Struts2 Servelet重构

Posted 2020-10-05 下路派出所

这是利用action模仿请求Servelet（单例）

作用：

1.减少web.xml代码量

2.将servelet中的代码转移到action中，只需要在action中定义业务逻辑则可。

 

1.定义一个过滤器

package com.struts2.filter;

import java.io.IOException;

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

import com.struts2.action.Action;
import com.struts2.action.HelloWorldAction;
import com.struts2.utils.ServletUtils;

public class DispatchFilter implements Filter {
	
	private HttpServletRequest request;
	private HttpServletResponse response;
	
	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain arg2) throws IOException, ServletException {
		
		/**
		 * 1.先获取HttpServletRequest,HttpServletResponse
		 * 2.获取HelloWorldAction.action中的HelloWorldAction
		 * 3.利用java的反射机制进行调用
		 */
		this.request=(HttpServletRequest) request;
		this.response=(HttpServletResponse) response;
		
		String requestURI = this.request.getRequestURI();
		System.out.println(requestURI);
		String actionName = ServletUtils.convert(requestURI);
		
		//利用java的反射机制调用该方法
		try {
			//利用java反射机制创建一个新的HelloWorldAction对象
			HelloWorldAction action = (HelloWorldAction) Class.forName("com.struts2.action."+actionName).newInstance();
			String forward = action.execute(this.request, this.response);
			
			/**
			 * 2种跳转方法
			 *  *重定向
			 *  	request里的参数不起作用
			 *  	this.response.sendRedirect(jsp页面)
			 *  *转发
			 *  	放在	request中的值可以取出来
			 *  	this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);
			 *  
			 */
			this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);
		} catch (InstantiationException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
	}

}

　

web.xml中配置为：

  <filter>
  	<filter-name>DispatchFilter</filter-name>
  	<filter-class>com.struts2.filter.DispatchFilter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>DispatchFilter</filter-name>
  	<url-pattern>*.action</url-pattern>
  </filter-mapping>

 

当接受到一个请求后

 	<a href="HelloWorldAction.action">请求一个action</a>

　　当过滤器接受到一个请求以后，进行过滤

1.先取出请求uri.

2.根据java反射机制取出action

package com.struts2.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloWorldAction implements Action {

	@Override
	public String execute(HttpServletRequest request,
			HttpServletResponse response) {
		System.out.println("Hello World Struts2");
		return "index.jsp";
	}

}

3.取出action以后，就可以执行action中的方法

4.利用request/response转发

/**
			 * 2种跳转方法
			 *  *重定向
			 *  	request里的参数不起作用
			 *  	this.response.sendRedirect(jsp页面)
			 *  *转发
			 *  	放在	request中的值可以取出来
			 *  	this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);
			 *  
			 */
			this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);