Servlet技巧ABC

<script type="text/javascript">google_ad_client = "pub-8800625213955058";/* 336x280, 创建于 07-11-21 */google_ad_slot = "0989131976";google_ad_width = 336;google_ad_height = 280;//</script><script type="text/javascript"src="http://pagead2.googlesyndication.com/pagead/show_ads.js"></script>Servlet技巧ABC1.利用StringBuffer提高速度.Servlets经常需要显示HTML标记,我们很自然想到println()和String串联起来,但是String是很慢的,但是我们用StringBuffer它快很多. 比较这两例:用String,

  for (int i=0; i<100; i  ) {      out.println("Data for "   i   " is "   method1()   " , "   method2()   ".<br>");  }  out.close();

用StringBuffer,可发这样:

  StringBuffer buf = new StringBuffer();  for (int i=0; i<100; i  ) {      buf.append("Data for ").append(i).append(" is ").append(method1());      buf.append(" , ").append(method2()).append(".<br>");  }  response.setContentLength(buf.length());  out.println(buf.toString());  out.close(); 

我们用StringBuffer实现我个问题减少了对像的创建个数,所以它比out.println()更有效. 2.利用HTTP Status Codes显示出错信息.比如我们常用类似下面的处理

public void openFile( String fileName ) {    try {        someOtherMethodToOpenAFile( fileName );    } catch( FileNotFoundException e ) {        out.println( "Sorry... File not found." );    }}

为了得用status codes,我们可以这样得用HTTP出错信息:

/* 'response' variable is an object of the    HttpServletResponse class.*/public void openFile( String fileName ) {    try {        someOtherMethodToOpenAFile( fileName );    } catch( FileNotFoundException e ) {        response.sendError( response.SC_NOT_FOUND );    }}

3.在Frame调用Servlet动态生成页面.在静态页内包含Frame,使"src"指向你希望的Servlet,如:

<frameset rows="20%,*" cols="80%,*">    <frame name="Frame1" src="/servlet/someServlet">    <frame name="Frame2" src="/servlet/anotherServlet"></frameset>

Frame的src属性可以指向静态页或是servlet.