struts原理

struts原理

配置文件：strust.xml

  //name:访问这个资源使用的url
  //class:资源的位置
  //method:资源中的方法名
  
    //结果集
    //name:方法的返回值
    //对应的资源名
    /index.jsp
    /error.jsp
  

实体类：ActionMapping.java

package com.javawu.action;
import java.util.Map;
public class ActionMapping {
    private String name;
    private String cls;
    private String method;
    private Map result;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getCls() {
        return cls;
    }
    public void setCls(String cls) {
        this.cls = cls;
    }
    public String getMethod() {
        return method;
    }
    public void setMethod(String method) {
        this.method = method;
    }
    public Map getResult() {
        return result;
    }
    public void setResult(Map result) {
        this.result = result;
    }   
}

解析xml类：ActionManager.java

package com.javawu.action;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
//解析xml文件
public class ActionManager {
    private List list = null;
    public List getList() {
        return list;
  }
    public ActionManager() {
        list = new ArrayList<>();
        try {
          parseXML();
        } catch (Exception e) {
        // TODO Auto-generated catch block
          e.printStackTrace();
        }
    }
    private void parseXML() throws Exception {
        SAXReader saxReader = new SAXReader();
        InputStream inputStream = ActionManager.class.getResourceAsStream("/struts.xml");
        Document document = saxReader.read(inputStream);
        Element rootElement = document.getRootElement();
        List aEles = rootElement.elements("action");
        if(aEles != null) {
            for (Element element : aEles) {
                ActionMapping actionMapping = new ActionMapping();
                actionMapping.setName(element.attributeValue("name"));
                actionMapping.setCls(element.attributeValue("class"));
                actionMapping.setMethod(element.attributeValue("method"));
                List rEles = element.elements("result");
                if(rEles != null) {
                    Map map = new HashMap<>();
                    for(Element res : rEles) {
                        map.put(res.attributeValue("name"), res.getText());
                    }
                    actionMapping.setResult(map);
                }
                list.add(actionMapping);
            }
        }
    }   
}

页面资源：login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







    //访问资源时使用在配置文件中配置的url
    

        user

        password

        
    

在web.xml中增加配置

    
        
        ActionServlet
        ActionServlet
        com.javawu.action.ActionServlet
    
        
        ActionServlet
        //访问所有以.action为结尾的资源时都会被ActionServlet.java拦截
        *.action
    

ActionServlet.java

package com.javawu.action;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.swing.internal.plaf.metal.resources.metal;
/**
 * Servlet implementation class ActionServlet
 */
public class ActionServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ActionServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
    /**
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        ActionManager actionManager = new ActionManager();
        List list = actionManager.getList();
        //获取请求的uri
        String uri = request.getRequestURI();
        //根据uri获取请求的资源
        uri = uri.substring(uri.lastIndexOf("/") + 1, uri.lastIndexOf(".action"));
        for(ActionMapping actionMapping : list) {
            if(actionMapping.getName().equals(uri)) {
                try {
                    Class cls = Class.forName(actionMapping.getCls());
                    Object newInstance = cls.newInstance();
                    Method method = cls.getDeclaredMethod(actionMapping.getMethod(), HttpServletRequest.class, HttpServletResponse.class);
                    String ret = (String)method.invoke(newInstance, request, response);
                    for(String result : actionMapping.getResult().keySet()) {
                        if (result.equals(ret)) {
                            response.sendRedirect(request.getContextPath() + actionMapping.getResult().get(result));
                        }
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } 
            }
        }   
    }
    /**
    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }
}

LoginAction.java

package com.javawu.action;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginAction {
    public String login(HttpServletRequest request, HttpServletResponse response) {
        if(request.getParameter("user_name").equals("admin") && request.getParameter("user_password").equals("123")) {
            return "success";
        }else {
            return "error";
        }   
    }   
}