增强版JAVA实现文本形式的树状结构显示

 
应网友要求，重新书写了代码，请参考使用。旧代码毅然保留，在文章的后半部

此最新代码增加了对下拉列表的输出支持，可以直接使用在<select>里面
同时可以访问父节点和兄弟节点。

package net.java2000.tools;

import java.util.ArrayList;
import java.util.List;

/** *//**
 * 树状结构的文本显示和下拉框显示。<br>
 * 转载请保留本说明,并注明出处<br>
 * www.java2000.net<br>
 * blog.csdn.net/java2000_net/
 * 
 * @version 2008.02.23
 * @author 赵学庆
 */
public class ForumFolder ...{
  // 编号
  private long id;

  // 标题
  private String title;

  // 下级列表
  private List<ForumFolder> children = new ArrayList<ForumFolder>();

  // 上级，顶层为null
  private ForumFolder parent;

  // 前一个节点
  private ForumFolder prev;

  // 后一个节点
  private ForumFolder next;

  // 当前处理的节点
  private ForumFolder current;

  /** *//**
   * 默认的构造器
   */
  public ForumFolder() ...{
  }

  /** *//**
   * 推荐使用的构造器
   * 
   * @param id 编号
   * @param title 文本
   */
  public ForumFolder(long id, String title) ...{
    this.id = id;
    this.title = title;
  }

  /** *//**
   * 增加一个下属。<br>
   * 自动对应上级和兄弟结点
   * 
   * @param f 被增加的节点
   */
  public void addChild(ForumFolder f) ...{
    children.add(f);
    f.setParent(this);
    if (current != null) ...{
      current.next = f;
    }
    f.prev = current;
    current = f;
  }

  /** *//**
   * 输出为下拉列表的方法
   * 
   * @param selectedId 被选中的编号
   * @return 下拉列表的字符串。可以直接放到<select></select>里面
   */
  public String getOption(long selectedId) ...{
    return "<option>" + toStringOption("", "", selectedId);
  }

  /** *//**
   * 输出为Text的方法。<br>
   * 应网友建议，更改toString为toStringText方法。
   * 
   * @param lftStr 左侧额外的字符串
   * @param append 右侧显示的字符串
   * @return 文本形式的字符串
   */
  public String toStringText(String lftStr, String append) ...{
    StringBuilder b = new StringBuilder();
    b.append(append + title);
    b.append(" ");
    if (children.size() > 0) ...{
      for (int i = 0; i < children.size() - 1; i++) ...{
        b.append(lftStr + children.get(i).toStringText(lftStr + "│", "├"));
      }
      b.append(lftStr + children.get(children.size() - 1).toStringText(lftStr + " ", "└"));
    }
    return b.toString();
  }

  public static void main(String[] args) ...{
    ForumFolder root = new ForumFolder(0, "菜单列表");
    ForumFolder f1 = new ForumFolder(1, "开始菜单");
    root.addChild(f1);
    ForumFolder f1_1 = new ForumFolder(11, "程序");
    f1.addChild(f1_1);
    ForumFolder f1_1_1 = new ForumFolder(111, "附件");
    f1_1.addChild(f1_1_1);
    ForumFolder f1_1_1_1 = new ForumFolder(1111, "娱乐");
    f1_1_1.addChild(f1_1_1_1);
    ForumFolder f1_1_1_2 = new ForumFolder(1112, "娱乐2");
    f1_1_1.addChild(f1_1_1_2);
    ForumFolder f1_2 = new ForumFolder(12, "辅助工具");
    f1.addChild(f1_2);
    ForumFolder f2 = new ForumFolder(2, "My Documents ");
    root.addChild(f2);
    ForumFolder f3 = new ForumFolder(3, "My Documents2 ");
    root.addChild(f3);
    System.out.println(root.toStringText(" ", ""));
    System.out.println(root.getOption(111));
    System.out.println(f1_1_1_2.getPrev().getTitle());
    System.out.println(f1_1_1_2.getPrev().getParent().getTitle());
  }

  public List<ForumFolder> getChildren() ...{
    return children;
  }

  public long getId() ...{
    return id;
  }

  /** *//**
   * 得到下一个兄弟结点。
   * 
   * @return 如果是最后一个，则返回null
   */
  public ForumFolder getNext() ...{
    return next;
  }

  public ForumFolder getParent() ...{
    return parent;
  }

  /** *//**
   * 得到前一个兄弟结点。
   * 
   * @return 如果是第一个，则返回null
   */
  public ForumFolder getPrev() ...{
    return prev;
  }

  public String getTitle() ...{
    return title;
  }

  public void setId(long id) ...{
    this.id = id;
  }

  public void setNext(ForumFolder next) ...{
    this.next = next;
  }

  public void setParent(ForumFolder parent) ...{
    this.parent = parent;
  }

  public void setPrev(ForumFolder prev) ...{
    this.prev = prev;
  }

  public void setTitle(String title) ...{
    this.title = title;
  }

  /** *//**
   * 构造下拉列表.
   * 
   * @param lftStr 左侧的字符
   * @param append 增加的字符
   * @param idSelected 被选中的编号
   * @return 下拉列表字符串
   */
  private String toStringOption(String lftStr, String append, long idSelected) ...{
    StringBuilder b = new StringBuilder();
    b.append(append + title + "</option>");
    b.append(" ");
    if (children.size() > 0) ...{
      for (int i = 0; i < children.size() - 1; i++) ...{
        b.append("<option value='" + children.get(i).getId() + "'" + (idSelected == children.get(i).getId() ? " selected" : "")
            + ">" + lftStr + children.get(i).toStringOption(lftStr + "│", "├", idSelected));
      }
      b.append("<option value='" + children.get(children.size() - 1).getId() + "'"
          + (idSelected == children.get(children.size() - 1).getId() ? " selected" : "") + ">" + lftStr
          + children.get(children.size() - 1).toStringOption(lftStr + " ", "└", idSelected));
    }
    return b.toString();
  }
}

运行结果如下：


菜单列表
 ├开始菜单
 │├程序
 ││└附件
 ││ ├娱乐
 ││ └娱乐2
 │└辅助工具
 ├My Documents 
 └My Documents2 

<option>菜单列表</option>
<option value='1'>├开始菜单</option>
<option value='11'>│├程序</option>
<option value='111' selected>││└附件</option>
<option value='1111'>││ ├娱乐</option>
<option value='1112'>││ └娱乐2</option>
<option value='12'>│└辅助工具</option>
<option value='2'>├My Documents </option>
<option value='3'>└My Documents2 </option>

娱乐
附件

原文出处: http://www.java2000.net/viewthread.jsp?tid=944

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----------------------------------------------- 以下为老版本的代码，仅供参考 -------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------




代码如下，可根据需求衍生出各种格式的输出和使用

package test;

import java.util.ArrayList;
import java.util.List;

public class Folder ...{
    public Folder(String title) ...{
        this.title = title;
    }

    private String title;

    private List<Folder> children = new ArrayList<Folder>();

    public void addChild(Folder f) ...{
        children.add(f);
    }

    public List<Folder> getChildren() ...{
        return children;
    }

    public void setChildren(List<Folder> children) ...{
        this.children = children;
    }

    public String getTitle() ...{
        return title;
    }

    public void setTitle(String title) ...{
        this.title = title;
    }

    public String toString(String lftStr, String append) ...{
        StringBuilder b = new StringBuilder();
        b.append(append + title);
        b.append("\n");
        if (children.size() > 0) ...{
            for (int i = 0; i < children.size() - 1; i++) ...{
                b.append(lftStr+children.get(i).toString(lftStr + "│", "├"));
            }
            b.append(lftStr + children.get(children.size() - 1).toString(
                    lftStr + " ", "└"));

        }
        return b.toString();

    }

    public static void main(String[] args) ...{
        Folder root = new Folder("菜单列表");
        Folder f1 = new Folder("开始菜单");
        root.addChild(f1);
        Folder f1_1 = new Folder("程序");
        f1.addChild(f1_1);
        Folder f1_1_1 = new Folder("附件");
        f1_1.addChild(f1_1_1);
        Folder f1_1_1_1 = new Folder("娱乐");
        f1_1_1.addChild(f1_1_1_1);
        Folder f1_1_1_2 = new Folder("娱乐2");
        f1_1_1.addChild(f1_1_1_2);
        Folder f1_2 = new Folder("辅助工具");
        f1.addChild(f1_2);
        Folder f2 = new Folder("My Documents ");
        root.addChild(f2);
        Folder f3 = new Folder("My Documents2 ");
        root.addChild(f3);

        System.out.println(root.toString(" ", ""));
    }
}

 运行结果如下：

菜单列表
 ├开始菜单
 │├程序
 ││└附件
 ││ ├娱乐
 ││ └娱乐2
 │└辅助工具
 ├My Documents 
 └My Documents2 
应网友要求，增加了JDK 1.4版及以下的程序版本，取消了泛型

import java.util.ArrayList;
import java.util.List;

public class Folder ...{
  public Folder(String title) ...{
    this.title = title;
  }

  private String title;

  private List children = new ArrayList();

  public void addChild(Folder f) ...{
    children.add(f);
  }

  public List getChildren() ...{
    return children;
  }

  public void setChildren(List children) ...{
    this.children = children;
  }

  public String getTitle() ...{
    return title;
  }

  public void setTitle(String title) ...{
    this.title = title;
  }

  public String toString(String lftStr, String append) ...{
    StringBuilder b = new StringBuilder();
    b.append(append + title);
    b.append(" ");
    if (children.size() > 0) ...{
      for (int i = 0; i < children.size() - 1; i++) ...{
        b.append(lftStr + ((Folder) children.get(i)).toString(lftStr + "│", "├"));
      }
      b.append(lftStr + ((Folder) children.get(children.size() - 1)).toString(lftStr + " ", "└"));
    }
    return b.toString();
  }

  public static void main(String[] args) ...{
    Folder root = new Folder("菜单列表");
    Folder f1 = new Folder("开始菜单");
    root.addChild(f1);
    Folder f1_1 = new Folder("程序");
    f1.addChild(f1_1);
    Folder f1_1_1 = new Folder("附件");
    f1_1.addChild(f1_1_1);
    Folder f1_1_1_1 = new Folder("娱乐");
    f1_1_1.addChild(f1_1_1_1);
    Folder f1_1_1_2 = new Folder("娱乐2");
    f1_1_1.addChild(f1_1_1_2);
    Folder f1_2 = new Folder("辅助工具");
    f1.addChild(f1_2);
    Folder f2 = new Folder("My Documents ");
    root.addChild(f2);
    Folder f3 = new Folder("My Documents2 ");
    root.addChild(f3);
    System.out.println(root.toString(" ", ""));
  }
}