regnamevalid.java

使用servlet写的简单网上书店

package c;


import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Vector;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;

import entity.Book;
import entity.Users;

public class RegNameValid extends HttpServlet {

	private DataSource ds;

	public void init(ServletConfig config) throws ServletException {		
		super.init(config);		
		ds = (DataSource)config.getServletContext().getAttribute("dataSource");		
	}
	
	public void service(HttpServletRequest req,HttpServletResponse res){		
		Vector books = this.findBookByName(req);		
		this.displayResult(res,books);	
	}

	private Vector findBookByName(HttpServletRequest req) {
		Vector vector = new Vector();
		Connection con = null;
		PreparedStatement ps = null; 
		ResultSet rs=null;
		try {
			String username = req.getParameter("username");
			System.out.println(username);
			con = ds.getConnection();
			ps = con.prepareStatement("select * from users where username like(?) order by username "); 
			ps.setString(1,"%"+username+"%");
			
			rs = ps.executeQuery();
			Users user = null;
			while(rs.next()){				
				user =new Users(rs.getString(2));				
				vector.add(user);				
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			try {
				if(rs!=null)rs.close();
				if(ps!=null)ps.close();
				if(con!=null)con.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}		
		}		
		return vector;
	}
	private void displayResult(HttpServletResponse res, Vector user) {
		res.setContentType("text/html;charset=gbk");
		PrintWriter out = null;
		try {
			if(user.size()>0)	{
		   
			out = res.getWriter();
			
			//out.println("<table border=1 width=400>");
			StringBuffer sb = new StringBuffer();
			
			for(int i=0;i<user.size();i++){
				Users users = (Users)user.get(i);
				//out.println("<tr><td>"+book.getId()+"</td>");
				//out.println("<td>"+book.getName()+"</td>");
				sb.append(users.getUsername()+"<br>");
				//out.println("<td>"+book.getPrice()+"</td>");
				//out.println("<td>"+book.getAuthor()+"</td>");
				//out.println("</tr>");				
			} 		 
			//out.println("</table>");
			out.println(sb.substring(0,sb.lastIndexOf("<br>")));
			out.close();			 
		  }			 
		} catch (IOException e) {
			e.printStackTrace();
		}			
	}
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
	}
}