connectionpooling.java

这个是j2eejava web 编程精要十五讲的全部源码。对学习java web编程的人来说是很能得的资料

package foton.util;

import java.io.*;
import java.util.*;
import java.sql.*;

public class ConnectionPooling{
    private static ConnectionPooling instance = null;

    public static synchronized Connection getConnection() {
        if (instance == null){
            instance = new ConnectionPooling();
        }
        return instance._getConnection();
    }

    private ConnectionPooling(){
        super();
    }

    private  Connection _getConnection(){
        try{
            String sDBDriver  = null;
            String sConnection   = null;
            String sUser = null;
            String sPassword = null;

            Properties p = new Properties();
            InputStream is = getClass().getResourceAsStream("/db.properties");
            p.load(is);
            sDBDriver = p.getProperty("driver",sDBDriver);
            sConnection = p.getProperty("url",sConnection);
            sUser = p.getProperty("user","");
            sPassword = p.getProperty("password","");

            String myConnection = sConnection + "?user=" + sUser
                                   + "&password=" + sPassword;

            Properties pr = new Properties();
            //pr.put("user",sUser);
            //pr.put("password",sPassword);
            pr.put("characterEncoding", "GB2312");
            pr.put("useUnicode", "TRUE");

            Class.forName(sDBDriver).newInstance();
            return DriverManager.getConnection(myConnection+"",pr);
        }
        catch(Exception se){
            System.out.println(se);
            return null;
        }
    }

    public static void clearConn(PreparedStatement ps,ResultSet rs){
   closeResultSet(rs);
   closePreparedStatement(ps);
   }

 public static void clearConn(Connection con, PreparedStatement ps,ResultSet rs){
   closeResultSet(rs);
   closePreparedStatement(ps);
   freeConncetion(con);
 }
 /**
  * 释放连接池中的所有Connection
  *
  * @throws SQLException
  */
 public static void freeConncetion(Connection conn){
   try{
     if(conn != null) conn.close();
   }catch(SQLException Ex_Connection){
         System.out.println("SQLException when close Connection. "+Ex_Connection);
   }
 }


 /**
  * 释放连接池中的所有ResultSet
  *
  * @throws SQLException
  */
 public static void closeResultSet(ResultSet resultset){
   try{
     if(resultset != null) resultset.close();
   }catch(SQLException Ex_Resultset){
     System.out.println("SQLException when close ResultSet. "+Ex_Resultset);
   }
 }

 /**
  * 释放连接池中的所有PreparedStatement
  *
  * @throws SQLException
  */
 public static void closePreparedStatement(PreparedStatement ps){
   try {
     if (ps != null) ps.close();
   } catch (SQLException Ex_Statement) {
     System.out.println("SQLException when close PreparedStatement."+Ex_Statement);
   }
 }

 public static void rollBack(Connection conn)
 {
   try{
     conn.rollback();
   }catch(SQLException se){
     System.out.println("SQLException when close rollBack."+se);
   }
 }

 public static void log(String s){
   if(isDebug == true)
       System.out.println(s);
 }

  private static boolean isDebug = true;

}