树形目录的递归实现(一)数据库+jsp+javabean <%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %> <%!//方便起见这里就不写成javabean了 class cn {//连接数据库,这里以MS-SQL为例 String jdbcDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";//jdbc驱动 String connectionString="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=test";//数据库连接字符串 String user="sa";//数据库用户名 String pass="";//数据库密码 Connection conn=null; ResultSet rs=null; public cn() { try { Class.forName(jdbcDriver); } catch(ClassNotFoundException e) { System.err.println(e.toString()); } } public ResultSet executeQuery(String sql) { rs=null; try { conn=DriverManager.getConnection(connectionString,user,pass); Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); rs=stmt.executeQuery(sql); } catch(SQLException e) { System.err.println(e.toString()); } return rs; } public void executeUpdate(String sql) { try { conn=DriverManager.getConnection(connectionString,user,pass); Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); stmt.executeUpdate(sql); } catch(SQLException e) { System.err.println(e.toString()); } } } class tree { cn conn=new cn(); public void init(javax.servlet.jsp.JspWriter out,javax.servlet.http.HttpServletRequest request) throws Exception { out.println(" dowith(request); buildTree(out,0,0);//初始调用 } private void dowith(javax.servlet.http.HttpServletRequest request) { if(request.getParameter("parentid")==null||request.getParameter("parentid").equals(""))return; String action=request.getParameter("action"); if(action.equals("add")) conn.executeUpdate("insert into tree(parentid,message) values('"+request.getParameter("parentid")+"','"+request.getParameter("message")+"')"); else if(action.equals("delete")) conn.executeUpdate("delete from tree where id="+request.getParameter("parentid")+" or parentid="+request.getParameter("parentid")); } public void buildTree(javax.servlet.jsp.JspWriter out,int parentid,int level) throws Exception { level++; ResultSet rs=conn.executeQuery("select * from tree where parentid="+parentid+" order by id"); while(rs.next()) { out.println(" "); ");for(int i=0;i if(has_child(rs.getInt("id"))) { out.print(" "); out.print(""+rs.getString("message")+" id="+rs.getInt("id")+""); out.println(" "); } else out.print(" "+rs.getString("message")+" id="+rs.getInt("id")+""); out.println(" } rs.close(); rs=null; } private boolean has_child(int parentid) throws Exception { ResultSet rs=conn.executeQuery("select * from tree where parentid="+parentid+" order by id"); return rs.next(); } public String getOption() throws Exception { String option=""; ResultSet rs=conn.executeQuery("select * from tree order by id"); while(rs.next()) option+=" "; return option; } } %>
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