📄 j-javalibrary-2-4.shtml
字号:
<html><!--This panel generated from the developerWorks XML tag set for tutorials, Version 1.8.9. (C) Copyright 2000 IBM Corporation. All rights reserved.--><head><title>Introduction to libraries</title><style type="text/css"><!-- body { color: #000000; background-color: #ffffff; } dt { font-weight: bold; } code { font-family: Courier, monospace; font-size: +2; } titleCode { font-family: Courier, monospace; font-size: +4; } ol.alpha { list-style-type: upper-alpha; } span.center { text-align: center; } span.right { text-align: right; } span.constant { color: #990099; } span.keyword { color: #993333; } span.function-name { color: #666633; } span.comment { color: #666666; } span.string { color: #0000ff; } span.variable-name { color: #000066; } span.type { color: #006600; } span.spacer { font-size: 1pt; } --></style><meta http-equiv="content-Type" content="text/html; charset=gb2312"></head><body bgcolor="ffffff"><script language="javascript"><!--var emailAbstract="This tutorial reviews how the Java language can help you make a good, reusable library. It covers the key principles of good library design and the most efficient ways to implement each of these ideas in the Java language.";var justTitle="Build your own Java library";var tutorialPrereqs="http://www-4.ibm.com/software/developer/education/r-jlib.shtml";var menu1blurb="Tutorial tips"; var menu2blurb="Introduction to libraries"; var menu3blurb="Design issue: Encapsulation"; var menu4blurb="Design issue: Extensibility"; var menu5blurb="Design issue: Debugging information"; var menu6blurb="The source code"; var menu7blurb="Wrapup"; var browser = "x"; if (navigator.userAgent.indexOf("Mozilla/4") != -1) browser = "N3"; else if (navigator.userAgent.indexOf("Mozilla/3") != -1) browser = "N3"; else browser = "x"; if (browser=="N3") { var menu1over=new Image(108,68); var menu1out=new Image(108,68); var menu2over=new Image(108,68); var menu2out=new Image(108,68); var menu3over=new Image(108,68); var menu3out=new Image(108,68); var menu4over=new Image(108,68); var menu4out=new Image(108,68); var menu5over=new Image(108,68); var menu5out=new Image(108,68); var menu6over=new Image(108,68); var menu6out=new Image(108,68); var menu7over=new Image(108,68); var menu7out=new Image(108,68); var topmainover=new Image(77,15); var topmainout=new Image(77,15); var bottommainover=new Image(77,15); var bottommainout=new Image(77,15); var topsectionover=new Image(98,15); var topsectionout=new Image(98,15); var bottomsectionover=new Image(98,15); var bottomsectionout=new Image(98,15); var topfeedbackover=new Image(80,15); var topfeedbackout=new Image(80,15); var bottomfeedbackover=new Image(80,15); var bottomfeedbackout=new Image(80,15); var toppreviousover=new Image(77,15); var toppreviousout=new Image(77,15); var bottompreviousover=new Image(77,15); var bottompreviousout=new Image(77,15); var topnextover=new Image(60,15); var topnextout=new Image(60,15); var bottomnextover=new Image(60,15); var bottomnextout=new Image(60,15); var topnextsectionover=new Image(108,15); var topnextsectionout=new Image(108,15); var bottomnextsectionover=new Image(108,15); var bottomnextsectionout=new Image(108,15); menu1over.src="imagemaster/himenu1.jpg"; menu1out.src="imagemaster/menu1.jpg"; menu2over.src="imagemaster/himenu2.jpg"; menu2out.src="imagemaster/menu2.jpg"; menu3over.src="imagemaster/himenu3.jpg"; menu3out.src="imagemaster/menu3.jpg"; menu4over.src="imagemaster/himenu4.jpg"; menu4out.src="imagemaster/menu4.jpg"; menu5over.src="imagemaster/himenu5.jpg"; menu5out.src="imagemaster/menu5.jpg"; menu6over.src="imagemaster/himenu6.jpg"; menu6out.src="imagemaster/menu6.jpg"; menu7over.src="imagemaster/himenu7.jpg"; menu7out.src="imagemaster/menu7.jpg"; var mainblurb="Main menu"; var sectionblurb="Section menu"; var feedbackblurb="Give feedback on this tutorial"; var previousblurb="Go to previous panel"; var nextblurb="Go to next panel"; var nextsectionblurb="Go to next section"; topmainover.src="../i/h-main.gif"; topmainout.src="../i/main.gif"; bottommainover.src="../i/h-main.gif"; bottommainout.src="../i/main.gif"; topsectionover.src="../i/h-section.gif"; topsectionout.src="../i/section.gif"; bottomsectionover.src="../i/h-section.gif"; bottomsectionout.src="../i/section.gif"; topfeedbackover.src="../i/h-feedback.gif"; topfeedbackout.src="../i/feedback.gif"; bottomfeedbackover.src="../i/h-feedback.gif"; bottomfeedbackout.src="../i/feedback.gif"; toppreviousover.src="../i/h-previous.gif"; toppreviousout.src="../i/previous.gif"; bottompreviousover.src="../i/h-previous.gif"; bottompreviousout.src="../i/previous.gif"; topnextover.src="../i/h-next.gif"; topnextout.src="../i/next.gif"; bottomnextover.src="../i/h-next.gif"; bottomnextout.src="../i/next.gif"; topnextsectionout.src="../i/nextsection.gif"; topnextsectionover.src="../i/h-nextsection.gif"; bottomnextsectionout.src="../i/nextsection.gif"; bottomnextsectionover.src="../i/h-nextsection.gif"; } function iOut(image) { if (browser=="N3")document[image].src=eval(image + "out.src"); } function iOver(image) { if (browser=="N3")document[image].src=eval(image + "over.src"); } // --></script><a href="#navskip"><img border="0" alt="Skip to main content" src="../i/c.gif"></a><!--#include virtual="/developerWorks/inc/tuto-inc/tuto-header.inc" --><!--#include virtual="/developerWorks/inc/tuto-inc/tuto-java-header.inc" --><br x="7"><img src="imagemaster/masthead.jpg" alt="Build your own Java library"></td><td width="*" valign="bottom" align="right"><a border="0" href="../j-library.zip"><img alt="下载教程 zip 文件" border="0" src="../i/icon-zip.gif"></a> </td></tr><tr><td height="2" colspan="2"><img height="2" width="1" src="../i/c.gif"></td></tr></table><TABLE border="0" cellpadding="0" cellspacing="0" width="100%"><TR><TD width="150" height="1" bgcolor="#000000" colspan="6"><IMG alt="" height="1" width="150" src="../i/c.gif"></TD></TR><TR><TD background="../i/sw-gold.gif"><a border="0" href="index.shtml" onMouseOver="iOver('topmain'); iOver('bottommain'); self.status=mainblurb; return true;" onMouseOut="iOut('topmain'); iOut('bottommain'); self.status=''; return true;"><img alt="Main menu" border="0" src="../i/main.gif" name="topmain"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topsection'); iOver('bottomsection'); self.status=sectionblurb; return true;" onMouseOut="iOut('topsection'); iOut('bottomsection'); self.status=''; return true;" href="index2.shtml"><img alt="Section menu" border="0" src="../i/section.gif" name="topsection"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topfeedback'); iOver('bottomfeedback'); self.status=feedbackblurb; return true;" onMouseOut="iOut('topfeedback'); iOut('bottomfeedback'); self.status=''; return true;" href="j-javalibrary-7-3.shtml"><img alt="Give feedback on this tutorial" border="0" src="../i/feedback.gif" name="topfeedback"></a></TD><TD width="100%" background="../i/sw-gold.gif"><img src="../i/c.gif"></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topprevious'); iOver('bottomprevious'); self.status=previousblurb; return true;" onMouseOut="iOut('topprevious'); iOut('bottomprevious'); self.status=''; return true;" href="j-javalibrary-2-3.shtml"><img alt="Previous" border="0" src="../i/previous.gif" name="topprevious"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topnext'); iOver('bottomnext'); self.status=nextblurb; return true;" onMouseOut="iOut('topnext'); iOut('bottomnext'); self.status=''; return true;" href="j-javalibrary-2-5.shtml"><img alt="Next" border="0" src="../i/next.gif" name="topnext"></a></TD></TR></TABLE><table bgcolor="ffffff" cellspacing="0" cellpadding="2" border="0" height="400" width="100%"><tr valign="bottom"><a name="navskip"></a><td height="25" colspan="4"><img border="0" height="25" width="562" src="imagemaster/titlebar2.jpg" alt="2. Introduction to libraries"></td></tr><tr><td bgcolor="ffffff" width="15"> </td><td bgcolor="ffffff" width="12"> </td><td valign="top" align="left" bgcolor="ffffff" width="*"><p><br x="7"><table cellspacing="0" cellpadding="0" border="0"><tr><td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Put yourself in the user's shoes</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr> page 4 of 6</nobr></font></td></tr></table><br x="7"><br x="7"></p><font size="2" face="Verdana, Arial, Helvetica"><p>
When designing a library, it's important to put yourself in the place of the person who is going to be using the library. Ask these questions:
</p><p>
<ul><li>What problem will the library solve? (For example, what should the end result be?)
</li><li>What details do the users care about? (For example, how do they want to get to the end results?)
</li><li>What details would the users rather forget about? (For example, what elements and operations do they want other parts of the program to handle?)
</li></ul>
</p><p>
In the final analysis, good library design involves a bit of
psychology. Sure, your code works well, but does it <i>seem</i>
like it works well? When people hear or read about it, will they say
to themselves, "Wow, that's exactly what I need and exactly how I would have done it myself!"
</p><br x="7"></font></td></tr></table><TABLE border="0" cellpadding="0" cellspacing="0" width="100%"><TR><TD background="../i/sw-gold.gif"><a border="0" href="index.shtml" onMouseOver="iOver('topmain'); iOver('bottommain'); self.status=mainblurb; return true;" onMouseOut="iOut('topmain'); iOut('bottommain'); self.status=''; return true;"><img alt="Main menu" border="0" src="../i/main.gif" name="bottommain"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topsection'); iOver('bottomsection'); self.status=sectionblurb; return true;" onMouseOut="iOut('topsection'); iOut('bottomsection'); self.status=''; return true;" href="index2.shtml"><img alt="Section menu" border="0" src="../i/section.gif" name="bottomsection"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topfeedback'); iOver('bottomfeedback'); self.status=feedbackblurb; return true;" onMouseOut="iOut('topfeedback'); iOut('bottomfeedback'); self.status=''; return true;" href="j-javalibrary-7-3.shtml"><img alt="Give feedback on this tutorial" border="0" src="../i/feedback.gif" name="bottomfeedback"></a></TD><TD width="100%" background="../i/sw-gold.gif"><img src="../i/c.gif"></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topprevious'); iOver('bottomprevious'); self.status=previousblurb; return true;" onMouseOut="iOut('topprevious'); iOut('bottomprevious'); self.status=''; return true;" href="j-javalibrary-2-3.shtml"><img alt="Previous" border="0" src="../i/previous.gif" name="bottomprevious"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topnext'); iOver('bottomnext'); self.status=nextblurb; return true;" onMouseOut="iOut('topnext'); iOut('bottomnext'); self.status=''; return true;" href="j-javalibrary-2-5.shtml"><img alt="Next" border="0" src="../i/next.gif" name="bottomnext"></a></TD></TR><TR><TD width="150" height="1" bgcolor="#000000" colspan="6"><IMG alt="" height="1" width="150" src="../i/c.gif"></TD></TR></TABLE><!--#include virtual="/developerWorks/inc/tuto-inc/tuto-footer.inc" --></body></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 + -