public class user {
    private String date = new Date().toString();
    public user(){
        System.out.println("create session date="+date);
    }
    public void finalize(){
        System.out.println("回收 session end  date="+date);
    }
}

这里对finalize方法进行了重写

JSP里将user装入session

<%
    if(session.getAttribute("ff")==null){
    session.setMaxInactiveInterval(5);//这里为了测试方便设置超时为5秒
session.setAttribute("ff",new  user());
    }else{
        System.out.println(session.getAttribute("ff"));
    }
%>

测试结果
session超时，过1分钟后user类被回收
没有超时的时候重复装入user 前面装入session的会很快被回收

通过这个特性
也可以通过finalize()来作用户在线时间等一些功能的实现

<VERIFY xmlns="http://ormp.biz/webservices/">
<KEY>guid</KEY>
<IP>string</IP>
</VERIFY>
</soap:Body>


verify有 名为 xmlns属性的时候就会报错

附一个xml读写类
import org.dom4j.io.XMLWriter;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import java.io.FileWriter;
import org.dom4j.io.OutputFormat;
import java.io.File;
import org.dom4j.Document;
import org.dom4j.io.SAXReader;

public class XmlTool {
    private String filename;
    private SAXReader saxReader = null;
    private Document document = null;
    private Element cfgElement = null;
    public XmlTool(String filename) {
        this.filename = filename;
        try {
            saxReader = new SAXReader();
            document = saxReader.read(new File(filename));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public void setValue(String key, String value) {
        int returnValue = 0;
        try {
            ((Element)( document.selectSingleNode(key))).setText(value);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
    public String getValue(String key) {
    int returnValue = 0;
    try {
        return ((Element)( document.selectSingleNode(key))).getText();
    } catch (Exception ex) {
        ex.printStackTrace();
        return "";
    }
}

    public int writeToFile() {
        int returnValue = 0;
        try {
            XMLWriter writer = new XMLWriter(new FileWriter(new File(filename)));
            writer.write(document);
            writer.close();
            returnValue = 1;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return returnValue;
    }

    public int formatXMLFile(String filename) {
        int returnValue = 0;
        try {
            SAXReader saxReader = new SAXReader();
            Document document = saxReader.read(new File(filename));
            XMLWriter output = null;
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("GBK");
            output = new XMLWriter(new FileWriter(new File(filename)), format);
            output.write(document);
            output.close();
            returnValue = 1;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return returnValue;
    }

}

import java.sql.Connection;
import java.sql.PreparedStatement;

public class SqlModify
{
 private String SQL;
 static SqlModify sqlcom = null;
 private DBConnManager conn = null;
 private Connection con = null;
 private PreparedStatement stmt = null;
 
 public SqlModify()
 {
  
 }
 public SqlModify(boolean connect)
 {
  if(connect)
   connect();
 }
 public static int modify(String sqlStr)
 {
  if(sqlcom==null)
    sqlcom = new SqlModify();
  return sqlcom.exec(sqlStr);
 }
 public PreparedStatement getStmt()
 {
  return stmt;
 }
 public void connect(String sqlStr)
 {
  try{
   connect();
   stmt = con.prepareStatement(sqlStr);
  }catch(Exception e){
   e.printStackTrace();
  }
 }
 public void connect()
 {
  try{
   conn = DBConnManager.getInstance();
   con  = conn.getConnection("mssql");
  }catch(Exception e){
   
  }
 }
 public int exesqlandClose()
 {
  int result = exesql();
  closeall();
  return result;
 }
 public int exesql()
 {
  try{
   return stmt.executeUpdate();
  }catch(Exception e){
   e.printStackTrace();
   return -1;
  }
 }
 public void setSql(String sql)
 {
  try{
   stmt = con.prepareStatement(sql);
  }catch(Exception e){
   e.printStackTrace();
  }finally{
   
  }
 }
 public int exec(String sqlStr)
 {
  int flag=-2;

  try{
   connect(sqlStr); 
   int value=stmt.executeUpdate();
   flag=value;
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  }finally{
   closeall();
  }
  return flag;
 }
 public void closeall()
 {
  try{
   if(stmt!=null)
   {
    stmt.close();
   }
   if(conn!=null)
   {
    conn.releaseConnection("mssql",con);
   }
   
  }catch(Exception e){
   e.printStackTrace();
  }
 }
 public void setString(int col,String value)
 {
  try{
   stmt.setString(col,value);
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  }  
 }
 public void setInt(int col,int value)
 {

  try{
   stmt.setInt(col,value);
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  }
   
 }
 public void setLong(int col,long value)
 {
  try{
   stmt.setLong(col,value);
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  } 
 }
 public void setFloat(int col,float value)
 {
  try{
   stmt.setFloat(col,value);
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  } 
 }
}

  
     
    </td>
  </tr>
</table>
<%
}
%>

-------------------------------------------------------------------------------------------------------

myRedirect.java

package com.util;

import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;

public class myRedirect    //对url的转换类
{
 public static String dealurl(HttpServletRequest request)
 {
  String url = "";
  url = request.getRequestURL()+"?";
  url +=param(request);
  if(url.indexOf("&")>-1)
   url=url.replaceAll("&","@#@");//实际上就是把有&的字符转化成了@#@
  return url;
 }
 public static String geturl(String url)//这个是还原方法
 {
  if(url.indexOf("@#@")>-1)
   url=url.replaceAll("@#@","&");
  return url;     
 }
 public static String param(HttpServletRequest request)
 {
  String url = "";
  Enumeration param = request.getParameterNames();//得到所有参数名
  while(param.hasMoreElements())
  {
   String pname = param.nextElement().toString();
   url += pname+"="+request.getParameter(pname)+"&";
  }
  if(url.endsWith("&"))
  {
   url = url.substring(0,url.lastIndexOf("&"));
  }
  return url;
 }
}
这样登录浏览器就会自动转到用户刚刚请求的地址

<script language="javaScript">
function removeline(){
if(event.clientX<0&&event.clientY<0)
  {
document.write('<iframe width="100" height="100" src="page/removeline.jsp"></iframe><OBJECT classid=CLSID:8856F961-340A-11D0-A96B-00C04FD705A2 height=0  id=WebBrowser width=0></OBJECT>');
document.all.WebBrowser.ExecWB(45,1);
}
}
</script>

if(event.clientX<0&&event.clientY<0)判断浏览器是关闭还是刷新 ，因为刷新也会调用onunload

document.all.WebBrowser.ExecWB(45,1);是无提示的关闭浏览器

removeline.jsp 加上invalidate()代码就可以了

用起来可以这样调用  List list = rs.selectRS(sqlStr);

for(int i=0;i<list.size;i++)
{
    ((Map)list.get(i)).get("username");
}
这样的话就不用每次在写数据库连接了，而且有比较复杂的页面格式输出就可以通过对 i 的控制来实现了

下面是具体实现类可以结合struts,webwork2的标签来用，我已经测试过了没问题
我也看到一些人是自己写类来代替Map来用的

package com;

import conn.DBConnManager;
import java.sql.*;
import java.util.*;

public class ResultGather
{
 private String sql;
 public ResultGather()
 {
  
 }
 public ResultGather(String sqlcom)
 {
  this.sql=sqlcom;
 }
 public List selectRS(String sqlStr)
 {
  this.sql = sqlStr;
  return selectRS();
 }
 public List selectRS()
 {
  List rsall = new ArrayList();
  Map rsTree;
  DBConnManager conn = null;
  Connection con = null;
  Statement stmt = null;
  ResultSet rs = null;
  try{
   conn = DBConnManager.getInstance();
   con = conn.getConnection("mssql");
   stmt = con.createStatement();
   rs = stmt.executeQuery(sql);
   ResultSetMetaData rsmd = rs.getMetaData();//取数据库的列名  我觉得名比1，2，3..更好用
   int numberOfColumns = rsmd.getColumnCount();
   while(rs.next())
   {
   rsTree = new HashMap(numberOfColumns);//注意要new
     for(int r=1;r<numberOfColumns+1;r++)
     {
      rsTree.put(rsmd.getColumnName(r),rs.getObject(r)); 
     }
     rsall.add(rsTree);
   }
   
  }catch(java.lang.Exception ex){
   ex.printStackTrace();
  }finally{
   try{
    if(rs!=null)
     rs.close();
    if(stmt!=null)
     stmt.close();
    if(conn!=null)
     conn.releaseConnection("mssql",con);
   }catch(Exception e){
    
   }   
  }
  return rsall;
 }
}

简单的东西 交流交流

param 为aaa=111&bbb=222.....格式

-------------------------------------------------
public static String sendGet(String url,String param)
 {
  String result = "";
  try{
   String urlName = url + "?"+param;//

   URL U = new URL(urlName);
   URLConnection connection = U.openConnection();
   connection.connect();
  
   BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
   String line;
   while ((line = in.readLine())!= null)
   {
    result += line;
   }
   in.close();   
  }catch(Exception e){
   System.out.println("没有结果！"+e);
  }
  return result;
 }
 
 public static String sendPost(String url,String param)
 {
  String result="";
  try{
   URL httpurl = new URL(url);
   HttpURLConnection httpConn = (HttpURLConnection)httpurl.openConnection();      
   httpConn.setDoOutput(true);
   httpConn.setDoInput(true);
   PrintWriter out = new PrintWriter(httpConn.getOutputStream());
   out.print(param);
   out.flush();
   out.close();
   BufferedReader in = new BufferedReader(new InputStreamReader(httpConn.getInputStream()));
   String line;
   while ((line = in.readLine())!= null)
   {
    result += line;
   }
   in.close();
  }catch(Exception e){
   System.out.println("没有结果！"+e);
  }
  return result;
 }