Go语言视频零基础入门到精通

javalearner

一、这个简单的应用用到了模型－视图－控制器模式。

     其中HTreeViewForHTML.java是我们的树型目录的模型，它有一个如下形式的构造方法public HTreeViewForHtml(MutableDefaultTreeNode root)也就是说我们可以用平常在JAVA GUI编程中构造树型目录的方法事先构造一个树，然后再把树的根结点作为参数传递给这个构造函数从而得到HTreeViewForHtml的一个实例。HTreeController实际上是一个Servlet它继承自HttpServlet。

原理图：                 



二、目录结构
工程根目录
     index.jsp
     WEB-INF
         web.xml
         classes
               shilei
                   HTreeViewForHtml.java
                   HTreeController.java

三、具体实现

3.1、HTreeViewForHtml.java
package shilei;
import javax.servlet.http.*;
import java.util.*;
import java.io.PrintWriter;
import java.io.IOException;
import javax.swing.tree.*;
import javax.swing.JTree;
public class HTreeForHtml{
  //根结点
  private MutableTreeNode root;
  //根据id查找结点或者根据结点查找id
  private Map<Integer,MutableTreeNode> idToNode;
  private Map<MutableTreeNode,Integer> nodeToId;
  //根据结点查找它的允许孩子可见性
  private Map<MutableTreeNode,Boolean> childrenVisible;
  //HTreeForHtml对象在HTreeController中的唯一标识
  private Integer id;

  public HTreeForHtml(MutableTreeNode root){
   this.root=root;
   this.idToNode=new HashMap<Integer,MutableTreeNode>();
   this.nodeToId=new HashMap<MutableTreeNode,Integer>();
   this.childrenVisible=new HashMap<MutableTreeNode,Boolean>();
   //对所有树结点编码
   this.coder(root,0);
   //注册到HTreeController
   this.id=HTreeController.register(this);
  }

  public String getTreeViewForHtml(){
   String result="<table width="100%" border="0" cellspacing="0px" cellpadding="5px" bgcolor="#CCCCCC">";
   return result+this.deepFirstVisitor(root,0)+"</table>";
  }

  public String deepFirstVisitor(MutableTreeNode node,int level){
   String result="";
   if(level!=0)result+="<tr><td height="1px" bgcolor="#FFFFFF"></td></tr>";//打印一条白线
   result+="<tr bgcolor="#336699" width="100%"><td>";
   //控制缩进
   for(int i=0;i<level;i++)result+="  ";
   //如果node不是叶子节点
   if(!node.isLeaf()){
    result+="<a href="HTreeController?receiverId="+this.id+
     "&nodeId="+this.nodeToId.get(node)+"">";
    result+="<font color="#FFFFFF">";//设置字体颜色
    //如果node不允许孩子节点可见
    if(!((Boolean)this.childrenVisible.get(node)).booleanValue()){
     result+=">>"+node.toString()+"</font></a></td></tr>
";
    }else{
     result+=">>"+node.toString()+"</font></a></td></tr>
";
     //遍历孩子
     Enumeration children=node.children();
     if(!children.hasMoreElements())return result;//do nothing
     else{
      level++;
      while(children.hasMoreElements())
      result+=deepFirstVisitor((MutableTreeNode)children.nextElement(),level);
     }
    }
   }//如果node是叶子节点
   else if(node.isLeaf()){
    result+="<font color="#FFFFFF">*"+
     node.toString()+"</font></a></td></tr>
";
   }
   return result;
  }

  public void nodeIsClicked(String nodeId){
   MutableTreeNode node=(MutableTreeNode)this.idToNode.get(new Integer(nodeId));
   Boolean originalVisible=this.childrenVisible.get(node);
   this.childrenVisible.put(node,new Boolean(!originalVisible.booleanValue()));
  }

  private void coder(MutableTreeNode node,int id){
   Integer sign=new Integer(id++);
   this.idToNode.put(sign,node);
   this.nodeToId.put(node,sign);
   //默认所有结点的孩子均可见
   this.childrenVisible.put(node,new Boolean(true));
   Enumeration children=node.children();
   while(children.hasMoreElements())
    coder((MutableTreeNode)children.nextElement(),id);
  }
  public static void main(String[] args){
   DefaultMutableTreeNode root=new DefaultMutableTreeNode("root");
   root.add(new DefaultMutableTreeNode("shilei"));
   System.out.println(new HTreeForHtml(root).getTreeViewForHtml());
  }
}


3.2、HTreeController.java

package shilei;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*; public class HTreeController extends HttpServlet {
  //存放消息接收者与代表其唯一身份的ID
  private static Map<Integer,HTreeForHtml> receivers=
   new HashMap<Integer,HTreeForHtml>();
  //用于产生对于HTreeContorller来说是唯一的标识符
  private static int ID=0;
  public static Integer register(HTreeForHtml tree){
   Integer result=new Integer(ID++);
   receivers.put(result,tree);
   return result;
  }
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException
     {
         String receiverId=(String)request.getParameter("receiverId");
         String nodeId=(String)request.getParameter("nodeId");
         ((HTreeForHtml)receivers.get(new Integer(receiverId))).nodeIsClicked(nodeId);
         response.sendRedirect("index.jsp");
     }
}

3.3、web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd"
     version="2.5">   <display-name>Welcome to Tomcat</display-name>
   <description>Welcome to Tomcat </description>
   <servlet>
       <servlet-name>HTreeController</servlet-name>
       <servlet-class>shilei.HTreeController</servlet-class>
   </servlet>
   <servlet-mapping>
         <servlet-name>HTreeController</servlet-name>
         <url-pattern>/HTreeController</url-pattern>
   </servlet-mapping>
</web-app>

3.4、index.jsp

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<%@ page import="javax.swing.tree.*" %>
<%@ page import="shilei.*" %>
<%!
HTreeForHtml hTree;
%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>树形目录</title>
</head>
<body bgcolor="#999999">
<%
if(hTree==null){
  DefaultMutableTreeNode root=new DefaultMutableTreeNode("root");
  root.add(new DefaultMutableTreeNode("shilei"));
  DefaultMutableTreeNode firstDir=new DefaultMutableTreeNode("firstDir");
  firstDir.add(new DefaultMutableTreeNode("<a href="http://sina.com" target="blank">sina</a>"));
  root.add(firstDir);
  hTree=new HTreeForHtml(root);
}
out.println(hTree.getTreeViewForHtml());
%>
</body>
</html>

4、测试
将我们的工程根目录部署在tomcat的webapps目录下，假设我们的工程根目录名称为test,在浏览器中键入http://localhost:8080/Test/index.jsp,就可以测试我们的简单应用了。如图：



5、说明：具体应用中我们可以按照实际情况构造树型目录(用JDK中的API)，然后借助于我们上面提供的类使树形目录在网页中显示出来。

  
  
   
   

     
   

     
   
  


源码下载：http://file.javaxxz.com/2014/10/1/192515000.zip