J2EE DAO模式解析（三）
我们先看一下界面
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<%
String path=request.getContextPath();
String basePath=request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<html>
<head>
<base href="<%=basePath %>">
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>添加流向单维护</title>
</head>
<body>
<form name="flowCardAddForm" method="post" action="servlet/flowcard/FlowCardServlet" >
<input type="hidden" name="command" value="add">
<input type=”submit” id=”btnAdd” value=”添加”/>
</form>
</body>
</html>
下面看一下Servlet
public class FlowCardServlet extends HttpServlet {
private FlowCardManager flowCardManager;
public void init() throws ServletException {
flowCardManager=(FlowCardManager)getBeanFactory().getServiceObject(FlowCardManager.class);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
add(request,response);
}
private void add(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException
{
/**
***调用业务逻辑层代码之前的准备代码***
*/
//通过工厂取得业务逻辑对象
FlowCardManager flowCardManager=(FlowCardManager)getBeanFactory().getServiceObject(FlowCardManager.class);
flowCardManager.addFlowCard(flowCard); response.sendRedirect(request.getContextPath()+"/flowcard/flow_card_maint.jsp");
}
protected BeanFactory getBeanFactory()
{
BeanFactory beanFactory=BeanFactory.getInstance();
return beanFactory;
}
}
下面看一下业务逻辑层
public interface FlowCardManager {
public void addFlowCard(FlowCard flowCard) throws ApplicationException;
}public class FlowCardManagerImpl implements FlowCardManager {
private FlowCardDao flowCardDao;
public FlowCardManagerImpl()
{
this.flowCardDao=(FlowCardDao)BeanFactory.getInstance().getDaoObject(FlowCardDao.class);
}
public void addFlowCard(FlowCard flowCard) throws ApplicationException {
Connection conn=null;
try{
//取得Connection
conn=ConnectionManager.getConnection();
//开始事务
ConnectionManager.beginTransaction(conn);
//添加前的准备工作，给参数赋值***************省略
//添加流向单主信息
flowCardDao.addFlowCardMaster(flowCardVouNo, flowCard);
//提交事务
ConnectionManager.commitTransaction(conn);
}catch(DaoException e)
{
//回滚事务
ConnectionManager.rollbackTransaction(conn);
throw new ApplicationException("添加流向单失败");
}finally
{
//关闭Connection并从ThreadLocal清除
ConnectionManager.closeConnection();
}
}
}
最后Dao层
public interface FlowCardDao {
/**
* 添加流向单主信息
* @param flowCardVouNo
* @param flowCard
*/
public void addFlowCardMaster(String flowCardVouNo,FlowCard flowCard);
}public class FlowCardDaoImpl implements FlowCardDao {
@Override
public void addFlowCardMaster(String flowCardVouNo, FlowCard flowCard) {
StringBuffer sbSql=new StringBuffer();
sbSql.append("……………省略…………………..");
PreparedStatement pstmt=null;
try{
Connection conn=ConnectionManager.getConnection();
pstmt=conn.prepareStatement(sbSql.toString());
pstmt.setString(…为sql语句中需要的参数赋值……….);
pstmt.executeUpdate();
}catch(SQLException e){
e.printStackTrace();
System.out.println("FlowCardDaoImpl-->>addFlowCardMater,exception:"+e);
throw new DaoException(e);
}finally{
ConnectionManager.close(pstmt); //此处并没有关闭connection
}
}
}
整个DAO模式就是这样子了。
