自己写框架-MVC(二)

2016 年 2 月 18 日 jslfl 架构

技术要点:
反射

改造计划：
1.自动封装formbean对象
2.业务处理代码从servlet中分离

代码结构:

1、创建FormBeanUtil工具类，用来完成自动封装formbean的任务

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package cn.jslfl.mvc.core.form;

import java.lang.reflect.Field;
import javax.servlet.http.HttpServletRequest;

/**
* 请求表单form对象封装工具类
* @author jslfl
*/
public class FormBeanUtil {
/**
* @param req HttpServletRequest对象
* @param formBeanName formBean类全名
* @return formBean实例
*/
public static Object packFormBean(HttpServletRequest req, String formBeanName){
Object form = null;
try {
Class c = Class.forName(formBeanName);
form = c.newInstance();

Field[] fieldArr = c.getDeclaredFields();
for(Field f : fieldArr){
f.setAccessible(true);//设置private的属性可访问
f.set(form, req.getParameter(f.getName()));
f.setAccessible(false);
}
} catch (Exception e) {
e.printStackTrace();
}
return form;
}
}

注意：这儿用到反射来实例化类，并且newInstance()是通过类的无参构造方法进行实例化，所以如果类中没有定义无参构造方法的话，会出错。因此如果Form类中(LoginForm、RegForm)如果重载了参构造方法(带参)，则必须也定义一个无参构造方法。

2、改造登录业务
新建LoginAction.java,把LoginServlet中的业务处理代码抽离到LoginAction的doService方法中
2.1、LoginAction.java代码清单:

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package cn.jslfl.mvc.demo.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.form.FormBeanUtil;
import cn.jslfl.mvc.demo.form.LoginForm;

public class LoginAction {
public String doService(HttpServletRequest req, HttpServletResponse resp){
LoginForm formBean = (LoginForm)FormBeanUtil.packFormBean(req, "cn.jslfl.mvc.demo.form.LoginForm");

//业务处理开始...
boolean flag = false;
if("aa".equals(formBean.getUserName()) && "bb".equals(formBean.getPassWord())){
flag = true;
}
//业务处理结束...

String info = "<h1>登录" + (flag ? "成功" : "失败") + "!userName: " + formBean.getUserName()+ ", " + "password: " + formBean.getPassWord() + "</h1>";

req.setAttribute("info", info);

return "/web/userInfo.jsp";
}
}

LoginAction处理流程：
a.从request中封装form表单对象
b.业务处理操作
c.request中设置返回数据
d.返回请求要跳转的路径

2.2、LoginServlet.java代码清单:

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package cn.jslfl.mvc.demo.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.demo.action.LoginAction;

public class LoginServlet extends HttpServlet{
private static final long serialVersionUID = 1L;

public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("GBK");

LoginAction action = new LoginAction();
String returnPath = action.doService(req, resp);

req.getRequestDispatcher(returnPath).forward(req, resp);
}

public void doGet(HttpServletRequest req, HttpServletResponse resp){
try {
doPost(req, resp);
} catch (Exception e) {
e.printStackTrace();
}
}
}

LoginServlet处理流程：
a.创建LoginAction对象，并调用其doService方法
b.跳转到指定(获取的doService返回值)路径

2.3、发布到tomcat测试
访问登录页面提交表单

3、改造注册业务
3.1、RegAction.java代码清单:

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package cn.jslfl.mvc.demo.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.form.FormBeanUtil;
import cn.jslfl.mvc.demo.form.RegForm;

public class RegAction {
public String doService(HttpServletRequest req, HttpServletResponse resp){

RegForm regBean = (RegForm)FormBeanUtil.packFormBean(req, "cn.jslfl.mvc.demo.form.RegForm");

//业务处理开始...
String msg = "";
if(regBean.getUserName() == null || "".equals(regBean.getUserName().trim())
||regBean.getPassWord() == null || "".equals(regBean.getPassWord().trim())
|| regBean.getPassWord2() == null || "".equals(regBean.getPassWord2().trim())){
msg = "数据不完整";
}else if(!regBean.getPassWord().equals(regBean.getPassWord2())){
msg = "两次密码不匹配";
}else{
msg = "成功";
}
//业务处理结束...

String info = "<h1>注册" + msg + "!userName: " + regBean.getUserName() + ", " + "password: " + regBean.getPassWord() + ", " + "password2: " + regBean.getPassWord2() +"</h1>";
req.setAttribute("info", info);

return "/web/login.jsp";
}
}

3.2、RegServlet.java代码清单:

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package cn.jslfl.mvc.demo.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.demo.action.RegAction;

public class RegServlet extends HttpServlet{
private static final long serialVersionUID = 1L;

public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("GBK");

RegAction action = new RegAction();
String returnPath = action.doService(req, resp);

req.getRequestDispatcher(returnPath).forward(req, resp);
}

public void doGet(HttpServletRequest req, HttpServletResponse resp){
try {
doPost(req, resp);
} catch (Exception e) {
e.printStackTrace();
}
}
}

3.3、发布到tomcat测试
访问登录页面提交表单

本节中login.jsp、reg.jsp、userInfo.jsp、LoginForm.java、RegForm.java、web.xml未做修改，后台业务处理操作已转移到action中，servlet中代码已经很简单和单一，下一节将继续改造servlet。

mvc

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