程序包 org.apache.velocity.tools.view

类 BreadcrumbTool

java.lang.Object
org.apache.velocity.tools.generic.SafeConfig
org.apache.velocity.tools.generic.LocaleConfig
org.apache.velocity.tools.view.BreadcrumbTool
所有已实现的接口:
Iterable<BreadcrumbTool.NavigationElement>
@DefaultKey("breadcrumb") @ValidScope("request") public class BreadcrumbTool extends LocaleConfig implements Iterable<BreadcrumbTool.NavigationElement>

Helper tool to display a navigation breadcrumb to the end user.

It relies on the asumption that your URI hierarchy corresponds to the navigation hierarchy you want to present to your users, each level having its landing index page. Please note that this asumption is considered a *good practice*.

Each intermediate path element becomes a navigation element, and there is an additional ending navigation element when the page is not an index page.

For instance, if the URI is `/colors/red/nuances.html`, the provided path elements will be:

  • 'colors', pointing towards '/colors/index.html'
  • 'red', pointing towards '/colors/red/index.html'
  • 'nuances', pointing towards '/colors/red/nuances.html'

The filename extension (`html` in the above example) is inferred from found URIs.

By default, the displayed name of a navigation element is the name of its corresponding path element with all '_' replaced by spaces, transformed to lowercase.

You can customize this displayed name and the URL of every path element using tools properties:


     tool key="breadcrumb" colors.name="My Colors" colors.url="/colors/all.vhtml"

where 'colors' refers to the /colors/ path element. The name and destination of the root path element can be changed with 'home.name' and 'home.url'.

If you provide a name property prefixed with '?', the breadcrumb tool will use the value of the corresponding query parameter as navigation element name, and will keep this query parameter in the navigation element URL.

You can also define your own rules programmatically by subclassing BreadcrumbTool and override the boolean customize(NavigationElement, HttpServletRequest) method, which will be called for every navigation element. Returning false will skip this navigation element from the breadcrumb.

Inside a template, you would either render directly the default resulting HTML fragment with:

$breadcrumb

which would produce simething like:

<a href="/index.vhtml">home</a>&nbsp;&gt;&nbsp;<a href="/colors/all.vhtml">My Colors</a>&nbsp;&gt;&nbsp;nuances

or you would iterate through navigation elements for a better control of the output with:


 div id="breadcrumb"
 #foreach($element in $breadcrumb)
  #if(!$foreach.first)
   >
  #end
  #if(!$foreach.last)#end
   $element.name
  #if(!$foreach.last)#end
 #end
div

And of course, you would supply the necessary CSS, for instance:


 #breadcrumb { font-size: smaller; }
 #breadcrumb a { color: #4183c4; text-decoration: none; }
 #breadcrumb .divider { color: rgba(0, 0, 0, 0.4); vertical-align: baseline; margin: 0 0.2rem; }
从以下版本开始:
3.1
版本:
$$
作者:
Claude Brisson

  • 字段详细资料

    • request

      protected jakarta.servlet.http.HttpServletRequest request
      Current request

  • 构造器详细资料

    • BreadcrumbTool

      public BreadcrumbTool()

  • 方法详细资料

    • setRequest

      public void setRequest(jakarta.servlet.http.HttpServletRequest request)
      Current request setter
      参数:
      request -

    • customize

      protected boolean customize(BreadcrumbTool.NavigationElement navElem, jakarta.servlet.http.HttpServletRequest request)

      Let the user customize programmatically the name and URL of a specific element.

      For instance, one can do use query parameters to customize the displayed name or target URL.

      参数:
      navElem - navigation element
      request - initial request
      返回:
      true (default value) to include this navigation element, false to skip it

    • formatElementName

      protected String formatElementName(String elem)
      Automatic default formatting of URI elements

    • configure

      protected void configure(ValueParser config)
      Configuration
      覆盖:
      configure 在类中 LocaleConfig

    • iterator

      public Iterator<BreadcrumbTool.NavigationElement> iterator()
      Navigation elements iteration
      指定者:
      iterator 在接口中 Iterable<BreadcrumbTool.NavigationElement>
      返回:
      Iterator over navigation elements

    • getExtension

      protected static String getExtension(String filename)
      Utility method to return URI file extension
      参数:
      filename -
      返回:

    • toString

      public String toString()
      Default concatenation of navigation elements, separated by '>'
      覆盖:
      toString 在类中 Object
      返回:
      string representation