listservlet.java

自己写的基于JSP+servlet+Javabean的bookshop源代码

package bookstore;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Iterator;

import javax.servlet.*;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import beans.BookBean;

public class ListServlet extends HttpServlet
{
    private String url;
    private String user;
    private String password;
    
    public void init() throws ServletException
    {
        ServletContext sc=getServletContext();
        String driverClass=sc.getInitParameter("driverClass");
        url=sc.getInitParameter("url");
        user=sc.getInitParameter("user");
        password=sc.getInitParameter("password");
        try
        {
            Class.forName(driverClass);
            
        }
        catch(ClassNotFoundException ce)
        {
        	throw new ServletException("加载数据库驱动失败！");
        }
    }
    
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
               throws ServletException,IOException
    {
        Connection conn=null;
        Statement stmt=null;
        ResultSet rs=null;
        req.setCharacterEncoding("gb2312");
        String condition=req.getParameter("cond");
        if(null==condition || condition.equals(""))
        {
            resp.sendRedirect("search2.jsp");
            return;
        }
        resp.setContentType("text/html;charset=gb2312");
        PrintWriter out=resp.getWriter();
        try
        {
            conn=DriverManager.getConnection(url,user,password);
            stmt=conn.createStatement();
            if(condition.equals("all"))
            {
                rs=stmt.executeQuery("select * from bookinfo");
                printBookInfo(out,rs);
                out.close();
            }
            else if(condition.equals("precision"))
            {
                String title=req.getParameter("title");
                String author=req.getParameter("author");
                String bookconcern=req.getParameter("bookconcern");
                
                if((null==title || title.equals("")) &&
                   (null==author || author.equals("")) &&
                   (null==bookconcern || bookconcern.equals("")))
                {
                    resp.sendRedirect("search2.jsp");
                    return;
                }
                
                StringBuffer sb=new StringBuffer("select * from bookinfo where ");
                boolean bFlag=false;
                
                if(!title.equals(""))
                {
                    sb.append("title = "+"'"+title+"'");
                    bFlag=true;
                }
                if(!author.equals(""))
                {
                    if(bFlag)
                        sb.append("and author = "+"'"+author+"'");
                    else
                    {
                       sb.append("author = "+"'"+author+"'");
                       bFlag=true;
                    }
                }
                if(!bookconcern.equals(""))
                {
                    if(bFlag)
                        sb.append("and bookconcern = "+"'"+bookconcern+"'");
                    else
                        sb.append("bookconcern = "+"'"+bookconcern+"'");
                }
                rs=stmt.executeQuery(sb.toString());
                printBookInfo(out,rs);
                out.close();
            }
            else if(condition.equals("keyword"))
            {
                String keyword=req.getParameter("keyword");
                if(null==keyword || keyword.equals(""))
                {
                    resp.sendRedirect("search2.jsp");
                    return;
                }
                String strSQL="select * from bookinfo where title like '%"+keyword+"%'";
                
                rs=stmt.executeQuery(strSQL);
                printBookInfo(out,rs);
                out.close();
            }
            else
            {
                resp.sendRedirect("search2.jsp");
                return;
            }
        }
        catch(SQLException se)
        {
            se.printStackTrace();
        }
        finally
        {
        	closeResultSet(rs);
        	closeStatement(stmt);
        	closeConnection(conn);         
        }
    }
    
    public void doPost(HttpServletRequest req, HttpServletResponse resp)
               throws ServletException,IOException
    {
        doGet(req,resp);
    }
    
    private void printBookInfo(PrintWriter out,ResultSet rs)
                 throws SQLException
    {
    	 ArrayList<BookBean> bookList=new ArrayList<BookBean>();
    	 while (rs.next())
         {
         
             BookBean book = new BookBean(rs.getInt(1), rs.getString(2), rs.getString(3),
                                          rs.getString(4), rs.getString(5),
                                          rs.getFloat(6), rs.getInt(7),
                                          rs.getString(8));
             bookList.add(book);
         }
    
    	out.println("<html><head>");
        out.println("<title>图书信息</title>");
        out.println("<link href=\"incoming/style.css\" rel=\"stylesheet\" type=\"text/css\">");
        out.println("</head><body>"); 
        out.println("<table><tr><th>书名</th><th>作者</th><th>出版社</th><th>价格</th><th>查看</th></tr>");
        Iterator<BookBean> it=bookList.iterator();
        while(it.hasNext())
        {
            BookBean book=(BookBean)it.next();
            String title=book.getTitle();
            String author=book.getAuthor();
            String bookconcern=book.getBookconcern();
            int bookId=book.getId();
            float price=book.getPrice();
            out.println("<tr><td><a href=\"bookinfo.jsp?id="+bookId+"\">《"+title+"》</a></td><td>"+author+"</td><td>"+bookconcern+"</td><td>"+price+"</td><td><a href=\"bookinfo.jsp?id="+bookId+"\">详细信息</a></td></tr>");
        }
        out.println("</table><a href=\"index.jsp\">回到主页</a><br></body></html>");
    }
    private void closeResultSet(ResultSet rs)
    {
    	if(rs!=null)
        {
            try
            {
                rs.close();
            }
            catch(SQLException se)
            {
                se.printStackTrace();
            }
            rs=null;
        }
    }
    
    private void closeStatement(Statement stmt)
    {
    	if(stmt!=null)
        {
            try
            {
                stmt.close();
            }
            catch(SQLException se)
            {
                se.printStackTrace();
            }
            stmt=null;
        }
    }
    
    private void closeConnection(Connection conn)
    {
    	if(conn!=null)
        {
            try
            {
                conn.close();
            }
            catch(SQLException se)
            {
                se.printStackTrace();
            }
            conn=null;
        }
    }
}