struts2中 Action获取表单参数的几种方式

struts2 Action获取表单传值
1.通过属性驱动式
JSP:
<form action="sys/login.action" method="post">
      <input type="text" name="username">
      <input type="submit" value="submit">
</form>

Action:直接通过get、set方法获取。

public class sysAction extends ActionSupport{
     private String username;

     public String login() throws Exception {
            System.out.println(username);
            return SUCCESS;
     }

     public String getUsername() {
            return username;
     }
     public void setUsername(String username) {
            this.username= username;
     }
}

2.模型驱动方式，必须要实现ModelDriven<T>接口。对于要传入多个model第二种方式不方便
JSP:
<form action="sys/login.action" method="post">
       <input type="text" name="username">
       <input type="submit" value="submit">
</form>

Action:必须实现getModel() 方法

public class sysAction extends ActionSupport implements ModelDriven<User>{
     private User user;

     public String login() throws Exception {
            System.out.println(getModel().getUsername());
            return SUCCESS;
     }

      public User getModel() {
              if (null == user) {
                       return user = new User();
              }
              return user;
      }
}

3.第三种方式可以完全不实现ModelDriven<T>，也可使用多个model对象的属性。
JSP:
<form action="sys/login.action" method="post">
          <input type="text" name="user.username">
          <input type="text" name="teacher.level">
          <input type="submit" value="submit">
 </form>

Action: 必须提供set方法

public class sysAction extends ActionSupport{
          private User user;
          private Teacher teacher;

          public String login() throws Exception {
                    System.out.println(user.getUsername());
                    System.out.println(teacher.getLevel());
                    return SUCCESS;
         }

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