercepting All Accesses to External Entities During XML SAX Parsing</h3>

This capability is useful in situations where the public or system id
in an XML file do not refer to actual resources and must be
redirected.  An <code>EntityResolver</code> object must be installed on the parser
in order to intercept the accesses. If a mapping is made, the entity
resolver must return an <code>InputSource</code> object to the resource.


<pre>
    try {
        // Create an XML parser
        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    
        // Install the entity resolver
        builder.setEntityResolver(new MyResolver());
    
        // Parse the XML file
        Document doc = builder.parse(new File(<font color="#0066ff"><i>"infilename.xml"</i></font>));
    } catch (SAXException e) {
        // A parsing error occurred; the xml input is not valid
    } catch (ParserConfigurationException e) {
    } catch (IOException e) {
    }
    
    public class MyResolver implements EntityResolver {
        // This method is called whenever an external entity is accessed
        // for the first time.
        public InputSource resolveEntity (String publicId, String systemId) {
            try {
                // Wrap the systemId in a URI object to make it convenient
                // to extract the components of the systemId
                URI uri = new URI(systemId);
    
                // Check if external source is a file
                if ("file".equals(uri.getScheme())) {
                    String filename = uri.getSchemeSpecificPart();
                    return new InputSource(new FileReader(filename));
                }
            } catch (URISyntaxException e) {
            } catch (IOException e) {
            }
    
            // Returning null causes the caller to try accessing the systemid
            return null;
        }
    }
</pre>
This is the sample input for the example:

<pre>
    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
    &lt;!DOCTYPE root SYSTEM "System.dtd" [
        &lt;!ENTITY entity1 SYSTEM "External.xml"&gt;
        &lt;!ENTITY entity2 SYSTEM "http://hostname.com/my.dtd"&gt;
        &lt;!ENTITY % entity3 SYSTEM "More.dtd"&gt;
        %entity3;
    ]&gt;
    &lt;root&gt;
        &amp;entity1;
        &amp;entity2;
    &lt;/root&gt;
</pre>
The resulting system ids passed into <code>MyResolve.resolveEntity()</code> are:

<pre>
    file:d:/almanac/1.4/egs/org.xml.sax/More.dtd
    file:d:/almanac/1.4/egs/org.xml.sax/Systemid.dtd
    file:d:/almanac/1.4/egs/org.xml.sax/External.dtd
    http://hostname.com/my.dtd
</pre>
<P><table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td bgcolor="#6666cc" align="center"><font color="#ffffff">
            &nbsp;Related Examples
        </font></td>
</tr>
</table>


e554. <a class="eglink" href="GetAttr.html?l=rel">
    Getting the Attributes of an Element During XML SAX Parsing
</a>
<br>

e555. <a class="eglink" href="SetLocator.html?l=rel">
    Determining the Parsing Location of an XML SAX Parser
</a>
<br>


<br>

<br>
<FONT FACE="Verdana, Arial, Helvetica, sans-serif" SIZE="0">
&copy; 2002 Addison-Wesley.
</FONT>
</BODY>
</HTML>

resolveext.html - 源码说明

本页面展示了「java类库详细讲解」中的 resolveext.html 源码文件，采用 HTML 编程语言编写，共 154 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

虫虫下载站收录了大量与java相关的技术资源，包括源代码、技术文档、电路图等，是电子工程师和嵌入式开发者的专业学习平台。

⌨️ 快捷键说明

复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?