cartdatabean.java~22~

购物车模块实例。购物车模块可以浏览商品类别；可以根据商品类别浏览商品信息；可以购买商品；可以查看购物车的商品；可以修改购买商品的数量和删除购买的商品。

package cmscartpro;

import javax.ejb.*;
import javax.naming.*;
import javax.sql.DataSource;
import java.sql.*;

public class CartDataBean implements SessionBean {
  SessionContext sessionContext;
  public void ejbCreate() throws CreateException {
  }
  public void ejbRemove() {
  }
  public void ejbActivate() {
  }
  public void ejbPassivate() {
  }
  public void setSessionContext(SessionContext sessionContext) {
    this.sessionContext = sessionContext;
  }
  //取得数据库联接缓冲池的联接
  public java.sql.Connection getConnection() {
    //创建服务器对象查找类
    InitialContext initCtx = null;
   try {
     initCtx = new InitialContext();
     //取得JNDI名字=InforSQLServer的数据源
     DataSource ds = (javax.sql.DataSource)initCtx.lookup("InforSQLServer");
     //取得数据库联接
     return ds.getConnection();
   } catch(Exception ne) {
     System.out.println("找不到数据源");
     throw new EJBException(ne);
   } finally {
     try {
       if(initCtx != null) initCtx.close();
     } catch(NamingException ne) {
       System.out.println(ne.getMessage());
       throw new EJBException(ne);
     }
   }
  }
  //关闭数据库联接的方法
  private void cleanup(Connection con) {
    //将数据库联接返回缓冲池
    try {
      if (con != null) con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  //取得产品类别数组的方法
  public String[][] getCategories() {
    //创建存取产品类别数据表数据的数组
    String[][] categories = null;
    //取得Infor数据库联接缓冲池的联接
    Connection conn = getConnection();
    int rowCount = 0;
    try{
      //创建SQL语句执行类
      Statement stmt = conn.createStatement();
      String sql = "select count(*) from category";
      ResultSet rs = stmt.executeQuery(sql);
      //取得总记录数
      if(rs.next()){
        rowCount = rs.getInt(1);
      }
      if(rowCount > 0){
        //根据总记录数创建数组
        categories = new String[rowCount][3];
        sql = "select * from category";
        rs = stmt.executeQuery(sql);
        int row = 0;
        while(rs.next()){
          //取得类别ID
          categories[row][0] = rs.getString(1);
          //取得类别名字
          categories[row][1] = rs.getString(2);
          //取得类别描述
          categories[row][2] = rs.getString(3);
          row++;
        }
      }else{
        categories = new String[1][1];
        categories[0][0] = "没有产品类别数据.";
      }
      stmt.close();
    }catch(Exception ex){
      ex.printStackTrace();
    }
    //关闭数据库的联接
    cleanup(conn);
    return categories;
  }
  //取得产品数组的方法
  public String[][] getProducts(int categoryId) {
    //创建存取产品数据表数据的数组
    String[][] products = null;
    //取得Infor数据库联接缓冲池的联接
    Connection conn = getConnection();
    int rowCount = 0;
    try{
      //创建SQL语句执行类
      Statement stmt = conn.createStatement();
      String sql = "select count(*) from product where categoryId = " + categoryId;
      ResultSet rs = stmt.executeQuery(sql);
      //取得总记录数
      if(rs.next()){
        rowCount = rs.getInt(1);
      }
      if(rowCount > 0){
        //根据总记录数创建数组
        products = new String[rowCount][4];
        sql = "select id, name, quantity, price from product where categoryId = "
            + categoryId;
        rs = stmt.executeQuery(sql);
        int row = 0;
        while(rs.next()){
          //将product数据表的数据放入products数组
          for(int i = 0; i < 4; i++){
            products[row][i] = rs.getString(i + 1);
          }
          row++;
        }
      }else{
        products = new String[1][1];
        products[0][0] = "没有产品数据.";
      }
      stmt.close();
    }catch(Exception ex){
      ex.printStackTrace();
    }
    //关闭数据库的联接
    cleanup(conn);
    return products;
  }
}