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Java 创徏数据库连接池(�?

abin — Mon, 03 Sep 2012 16:20:00 GMT

package com.abin.lee.collection.pool;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class ConnectionPool {
private List pool;
private static final String Url = "jdbc:oracle:thin:@localhost:1521:XE";
private static final String USERNAME = "abing";
private static final String PASSWORD = "abing";
private static final String DRIVER = "oracle.jdbc.driver.OracleDriver";
private int poolSize = 10;
private static volatile ConnectionPool instance = null;

private ConnectionPool() {
init();
}

public void init() {
pool = new ArrayList(poolSize);
addConnection();
}

public synchronized void release(Connection conn) {
pool.add(conn);
}

public synchronized void closePool() {
  for (int i = 0; i < pool.size(); i++) {
   try {
    ((Connection) pool.get(i)).close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
   pool.remove(i);
  }
}

public static ConnectionPool getInstance() {
  if (null == instance) {
   synchronized (ConnectionPool.class) {
    if (null == instance) {
     return new ConnectionPool();
    }
   }
  }
  return instance;
}

public synchronized Connection getConnection() {
  if (pool.size() > 0) {
   Connection conn = pool.get(0);
   if(conn!=null){
    System.out.println("Connection Pool Create Success");
   }
   pool.remove(conn);
   return conn;
  }else{
   return null;
  }
}

public void addConnection() {
  Connection conn = null;
  for (int i = 0; i < poolSize; i++) {
   try {
    Class.forName(DRIVER);
    conn = DriverManager.getConnection(Url, USERNAME, PASSWORD);
    pool.add(conn);
   } catch (Exception e) {
    e.printStackTrace();
   }

}
}

}

��试代码�Q?br />

package com.abin.lee.collection.pool;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.abin.lee.collection.threadlocal.UserBean;

public class TestConnectionPool {

public static List findAll(){
  Connection conn=null;
  PreparedStatement ps=null;
  ResultSet rs=null;
  String sql="select * from userbean order by id desc";
  List list=new ArrayList();
  UserBean user=null;
  try {
   conn=ConnectionPool.getInstance().getConnection();
   ps=conn.prepareStatement(sql);
   rs=ps.executeQuery();
   while (rs.next()&&rs!=null) {
    user=new UserBean();
    user.setId(rs.getString("id"));
    user.setUsername(rs.getString("username"));
    user.setPassword(rs.getString("password"));
    list.add(user);
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  return list;
}
public static void main(String[] args) {
  List list=findAll();
  for(UserBean lst:list){
   System.out.println("id="+lst.getId());
   System.out.println("username="+lst.getUsername());
   System.out.println("id="+lst.getPassword());
  }
}

}

abin 2012-09-04 00:20 发表评论

Java 创徏数据库连接池(一)

abin — Mon, 03 Sep 2012 16:18:00 GMT

package com.abin.lee.collection.pool;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;

public class ConnectionManage {
private static List pool=new LinkedList();;
private static final String Url = "jdbc:oracle:thin:@localhost:1521:XE";
private static final String USERNAME = "abing";
private static final String PASSWORD = "abing";
private static final String DRIVER = "oracle.jdbc.driver.OracleDriver";
private static int initCount = 5;
private static int maxCount = 10;
private static int currentCount = 5;
private static volatile ConnectionManage instance = null;
private ConnectionManage(){
  init();
}
public static ConnectionManage getInstance(){
  if(null == instance){
   synchronized (ConnectionManage.class) {
    if(null == instance){
     return new ConnectionManage();
    }
   }
  }
  return instance;
}
public void init(){
  addConnection();
}
public static Connection createConnection() throws ClassNotFoundException {
  Connection conn=null;
  try {
   Class.forName(DRIVER);
   conn=DriverManager.getConnection(Url, USERNAME, PASSWORD);
  } catch (SQLException e) {
   e.printStackTrace();
  }
  return conn;
}
public static void addConnection(){
  for(int i=0;i   try {
    pool.add(createConnection());
   } catch (ClassNotFoundException e) {
    e.printStackTrace();
   }
  }
}

public static void release(Connection conn){
  pool.add(conn);
}
public static Connection getConnection() throws SQLException, ClassNotFoundException{
  synchronized (pool) {
   if(pool.size()>0){
    System.out.println("Current Connection size is:"+pool.size());
    return pool.get(0);
   }else if(currentCount    Class.forName(DRIVER);
    Connection conn=createConnection();
    pool.add(conn);
    currentCount++;
    return conn;
   }else{
    throw new SQLException("Current Connection is Zero");
   }
  }
}

}

��试代码�Q?br />

package com.abin.lee.collection.pool;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.abin.lee.collection.threadlocal.UserBean;

public class TestConnectionPool {

public static List findAll(){
  Connection conn=null;
  PreparedStatement ps=null;
  ResultSet rs=null;
  String sql="select * from userbean order by id desc";
  List list=new ArrayList();
  UserBean user=null;
  try {
   conn=ConnectionManage.getInstance().getConnection();
   ps=conn.prepareStatement(sql);
   rs=ps.executeQuery();
   while (rs.next()&&rs!=null) {
    user=new UserBean();
    user.setId(rs.getString("id"));
    user.setUsername(rs.getString("username"));
    user.setPassword(rs.getString("password"));
    list.add(user);
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  return list;
}
public static void main(String[] args) {
  List list=findAll();
  for(UserBean lst:list){
   System.out.println("id="+lst.getId());
   System.out.println("username="+lst.getUsername());
   System.out.println("id="+lst.getPassword());
  }
}

}

abin 2012-09-04 00:18 发表评论

Java数据库连接池实现

abin — Mon, 03 Sep 2012 13:56:00 GMT

http://06peng.com/read.php/13.htm
http://blog.sina.com.cn/s/blog_70ce7e9e0100v9dh.html
http://blog.163.com/lgw1984_12/blog/static/4122245520096239913479/
http://mzba520.iteye.com/blog/939691
http://blog.csdn.net/java_blue/article/details/6581480
http://blog.csdn.net/a600423444/article/details/6542521
http://blog.csdn.net/caoyinghui1986/article/details/2315864

abin 2012-09-03 21:56 发表评论

abin — Mon, 03 Sep 2012 13:55:00 GMT

下面是以前学java 的时候写的一个实玎ͼ�没有考虑很多�Q�比如同步处理等�{�。懒得改�Q�你��q��看吧�?/p>

package com.wangjia.tools;

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

/**
* 数据库连接池的简单实�?br />* @author wangjia
* @version 1.0
*@serial 2301410997974776106L
*/
public class DbConn implements Serializable{

/**
*
*/
private static final long serialVersionUID = 2301410997974776106L;
private static List connList=new ArrayList();
//private static String driver="com.microsoft.jdbc.sqlserver.SQLServerDriver";//sql2000
private static String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver";//sql2005
private static String url="jdbc:sqlserver://127.0.0.1:1433;DatabaseName=Forum";
private static String userName="sa";
private static String password="sa";
private static int maxConn=20;
private static int minConn=5;
private static int usedConn=0;
private static DbConn dbconn=null;
// private static int flag=1;
/**
* �?a style="border-bottom: rgb(0,85,153) 1px dotted; color: rgb(0,85,153); text-decoration: none" target="_blank">�|�数�?/a>库连接的驱动
* @param driver 数据库连�?/a>的驱�?lt;br/>例如:"com.microsoft.sqlserver.jdbc.SQLServerDriver"
*/
public static void setDriver(String driver) {
DbConn.driver = driver;
}

/**
* 讄��数据�?a style="border-bottom: rgb(0,85,153) 1px dotted; color: rgb(0,85,153); text-decoration: none" target="_blank">�q�接�?/a>的最 ��数�?br />* @param maxConn 数据库连接池的最��数�?br />*/
public static void setMaxConn(int maxConn) {
DbConn.maxConn = maxConn;
}

/**
* 讄��数据库连接池的最大数�?br />* @param minConn 数据库连接池的最大数�?br />*/
public static void setMinConn(int minConn) {
DbConn.minConn = minConn;
}

/**
* 讄��数据库连接的URL
* @param url 数据库连接的URL,包括数据�?/a>的名�U?lt;br/>例如: "jdbc:sqlserver://127.0.0.1:1433;DatabaseName=master"
*/
public static void setUrl(String url) {
DbConn.url = url;
}

private DbConn() throws MyException{
try{
Class.forName(driver);
for(int i=0;iconnList.add(DriverManager.getConnection(url,userName.toString(),password.toString()));
}
}catch(ClassNotFoundException e){
throw new MyException("误��|�正��的数据库连接驱�?\nusing: DbConn.setDriver(String driver)");

}catch(SQLException e){
throw new MyException("误��|�正��的数据库连接URL以及�?a style="border-bottom: rgb(0,85,153) 1px dotted; color: rgb(0,85,153); text-decoration: none" target="_blank">于连接的用户名和密码!\n" +
"using: DbConn.setUrl(String url),DbConn.setUserName(String userName),DbConn.setPassword(String password)");

}
}
/**
* 用于得到DbConn对象
* @return �q�回一个DbConn对像
*/

public static Connection getConn() throws MyException{
// flag++;
if(dbconn==null)dbconn=new DbConn();
// System.out.println("falg="+flag);
// System.out.println("usedConn="+usedConn);
if(connList.size()==0){
throw new MyException("没有正确的设�|�相关信�?以至�q�接池未初始�?);
}
if(usedConn==maxConn){

Thread thread=new Thread(new Runnable(){

@SuppressWarnings("static-access")
public void run() {
if(usedConntry {
try {
Thread.currentThread().sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
getConn();
} catch (MyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

});
thread.start();
}
if(usedConn>=minConn&&usedConntry {
connList.add(DriverManager.getConnection(url,userName.toString(),password.toString()));
} catch (SQLException e) {

}
return connList.get(usedConn++);
}
if(usedConn<5){
return connList.get(usedConn++);
}
return null;
}

public static void close(){
try {
if(usedConn>5)
connList.get(--usedConn).close();
else usedConn--;
} catch (SQLException e) {
// TODO 自动生成 catch �?br />e.printStackTrace();
}

}

/**
* 讄��用于�q�接数据库的密码
* @param password 用于�q�接数据库的密码
*/
public static void setPassword(String password) {
DbConn.password = password;
}

/**
* 讄��用于�q�接数据库的用户�?br />* @param userName 用于�q�接数据库的用户�?br />*/
public static void setUserName(String userName) {
DbConn.userName = userName;
}

}

在项目中用到�q�接池的话，一般会直接使用已有的开源连接池实现�Q�比如用 apache 的common-dbcp.jar和common-pool.jar 相结合，很少去自己实现�?/p>

abin 2012-09-03 21:55 发表评论