displaytag.java

java编写的电子商务网站源码,做的一个电脑直销网站,后台数据库使用的是MS SQL2000 Server,数据流的流向主要有两个方向

package tag;

import java.io.*;
import java.util.*;
import java.sql.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import javax.servlet.http.*;

public class DisplayTag extends BodyTagSupport{
	
	private int trend = 0;
	private int begin = 1;
	private int index = 0;
	private boolean cont = false;
	private ResultSet rs = null;	
	
	public ResultSet getResult(){
		return this.rs;
	}
	
	public void setResult(ResultSet rs){		
		this.rs = rs;
	}
	
	public int getBegin(){
		return this.begin;
	}
	
	public void setBegin(int begin){
		this.begin = begin;
	}
	
	public int doStartTag() throws JspTagException{	
		setHeader();				
		try{
			index = 0;			
			cont = true;			
			rs.absolute(begin);			
		}
		catch(SQLException sqle){sqle.printStackTrace();}
		return BodyTag.EVAL_BODY_BUFFERED;
	}

	public int doAfterBody() {
		if(cont){
			setValue();
			index++;
			try {
				cont = (rs.next() && index<7);
				return BodyTag.EVAL_BODY_BUFFERED;
			}
			catch (SQLException sqle) {
				return BodyTag.SKIP_BODY;
			}
		}
		else
			return BodyTag.SKIP_BODY;	
	}
	
	public int doEndTag() throws JspTagException{	
		if(bodyContent != null){
			try{
				bodyContent.writeOut(bodyContent.getEnclosingWriter());
			}
			catch(IOException ioe){}			
		}
		return Tag.EVAL_PAGE;
	}

	private void setHeader(){
		pageContext.setAttribute("id","序号");
		pageContext.setAttribute("manufactor","生产厂商");				
		pageContext.setAttribute("name","型号");				
		pageContext.setAttribute("chip","芯片组");
		pageContext.setAttribute("volumn","显存(M)");				
		pageContext.setAttribute("price","价格(元)");				
		pageContext.setAttribute("trend","涨跌");						
	}

	private void setValue(){				
		try{
			pageContext.setAttribute("id",String.valueOf(rs.getInt(1)));
			pageContext.setAttribute("manufactor",rs.getString(2));		
			pageContext.setAttribute("name",rs.getString(3));			
			pageContext.setAttribute("chip",rs.getString(4));			
			pageContext.setAttribute("volumn",String.valueOf(rs.getInt(5)));		
			pageContext.setAttribute("price",String.valueOf(rs.getInt(6)));		
	
			switch(rs.getInt(7)){
				case -1:pageContext.setAttribute("trend","<font color='green'>下跌</font>");
					break;
				case 0:pageContext.setAttribute("trend","<font color='blue'>持平</font>");
					break;
				case 1:pageContext.setAttribute("trend","<font color='red'>上涨</font>");	
					break;
			}			
		}	
		catch(SQLException sqle){}
	}
}