JSP 树状菜单

最新推荐文章于 2016-07-14 14:55:09 发布

原创最新推荐文章于 2016-07-14 14:55:09 发布 · 1.3k 阅读

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#jsp #tree #string #import #null #javascript

本文介绍了如何利用JSP动态生成JavaScript树形菜单。通过创建数据库表`tree_info`存储节点信息，编写Java类`TreeInfo`和`TreeUtil`从数据库获取并转换为JavaScript数组，然后定义两个自定义标签`InitTreeTag`和`ShowTreeTag`，在JSP中调用这些标签来展示树形菜单。示例中提供了完整的数据库脚本、Java代码和JSP页面结构。

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1）初始化菜单 <script type="text/javascript">  </script> 2）调用函数 <div class="tree"> <script type="text/javascript">  </script> </div> 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(""); 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"> <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。