tij0185.html

学习java的经典书籍

      <font color="#0000ff">for</font>(<font color="#0000ff">int</font> i = 0; i &lt; v.size(); i++) {
        SourceCodeFile f = 
          (SourceCodeFile)v.elementAt(i);
        f.writePacked(packed);
      }
    }
    IO.close(packed);
  }
  <font color="#009900">// Write all the files in their directories:</font>
  <font color="#0000ff">public</font> <font color="#0000ff">void</font> write() {
    Enumeration e = t.keys();
    <font color="#0000ff">while</font>(e.hasMoreElements()) {
      String dir = (String)e.nextElement();
      Vector v = (Vector)t.get(dir);
      <font color="#0000ff">for</font>(<font color="#0000ff">int</font> i = 0; i &lt; v.size(); i++) {
        SourceCodeFile f = 
          (SourceCodeFile)v.elementAt(i);
        f.writeFile(rootpath);
      }
      <font color="#009900">// Add file indicating file quantity</font>
      <font color="#009900">// written to this directory as a check:</font>
      IO.close(IO.dosOpen(
        <font color="#0000ff">new</font> File(<font color="#0000ff">new</font> File(rootpath, dir),
          Integer.toString(v.size())+".files")));
    }
  }
}

<font color="#0000ff">public</font> <font color="#0000ff">class</font> CodePackager {
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> <font color="#0000ff">final</font> String usageString =
  "usage: java CodePackager packedFileName" +
  "\nExtracts source code files from packed \n" +
  "version of Tjava.doc sources into " +
  "directories off current directory\n" +
  "java CodePackager packedFileName newDir\n" +
  "Extracts into directories off newDir\n" +
  "java CodePackager -p source.txt packedFile" +
  "\nCreates packed version of source files" +
  "\nfrom text version of Tjava.doc";
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> usage() {
    System.err.println(usageString);
    System.exit(1);
  }
  <font color="#0000ff">public</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> main(String[] args) {
    <font color="#0000ff">if</font>(args.length == 0) usage();
    <font color="#0000ff">if</font>(args[0].equals("-p")) {
      <font color="#0000ff">if</font>(args.length != 3)
        usage();
      createPackedFile(args);
    }
    <font color="#0000ff">else</font> {
      <font color="#0000ff">if</font>(args.length &gt; 2)
        usage();
      extractPackedFile(args);
    }
  }
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> String currentLine; 
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> BufferedReader in;
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> DirMap dm;
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> 
  createPackedFile(String[] args) {
    dm = <font color="#0000ff">new</font> DirMap();
    in = IO.disOpen(args[1]);
    <font color="#0000ff">try</font> {
      <font color="#0000ff">while</font>((currentLine = in.readLine()) 
          != <font color="#0000ff">null</font>) {
        <font color="#0000ff">if</font>(currentLine.startsWith(
            SourceCodeFile.startMarker)) {
          dm.add(<font color="#0000ff">new</font> SourceCodeFile(
                   currentLine, in));
        }
        <font color="#0000ff">else</font> <font color="#0000ff">if</font>(currentLine.startsWith(
            SourceCodeFile.endMarker))
          Pr.error("file has no start marker");
        <font color="#009900">// Else ignore the input line</font>
      }
    } <font color="#0000ff">catch</font>(IOException e) {
      Pr.error("Error reading " + args[1]);
    }
    IO.close(in);
    dm.writePackedFile(args[2]);
  }
  <font color="#0000ff">private</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> 
  extractPackedFile(String[] args) {
    <font color="#0000ff">if</font>(args.length == 2) <font color="#009900">// Alternate directory</font>
      dm = <font color="#0000ff">new</font> DirMap(args[1]);
    <font color="#0000ff">else</font> <font color="#009900">// Current directory</font>
      dm = <font color="#0000ff">new</font> DirMap();
    in = IO.disOpen(args[0]);
    String s = <font color="#0000ff">null</font>;
    <font color="#0000ff">try</font> {
       s = in.readLine();
    } <font color="#0000ff">catch</font>(IOException e) {
      Pr.error("Cannot read from " + in);
    }
    <font color="#009900">// Capture the separator used in the system</font>
    <font color="#009900">// that packed the file:</font>
    <font color="#0000ff">if</font>(s.indexOf("###Old Separator:") != -1 ) {
      String oldsep = s.substring(
        "###Old Separator:".length());
      oldsep = oldsep.substring(
        0, oldsep. indexOf('#'));
      SourceCodeFile.oldsep = oldsep;
    }
    SourceCodeFile sf = <font color="#0000ff">new</font> SourceCodeFile(in);
    <font color="#0000ff">while</font>(sf.hasFile()) {
      dm.add(sf);
      sf = <font color="#0000ff">new</font> SourceCodeFile(in);
    }
    dm.write();
  }
} <font color="#009900">///:~ </PRE></font></font><DIV ALIGN=LEFT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">You&#8217;ll
first notice the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>package</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
statement that is commented out. Since this is the first program in the
chapter, the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>package
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">statement
is necessary to tell 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>CodePackager
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">that
the chapter has changed, but putting it in a package would be a problem. When
you create a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>package</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
you tie the resulting program to a particular directory structure, which is
fine for most of the examples in this book. Here, however, the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>CodePackager</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
program must be compiled and run from an arbitrary directory, so the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>package</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
statement is commented out. It will still 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><I>look</I></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
like an ordinary 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>package</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
statement to 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>CodePackager</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
though, since the program isn&#8217;t sophisticated enough to detect multi-line
comments. (It has no need for such sophistication, a fact that comes in handy
here.)
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
first two classes are support/utility classes designed to make the rest of the
program more consistent to write and easier to read. The first, 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Pr</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
is similar to the ANSI C library 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>perror</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
since it prints an error message (but also exits the program). The second class
encapsulates the creation of files, a process that was shown in Chapter 10 as
one that rapidly becomes verbose and annoying. In Chapter 10, the proposed
solution created new classes, but here 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>static
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">method
calls are used. Within those methods the appropriate exceptions are caught and
dealt with. These methods make the rest of the code much cleaner to read.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
first class that helps solve the problem is 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>SourceCodeFile</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
which represents all the information (including the contents, file name, and
directory) for one source code file in the book. It also contains a set of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>String</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
constants representing the markers that start and end a file, a marker used
inside the packed file, the current system&#8217;s end-of-line separator and
file path separator (notice the use of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>System.getProperty(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to get the local version), and a copyright notice, which is extracted from the
following file 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Copyright.txt</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//////////////////////////////////////////////////</font>
<font color="#009900">// Copyright (c) Bruce Eckel, 1998</font>
<font color="#009900">// Source code file from the book "Thinking in Java"</font>
<font color="#009900">// All rights reserved EXCEPT as allowed by the</font>
<font color="#009900">// following statements: You may freely use this file</font>
<font color="#009900">// for your own work (personal or commercial),</font>
<font color="#009900">// including modifications and distribution in</font>
<font color="#009900">// executable form only. Permission is granted to use</font>
<font color="#009900">// this file in classroom situations, including its</font>
<font color="#009900">// use in presentation materials, as long as the book</font>
<font color="#009900">// "Thinking in Java" is cited as the source. </font>
<font color="#009900">// Except in classroom situations, you may not copy</font>
<font color="#009900">// and distribute this code; instead, the sole</font>
<font color="#009900">// distribution point is http://www.BruceEckel.com </font>
<font color="#009900">// (and official mirror sites) where it is</font>
<font color="#009900">// freely available. You may not remove this</font>
<font color="#009900">// copyright and notice. You may not distribute</font>
<font color="#009900">// modified versions of the source code in this</font>
<font color="#009900">// package. You may not use this file in printed</font>
<font color="#009900">// media without the express permission of the</font>
<font color="#009900">// author. Bruce Eckel makes no representation about</font>
<font color="#009900">// the suitability of this software for any purpose.</font>
<font color="#009900">// It is provided "as is" without express or implied</font>
<font color="#009900">// warranty of any kind, including any implied</font>
<font color="#009900">// warranty of merchantability, fitness for a</font>
<font color="#009900">// particular purpose or non-infringement. The entire</font>
<font color="#009900">// risk as to the quality and performance of the</font>
<font color="#009900">// software is with you. Bruce Eckel and the</font>
<font color="#009900">// publisher shall not be liable for any damages</font>
<font color="#009900">// suffered by you or any third party as a result of</font>
<font color="#009900">// using or distributing software. In no event will</font>
<font color="#009900">// Bruce Eckel or the publisher be liable for any</font>
<font color="#009900">// lost revenue, profit, or data, or for direct,</font>
<font color="#009900">// indirect, special, consequential, incidental, or</font>
<font color="#009900">// punitive damages, however caused and regardless of</font>
<font color="#009900">// the theory of liability, arising out of the use of</font>
<font color="#009900">// or inability to use software, even if Bruce Eckel</font>
<font color="#009900">// and the publisher have been advised of the</font>
<font color="#009900">// possibility of such damages. Should the software</font>