bookservlet.java

JAVA网上书店的程序原代码,希望对大家偶用

package sample;


import javax.naming.Context;
import javax.naming.InitialContext;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
import javax.sql.DataSource;
import ebookshop.bean.BookBean;

public class BookServlet extends HttpServlet 
{
  
  public void doGet(HttpServletRequest req, HttpServletResponse res)
                                throws ServletException, IOException{           
          try {
        	  	 Context initCtx= new InitialContext();  //1.生成上下文
        	     Context envCtx = (Context) initCtx.lookup("java:comp/env");   //2.查询
        	     DataSource ds = (DataSource)envCtx.lookup("jdbc/mysql");  // jndi name //此名为任意的,但是必须和绑定的jndi name一样.
        	     Connection con = ds.getConnection();  // DataSource(数据源)call getConnection()方法返回一个连接的对象.
              
               //3. create statement
               Statement stmt = con.createStatement();
               String query = "SELECT * FROM book";
               //4. get Resultset
               ResultSet rs = stmt.executeQuery(query);

               //5. call method getResultSet to get an arraylist
               ArrayList list = getResultSet(rs);  // call business(成员) method
               rs.close();
               stmt.close();
               con.close();
               
               //6. put the Arraylist in request and relate  it with a name
               req.setAttribute("users", list);  // users -> key, list-> value                                       
              
               //7. forward the request to anotherservlet
               //getServletContext().getRequestDispatcher("/dbdisplayservlet").forward(req, res);
               ServletContext sc=getServletContext();
               RequestDispatcher rsd=sc.getRequestDispatcher("/bookDisplayServlet");
               
               rsd.forward(req, res);
               
          }catch(Exception e){e.printStackTrace();}
    }

    // extract data from resultset of database, and save them in an Arraylist
    private  ArrayList getResultSet(ResultSet rs) throws SQLException {
              ArrayList  users = new ArrayList();
              while(rs.next()) {
                // use the Javabean Student to save one row
            	  BookBean bk=new BookBean();
            	  // from database
            	     
            	  bk.setBookName(rs.getString("bookName"));
            	  bk.setPublisher(rs.getString("publisher"));
            	  bk.setPrice(new Float(rs.getFloat("price")));
            	  
            	  bk.setDescription(rs.getString("description"));
            	  
            	  System.out.println("bid: " +    rs.getInt("bid"));
            	  System.out.println("bookName: " +  rs.getString("bookName"));
            	  System.out.println("publisher: " + rs.getString("publisher"));
            	  System.out.println("price: " + rs.getFloat("price"));
            	  System.out.println("memberPrice: " + rs.getFloat("memberPrice"));
            	  System.out.println("description: " + rs.getString("description"));
            	  
                 users.add(bk); // add javabean to ArrayList
                 System.out.println();
              }           
             return users;  // return arraylist
     }
  }