简易购物车

最新推荐文章于 2024-09-28 23:02:25 发布

原创最新推荐文章于 2024-09-28 23:02:25 发布 · 422 阅读

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文章标签：

#exception #books #string #null #数据库 #table

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先建个大思路框架：显示层(JSP)---控制层(Servlet)---业务层(Service)---数据访问层(DAO)---数据库(DB).
今天就先搭一个数据库的架子，至于各个功能的实现，明天在做详细分析！
1.建表：
bookstore.sql:
# MySQL-Front 3.2 (Build 6.2)

;
;
;
;

# Host: localhost:3309 Database: bookstore
# ------------------------------------------------------
# Server version 5.0.18-nt

#
# Table structure for table books
#
CREATE DATABASE bookstore;

USE bookstore;

DROP TABLE IF EXISTS `books`;
CREATE TABLE `books` (
`id` varchar(8) NOT NULL,
`name` varchar(24) default NULL,
`title` varchar(96) default NULL,
`price` float default NULL,
`yr` int(11) default NULL,
`description` varchar(30) default NULL,
`saleAmount` int(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312;

#
# Dumping data for table books
#

INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('201','王芳','Java编程指南',33.75,1999,'让读者轻轻松松掌握Java语言',1);
INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('202','张丙','Weblogic技术参考',45.99,2002,'真的不错耶',1);
INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('203','孙艳','Oracle数据库教程',40,2003,'关于Oracle的最畅销的技术书',1);
INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('204','大卫','从Oak到Java: 语言的革命',20.75,1998,'很值得一看',1);
INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('205','阿明','Apache从入门到精通',50.75,2002,'权威的Apache技术资料',1);
INSERT INTO `books` (`id`,`name`,`title`,`price`,`yr`,`description`,`saleAmount`) VALUES ('206','洪军','Java与数据算法 ',54.75,2002,'权威的Java技术资料',1);

#
# Table structure for table customer
#

DROP TABLE IF EXISTS `customer`;
CREATE TABLE `customer` (
`id` int(11) NOT NULL default '0',
`name` varchar(30) default NULL,
`cardid` varchar(11) default NULL,
`balance` float(6,2) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312;

#
# Dumping data for table customer
#

INSERT INTO `customer` (`id`,`name`,`cardid`,`balance`) VALUES (1,'Tom','1234567890',1000);

;
;
;

2.数据库是必要要的！有了数据库就要有数据库连接：
这里要先导架包：
commons-collections-3.1.jar
commons-dbcp-1.2.2.jar
commons-pool-1.2.jar
mysql-connector-java-5.1.6-bin.jar
要导入连接池的配置文件
dbcpconfig_mysql.properties
dbcpconfig_oracle.properties

package com.myshopping.db;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

import com.myshopping.util.MyBookConstants;
import com.myshopping.web.MyBookWebConfig;

public class DBHelper {

  private static DataSource ds = null;

  static{
   String dbType = null;
   dbType = MyBookWebConfig.getInstance().getValue(MyBookConstants.DB_TYPE);
   String propFileName = null;
   if(dbType.equals("mysql")){
    propFileName = "dbcpconfig_mysql.properties";
   }
   if(dbType.equals("oracle")){
    propFileName = "dbcpconfig_oracle.properties";
   }

   InputStream is = null;
   is = DBHelper.class.getClassLoader().getResourceAsStream(propFileName);

   Properties prop = new Properties();

   try {
    prop.load(is);
   } catch (IOException e) {
    e.printStackTrace();
    throw new RuntimeException(MyBookConstants.LOAD_DBPROP_FILE_EXCEPTION_MESSAGE);
   }

   try {
    ds = BasicDataSourceFactory.createDataSource(prop);
   } catch (Exception e) {
    e.printStackTrace();
    throw new RuntimeException(MyBookConstants.GET_DATASOURCE_EXCEPTION_MESSAGE);
   }
  }

  public static Connection getonnection(){
   Connection conn = null;

   try {
    conn = ds.getConnection();
   } catch (SQLException e) {
    e.printStackTrace();
    throw new RuntimeException(MyBookConstants.GET_CONNECTION_EXCEPTION_MESSAGE);
   }
   return conn;
  }

  public static void releaseDBSource(ResultSet rs,Statement st,Connection conn){
   try {
    if(rs != null)
     rs.close();
    if(st != null)
     st.close();
    if(conn != null)
     conn.close();
   } catch (SQLException e) {
    e.printStackTrace();
    throw new RuntimeException(MyBookConstants.CLOSE_DATABASE_SOURCE_EXCEPTION_MESSAGE);
   }
  }


}
3.上段代码中用了 dbType，这里选择数据库时，我们要做个监听，并在WEB.XML中进行配置：
package com.myshopping.listener;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import com.myshopping.util.MyBookConstants;
import com.myshopping.web.MyBookWebConfig;

public class BookAppListener implements ServletContextListener {

public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub

}

public void contextInitialized(ServletContextEvent arg0) {
  // TODO Auto-generated method stub
  ServletContext sc = arg0.getServletContext();

  String dbType = sc.getInitParameter("dbType");

  MyBookWebConfig.getInstance().addParam(MyBookConstants.DB_TYPE, dbType);
}

}
4.有了dbType，就要添加键值：
package com.myshopping.web;

import java.util.HashMap;
import java.util.Map;

public class MyBookWebConfig {
private Map paramMap = null;

private MyBookWebConfig(){
  paramMap = new HashMap();
}

private static MyBookWebConfig instance = null;

static{
  instance = new MyBookWebConfig();
}

public static MyBookWebConfig getInstance(){
  return instance;
}

public void addParam(String key, String value){
  this.paramMap.put(key, value);
}
public String getValue(String key){
  if(this.paramMap.get(key) == null)
   return null;
  else
   return (String) this.paramMap.get(key);

}

}
5.这里我们还要定一个常量类，方便调用！
package com.myshopping.util;

public class MyBookConstants {
public static final String DB_TYPE = "dbType";

//异常信息
public static final String GET_CONNECTION_EXCEPTION_MESSAGE = "根据已经数据源获取数据连接异常";
public static final String GET_DATASOURCE_EXCEPTION_MESSAGE = "根据已经加载成功的属性文件获取数据源异常";
public static final String LOAD_DBPROP_FILE_EXCEPTION_MESSAGE = "加载数据库属性文件异常";
public static final String CLOSE_DATABASE_SOURCE_EXCEPTION_MESSAGE = "根据已经数据源获取数据库连接异常 ";
}
配置下web.xml，这里就写需要的配置的代码段：
<context-param>
<param-name>dbType</param-name>
<param-value>mysql</param-value>
</context-param>
<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>CatalogServlet</servlet-name>
    <servlet-class>com.myshopping.servlet.CatalogServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>CatalogServlet</servlet-name>
<url-pattern>/catalogServlet</url-pattern>
</servlet-mapping>

<listener>
<listener-class>com.myshopping.listener.BookAppListener</listener-class>
</listener>

上面这几部是完成功能实现的基础，就像建房子一样，没有根基，上层的思想再完美也是徒劳！明天实现获取图书的功能！