coursebean.java

< J2EE应用开发详解>>一书全部的源代码. 本书基于J2EE 1．4平台

package com.j2ee14.ch10;

import java.util.*;
import java.sql.*;
/**
 *CourseBean,它封装了和Course相关的业务逻辑
 */
public class CourseBean 
{
	Connection con=null;
	/**
	 *构造方法，用于获得一个数据库的连接
	 */
	public CourseBean()throws Exception
	{
	    Class.forName("org.gjt.mm.mysql.Driver").newInstance();
		con=java.sql.DriverManager.getConnection("jdbc:mysql://127.0.0.1/j2ee14","root","");

	}
	/**
	 *增加一门课程
	 */
	public void addCourse(Course st)throws Exception
	{
		String sql="insert into course values('"+st.getId()+"','"+st.getName()+"','"+st.getDescription()+"')";
		executeSql(sql);
    }
    /**
     *获得所有的课程
     */
    public Iterator getAllCourses()throws Exception
    {
    	String queryString = "select * from course";
        return executeQuery(queryString);        
    }
    public Iterator getCourseByName(String name)throws Exception
    {
    	String queryString = "select * from course where name like '%"+name+"%'";
        return executeQuery(queryString);        
    }
    
    /**
     *删除一门课程
     */
    public void deleteCourse(String id)throws Exception
    {
    	String sql="delete from course where id='"+id+"'";
		executeSql(sql);
     }
    /**
     *帮助方法，用于执行没有返回的sql语句
     */
   public void executeSql(String sql)
   {
   	 try
   	 {
   	 	Statement stmt=con.createStatement();
   	    stmt.execute(sql);
   	    stmt.close();
   	}
   	catch(Exception e)
   	{
   	}
   }
   /**
    *帮助方法，用于执行查询数据库的操作，返回包含course值对象的iterator
    */
   public Iterator executeQuery(String sql)
   {
   	  Collection ret=new ArrayList();	
   	 try
   	 {
   	 	Statement stmt=con.createStatement();
   	    ResultSet rst=stmt.executeQuery(sql);
   	    while(rst.next())
   	    {
   	    	Course temp=new Course();
   	    	temp.setId(rst.getString("id"));
   	    	temp.setName(rst.getString("name"));
   	    	temp.setDescription(rst.getString("description"));
   	    	ret.add(temp);
   	    }
   	    rst.close();
   	    stmt.close();
   	    return ret.iterator();
   	}
   	catch(Exception e)
   	{
   		e.printStackTrace();
   		return null;
   	} 
   }
    	
}