互联网开发技术第七讲Web技术.ppt
互联网开发技术Internet Systems Development Technologies,蔡 剑,Ph.D.Assistant Professor in Management Science and E-BusinessGuanghua School of ManagementPeking University,本讲内容,Web层技术(III)Custom TagsJSP and XMLJSTLAbout The Course Project:Group present there projects in next weekProposals due in next week,Review:Use JavaBeans with JSP,JSP handles the face.JavaBean handles the logic and complexity.,Custom JSP Tag,Simple Custom Tag:Attribute Custom Tag:/Use tld file to config the tag attributes3.Body Custom Tag:,Custom JSP Tag(Cont),4.Custom Tag can be used in Script:,Custom Tag Development,采用特定的API编写实现标签处理的程序位置/WEB-INF/classes or/WEB-INF/lib 建立一个tag library descriptor(TLD)文件用来描述custom tag位置/WEB-INF,Tag Library Descriptor,1.0 1.2 ics IcsampleTag Sample TLD in JWAD Book,Tag Library Descriptor(Cont),wordcount empty inputname true false warnEmpty true true boolean,A Simple Tag,public class TimeTag implements Tag public int doStartTag()throws JspException try calendar=Calendar.getInstance();pageContext.getOut().print(DateFormat.getDateInstance().format(calendar.getTime()+DateFormat.getTimeInstance().format(calendar.getTime();catch(IOException tage)throw new JspException(TimeTag Error:+tage.getMessage();return SKIP_BODY;public int doEndTag()throws JspException return SKIP_PAGE;,Simple Tag Result,Current Time is:,A Attribute Tag,public class WordCount extends TagSupport public void setInputname(String _inputname)this.inputname=_inputname;public void setWarnEmpty(boolean _warnempty)this.warnEmpty=_warnempty;public int doEndTag()throws JspException JspWriter out=pageContext.getOut();inputword=pageContext.getRequest().getParameter(inputname);tryif(inputword=null)&(warnEmpty=true),A Attribute Tag,else StringTokenizer st=new StringTokenizer(inputword);int wordnumber=st.countTokens();out.println(wordnumber);catch(IOException ioe)System.out.println(Error:+ioe.getMessage();return EVAL_PAGE;,Tld for the Example,wordcount jwadbook.taglib.WordCount empty inputname true false warnEmpty true true boolean,JSP with Custom Tag,Enter A Brief Description Here Your have entered words in the above text area.,BodyTagSupport Sequences,BodyTagSupport Example,public class ListTag extends BodyTagSupport private int times;public void setTimes(int _times)if(_times0)times=_times;else times=1;public int doStartTag()if(times=1)String timeString=String.valueOf(times);pageContext.getSession().setAttribute(ListTagTime,timeString);return(EVAL_BODY_INCLUDE);else return(SKIP_BODY);,BodyTagSupport Example,public void doInitBody()public int doAfterBody()if(times-1)String timeString=String.valueOf(times);pageContext.getSession().setAttribute(ListTagTime,timeString);return(EVAL_BODY_AGAIN);else return(SKIP_BODY);,RowTag inside ListTag,public class RowTag extends TagSupport public int doStartTag()try JspWriter out=pageContext.getOut();int rowtime=0;rowtime=Integer.parseInt(String)pageContext.getSession().getAttribute(ListTagTime);out.print(Row Number:+String.valueOf(rowtime)+Created in RowTag);catch(IOException ioe)System.err.println(RowTag error);return(EVAL_BODY_INCLUDE);,BodyTagSupport Example Result,XML and Web Components,A XML Example,JOB101 Prepare the design requirements 10/1/2002 10/10/2002 JOB102 Write design documents 10/9/2002 11/15/2002,XML Parsing using SAX,XML Parsing using DOM,A Example of Using DOM,public static void main(String argv)if(argv.length!=1)System.err.println(Usage:java ProcessParser filename);System.exit(1);DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();try DocumentBuilder builder=factory.newDocumentBuilder();document=builder.parse(new File(argv0);makeFrame();catch(SAXException sxe)/Error generated during parsing)Exception x=sxe;if(sxe.getException()!=null)x=sxe.getException();x.printStackTrace();catch(ParserConfigurationException pce)pce.printStackTrace();catch(IOException ioe)ioe.printStackTrace();/main,JSP using XML,JSP using XSLT to Convert XML,
