模拟Struts2实现

红太狼 2022-08-21 08:00 180阅读 0赞

### 本文主要是一个模拟的Struts2的简单实现 ###

### 真正的MVC架构 ###

![这里写图片描述][20160424163431279]

### 实现主要思路 ###

定义一个过滤器，接收传递过去的Action，根据处理的结果重定向或者转发。

### 首先定义index.jsp ###

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        <title></title>
    
        <meta http-equiv="pragma" content="no-cache">
        <meta http-equiv="cache-control" content="no-cache">
        <meta http-equiv="expires" content="0">    
        
    
      </head>
    
      <body>
        <form action="${pageContext.request.contextPath}/addCustomer.action" method="post">
            姓名:<input type="text" name="name"/><br/>
            年龄:<input type="text" name="age"/><br/>
            <input type="submit" value="保存"/>
        </form>
      </body>
    </html>

### 在web.xml中配置过滤器 ###

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
      <display-name>MyStruct2</display-name>
    
      <filter>
            <filter-name>CenterFilter</filter-name>
            <filter-class>cn.itcast.framework.core.CenterFilter</filter-class>
    
    
    
    
        </filter>
        <filter-mapping>
            <filter-name>CenterFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
      <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
      </welcome-file-list>
    </web-app>

### 核心配置文件 ###

<?xml version="1.0" encoding="UTF-8"?>
    
    <framework>
        
        <action name="addCustomer" class="cn.itcast.domain.Customer" method="addCustomer">
            
            <result type="redirect" name="success">/success.jsp</result>
            <result type="dispatcher" name="error">/error.jsp</result>
        </action>
        <action name="updateCustomer" class="cn.itcast.domain.Customer" method="updateCustomer">
            <result type="dispatcher" name="success">/success.jsp</result>
        </action>
    </framework>

### 核心过滤器实现 ###

1.  初始化配置文件,读取XML配置文件：把配置文件中的信息封装到对象中.再放到actions中
2.  取配置参数，如果你请求的地址以action\\do\\空结尾的话，才真正过滤。
3.  解析用户请求的URI，截取后缀名，看看是否需要我们的框架进行处理
4.  如果需要框架处理，解析uri中的动作名称，获得相应方法处理
5.  根据结果中的type决定是转发还是重定向，重定向的目标就是结果中的targetUri

package cn.itcast.framework.core;
    
    import java.io.IOException;
    import java.lang.reflect.Method;
    import java.util.HashMap;
    import java.util.List;
    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 org.apache.commons.beanutils.BeanUtils;
    import org.dom4j.Document;
    import org.dom4j.Element;
    
    import cn.itcast.framework.util.Dom4JUtil;
    
    public class CenterFilter implements Filter {
        
        //存取配置文件信息。key：对应action中的name value：Action对象
        private Map<String, Action> actions = new HashMap<String, Action>();
        private FilterConfig filterConfig;
    
        public void init(FilterConfig filterConfig) throws ServletException {
            initCfg();//初始化配置文件
            this.filterConfig = filterConfig;
    
        }
        //初始化配置文件
        private void initCfg() {
            //读取XML配置文件：把配置文件中的信息封装到对象中.再放到actions中
    
            Document document = Dom4JUtil.getDocument();
            Element root = document.getRootElement();
            //得到所有的action元素，创建Action对象，封装信息
            List<Element> actionElements = root.elements("action");
            if(actionElements!=null&&actionElements.size()>0){
                for(Element actionElement:actionElements){
                    //封装action信息开始
                    Action action = new Action();
                    action.setName(actionElement.attributeValue("name"));
                    action.setClassName(actionElement.attributeValue("class"));
                    String methodXmlAttrValue = actionElement.attributeValue("method");
                    if(methodXmlAttrValue!=null)
                        action.setMethod(methodXmlAttrValue);
                    //封装action信息结束
    
    
                    //得到每个action元素中的result元素，创建Result对象，封装信息
                    //封装属于当前action的结果
                    List<Element> resultElements = actionElement.elements("result");
                    if(resultElements!=null&&resultElements.size()>0){
                        for(Element resultElement:resultElements){
                            Result result = new Result();
                            result.setName(resultElement.attributeValue("name"));
                            result.setTargetUri(resultElement.getText().trim());
                            String typeXmlValue = resultElement.attributeValue("type");
                            if(typeXmlValue!=null){
                                result.setType(ResultType.valueOf(typeXmlValue));
                            }
                            action.getResults().add(result);
                        }
                    }
                    //封装属于当前action的结果
    
    
    
                    //把Action对象都放到Map中
                    actions.put(action.getName(), action);
                }
            }
        }
        public void doFilter(ServletRequest req, ServletResponse resp,
                FilterChain chain) throws IOException, ServletException {
            try {
                HttpServletRequest request = (HttpServletRequest)req;
                HttpServletResponse response = (HttpServletResponse)resp;
                //真正的控制器部分
    
                //取一个配置参数
                String aciontPostFixs [] = {
       "action","","do"};//你请求的地址以action\do\空结尾的话，才真正过滤。默认值
                String aciontPostFix = filterConfig.getInitParameter("aciontPostFix");
                if(aciontPostFix!=null){
                    aciontPostFixs = aciontPostFix.split("\\,");
                }
    
                //解析用户请求的URI
                String uri = request.getRequestURI();//   /strutsDay01MyFramework/addCustomer.action
    
                //截取后缀名，看看是否需要我们的框架进行处理
                //切后缀名
                String extendFileName = uri.substring(uri.lastIndexOf(".")+1);// /strutsDay01MyFramework/addCustomer.action   action
                                                                                // /strutsDay01MyFramework/addCustomer.do   do
                                                                                // /strutsDay01MyFramework/addCustomer   ""
                boolean needProcess = false;
                for(String s:aciontPostFixs){
                    if(extendFileName.equals(s)){
                        needProcess = true;
                        break;
                    }
                }
    
                if(needProcess){
                    //需要框架处理
                    //解析uri中的动作名称
                    String requestActionName = uri.substring(uri.lastIndexOf("/")+1, uri.lastIndexOf("."));
                    System.out.println("您的请求动作名是："+requestActionName);
                    //查找actions中对应的Action对象
                    if(actions.containsKey(requestActionName)){
                        Action action = actions.get(requestActionName);
                        //得到类名称的字节码
                        Class clazz = Class.forName(action.getClassName());
                        //封装数据到JavaBean中,利用BeanUtils框架
                        Object bean = clazz.newInstance();
                        BeanUtils.populate(bean, request.getParameterMap());
                        //实例化，调用其中指定的方法名称
                        Method m = clazz.getMethod(action.getMethod(), null);
                        //根据方法的返回值，遍历结果
                        String resultValue = (String)m.invoke(bean, null);
    
                        List<Result> results = action.getResults();
                        if(results!=null&&results.size()>0){
                            for(Result result:results){
    
                                if(resultValue.equals(result.getName())){
                                    //根据结果中的type决定是转发还是重定向
                                    //重定向的目标就是结果中的targetUri
                                    if("dispatcher".equals(result.getType().toString())){
                                        //转发
                                        request.getRequestDispatcher(result.getTargetUri()).forward(request, response);
                                    }
                                    if("redirect".equals(result.getType().toString())){
                                        //重定向
                                        response.sendRedirect(request.getContextPath()+result.getTargetUri());
                                    }
                                }
                            }
                        }
                    }else{
                        throw new RuntimeException("The action "+requestActionName+" is not founded in your config files!");
                    }
    
                }else{
                    chain.doFilter(request, response);
                }
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
    
        }
    
        public void destroy() {
    
        }
    
    }

### javabean如下 ###

package cn.itcast.domain;
    
    import java.io.Serializable;
    
    public class Customer implements Serializable {
        
        private String name;
        private int age;
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        public String addCustomer(){
            if("wzhting".equals(name)){
                return "success";
            }else{
                return "error";
            }
        }
    }

### 完成 ###

[20160424163431279]: /images/20220724/d1fb465c1415449380d8822f25b0298c.png