jsp与树形菜单

比眉伴天荒 2022-06-12 08:59 291阅读 0赞

显然，如果用动态的脚本来初始化菜单数组（asp,jsp均可），那就可以很方便的实现动态的树型菜单了。

2。jsp动态实现  
   分以下步骤实现动态的树型菜单：  
   1）在数据库建tree\_info表，有nodeId，parentNodeId，nodeName，nodeUrl四个字段，来存储节点信息。  
   2）编写java类，用于从数据库找出节点信息，并且生成javascript脚本。  
   3）编写tag类。用于封装逻辑，简化jsp的开发。  
   4）建一个web程序进行测试。

3。详细过程  
   1）在数据库建表，脚本如下：  
   CREATE TABLE \`test\`.\`tree\_info\` (  
   \`node\_id\` INTEGER UNSIGNED NOT NULL DEFAULT -1,  
   \`parent\_id\` INTEGER UNSIGNED NOT NULL DEFAULT -1,  
   \`node\_name\` VARCHAR(45) NOT NULL,  
   \`ref\_url\` VARCHAR(45) NOT NULL,  
   PRIMARY KEY(\`node\_id\`)  
)  
我使用mysql数据库，如果脚本细节有出入，请自行修改  
    按照上面的dTree示例插入数据  
   2）编写TreeInfo.java，这个类用于封装节点信息  
     package com.diegoyun.web.tree;  
   /\*\*  
   \* @author Diegoyun  
   \* @version 1.0  
   \*/  
   public class TreeInfo \{  
    private int nodeId = -1;//node id  
    private int parentId = -1;//parentId  
    private String nodeName = null;//node name  
    private String url = null;//url references

public int getNodeId() \{  
     return nodeId;  
    \}

public void setNodeId(int nodeId) \{  
     this.nodeId = nodeId;  
    \}

public int getParentId() \{  
     return parentId;  
    \}

public void setParentId(int parentId) \{  
     this.parentId = parentId;  
    \}

public String getNodeName() \{  
     return nodeName;  
    \}

public void setNodeName(String nodeName) \{  
     this.nodeName = nodeName;  
    \}

public String getUrl() \{  
     return url;  
    \}

public void setUrl(String url) \{  
     this.url = url;  
    \}

\}  
   编写TreeUtil.java，用于从数据库得到节点信息，封装到TreeInfo对象，并生成javascript脚本  
   TreeUtil.java  
   package com.diegoyun.web.tree;  
   import java.util.Collection;  
   import java.util.ArrayList;  
   import java.util.Iterator;  
   import java.util.List;  
   import java.sql.PreparedStatement;  
   import java.sql.ResultSet;  
   import java.sql.Connection;  
   import java.sql.DriverManager;

/\*\*  
   \* @author Diegoyun  
   \* @version 1.0  
   \*/  
   public class TreeUtil \{  
    public static List retrieveNodeInfos()\{  
     List coll = new ArrayList();

String driverName = "com.mysql.jdbc.Driver";  
     String host = "localhost";  
     String port = ":3306";  
     String serverID = "test";  
     String userName = "root";  
     String userPwd = "root";  
     String url = "jdbc:mysql://" + host + port + "/" + serverID ;

Connection conn = null ;  
     PreparedStatement ps = null;  
     ResultSet rs = null;  
     try\{  
      Class.forName(driverName).newInstance();  
      conn = DriverManager.getConnection(url , userName , userPwd);  
      String sql = "select \* from tree\_info";  
      ps = conn.prepareStatement(sql);  
      rs = ps.executeQuery();

TreeInfo info = null;  
      while(rs!=null && rs.next())\{  
       info = new TreeInfo();  
       info.setNodeId(rs.getInt(1));  
       info.setParentId(rs.getInt(2));  
       info.setNodeName(rs.getString(3));  
       info.setUrl(rs.getString(4));  
       coll.add(info);  
      \}  
   //            if(rs!=null)\{  
   //                rs.close();  
   //                rs=null;  
   //            \}  
   //            if(ps!=null)\{  
   //                ps.close();  
   //                ps=null;  
   //            \}  
     \}catch(Exception e)\{  
      System.out.println(e);  
     \}

return coll;  
    \}  
    public static String createTreeInfo(List alist)\{  
     StringBuffer contents = new StringBuffer();  
     contents.append("<!--\\n");  
     contents.append("var Tree = new Array;");//create a array in javascript  
     TreeInfo info =null;  
     for(int max = alist.size(),i=0;i<max;i++)\{  
      info = (TreeInfo)alist.get(i);  
      //define elements of array  
      contents.append("Tree\[");  
      contents.append(i);  
      contents.append("\]=\\"");  
      contents.append(info.getNodeId());  
      contents.append("|");  
      contents.append(info.getParentId());  
      contents.append("|");  
      contents.append(info.getNodeName());  
      contents.append("|");  
      contents.append(info.getUrl());  
      contents.append("\\";");  
     \}

contents.append("docment.writer(Tree);");  
     contents.append("//-->");

return contents.toString();  
    \}  
    public static void main(String\[\]args)\{  
     List alist = TreeUtil.retrieveNodeInfos();  
   //        TreeInfo info = null;  
   //        for(Iterator i = c.iterator();i.hasNext();)\{  
   //            info = (TreeInfo)i.next();  
   //            System.out.println("\*\*\*\*\*" + info.getNodeName());  
   //        \}  
     System.out.println(TreeUtil.createTreeInfo(alist));  
    \}  
   \}

3)编写标签类  
InitTreeTag.java  
package com.diegoyun.web.taglibs;  
import com.diegoyun.web.tree.TreeUtil;  
import javax.servlet.jsp.tagext.TagSupport;  
import javax.servlet.jsp.JspException;  
import java.io.IOException;

/\*\*  
\* @author Diegoyun  
\* @version 1.0  
\*/  
public class InitTreeTag extends TagSupport\{

public int doEndTag() throws JspException \{  
    StringBuffer tree = new StringBuffer();  
    tree.append("<script type=\\"text/javascript\\">\\n");  
    tree.append(TreeUtil.createTreeInfo(TreeUtil.retrieveNodeInfos()));  
    tree.append("</script>\\n");  
    try\{  
     pageContext.getOut().println(tree.toString());  
    \}catch(IOException ioe)\{  
     ioe.printStackTrace();  
    \}  
    return super.doEndTag();  
   \}  
\}

ShowTreeTag.java :

package com.diegoyun.web.taglibs;

import javax.servlet.jsp.tagext.TagSupport;  
import javax.servlet.jsp.JspException;  
import java.io.IOException;

/\*\*  
\* @author Diegoyun  
\* @version 1.0  
\*/  
public class ShowTreeTag extends TagSupport\{  
   public int doEndTag() throws JspException \{  
    StringBuffer buffer = showTree();  
    try \{  
     pageContext.getOut().println(buffer.toString());  
    \}  
    catch (IOException ioe) \{  
     ioe.printStackTrace();  
    \}  
    return super.doEndTag();  
   \}  
   private StringBuffer showTree()\{  
    StringBuffer sb = new StringBuffer();  
    sb.append("<div class=\\"tree\\">\\n");  
    sb.append("<script type=\\"text/javascript\\">\\n");  
    sb.append("\\n");  
    sb.append("</script>\\n");  
    sb.append("</div>\\n");  
    return sb;  
   \}    
\}

标签的tld如下：  
<?xml version="1.0" encoding="ISO-8859-1" ?>  
<!DOCTYPE taglib  
   PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"  
   "[http://java.sun.com/dtd/web-jsptaglibrary\_1\_2.dtd][http_java.sun.com_dtd_web-jsptaglibrary_1_2.dtd]">  
<taglib>  
<tlib-version>1.0</tlib-version>  
<jsp-version>1.2</jsp-version>  
<short-name>tree</short-name>  
  
<tag>  
   <name>init</name>  
   <tag-class>com.diegoyun.web.taglibs.InitTreeTag</tag-class>  
   <body-content>empty</body-content>  
</tag>  
  
<tag>  
   <name>show</name>  
   <tag-class>com.diegoyun.web.taglibs.ShowTreeTag</tag-class>  
   <body-content>empty</body-content>  
</tag>  
</taglib>

4）建立web过程，编写jsp进行测试。

index.jsp如下：  
<%@ page language="java"%>  
<%@ taglib uri="/WEB-INF/tlds/tree.tld" prefix="tree"%>

<html>  
<head>  
   <title>Tree example</title>  
   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">  
   <link rel="StyleSheet" href="tree.css" type="text/css">  
   <script type="text/javascript" src="tree.js"></script>  
   <tree:init/>  
</head>

<body>

<b>Tree example :</b><br /><br />  
<tree:show/>  
<br /><br />

</body>  
</html>

测试，enjoy yourself！

4。待解决问题  
dTree有点小bug，如果把css，img，js的路径改变，树就有可能不会正确显示。

[http_www.destroydrop.com_javascripts_tree]: http://www.destroydrop.com/javascripts/tree/
[http_java.sun.com_dtd_web-jsptaglibrary_1_2.dtd]: http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd