FilterDispather.java

package com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.controller;


import com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.action.ActionDispather;
import com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.action.IActionDispather;
import com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.valuestack.ValueStack;
import com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.helper.ValueStackHelper;
import com.cheng.zenofdesignpatterns.extension.mvcframework.cheng.view.ViewManager;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 */
public class FilterDispather implements Filter {

    // 定义一个值栈辅助类
    private ValueStackHelper valueStackHelper = new ValueStackHelper();
    // 应用IActionDispather
    IActionDispather actionDispather = new ActionDispather();

    // server销毁时要做的事情
    public void destroy() {

    }

    // 过滤器必须实现的
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        // 转换为HttpServletRequest
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        // 传递到其他过滤器处理
        chain.doFilter(req, res);
        // 获得从HTTP请求的ACTION名称
        String actionName = getActionNameFromURI(req);
        // 对ViewManager的应用
        ViewManager viewManager = new ViewManager(actionName);
        // 所有参数放入值栈
        ValueStack valueStack = valueStackHelper.putIntoStack(req);
        // 把所有的请求传递给ActionDispatcher处理
        String result = actionDispather.actionInvoke(actionName);
        String viewPath = viewManager.getViewPath(result);
        // 直接转向
        RequestDispatcher rd = req.getRequestDispatcher(viewPath);
        rd.forward(req, res);
    }

    public void init(FilterConfig arg0) throws ServletException {
        /*
		 * 1、检查XML配置文件是否正确
		 * 2、启动监控程序，观察配置文件是否正确
		 */
    }

    // 通过url获得actionName
    private String getActionNameFromURI(HttpServletRequest req) {
        String path = (String) req.getRequestURI();
        String actionName = path.substring(path.lastIndexOf("/") + 1, path.lastIndexOf("."));
        return actionName;
    }

}