jsf托管bean的动态变化 [英] jsf dynamic change of managedbean

问题描述

如何动态更改值"属性的托管bean?例如，我有h:inputText，并且根据键入的文本，托管bean必须是#{studentBean.login}或#{lecturerBean.login}.简化形式:

How can I dynamically change managed bean of "value" attribute? For example, I have h:inputText and, depending on typed-in text, managed bean must be #{studentBean.login} or #{lecturerBean.login}. In a simplified form:

<h:inputText id="loginField" value="#{'nameofbean'.login}" />

我尝试嵌入另一个el表达式，而不是'nameofbean':

I tried to embed another el-expression instead of 'nameofbean':

value="#{{userBean.specifyLogin()}.login}"

但没有成功.

推荐答案

多态性应该在模型中完成，而不是在视图中完成.

Polymorphism should rather be done in the model, not in the view.

例如

<h:inputText value="#{person.login}" />

使用

public interface Person {
    public void login();
}

和

public class Student implements Person {
    public void login() {
        // ...
    }
}

和

public class Lecturer implements Person {
    public void login() {
        // ...
    }
}

最后在托管bean中

private Person person;

public String login() {
    if (isStudent) person = new Student(); // Rather use factory.
    // ...
    if (isLecturer) person = new Lecturer(); // Rather use factory.
    // ...
    person.login();
    // ...
    return "home";
}

否则，每次添加/删除其他类型的Person时，都必须更改视图.这是不对的.

Otherwise you have to change the view everytime when you add/remove a different type of Person. This is not right.

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