ch8.htm

汤子瀛《操作系统》电子教案

      </span>/</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">写位置</span></font></p>
      <p><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><font color="#FFFFFF"><o:p>
      </o:p>
      </font></span></td>
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    <p style="TEXT-ALIGN: center" align="center"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><font color="#FFFFFF"><a name="ch82"></a>8．2<span style="mso-spacerun: yes">&nbsp; 
    </span>文件的逻辑结构<o:p>
    </o:p>
    </font></span></p>
    <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">文件的逻辑结构：又称文件组织</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">文件的物理结构：又称文件的存储结构</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">对文件的逻辑结构的要求：提高检索效率、便于修改、降低文件存储费用</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p style="MARGIN-LEFT: 18pt; TEXT-INDENT: -18pt; tab-stops: list 18.0pt; mso-list: l7 level1 lfo25"><font color="#FFFFFF"><span lang="EN-US" style="mso-fareast-font-family: 黑体">1．</span><span style="mso-ascii-font-family: Times New Roman">文件逻辑结构的类型：</span><span lang="EN-US" style="mso-fareast-font-family: 黑体"><o:p>
    </o:p>
    </span></font></p>
    <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
    </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴有结构文件（记录式文件）</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp;&nbsp; 
    </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">定长记录、变长记录</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p style="MARGIN-LEFT: 36pt; TEXT-INDENT: -12pt; tab-stops: list 36.0pt; mso-list: l19 level1 lfo26"><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">①<span style="font-style: normal; font-variant: normal; font-weight: normal"> 
    </span></span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">顺序文件</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p style="MARGIN-LEFT: 36pt; TEXT-INDENT: -12pt; tab-stops: list 36.0pt; mso-list: l19 level1 lfo26"><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">②<span style="font-style: normal; font-variant: normal; font-weight: normal"> 
    </span></span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">索引文件</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p style="MARGIN-LEFT: 36pt; TEXT-INDENT: -12pt; tab-stops: list 36.0pt; mso-list: l19 level1 lfo26"><font color="#FFFFFF"><span lang="EN-US" style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">③</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">索引顺序文件</span></font></p>
    <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
    </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵无结构文件（流式文件）</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
    </o:p>
    </span></font></p>
    <p style="MARGIN-LEFT: 18pt; TEXT-INDENT: -18pt; tab-stops: list 18.0pt; mso-list: l7 level1 lfo25"><font color="#FFFFFF"><span lang="EN-US">2．</span>顺序文件<span lang="EN-US"><o:p>
    </o:p>
    </span></font></p>
    <p><span style="mso-bidi-font-size: 10.0pt; mso-hansi-font-family: Times New Roman"><font color="#FFFFFF">（<span lang="EN-US">1）逻辑记录的排序——串结构、顺序结构<o:p>
    </o:p>
    </span></font></span></p>
    <p><span style="mso-bidi-font-size: 10.0pt; mso-hansi-font-family: Times New Roman"><font color="#FFFFFF">（<span lang="EN-US">2）对顺序文件的读或写操作<o:p>
    </o:p>
    </span></font></span></p>
    <p><span style="mso-bidi-font-size: 10.0pt; mso-hansi-font-family: Times New Roman"><font color="#FFFFFF">（<span lang="EN-US">3）顺序文件的优缺点<o:p>
    </o:p>
    </span></font></span></p>
    <p><span lang="EN-US"><font color="#FFFFFF">3．索引文件<o:p>
    </o:p>
    </font></span></p>
    <p><span lang="EN-US"><font color="#FFFFFF">4．索引顺序文件</font></span></p>
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      <p style="TEXT-ALIGN: center" align="center"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><font color="#FFFFFF"><a name="ch83"></a>8．3<span style="mso-spacerun: yes">&nbsp; 
      </span>目录管理<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">对目录管理的要求：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">实现按名存取；提高对目录的检索速度；文件的共享；允许文件重名。</span></font></p>
      <p style="MARGIN-LEFT: 18pt; TEXT-INDENT: -18pt; tab-stops: list 18.0pt; mso-list: l27 level1 lfo27"><font color="#FFFFFF"><span lang="EN-US" style="mso-fareast-font-family: 黑体">1．</span><span style="mso-ascii-font-family: Times New Roman">文件控制块和索引结点</span><span lang="EN-US" style="mso-fareast-font-family: 黑体"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴文件控制块（</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">FCB</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">基本信息类；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">存取控制信息类；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">使用信息类；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵索引结点</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">索引结点的引入；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">磁盘索引结点；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 24pt"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font color="#FFFFFF">内存索引结点；</font></span></p>
      <p><span lang="EN-US"><font color="#FFFFFF">2．单级目录结构<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">缺点：查找速度慢；不允许重名；不便于实现共享。</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><span lang="EN-US"><font color="#FFFFFF">3．两级目录结构<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">优点：提高了检索目录的速度；在不同的用户目录中，可以使用相同的文件名；不同用</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">户可以通过不同文件名，来访问系统中的同一个共享文件。</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><span lang="EN-US"><font color="#FFFFFF">4．树型目录结构<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">树型目录</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">路径名</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp;