custom struts framework

1. Difference between stucts1 and struts2

struts1 : Servlet used as Controller , you can visit the Servlet directly, code like if---else if--else

struts2 : Filter used as Controller , you can only visit it passively, though setting the condition like "/*"

2. Imitate the core Filter of Struts2 (StrutsPrepareAndExecuterFilter.java)

version 1.0(like struts1)

package com.cdv.web.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;

/**
* Servlet Filter implementation class StrutsPreparedAndExecuterFilter
*/
public class StrutsPreparedAndExecuterFilter implements Filter {

/**
* Default constructor.
*/
public StrutsPreparedAndExecuterFilter() {
// TODO Auto-generated constructor stub
}

/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}

/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
String uri = request.getRequestURI();
boolean isDo = uri.endsWith(".do");
if(isDo){
//get the operation
String op = uri.substring(uri.lastIndexOf("/"), uri.lastIndexOf("."));
if(op.equals("login")){
request.setAttribute("username", "zhangsan");
}else{
//to do something
}
}else{
//
chain.doFilter(request, response);
}
}

/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}

}

version 2.0

we need create the interface , for creating different instance aim at different params condition, and use the map instead of if--else

package com.cdv.web.action;

import javax.servlet.http.HttpServletRequest;

public interface Action {

String execute(HttpServletRequest request);
}

package com.cdv.web.action;

import javax.servlet.http.HttpServletRequest;

public class LoginAction implements Action {

@Override
public String execute(HttpServletRequest request) {
String username = request.getParameter("username");
if(username.equals("zhangsan")){
return "ok";
}
return null;
}

}

package com.cdv.web.filter;

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

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.cdv.web.action.Action;
import com.cdv.web.action.LoginAction;

/**
* Servlet Filter implementation class StrutsPreparedAndExecuterFilter
*/
public class StrutsPreparedAndExecuterFilter2 implements Filter {

private Map<String, Action> actionMap = new HashMap<String, Action>();
/**
* Default constructor.
*/
public StrutsPreparedAndExecuterFilter2() {
// TODO Auto-generated constructor stub
}

/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}

/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
String uri = request.getRequestURI();
boolean isDo = uri.endsWith(".do");
if(isDo){
String op = uri.substring(uri.lastIndexOf("/"), uri.lastIndexOf("."));
Action instance = actionMap.get(op);
String result = instance.execute(request);
if(result.equals("ok")){
request.setAttribute("user", "zhangsan");
}
}else{
chain.doFilter(request, response);
}
}

/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
actionMap.put("login", new LoginAction());
//actionMap.put("logout", new LogoutAction());
//...
}

}

version 3.0

put the value of instance into xml file , use dom4j to parse it, and use reflect technology to create instance dynamic.

struts.xml

<?xml version="1.0" encoding="UTF-8"?>
<package name="mypackage">
<action name="loginAction" class="com.cdv.web.action.LoginAction"></action>
<action name="logoutAction" class="com.cdv.web.action.LogoutAction"></action>
</package>

package com.cdv.web.filter;

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

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.cdv.web.action.Action;
import com.cdv.web.action.LoginAction;

/**
* Servlet Filter implementation class StrutsPreparedAndExecuterFilter
*/
public class StrutsPreparedAndExecuterFilter3 implements Filter {

private Map<String, Action> actionMap = new HashMap<String, Action>();
/**
* Default constructor.
*/
public StrutsPreparedAndExecuterFilter3() {
// TODO Auto-generated constructor stub
}

/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}

/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
String uri = request.getRequestURI();
boolean isDo = uri.endsWith(".do");
if(isDo){
String op = uri.substring(uri.lastIndexOf("/"), uri.lastIndexOf("."));
Action instance = actionMap.get(op);
String result = instance.execute(request);
if(result.equals("ok")){
request.setAttribute("user", "zhangsan");
}
}else{
chain.doFilter(request, response);
}
}

/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
//进行dom4j解析，将struts.xml中的name 和 value取出，
//并利用反射将class的值转化为对象
/*        Document document = Dom4jUtil.getDocument();
List<Node> list = document.selectNodes("//action");
for(Node node : list){
//遍历action节点，取出值
String key = node.valueOf("@name");
String value = node.valueOf("@class");
actionMap.put(key, (Action) Class.forName(value).newInstance());
}*/
}

}