实例模拟struts核心流程

Struts，经典框架之一，每个java  web 开发人员都应该晓得它的大名。这里，我就用一个简单实例来模拟一下struts的核心流程。具体实例如下：

主界面：

点击提交后，程序根据具体的action，跳转到不同的页面。下面看一下具体的实现代码。

文件树：

ActionConfig.xml 代码：

<?xml version="1.0" encoding="UTF-8"?>
<action-config>
	<action path = "/addUser.action" type = "com.tigaoban.manager.AddUserAction">
		<forward name = "success">/addSuccess.jsp</forward>
		<forward name = "error">/addError.jsp</forward>
	</action>

	<action path = "/delUser.action" type = "com.tigaoban.manager.DelUserAction">
		<forward name = "success">/delSuccess.jsp</forward>
		<forward name = "error">/delError.jsp</forward>
	</action>

	<action path = "/modifyUser.action" type = "com.tigaoban.manager.ModifyUserAction">
		<forward name = "success">/modifySuccess.jsp</forward>
		<forward name = "error">/modifyError.jsp</forward>
	</action>

	<action path = "/queryUser.action" type = "com.tigaoban.manager.QueryUserAction">
		<forward name = "success">/querySuccess.jsp</forward>
		<forward name = "error">/queryError.jsp</forward>
	</action>
</action-config>

ActionMapping 代码：

package com.tigaoban.domain;

import java.util.Map;

public class ActionMapping {
	private String path;

	private String type;

	private Map<String, String> forwardMap;

	public String getPath() {
		return path;
	}

	public void setPath(String path) {
		this.path = path;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public Map<String, String> getForwardMap() {
		return forwardMap;
	}

	public void setForwardMap(Map<String, String> forwardMap) {
		this.forwardMap = forwardMap;
	}
}

XmlConfigReader 代码：

package com.tigaoban.util;

import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import com.tigaoban.domain.ActionMapping;

/**
 * 采用单例模式解析ActionConfig.xml文件
 * @author Haitao
 *
 */
public class XmlConfigReader {

	//懒汉式
	private static XmlConfigReader instance = null;//XmlConfigReader 实例

	//key=名称，value = 具体的动作实体类
	private Map<String, ActionMapping> actionMap = new HashMap<String, ActionMapping>();

	/**
	 * 构造方法
	 */
	private XmlConfigReader(){
		SAXReader reader = new SAXReader();
		InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("ActionConfig.xml");

		try {
			Document doc = reader.read(in);

			//取得Action相关的配置信息,并存入ActionMapping实体中
			List<Element> actionList = doc.selectNodes("//action");
			for (Iterator<Element> iter = actionList.iterator(); iter.hasNext();){
				Element element = iter.next();

				String path = element.attributeValue("path");
				String type = element.attributeValue("type");
				//System.out.println(path);

				List<Element> forwardList = element.elements("forward");
				//存放forward中信息的map
				Map<String,String> forwardMap = new HashMap<String, String>();

				for (Iterator<Element> iterator = forwardList.iterator();iterator.hasNext();){
					Element forward = iterator.next();
					String name = forward.attributeValue("name");
					String value = (String)forward.getData();
					forwardMap.put(name, value);
				}

				//新建ActionMapping实体
				ActionMapping actionMapping = new ActionMapping();
				actionMapping.setPath(path);
				actionMapping.setType(type);
				actionMapping.setForwardMap(forwardMap);

				//将actionMapping放入map中
				actionMap.put(path, actionMapping);

			}
		} catch (DocumentException e) {
			e.printStackTrace();
		}
	}

	public static synchronized XmlConfigReader getInstance() {
		if(instance == null){
			instance = new XmlConfigReader();
		}
		return instance;
	}

	/**
	 * 取得action相关配置
	 * @return
	 */
	public Map<String, ActionMapping>  getMap() {
		return actionMap;
	}

}	

UserManager代码：

package com.tigaoban.manager;

import java.util.ArrayList;
import java.util.List;

public class UserManager {
	public void addUser(String username){
		System.out.println("添加成功" + username);
	}

	public void delUser(String username){
		System.out.println("删除成功" + username);
	}

	public void modifyUser(String username){
		System.out.println("修改成功" + username);
	}

	public List<String> queryUser(String username){
		System.out.println("查询成功" + username);
		List<String> userList = new ArrayList<String>();
		userList.add("a");
		userList.add("b");
		userList.add("c");
		return userList;

	}
}

Action代码：

package com.tigaoban.manager;

import javax.servlet.http.*;

public interface Action {
	public String execute(HttpServletRequest request,HttpServletResponse response)
	throws Exception;
}

AddUserAction代码

package com.tigaoban.manager;

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

public class AddUserAction implements Action {

	@Override
	public String execute(HttpServletRequest request,
			HttpServletResponse response) throws Exception {
		String userName = request.getParameter("userName");

		UserManager userManager = new UserManager();
		userManager.addUser(userName);
		return "/addSuccess.jsp";
	}

}

DelUserAction代码：

package com.tigaoban.manager;

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

public class DelUserAction implements Action {

	@Override
	public String execute(HttpServletRequest request,
			HttpServletResponse response) throws Exception {

		String userName = request.getParameter("userName");
		UserManager userManager = new UserManager();
		userManager.delUser(userName);
		return "/delSuccess.jsp";
	}

}

ModifyUserAction代码：

package com.tigaoban.manager;

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

public class ModifyUserAction implements Action {

	@Override
	public String execute(HttpServletRequest request,
			HttpServletResponse response) throws Exception {

		String userName = request.getParameter("userName");
		UserManager userManager = new UserManager();
		userManager.modifyUser(userName);
		return "/modifySuccess.jsp";
	}

}

QueryUserAction代码：

package com.tigaoban.manager;

import java.util.Iterator;
import java.util.List;

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

public class QueryUserAction implements Action {

	@Override
	public String execute(HttpServletRequest request,
			HttpServletResponse response) throws Exception {

		String userName = request.getParameter("userName");
		UserManager userManager = new UserManager();
		List<String> userList = userManager.queryUser(userName);
		for (Iterator<String> itor = userList.iterator();itor.hasNext();){
			String user = itor.next();
			System.out.println(user);
		}
		return "/querySuccess.jsp";
	}

}

TestServlet代码

package com.tigaoban.servlet;

import java.io.IOException;
import java.util.*;

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

import com.tigaoban.domain.ActionMapping;
import com.tigaoban.manager.Action;
import com.tigaoban.util.XmlConfigReader;

@SuppressWarnings("serial")
public class TestServlet extends HttpServlet {

	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String requestUrl = request.getServletPath();
		String path = requestUrl.substring(requestUrl.indexOf("/",1),requestUrl.length());
		//System.out.println(path);

		String forward = "";
		Action action = null;

		//取得actionMap
		Map<String,ActionMapping> actionMap = XmlConfigReader.getInstance().getMap();

		//根据path取得对应的ActionMapping
		ActionMapping actionMapping = (ActionMapping)actionMap.get(path);

		//取得本请求对应的Action类的完整路径
		String type = actionMapping.getType();

		try {
			//使用反射动态实例化Action
			action = (Action)Class.forName(type).newInstance();
		} catch (InstantiationException e1) {
			e1.printStackTrace();
		} catch (IllegalAccessException e1) {
			e1.printStackTrace();
		} catch (ClassNotFoundException e1) {
			e1.printStackTrace();
		}
		try {
			forward = action.execute(request, response);
		} catch (Exception e) {
			e.printStackTrace();
		}

		response.sendRedirect(request.getContextPath() + forward);
	}

}

一下是几个很简单的jsp页面：

user.jsp页面：

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
	<form action="servlet/addUser.action" method="post">
		姓名：<input type ="text" name = "userName" /><br>
		<input type="submit" value="提交"/>
	</form>
</body>
</html>

addSuccess.jsp、modifySuccess.jsp、delSuccess.jsp、querySuccess.jsp页面：

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
	添加/修改/删除/查询成功！
</body>
</html>

以上就是struts的核心流程，明白了这个例子，相信对你理解struts有很大帮助。