如何迭代 List<T>并在 JSF Facelets 中渲染每个项目 [英] How iterate over List<T> and render each item in JSF Facelets

问题描述

我想知道如何在 Facelet 中显示如下获得的 List:

公共列表searchByString(字符串字符串){return getEntityManager().createNamedQuery("Userdetails.findByUsername").setParameter("username", "%" + string + "%").getResultList();}

是一种合适的方式吗?

解决方案

您将需要对其进行迭代.JSF 2 提供了三个开箱即用的迭代组件.假设 User 实体如下所示，

@Entity公共类用户{私人 @Id 长 ID；私人字符串用户名；私人字符串电子邮件；私人 LocalDate 生日；//添加/生成 getter+setter.}

并且搜索结果被分配为List；可用作 #{bean},

的 bean 的 users 属性

@Named @RequestScoped公共类豆{私人列表<用户>用户；//添加/生成 postconstruct+getter.}

这里有一些基于它的例子:

1. <h:dataTable>，一个生成 HTML

   的 UI 组件.

   <h:column>#{user.id}</h:column><h:column>#{user.username}</h:column><h:column><a href="mailto:#{user.email}">#{user.email}</a></h:column><h:column>#{user.birthdate}</h:column></h:dataTable>

   <ui:repeat>，一个不生成 HTML 标记的 UI 组件(因此，您必须自己以所需的方式编写所有 HTML，可以很容易地将其更改为例如

   • ，或

     ，或

     > 等):

   <ui:repeat value="#{bean.users}" var="user"><tr><td>#{user.id}</td><td>#{user.username}</td><td><a href="mailto:#{user.email}">#{user.email}</a></td><td>#{user.birthdate}</td></td></ui:repeat>

2. <c:forEach>，一个在视图构建时间而不是视图渲染时间运行的标签处理程序(背景解释在这里:JSF2 Facelets 中的 JSTL ......有意义吗?)，它也不产生任何 HTML 标记:

   <c:forEach items="#{bean.users}" var="user"><tr><td>#{user.id}</td><td>#{user.username}</td><td><a href="mailto:#{user.email}">#{user.email}</a></td><td>#{user.birthdate}</td></td></c:forEach>

另见:

• Java EE 6 教程 - 向页面添加组件 - 使用
• 我应该如何以及何时从h:dataTable 的数据库

I am wondering how to display a List<T> as obtained below in a Facelet:

public List<T> searchByString(String string) {
    return getEntityManager().createNamedQuery("Userdetails.findByUsername").setParameter("username", "%" + string + "%").getResultList();
}

Would a <h:dataTable> be a suitable way?

解决方案

You're going need to iterate over it. JSF 2 offers three iteration components out the box. Provided that the User entity look like below,

@Entity
public class User {
    private @Id Long id;
    private String username;
    private String email;
    private LocalDate birthdate;
    // Add/generate getters+setters.
}

and that the search results are assigned as a List<User> users property of a bean which is available as #{bean},

@Named @RequestScoped
public class Bean {
    private List<User> users;
    // Add/generate postconstruct+getter.
}

here are some examples based on it:

1. <h:dataTable>, an UI component which generates a HTML <table>.

   <h:dataTable value="#{bean.users}" var="user">
       <h:column>#{user.id}</h:column>
       <h:column>#{user.username}</h:column>
       <h:column><a href="mailto:#{user.email}">#{user.email}</a></h:column>
       <h:column>#{user.birthdate}</h:column>
   </h:dataTable>
   

2. <ui:repeat>, an UI component which generates no HTML markup (so, you'd have to write all that HTML in the desired fashion yourself, which could easily be changed to e.g. <ul><li>, or <dl><dt><dd>, or <div><span>, etc):

   <table>
       <ui:repeat value="#{bean.users}" var="user">
           <tr>
               <td>#{user.id}</td>
               <td>#{user.username}</td>
               <td><a href="mailto:#{user.email}">#{user.email}</a></td>
               <td>#{user.birthdate}</td>
           </td>
       </ui:repeat>
   </table>
   

3. <c:forEach>, a tag handler which runs during view build time instead of view render time (background explanation here: JSTL in JSF2 Facelets... makes sense?), it also doesn't produce any HTML markup:

   <table>
       <c:forEach items="#{bean.users}" var="user">
           <tr>
               <td>#{user.id}</td>
               <td>#{user.username}</td>
               <td><a href="mailto:#{user.email}">#{user.email}</a></td>
               <td>#{user.birthdate}</td>
           </td>
       </c:forEach>
   </table>
   

See also:

• Java EE 6 tutorial - Adding components to a page - using <h:dataTable>
• How and when should I load the model from database for h:dataTable

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