Struts的属性驱动与模型驱动的区别

          1.Struts2的属性驱动.

          Struts2的属性驱动指的是在action中JSP页面的每一个form中的name都对应在action中有一个属性与之对应。看下面代码片段:

 

          <form action="register.do" name="RegisterForm" method="post">

                     Username:<input type="text" name="uname"><br>
                     Password:<input type="password" name="upass"><br>
                     Confirm: <input type="password" name="rpass"><br>
                     <input type="submit" value="Submit">

          </form>

 

          这是一个最基本的用户注册的表单,它有三个数据要提交: uname、upass、rpass，那么对应的Action也要有三个属性（其实是三个属性的setter），看register.do实际的Action定义类：

 

         package org.abu.csdn.action.user;

 

        import com.opensymphony.xwork2.ActionSupport;

        /**
           * Struts2属性驱动演示用的Action
           * @author  fy

           *
           */
         public class RegisterAction extends ActionSupport {

 

                   private String uname;
                   private String upass;
                   private String rpass;

 

                   public String getUname() {
                              return uname;
                  }

                   public void setUname(String uname) {
                             this.uname = uname;
                   }

                   public String getUpass() {
                             return upass;
                   }

                   public void setUpass(String upass) {
                             this.upass = upass;
                   }

                   public String getRpass() {
                             return rpass;
                   }

                   public void setRpass(String rpass) {
                             this.rpass = rpass;
                   }
   
                   @Override
                   public String execute() throws Exception {       
                             return ActionSupport.SUCCESS;
                   }

          }

 

 

         你会看到RegisterAction中的三个属性和RegisterForm表单中的name属性名字一模一样，没错，这就是Struts2的属性驱动，当表单提交到RegisterAction后，Struts2将会自动将根据表单的name属性调用Action中相应的属性setter，去自动赋值。

 

          2.Struts2的模型驱动

Struts2的模型驱动其实和Struts1.x中的ActionForm有点类似，在Struts1.x中每一个Action都必须有一个ActionForm与之对应，而Struts2.0中，每一个Action同样需要提供一个POJO对象，用来封装表单属性，看代码：

 

          <form  action="register.do" name="RegisterForm" method="post">

                      Username:<input type="text" name="uname"><br>
                      Password:<input type="password" name="upass"><br>
                      Confirm: <input type="password" name="rpass"><br>
                      <input type="submit" value="Submit">

           </form>

 

            这段表单的代码和上面的一模一样，就不赘述了。接下来看POJO的代码，其实就是普通的Java Bean：

            RegisterAction代码：

 
            package org.abu.csdn.action.user;

            import org.abu.csdn.dto.User;

            import com.opensymphony.xwork2.ActionSupport;
            import com.opensymphony.xwork2.ModelDriven;

            /**
             * Struts2模型驱动演示用的Action
             * 
             * @author  fy

             *
             */

             public class RegisterAction extends ActionSupport implements ModelDriven<User> {

 

                       private User user;
   
                       public User getUser() {
                                 return user;
                      }

                       public void setUser(User user) {
                                 this.user = user;
                       }

                       @Override
                       public String execute() throws Exception {       
                                 return ActionSupport.SUCCESS;
                       }

                       // 模型驱动必须实现的方法，也是ModelDriven接口中唯一的方法
                       public User getModel() {
       
                                 return user;
                       }

               }

 

 

               模型驱动和属性驱动的Action有很大的区别，下面一一列举：

 

              （1）模型驱动的Action必须实现ModelDriven接口，而且要提供相应的泛型，这里当然就是具体使用的Java Bean了。

              （2）实现ModelDriven的getModel方法，其实就是简单的返回泛型的一个对象。

              （3）在Action提供一个泛型的私有对象，这里就是定义一个User的user对象，并提供相应的getter与setter。 好了，上面的三件事做完之后，Action就会去自动调用User的setter将表单中的name属性的值赋给User中的属性。而Action的后续处理的Jsp页面后者是Servlet就可以使用user对象了。

 

               3.到底是用属性驱动和是模型驱动呢？

 

                这个问题困扰了很多Struts2的初学者，我这里提供一些建议：

               （1）请你统一整个系统中的Action使用的驱动模型，即要么都是用属性驱动，要么都是用模型驱动。

               （2）如果你的DB中的持久层的对象与表单中的属性都是一一对应的话，那么就使用模型驱动吧，毕竟看起来代码要整洁得多。

               （3）如果表单的属性不是一一对应的话，那么就应该使用属性驱动，否则，你的系统就必须提供两个Bean，一个对应表单提交的数据，另一个用与持久层。

 

                看上面的例子，其实密码确认rpass是不需要放到DB中去的，而仅仅是用于校验密码的，不是吗？那么如果使用模型驱动的话，就存在这个问题了，而使用属性驱动的话又有些繁琐，现在我们就来调整一个看我的解决方法：

 

                 4.完整的例子

                 （1）表单提交的JSP页面index.jsp

 

                 <%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%>
                <%@ taglib uri="/struts-tags" prefix="s"%>
                <%

                String path = request.getContextPath();
                String basePath = request.getScheme() + "://"
                + request.getServerName() + ":" + request.getServerPort()
                + path + "/";
                %>

               <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"                "http://www.w3.org/TR/html4/loose.dtd">
                <html>
                         <head>
                                     <base href="<%=basePath%>">
                                     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
                                     <title>CSDN首页</title>
                        </head>
                        <body>
                                     <s:a href="userManager/userRegister.jsp">用户注册</s:a>
       
                                      <form action="register.do" name="SampleForm" method="post">
                                      Username:<input type="text" name="uname"><br>
                                      Password:<input type="password" name="upass"><br>
                                      Confirm: <input type="password" name="rpass"><br>
                                      <input type="submit" value="Submit">
                                      </form>
                         </body>
                </html>

 

                (2)User的定义

 

                package org.abu.csdn.action.user;

                import com.opensymphony.xwork2.ActionSupport;

                /**
                  * Struts2属性驱动演示用的Java Bean
                  * @author fy

                  *
                  */
                public class User {

 

                          private String uname;
                          private String upass; 

 

                          public String getUname() {
                                    return uname;
                          }

                          public void setUname(String uname) {
                                    this.uname = uname;
                          }

                          public String getUpass() {
                                    return upass;
                          }

                          public void setUpass(String upass) {
                                    this.upass = upass;
                          }   
   
                }

 

                （3）RegisterAction的定义

 

                package org.abu.csdn.action.user;

                import com.opensymphony.xwork2.ActionSupport;

                /**
                 * Struts2属性驱动演示用的Action
                 * @author  fy

                 *
                 */
                 public class RegisterAction extends ActionSupport {

 

                 // 用来给spring注入，及属性拷贝 
                 private User user;

                 private String uname;
                 private String upass;
                 private String rpass;

 

                 public String getUname() {
                           return uname;
                 }

                 public void setUname(String uname) {
                           this.uname = uname;
                 }

                 public String getUpass() {
                            return upass;
                 }

                 public void setUpass(String upass) {
                           this.upass = upass;
                 }

                 public String getRpass() {
                           return rpass;
                 }

                 public void setRpass(String rpass) {
                           this.rpass = rpass;
                }
   
                 @Override
                 public String execute() throws Exception {

                          // 调用方法将属性copy到user中去，便于后续的service方法 
                           copyAttribute();

                          // TODO：编写自己的user业务代码
                           return ActionSupport.SUCCESS;
                  }

 

               /**
                * 注意这是一个action全局的校验
                */
               @Override

              public void validate() {

                        // 进行密码的校验
                        if (!(upass.trim()).equals((rpass.trim()))) {
                            // 注意这里addFieldError的fieldName参数必须用引号引起来,
                            // 不能这样使用addFieldError(rpass,"XXXXXX"),而必须是addFieldError("rpass","XXXXX")
                            this.addFieldError("rpass", this.getText("csdn.action.user.register.validate.verify"));
                        }
              }

 

 

 

              /**
               * 将表单属性中需要持久化的属性拷贝到user中去
               * @author fy

               *
               */

               private void copyAttributes () {

                           user.setUname(uname);

                           user.setUpass(upass);

               }

            }

 

 

 

            （4）Struts.xml配置

            <?xml version="1.0" encoding="UTF-8" ?>
            <!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN"
    "http://struts.apache.org/dtds/struts-2.1.dtd">
             <struts>
                     <package name="root" extends="struts-default" namespace="/userManager">
                                    <action name="userRegister" class="org.abu.csdn.action.user.RegisterAction">
                                              <result name="success">/index.jsp</result>
                                              <result name="input">/userManager/userRegister.jsp</result>
                                    </action>               
                     </package>
              </struts>