框架学习之自己动手实现Struts框架

前言：

MVC模式回顾：Model(模型) View（视图） Controller(控制器)

框架无非目的是为了简化代码，快捷开发，万变不离其宗。Structs就是对其中的Controller层进行优化，在JavaWeb中也就是Servlet。

现在回想下之前不用框架之前的麻烦点：

1. 跳转代码写死，不灵活；

2. 每次都去写Servlet,然后web.xml中配置Servlet。（配置目的： 请求, Servlet处理类）

于是想到能不能进行优化呢，如果有几十个甚至上百个Servlet那web.xml是不是会非常臃肿呢？现在先自己动手实现优化，实现第一个自己的MyStruct。

需求：

一个简单的登录注册

设计User实体类、DAO与Service

ppackage entity;

/**
* 实体类 User
* Created by Administrator on 2017/1/6.
*/
public class User {

private String name;
private String pwd;

public String getPwd() {
return pwd;
}

public void setPwd(String pwd) {
this.pwd = pwd;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

package dao;

import entity.User;

/**
* Created by Administrator on 2017/1/6.
*/
public class UserDao {

//模拟登陆
public User login(User user){
if("admin".equals(user.getName()) &&
"admin".equals(user.getPwd())){
return user;
}
return null;
}

//模拟注册
public void regist(User user){
System.out.println("注册成功，欢迎您 " + user.getName());
}

}

package service;

import dao.UserDao;
import entity.User;

/**
* Created by Administrator on 2017/1/6.
*/
public class UserService {

private UserDao dao = new UserDao();

// 模拟登陆
public User login(User user){
return dao.login(user);
}

// 模拟注册
public void regist(User user) {
dao.regist(user);
}

}

核心，模拟Structs中的设计，自己写一个ActionServlet，来管理项目中所有的Servlet，首先在src目录下新建一个mystructs.xml文件，配置项目中的Servlet。先设计配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<mystruts>
<package>
<!-- 配置请求路径，与处理action类的关系 -->
<!--
1. 请求路径与处理Action的关系
/login = LoginAction                          login
success = /index.jsp                     登陆成功(重定向)
loginFaild  = /login.jsp                 登陆失败

-->
<action name="login" class="framework.action.LoginAction" method="login">
<result name="loginSuccess" type="redirect">/index.jsp</result>
<result name="loginFaild">/login.jsp</result>
</action>

<action name="register" class="framework.action.RegistAction" method="register">
<result name="registerSuccess">/login</result>
</action>

</package>

</mystruts>

然后写两个Action类

package framework.action;

import entity.User;
import service.UserService;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
* Action表示动作类
* 1. 一个servlet对应一个action 2. action中负责处理具体的请求
* Created by Administrator on 2017/1/6.
*/
public class LoginAction {

public Object execute(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
return null;
}

/**
* 处理登陆请求
*/
public Object login(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Object uri = null;

//1.获取请求数据，封装
String name = request.getParameter("name");
String pwd = request.getParameter("pwd");
User user = new User();
user.setName(name);
user.setPwd(pwd);

//2.调用Service
UserService userService = new UserService();
User userInfo = userService.login(user);

//3.跳转
if(userInfo == null){
//登陆失败
uri = "loginFailed";
}else {
//登陆成功
request.getSession().setAttribute("userInfo",userInfo);
uri = "loginSuccess";
}
return uri;
}

}

package framework.action;

import entity.User;
import service.UserService;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
* RegistAction
* Created by Administrator on 2017/1/6.
*/
public class RegistAction {

public Object regist(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Object uri = null;

//1.获取请求数据，封装
String name = request.getParameter("name");
String pwd = request.getParameter("pwd");
User user = new User();
user.setName(name);
user.setPwd(pwd);

//2.调用Service
UserService userService = new UserService();
userService.regist(user);

//3.跳转
uri = "registSuccess";

return uri;
}

}

接着写一个ActionMapping来封装配置文件中的action节点

package framework.bean;

import java.util.Map;

/**
* 封装action节点
* Created by Administrator on 2017/1/6.
*/
public class ActionMapping {

//请求路径名称
private String name;
//处理action类的全名
private String className;
//处理方法
private String method;
//结果视图集合
private Map<String,Result> results;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getClassName() {
return className;
}

public void setClassName(String className) {
this.className = className;
}

public String getMethod() {
return method;
}

public void setMethod(String method) {
this.method = method;
}

public Map<String, Result> getResults() {
return results;
}

public void setResults(Map<String, Result> results) {
this.results = results;
}
}

还有一个封装结果视图的Result

package framework.bean;

/**
* 封装结果视图
* <result name="success" type="redirect">/index.jsp</result>
* Created by Administrator on 2017/1/6.
*/
public class Result {

// 跳转的结果标记
private String name;
// 跳转类型，默认为转发； "redirect"为重定向
private String type;
// 跳转的页面
private String page;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getType() {
return type;
}

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

public String getPage() {
return page;
}

public void setPage(String page) {
this.page = page;
}
}

再写一个ActionMappingManager类：

package framework.bean;

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

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

/**
* 加载配置文件, 封装所有的整个 mystruts.xml
* Created by Administrator on 2017/1/6.
*/
public class ActionMappingManager {

//保存action的集合
private Map<String, ActionMapping> allActions;

public ActionMappingManager() {
allActions = new HashMap<String, ActionMapping>();
this.init();
}

public ActionMapping getActionMapping(String actionName){
if (actionName == null) {
throw new RuntimeException("传入参数有误，请查看struts.xml配置的路径。");
}

ActionMapping actionMapping = allActions.get(actionName);
if (actionMapping == null) {
throw new RuntimeException("该路径在struts.xml中找不到，请检查");
}
return actionMapping;
}

//初始化allCollection集合
private void init() {
//DOM4J读取配置文件
try {
//1.得到解析器
SAXReader reader = new SAXReader();
//得到mystruct.xml文件流
InputStream in = this.getClass().getResourceAsStream("/mystructs.xml");

//2.加载文件
Document doc = reader.read(in);

//3，获取根节点
Element root = doc.getRootElement();

//4.得到packet节点
Element ele_package = root.element("package");

//5.得到根结点下所有的action节点
List<Element> listAction = ele_package.elements("action");

//6.遍历，封装
for (Element e : listAction) {
// 6.1 封装一个ActionMapping对象
ActionMapping actionMapping = new ActionMapping();
actionMapping.setName(e.attributeValue("name"));
actionMapping.setClassName(e.attributeValue("class"));
actionMapping.setMethod(e.attributeValue("method"));

// 6.2 封装当前aciton节点下所有的结果视图
Map<String,Result> results = new HashMap<String,Result>();

//得到action节点下的所有result节点
Iterator<Element> it = e.elementIterator("result");
while(it.hasNext()){
Element ele_result = it.next();

//封装对象
Result res = new Result();
res.setName(ele_result.attributeValue("name"));
res.setType(ele_result.attributeValue("type"));
res.setPage(ele_result.getTextTrim());

//添加到集合
results.put(res.getName(),res);
}

// 设置到actionMapping中
actionMapping.setResults(results);

//actionMapping添加到map集合
allActions.put(actionMapping.getName(),actionMapping);
}

} catch (Exception e) {
throw new RuntimeException("启动初始化出错",e);
}
}
}

然后记得在web.xml中配置ActionServlet

<servlet>
<servlet-name>ActionServlet</servlet-name>
<servlet-class>framework.ActionServlet</servlet-class>
<!-- 启动时候执行servlet初始化方法 -->
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>ActionServlet</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>

最后完成三个jsp页面，login.jsp,regist.jsp,index.jsp

//index.jsp
<body>
欢迎你，${sessionScope.userInfo.name}
</body>

//login.jsp
<body>
<form action="${pageContext.request.contextPath}/login.action" name="frmLogin" method="post">
用户名：<input type="text" name="name"><br/>
密 码：<input type="text" name="pwd"><br/>
<input type="submit" value="登陆"> <br/>
</form>
</body>

//regist.jsp
<body>
<form action="${pageContext.request.contextPath }/regist.action" name="frmRegister"  method="post">
用户名： <input type="text" name="name"> <br/>
密码： <input type="text" name="pwd"> <br/>
<input type="submit" value="注册"> <br/>
</form>
</body>

第一个自己动手的Structs框架项目完成！