📄 exporttree.htm
字号:
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>Exporting the Preferences in a Subtree of Preference Nodes (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">
<META CONTENT="no-cache" HTTP-EQUIV="Pragma">
<LINK href="/almanac.css" media="screen" type="text/css" rel="stylesheet">
</HEAD>
<BODY>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD></TD>
</TR>
</TABLE>
<br>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD></TD>
</TR>
<TR>
<TD rowspan="3"><A HREF="/?l=ex"><IMG BORDER="0" ALIGN="BOTTOM" HSPACE="10" SRC="/egs/almanac14a.jpg"></A></TD><TD VALIGN="top">
<h1>The Java Developers Almanac 1.4</h1>
<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">
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD valign="top"><script type="text/javascript">
<!--
google_ad_client = "pub-6001183370374757";
google_ad_width = 120;
google_ad_height = 600;
google_ad_format = "120x600_as";
google_ad_channel = "4777242811";
google_ad_type = "text_image";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "6666CC";
google_color_url = "6666CC";
google_color_text = "000000";
//--></script><script src="http://pagead2.googlesyndication.com/pagead/show_ads.js" type="text/javascript"></script></TD><TD> </TD><TD valign="top">
<DIV ALIGN="LEFT">
<A HREF="/">Home</A>
>
<A HREF="../index.html">List of Packages</A>
>
<A HREF="../java.util.prefs/pkg.html">java.util.prefs</A><font color="#666666" class="xsmall-font">
[18 examples]
</font>
>
<B><A HREF="../java.util.prefs/pkg.html#Importing and Exporting">Importing and Exporting</A></B><font color="#666666" class="xsmall-font">
[3 examples]
</font>
</DIV><P>
<h3>e420. Exporting the Preferences in a Subtree of Preference Nodes</h3>
This example demonstrates how to export the preferences of nodes in a
subtree of preference nodes to a file. The export values can be
imported using <code>Preferences.importPreferences()</code> (see
<a href="../java.util.prefs/Import.html" class="eglink"><b>e418</b> Importing Preferences</a>). The format of the exported data
is XML.
<P> For every node in the exported subtree, the path of the node
and the preferences in that node are exported. When the data is later
imported, the preferences are added to nodes with exactly the same
paths.
<pre> // Retrieve the user preference node for the package java.lang
Preferences prefs = Preferences.userNodeForPackage(<font color="#0066ff"><i>String.class</i></font>);
// Save some values
prefs.put(<font color="#0066ff"><i>"myString"</i></font>, <font color="#0066ff"><i>"a string"</i></font>); // String
prefs.putBoolean(<font color="#0066ff"><i>"myBoolean"</i></font>, <font color="#0066ff"><i>true</i></font>); // boolean
prefs.putInt(<font color="#0066ff"><i>"myInt"</i></font>, <font color="#0066ff"><i>123</i></font>); // int
prefs.putLong(<font color="#0066ff"><i>"myLong"</i></font>, <font color="#0066ff"><i>123L</i></font>); // long
// Save some values in the parent node
prefs = prefs.parent();
prefs.putFloat(<font color="#0066ff"><i>"myFloat"</i></font>, <font color="#0066ff"><i>12.3F</i></font>); // float
prefs.putDouble(<font color="#0066ff"><i>"myDouble"</i></font>, <font color="#0066ff"><i>12.3</i></font>); // double
byte[] bytes = new byte[<font color="#0066ff"><i>10</i></font>];
prefs.putByteArray(<font color="#0066ff"><i>"myByteArray"</i></font>, <font color="#0066ff"><i>bytes</i></font>); // byte[]
try {
prefs.exportSubtree(new FileOutputStream(<font color="#0066ff"><i>"output.xml"</i></font>));
} catch (IOException e) {
} catch (BackingStoreException e) {
}
</pre>
The code above generates the following XML data:
<pre> <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE preferences SYSTEM 'http://java.sun.com/dtd/preferences.dtd'>
<preferences EXTERNAL_XML_VERSION="1.0">
<root type="user">
<map />
<node name="java">
<map>
<entry key="myFloat" value="12.3" />
<entry key="myDouble" value="12.3" />
<entry key="myByteArray" value="AAAAAAAAAAAAAA==" />
</map>
<node name="lang">
<map>
<entry key="myString" value="a string" />
<entry key="myBoolean" value="true" />
<entry key="myInt" value="123" />
<entry key="myLong" value="123" />
</map>
</node>
</node>
</root>
</preferences>
</pre>
<P><table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td bgcolor="#6666cc" align="center"><font color="#ffffff">
<b>Related Examples</b></font></td>
</tr>
</table>
e418. <a class="eglink" href="Import.html?l=rel">
Importing Preferences
</a>
<br>
e419. <a class="eglink" href="Export.html?l=rel">
Exporting the Preferences in a Preference Node
</a>
<br>
<table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td align="left">
<br>
See also:
<a class="eglink" href="/egs/java.util.prefs/pkg.html?l=rel#Events">
Events
</a>
<a class="eglink" href="/egs/java.util.prefs/pkg.html?l=rel#Nodes">
Nodes
</a>
</td>
</tr>
</table>
<br>
<br>
<FONT class="xsmall-font">
© 2002 Addison-Wesley.
</FONT></TD><TD> </TD><TD valign="top"><A href="http://compositesw.com/devzone?ref=javaalmanac"><IMG alt="Click Here" height="600" width="120" border="0" src="/csw_oad_120x600_final.gif"></A></TD>
</TR>
</TABLE>
</BODY>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<META CONTENT="NO-CACHE" HTTP-EQUIV="PRAGMA">
</HEAD>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -