最近对一个别人的WEB项目进行维护，看到这样的实现方法：
1.只有一个Controller的servlet 类
2.一个Service接口
3.一些实现Service接口的类
Controller类负责进行控制，动态产生业务逻辑的类的实例（所有的类需要实现Service接口)，然后通过
httpservletrequest.setAttribute("USERLIST", userList);向WEB端赋值，
具体的可以参考部分代码:
Controller 类(extends HttpServlet )
protected void doPost(
HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
//service name,example for packagename.ServiceName
String serviceName = request.getParameter(Constant.SERVICE);
if (serviceName == null)
throw new ServletException("There isn't service parameter![?service=]");
String targetName = request.getParameter(Constant.TARGET);
//the targeted file name,example for /fileName.jsp
if (targetName == null)
throw new ServletException("There isn't target parameter![?target=]");
ServletContext servletcontext = getServletContext();
try {
//TODO:hashmap to reduce the generated instance?
Class serviceClass = Class.forName(serviceName);
Service service = (Service) serviceClass.newInstance();
service.execute(request, response, servletcontext);
} catch (ClassNotFoundException classnotfoundexception) {
throw new ServletException(classnotfoundexception.getMessage());
} catch (IllegalAccessException illegalaccessexception) {
throw new ServletException(illegalaccessexception.getMessage());
} catch (Exception exception) {
throw new ServletException(exception.getMessage());
}
forward(request, response, targetName);
}
Service 接口
public interface Service {
public abstract void execute(
HttpServletRequest httpservletrequest,
HttpServletResponse httpservletresponse,
ServletContext servletcontext)
throws Exception;
}
一个实现service的类（相当于业务类)
public class StartService implements Service {
public void execute(
HttpServletRequest httpservletrequest,
HttpServletResponse httpservletresponse,
ServletContext servletcontext)
throws Exception {
//test data
List userList = new ArrayList();
httpservletrequest.setAttribute("USERNAME", "TestUser");
httpservletrequest.setAttribute("USERLIST", userList);
}
}
JSP 页面文件
<%
String userName=(String)request.getAttribute("USERNAME");
List userList=(List)request.getAttribute("USERLIST");
%>
访问的时候：
/service.Controller?service=StartService&target=/StartPage.jsp
