system.html

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.5.0_03) on Wed Nov 02 09:50:03 CST 2005 --><META http-equiv="Content-Type" content="text/html; charset=gb2312"><TITLE>System (Java 2 Platform SE 5.0)</TITLE><META NAME="keywords" CONTENT="java.lang.System class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){    parent.document.title="System (Java 2 Platform SE 5.0)";}</SCRIPT><NOSCRIPT></NOSCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="跳过导航链接"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY="">  <TR ALIGN="center" VALIGN="top">  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>概述</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>软件包</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> &nbsp;<FONT CLASS="NavBarFont1Rev"><B>类</B></FONT>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="class-use/System.html"><FONT CLASS="NavBarFont1"><B>使用</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>树</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>已过时</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../index-files/index-1.html"><FONT CLASS="NavBarFont1"><B>索引</B></FONT></A>&nbsp;</TD>  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>帮助</B></FONT></A>&nbsp;</TD>  </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM><b>Java<sup><font size=-2>TM</font></sup>&nbsp;2&nbsp;Platform<br>Standard&nbsp;Ed. 5.0</b></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">&nbsp;<A HREF="SuppressWarnings.html" title="java.lang 中的注释"><B>上一个类</B></A>&nbsp;&nbsp;<A HREF="Thread.html" title="java.lang 中的类"><B>下一个类</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">  <A HREF="../../index.html@java_2Flang_2FSystem.html" target="_top"><B>框架</B></A>  &nbsp;&nbsp;<A HREF="System.html" target="_top"><B>无框架</B></A>  &nbsp;&nbsp;<SCRIPT type="text/javascript">  <!--  if(window==top) {    document.writeln('<A HREF="../../allclasses-noframe.html"><B>所有类</B></A>');  }  //--></SCRIPT><NOSCRIPT>  <A HREF="../../allclasses-noframe.html"><B>所有类</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">  摘要:&nbsp;嵌套&nbsp;|&nbsp;<A HREF="#field_summary">字段</A>&nbsp;|&nbsp;构造方法&nbsp;|&nbsp;<A HREF="#method_summary">方法</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">详细信息:&nbsp;<A HREF="#field_detail">字段</A>&nbsp;|&nbsp;构造方法&nbsp;|&nbsp;<A HREF="#method_detail">方法</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">java.lang</FONT><BR>类 System</H2><PRE><A HREF="Object.html" title="java.lang 中的类">java.lang.Object</A>  <IMG SRC="../../resources/inherit.gif" ALT="继承者 "><B>java.lang.System</B></PRE><HR><DL><DT><PRE>public final class <B>System</B><DT>extends <A HREF="Object.html" title="java.lang 中的类">Object</A></DL></PRE><P><code>System</code> 类包含一些有用的类字段和方法。它不能被实例化。<p>在 <code>System</code> 类提供的设施中,有标准输入、标准输出和错误输出流;对外部定义的属性和环境变量的访问;加载文件和库的方法;还有快速复制数组的一部分的实用方法。<P><P><DL><DT><B>从以下版本开始:</B></DT>  <DD>JDK1.0</DD></DL><HR><P><!-- =========== FIELD SUMMARY =========== --><A NAME="field_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>字段摘要</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;java.io.PrintStream</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#err">err</A></B></CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&ldquo;标准&rdquo;错误输出流。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;java.io.InputStream</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#in">in</A></B></CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&ldquo;标准&rdquo;输入流。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;java.io.PrintStream</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#out">out</A></B></CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&ldquo;标准&rdquo;输出流。</TD></TR></TABLE>&nbsp;<!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>方法摘要</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;void</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#arraycopy(java.lang.Object, int, java.lang.Object, int, int)">arraycopy</A></B>(<A HREF="Object.html" title="java.lang 中的类">Object</A>&nbsp;src,          int&nbsp;srcPos,          <A HREF="Object.html" title="java.lang 中的类">Object</A>&nbsp;dest,          int&nbsp;destPos,          int&nbsp;length)</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;从指定源数组中复制一个数组,复制从指定的位置开始,到目标数组的指定位置结束。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;<A HREF="String.html" title="java.lang 中的类">String</A></CODE></FONT></TD><TD><CODE><B><A HREF="System.html#clearProperty(java.lang.String)">clearProperty</A></B>(<A HREF="String.html" title="java.lang 中的类">String</A>&nbsp;key)</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;移除指定键指示的系统属性。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;long</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#currentTimeMillis()">currentTimeMillis</A></B>()</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;返回以毫秒为单位的当前时间。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;void</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#exit(int)">exit</A></B>(int&nbsp;status)</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;终止当前正在运行的 Java 虚拟机。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;void</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#gc()">gc</A></B>()</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;运行垃圾回收器。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;<A HREF="../util/Map.html" title="java.util 中的接口">Map</A>&lt;<A HREF="String.html" title="java.lang 中的类">String</A>,<A HREF="String.html" title="java.lang 中的类">String</A>&gt;</CODE></FONT></TD><TD><CODE><B><A HREF="System.html#getenv()">getenv</A></B>()</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;返回一个不能修改的当前系统环境的字符串映射视图。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;<A HREF="String.html" title="java.lang 中的类">String</A></CODE></FONT></TD><TD><CODE><B><A HREF="System.html#getenv(java.lang.String)">getenv</A></B>(<A HREF="String.html" title="java.lang 中的类">String</A>&nbsp;name)</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;获得指定的环境变量值。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;<A HREF="../util/Properties.html" title="java.util 中的类">Properties</A></CODE></FONT></TD><TD><CODE><B><A HREF="System.html#getProperties()">getProperties</A></B>()</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;确定当前的系统属性。</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static&nbsp;<A HREF="String.html" title="java.lang 中的类">String</A></CODE></FONT></TD><TD><CODE><B><A HREF="System.html#getProperty(java.lang.String)">getProperty</A></B>(<A HREF="String.html" title="java.lang 中的类">String</A>&nbsp;key)</CODE><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;获得指定键指示的系统属性。</TD></TR>

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