[原创]java WEB学习笔记65：Struts2 学习之路--Struts的CRUD操作( 查看 / 删除/ 添加) ModelDriven拦截器 paramter 拦截器

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1.代码结构

2.代码

 package com.jason.strut2.curd;

 public class EmployeeBean {

     private Integer employeeId;
     private String firstNmame;
     private String lastName;
     private String email;

     public Integer getEmployeeId() {
         return employeeId;
     }

     public void setEmployeeId(Integer employeeId) {
         this.employeeId = employeeId;
     }

     public String getFirstNmame() {
         return firstNmame;
     }

     public void setFirstNmame(String firstNmame) {
         this.firstNmame = firstNmame;
     }

     public String getLastName() {
         return lastName;
     }

     public void setLastName(String lastName) {
         this.lastName = lastName;
     }

     public String getEmail() {
         return email;
     }

     public void setEmail(String email) {
         this.email = email;
     }

     public EmployeeBean(Integer employeeId, String firstNmame, String lastName,
             String email) {
         super();
         this.employeeId = employeeId;
         this.firstNmame = firstNmame;
         this.lastName = lastName;
         this.email = email;
     }

     public EmployeeBean() {
         super();
     }

 }

EmployeeBean

 package com.jason.strut2.curd;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 public class Dao {

      private static Map<Integer, EmployeeBean> employees =  new HashMap<Integer, EmployeeBean>();

      static{

          employees.put(1001, new EmployeeBean(1001,"AA","aa","AA@163.com"));
          employees.put(1002, new EmployeeBean(1002,"BB","bb","BB@163.com"));
          employees.put(1003, new EmployeeBean(1003,"CC","cc","CC@163.com"));
          employees.put(1004, new EmployeeBean(1004,"DD","dd","DD@163.com"));
          employees.put(1005, new EmployeeBean(1005,"EE","ee","EE@163.com"));

      }

      //查看
      public List<EmployeeBean> getEmployees(){
          return new ArrayList<>(employees.values());
      }

      //删除
      public void delete(Integer id){
          employees.remove(id);
      }

      //保存
      public void save(EmployeeBean employeeBean){
          long time = System.currentTimeMillis();
          employeeBean.setEmployeeId((int) time);
          employees.put(employeeBean.getEmployeeId(), employeeBean);

      }

      //获取
      public EmployeeBean get(Integer employeeId){

          return  employees.get(employeeId);
      }

      //更新
      public void update(EmployeeBean employeeBean){
          employees.put(employeeBean.getEmployeeId(), employeeBean);
      }

 }

Dao

 package com.jason.strut2.curd;

 import java.util.Map;

 import org.apache.struts2.interceptor.RequestAware;

 public class EmployeeAction implements RequestAware {

     private Dao dao = new Dao();
     private Map<String, Object> requestMap;

     // 需要在当前的 EmployeeAction 中定义employeeId 属性，以接收页面请求参数：删除操作
     private Integer employeeId;

     public String list() {

         requestMap.put("emps", dao.getEmployees());
         return "list";
     }

     public String delete() {

         dao.delete(employeeId);
         // 返回结果的类型应为 ：redirectAction,也可以是chain：实际chain 是没有必要
         // 还有，若使用chain 则到达目标页面后，地址栏显示的依然是 删除 的那个连接，刷新时 会有重复提交
         return "delete";
     }

     @Override
     public void setRequest(Map<String, Object> requestMap) {
         this.requestMap = requestMap;
     }

     public Integer getEmployeeId() {
         return employeeId;
     }

     public void setEmployeeId(Integer employeeId) {
         this.employeeId = employeeId;
     }

 }

EmployeeAction

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
 <!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=UTF-8">
 <title>Insert title here</title>
 </head>
 <body>

     <a href="emp-list">List All Employees</a>

 </body>
 </html>

web.xml

　　

 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
     "http://struts.apache.org/dtds/struts-2.3.dtd">

 <struts>

      <constant name="struts.action.extension" value="action,do,"></constant>
      <package name="default" namespace="/" extends="struts-default">

          <action name="emp-*" class="com.jason.strut2.curd.EmployeeAction" method="{1}">
              <result name="{1}">/emp-{1}.jsp</result>
              <result name="delete" type="redirectAction">emp-list</result>
          </action>

      </package>
 </struts>

struts.xml

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
 <!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=UTF-8">
 <title>Insert title here</title>
 </head>
 <body>

     <a href="emp-list">List All Employees</a>

 </body>
 </html>

index.jsp

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

  <%@ taglib prefix="s" uri="/struts-tags" %>
 <!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=UTF-8">
 <title>Insert title here</title>
 </head>
 <body>

     <table cellpadding="10" cellspacing="0" border="1">
         <thead>
             <tr>
                 <td>ID</td>
                 <td>FirstName</td>
                 <td>LastName</td>
                 <td>Email</td>
                 <td>Edit</td>
                 <td>Delete</td>
             </tr>
         </thead>
         <tbody>
             <s:iterator  value="#request.emps">
                 <tr>
                     <td>${employeeId}</td>
                     <td>${firstName}</td>
                     <td>${lastName}</td>
                     <td>${email}</td>
                     <td><a href="">Eidt</a></td>
                     <td><a href="emp-delete?employeeId=${employeeId }">Delete</a></td>
                 </tr>
             </s:iterator>
         </tbody>

     </table>

 </body>
 </html>

emp-list.jsp

3.Struts2 运行流程图-1

　　

4.Params 拦截器：

Parameters 拦截器将把表单字段映射到 ValueStack 栈的栈顶对象的各个属性中. 如果某个字段在模型里没有匹配的属性, Param 拦截器将尝试 ValueStack 栈中的下一个对象

5.ModelDriven拦截器

　　1）当用户触发 add 请求时, ModelDriven 拦截器将调用 EmployeeAction 对象的 getModel() 方法, 并把返回的模型(Employee实例)压入到 ValueStack 栈.

　　2）接下来 Parameters 拦截器将把表单字段映射到 ValueStack 栈的栈顶对象的各个属性中. 因为此时 ValueStack 栈的栈顶元素是刚被压入的模型(Employee)对象, 所以该模型将被填充. 如果某个字段在模型里没有匹配的属性, Param 拦截器将尝试 ValueStack 栈中的下一个对象

　　Action 实现ModelDriven 接口后的运行流程

　

 @Override
         public String intercept(ActionInvocation invocation) throws Exception {

         //获取Action 对象:EmployeeAction对象，此时该Action 已经实现了ModelDriven 接口
          //public class EmployeeAction implements RequestAware ,ModelDriven<EmployeeBean>
             Object action = invocation.getAction();
            //判断：action是否是ModelDriven 的实例
             if (action instanceof ModelDriven) {
                 //强制转换 ModelDriven 类型
                 ModelDriven modelDriven = (ModelDriven) action;
                 //获取值栈
                 ValueStack stack = invocation.getStack();
                 //调用 ModelDriven 接口的getModel()方法
                  //即 调用 EmployeeAction 的 getModel()方法
                 /*
                  *     @Override
                     public EmployeeBean getModel() {
                               employeeBean  = new EmployeeBean();
                         return employeeBean;
                     }

                  */

                 Object model = modelDriven.getModel();
                 if (model !=  null) {
                     //把getModel 的返回值压入到值栈的栈顶：实际压入的是employeeAction 的成员变量，employeeBean
                     stack.push(model);
                 }
                 if (refreshModelBeforeResult) {
                     invocation.addPreResultListener(new RefreshModelBeforeResult(modelDriven, model));
                 }
             }
             return invocation.invoke();
         }

      //执行：PramaterInterception 的intercept() 方法:把请求的参数的值赋给栈顶对象，对应的属性，
      //若栈顶对象没有对应的属性，则查询值栈中的下一个对象，直到找到此属性，赋值。

 注意：getModel()方法不能如下实现
　　因为 可以将此对象压入值栈的栈顶；但是当前的Action 成员变量是 null；

  public EmployeeBean getModel() {
　　return new Employee();
}

　　

实现modelDriven 接口

 package com.jason.strut2.curd;

 import java.util.Map;

 import org.apache.struts2.interceptor.RequestAware;

 import com.opensymphony.xwork2.ActionInvocation;
 import com.opensymphony.xwork2.ModelDriven;
 import com.opensymphony.xwork2.util.ValueStack;

 public class EmployeeAction implements RequestAware ,ModelDriven<EmployeeBean>{

     private Dao dao = new Dao();
     private Map<String, Object> requestMap;
     private EmployeeBean employeeBean;

     // 需要在当前的 EmployeeAction 中定义employeeId 属性，以接收页面请求参数：删除操作

     public String list() {

         requestMap.put("emps", dao.getEmployees());
         return "list";
     }

     //删除
     public String delete() {

         dao.delete(employeeBean.getEmployeeId());
         // 返回结果的类型应为 ：redirectAction,也可以是chain：实际chain 是没有必要
         // 还有，若使用chain 则到达目标页面后，地址栏显示的依然是 删除 的那个连接，刷新时 会有重复提交
         return "success";
     }

     public String save(){

             //1.获取请求参数:通过定义属性的方式
             //2.调用DAO的 svae 方法

             dao.save(employeeBean);
             //3.通过redirectAction 的方式响应结果给 emp-list
             return "success";
     }

     @Override
     public void setRequest(Map<String, Object> requestMap) {
         this.requestMap = requestMap;
     }

     @Override
     public EmployeeBean getModel() {
           employeeBean  = new EmployeeBean();
         return employeeBean;
     }

 }

public class EmployeeAction implements RequestAware ,ModelDriven

图示说明：