RichFaces - 富樹

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在本章中，我們將瞭解 RichFaces 中的樹形處理。RichFaces 提供了建立和操作樹所需的所有元件。

<rich:treeNode>

此標記用於建立層次樹。<treeNode> 內提供的每個節點都將成為樹的子節點。此標記將與另一個名為 <rich:tree> 的標記一起使用。我們用於建立樹的所有例項變數都必須實現以下三個介面之一 - **org.richfaces.model.TreeNode、org.richfaces.model.TreeDataModel** 和 **javax.swing.tree.TreeNode**。

在以下示例中，我們將使用 <rich:treeNode> 標記從後端填充樹。

<?xml version = "1.0" encoding = "UTF-8"?>  
<!DOCTYPE html> 
<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"   
   xmlns:f = "http://java.sun.com/jsf/core"   
   xmlns:ui = "http://java.sun.com/jsf/facelets"   
   xmlns:a4j = "http://richfaces.org/a4j"   
   xmlns:rich = "http://richfaces.org/rich"> 
   
   <h:head> 
      <title>TreeNode Example</title> 
      <meta name = "viewport" content = "width = device-width, initial-scale = 1.0"/>
   </h:head> 
    
   <h:body> 
      <h:form>   
         <rich:tree value = "#{tree.populateNode}" var = "tree">   
            <rich:treeNode>   
               <rich:treeModelRecursiveAdaptor> 
               </rich:treeModelRecursiveAdaptor>  
               <h:outputText value = "#{tree.data}" />   
            </rich:treeNode>
         </rich:tree>   
      </h:form>   
   </h:body> 

</html>

以下是實現 **“TreeNodeImpl”** 介面的 Java 相關類。

import javax.faces.bean.ManagedBean;   
import javax.faces.bean.RequestScoped;   
import org.richfaces.model.TreeNodeImpl;    

@ManagedBean   
@RequestScoped   

public class Tree extends TreeNodeImpl {   
   private Tree stationRoot;   
   private Tree populateNode;   
   private Object data;   
   
   public Tree() {   
      super();   
   }   
   public Tree(boolean leaf, Object data) {   
      super(leaf);   
      this.data = data;   
   }   
   public Object getData() {   
      return data;   
   }   
   public Tree getPopulateNode() {   
      if (populateNode == null) {   
         String[] List_OF_Node = {
            "Frist Node", "Second Node", "Third Node", "Fourth Node", "Fifth Node"};
         stationRoot = new Tree(false, "Example Of Tree");
         
         for (int i = 0; i < List_OF_Node.length; i++) {   
            Tree child = new Tree(true, List_OF_Node[i]);   
            stationRoot.addChild(i, child);   
         }   
         populateNode = new Tree();   
         populateNode.addChild(0, stationRoot);   
      }   
      return populateNode;   
   }
}

以上程式碼段將在瀏覽器中生成以下輸出。

Rich Tree

<rich:treeModelAdaptor>

該元件將 Map 作為輸入，對其進行迭代，並在瀏覽器中生成所需輸出。每當我們需要填充遞迴對映時，我們都可以使用另一個稱為 **<rich:recursiveTreeModelAdaptor>** 的標記。

以下示例顯示瞭如何在瀏覽器中渲染專案結構。在 RichFaces 3 中，這兩個標記是 <rich:treeNodeAdaptor> 和 <rich:recursiveTreeNodeAdaptor>。

<?xml version = "1.0" encoding = "UTF-8"?>  
<!DOCTYPE html> 
<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"   
   xmlns:f = "http://java.sun.com/jsf/core"   
   xmlns:ui = "http://java.sun.com/jsf/facelets"   
   xmlns:a4j = "http://richfaces.org/a4j"   
   xmlns:rich = "http://richfaces.org/rich"> 
   
   <h:head>
      <title>Tree Model and Recursive Model Example</title> 
   </h:head> 
   
   <h:body> 
      <h:form id = "form"> 
         <rich:tree toggleType = "AJAX" var = "item" style = "max-width: 400px"> 
            <rich:treeModelRecursiveAdaptor roots = "#{fileSystemBean.sourceRoots}" 
               nodes = "#{item.directories}"> 
               
               <rich:treeNode> 
                  #{item.shortPath} 
               </rich:treeNode> 
               
               <rich:treeModelAdaptor nodes = "#{item.files}"> 
                  <rich:treeNode>#{item}</rich:treeNode> 
               </rich:treeModelAdaptor> 
            </rich:treeModelRecursiveAdaptor> 
            
         </rich:tree> 
      </h:form> 
   </h:body>
   
</html>

對於此示例，我們需要建立兩個新的 Java Bean。以下是 Bean 類 “FileSystemBean.java” 的程式碼片段，其中包含所需的資料夾名稱。

import java.util.List; 
import javax.faces.bean.ManagedBean; 
import javax.faces.bean.RequestScoped; 
  
@ManagedBean 
@RequestScoped 

public class FileSystemBean { 
   private static final String SRC_PATH = "/WEB-INF"; 
   private List<FileSystemNode> srcRoots; 
  
   public synchronized List<FileSystemNode> getSourceRoots() { 
      if (srcRoots == null) {
         srcRoots = new FileSystemNode(SRC_PATH).getDirectories(); 
      } 
      return srcRoots; 
   } 
}

以下是 Bean 類 “FileSystemNode.java” 的程式碼片段，其中包含所需的專案葉節點。

import static com.google.common.base.Predicates.containsPattern; 
import static com.google.common.base.Predicates.not; 
import static com.google.common.collect.Iterables.filter; 
import static com.google.common.collect.Iterables.transform; 
  
import java.util.ArrayList; 
import java.util.Collections; 
import java.util.List; 
import java.util.Set; 
  
import javax.faces.context.ExternalContext; 
import javax.faces.context.FacesContext; 
  
import com.google.common.base.Function; 
import com.google.common.collect.Iterables; 
import com.google.common.collect.Lists; 
  
public class FileSystemNode { 
   private static final Function<String, FileSystemNode> 
      FACTORY = new Function<String, FileSystemNode>() { 
      
      public FileSystemNode apply(String from) { 
         return new FileSystemNode(from.substring(0, from.length() - 1)); 
      }; 
   }; 
   private static final Function<String, String> 
      TO_SHORT_PATH = new Function<String, String>() {
      
      public String apply(String from) { 
         int idx = from.lastIndexOf('/'); 
         if (idx < 0) { 
            return from; 
         } 
         return from.substring(idx + 1); 
      }; 
   }; 
   private String path; 
   private List<FileSystemNode> directories; 
   private List<String> files; 
   private String shortPath; 
  
   public FileSystemNode(String path) { 
      this.path = path; 
      int idx = path.lastIndexOf('/'); 
      
      if (idx != -1) { 
         shortPath = path.substring(idx + 1); 
      } else { 
         shortPath = path; 
      } 
   } 
   public synchronized List<FileSystemNode> getDirectories() { 
      if (directories == null) { 
         directories = Lists.newArrayList(); 
  
         Iterables.addAll(directories, transform(filter(
            getResourcePaths(), containsPattern("/$")), FACTORY)); 
      } 
      return directories; 
   }
   public synchronized List<String> getFiles() { 
      if (files == null) { 
         files = new ArrayList<String>(); 
         
         Iterables.addAll(files, transform(filter(
            getResourcePaths(), not(containsPattern("/$"))), TO_SHORT_PATH)); 
      } 
      return files; 
   } 
   private Iterable<String> getResourcePaths() { 
      FacesContext facesContext = FacesContext.getCurrentInstance(); 
      ExternalContext externalContext = facesContext.getExternalContext(); 
      Set<String> resourcePaths = externalContext.getResourcePaths(this.path); 
      
      if (resourcePaths == null) { 
         resourcePaths = Collections.emptySet(); 
      } 
      return resourcePaths; 
   } 
   public String getShortPath() { 
      return shortPath; 
   } 
}

以上示例將在瀏覽器中生成以下輸出。

Rich Tree Model Adapter
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