如何将 Bean 中的项目列表显示到 JSF 网页上?

问题描述

我是 JSF 的新手，正在学习构建在线书店应用程序.

我有 1 个类和 1 个 bean:Book.java 和 BookCatelogBean.java.Book 类有 3 个属性:id、title 和 author 以及相应的 getter 和 setter.BookCatelogBean 包含一个 ArrayList，我在其中用 Books 填充它(将来我会将它连接到数据库).

我有两个页面:index.xhtml 和 book.xhtml.我想在 index.xhtml 上显示书名列表，每个书名都格式化为 REST 链接及其 ID 到 book.xhtml，如下所示:<h:link 结果="book?id=#{bookCatelogBean.id}" value="#{bookCatelogBean.title}"/>

我知道如何使用 BookCatelogBean 来显示 1 个 book 但我想显示所有这些?我有一个想法，从 BookCatelogBean 调用一个名为 getAllBooks() 的方法，该方法返回每本书的标题，但我将如何将每本书返回到 index.xhtml 作为JavaserverFace 链接而不是字符串?

谢谢

这是我的代码:

Book.java

包书店；导入 java.io.Serializable;公共类 Book 实现了 Serializable {私有整数 ID；私人字符串标题；私人字符串作者；公共书(int id，字符串标题，字符串作者){this.title = 标题；this.id = id;this.author = 作者；}公共字符串 getAuthor() {返回作者；}公共无效setAuthor(字符串作者){this.author = 作者；}公共 int getId() {返回标识；}公共无效 setId(int id) {this.id = id;}公共字符串 getTitle() {返回标题；}公共无效设置标题(字符串标题){this.title = 标题；}}

BookCatelogBean.java

包书店；导入 java.io.Serializable;导入 java.util.ArrayList;导入 java.util.Arrays;导入 javax.faces.bean.ManagedBean;导入 javax.faces.bean.SessionScoped;@ManagedBean@SessionScoped公共类 BookCatelogBean 实现了 Serializable {私人 int currentItem = 0;私有 ArrayListbook = new ArrayList(Arrays.asList(新书(1，货币与信用理论"，路德维希·冯·米塞斯")，新书(2，人，经济与国家"，默里罗斯巴德")，new Book(3, "实时关系", "Stefan Molyneux")));公共字符串 getTitle(){返回 book.get(currentItem).getTitle();}公共 int getId(){返回 book.get(currentItem).getId();}公共字符串 getAuthor(){返回 book.get(currentItem).getAuthor();}}

index.xhtml

解决方案

JSF2 提供了两个开箱即用的迭代组件: 和 .前者不向响应呈现任何内容(因此您可以 100% 控制最终的 HTML 输出)，而后者向响应呈现 HTML <table> 并需要 表示一列 .两个组件都可以将 List 作为值.

所以，你可以像下面这样拥有你的托管 bean:

@ManagedBean@RequestScoped公共类 BookCatalog 实现了 Serializable {私人列表<Book>图书;@PostConstruct公共无效初始化(){书籍 = 新的 ArrayList();book.add(new Book(1, "Theory of Money and Credit", "Ludwig von Mises"));book.add(new Book(2, "Man, Economic and State", "Murry Rothbard"));book.add(new Book(3, 实时关系", Stefan Molyneux"));}公共列表<Book>获取书籍(){还书；}}

您可以使用 生成例如

• :

  <ui:repeat value="#{bookCatalog.books}";var=书"><li><h:link value="#{book.title}";结果=书"><f:param name="id";值=#{book.id}"；/></h:link></ui:repeat>

  (请注意，var 属性基本上通过组件内 EL 范围内的给定名称公开当前迭代的项目)

  这里是如何使用 代替:

  <h:dataTable value="#{bookCatalog.books}"var=书"><h:列><h:link value="#{book.title}";结果=书"><f:param name="id";值=#{book.id}"；/></h:link></h:列></h:dataTable>

  对于 JSTL <c:forEach>，这也是很有可能的，但是您应该记住，JSTL 标记与 JSF 组件具有不同的生命周期.长话短说:JSF2 Facelets 中的 JSTL ......有意义吗?>

  另见:

  • 如何选择合适的 bean 范围?莉>
  • 我应该如何以及何时加载模型来自 h:dataTable 的数据库
  • 创建实体的主从页面，如何链接它们以及选择哪个 bean 范围

  I'm new to JSF and in the process of learning im building an online book store application.

  I have 1 class and 1 bean: Book.java and BookCatelogBean.java. The Book class has 3 properties: id, title, and author with it's corresponding getters and setters. The BookCatelogBean contains an ArrayList<Book> where I populate it with Books (in future I will connect it to a database).

  I have two pages: index.xhtml and book.xhtml. I want to display the list of book titles on index.xhtml each formatted as a REST link and their ID to book.xhtml, like so: <h:link outcome="book?id=#{bookCatelogBean.id}" value="#{bookCatelogBean.title}" />

  I know how to use BookCatelogBean to display 1 book but I want to display all of them? I have an idea to call a method from BookCatelogBean called getAllBooks() that returns each of the books titles but how would I return each one of them to index.xhtml as a JavaserverFace link instead of a string?

  Thanks

  Here is my code:

  Book.java

  package bookshop;
  
  import java.io.Serializable;
  
  public class Book implements Serializable {
  
      private int id;
      private String title;
      private String author;
  
      public Book(int id, String title, String author){
          this.title = title;
          this.id = id;
          this.author = author;
      }
  
      public String getAuthor() {
          return author;
      }
  
      public void setAuthor(String author) {
          this.author = author;
      }
  
      public int getId() {
          return id;
      }
  
      public void setId(int id) {
          this.id = id;
      }
  
      public String getTitle() {
          return title;
      }
  
      public void setTitle(String title) {
          this.title = title;
      }
  }
  

  BookCatelogBean.java

  package bookshop;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Arrays;
  import javax.faces.bean.ManagedBean;
  import javax.faces.bean.SessionScoped;
  
  @ManagedBean
  @SessionScoped
  public class BookCatelogBean implements Serializable {
      private int currentItem = 0;
  
      private ArrayList<Book> books = new ArrayList<Book>(Arrays.asList(
              new Book(1, "Theory of Money and Credit", "Ludwig von Mises"),
              new Book(2, "Man, Economy and State", "Murry Rothbard"),
              new Book(3, "Real Time Relationships", "Stefan Molyneux")));
  
      public String getTitle(){
          return books.get(currentItem).getTitle();
      }
  
      public int getId(){
          return books.get(currentItem).getId();
      }
  
      public String getAuthor(){
          return books.get(currentItem).getAuthor();
      }
  
  }
  

  index.xhtml

  <?

  解决方案

  JSF2 offers two iterating components out the box: <ui:repeat> and <h:dataTable>. The former renders nothing to the response (so you have 100% control over the final HTML output), while the latter renders a HTML <table> to the response and requires a <h:column> to represent a column of <td>s. Both components can take among others a List<E> as value.

  So, you can just have your managed bean like follows:

  @ManagedBean
  @RequestScoped
  public class BookCatalog implements Serializable {
  
      private List<Book> books;
  
      @PostConstruct
      public void init() {
          books = new ArrayList<Book>();
          books.add(new Book(1, "Theory of Money and Credit", "Ludwig von Mises"));
          books.add(new Book(2, "Man, Economy and State", "Murry Rothbard"));
          books.add(new Book(3, "Real Time Relationships", "Stefan Molyneux"));
      }
  
      public List<Book> getBooks() {
          return books;
      }
  
  }
  

  And you can use <ui:repeat> to generate for example an <ul><li>:

  <ul>
      <ui:repeat value="#{bookCatalog.books}" var="book">
          <li>
              <h:link value="#{book.title}" outcome="book">
                  <f:param name="id" value="#{book.id}" />
              </h:link>
          </li>
      </ui:repeat>
  </ul>
  

  (note that the var attribute basically exposes the currently iterated item by exactly the given name in the EL scope within the component)

  And here's how to use a <h:dataTable> instead:

  <h:dataTable value="#{bookCatalog.books}" var="book">
      <h:column>
          <h:link value="#{book.title}" outcome="book">
              <f:param name="id" value="#{book.id}" />
          </h:link>
      </h:column>
  </h:dataTable>
  

  As to the JSTL <c:forEach>, that's also quite possible, but you should keep in mind that JSTL tags have a different lifecycle than JSF components. Long story short: JSTL in JSF2 Facelets... makes sense?

  See also:

  • How to choose the right bean scope?
  • How and when should I load the model from database for h:dataTable
  • Creating master-detail pages for entities, how to link them and which bean scope to choose

  这篇关于如何将 Bean 中的项目列表显示到 JSF 网页上?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！