dispatcherservlet.java

简单的MVC实现

package pojo;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DispatcherServlet extends HttpServlet {
	private ServletContext context;
	private Map<String , Controller> controllers;
	//用于存放核心处理器
	@Override
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
		context = config.getServletContext();
		//将url和对应的Controller关联起来
		controllers = new HashMap<String,Controller>();
		controllers.put("/test.cmd", (Controller) new TestController());
		controllers.put("/login.cmd", (Controller) new LoginController());
	}
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String contextPath = request.getContextPath();
		System.out.println(contextPath);
		String uri = request.getRequestURI().
		substring(contextPath.length());
		System.out.println(uri);
		Controller controller = controllers.get(uri);
		if(controller == null){
			response.sendError(404);
			return;
			//没找到合适的核心处理器就返回一个404错误
			//结束方法
		}
		try{
			//将请求交给testcontroller处理
			ModelAndView mv = controller.handerRequest(request, response);
			//将Model绑到request中
			Map<String , Object> model = mv.getModel();
			Set<String> keys = model.keySet();
			for(String key:keys){
				request.setAttribute(key, model.get(key));
			}
			String url = mv.getView();
			context.getRequestDispatcher(url).forward(request, response);
			
		}catch(Exception e){
			response.sendError(500);
		}
		
	}
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request,response);
	}
	
	
	
	
}