功能完善的Java连接池调用实例

 

/** 
* Title: ConnectPool.java 
* Description: 连接池管理器 
* Copyright: Copyright (c) 2002/12/25 
* Company: 
* Author : 
* Version 2.0 
*/ 


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

/** 
* 管理类DBConnectionManager支持对一个或多个由属性文件定义的数据库连接 
* 池的访问.客户程序可以调用getInstance()方法访问本类的唯一实例. 
*/ 
public class ConnectPool 
{ 
static public ConnectPool instance; // 唯一实例 
static public int clients; 
public Vector drivers = new Vector(); //驱动 
public PrintWriter log; 
public Hashtable pools = new Hashtable(); //连接 

/** 
* 返回唯一实例.如果是第一次调用此方法,则创建实例 
* 
* @return DBConnectionManager 唯一实例 
*/ 
static synchronized public ConnectPool getInstance() 
{ 
if (instance == null) 
{ 
instance = new ConnectPool(); 
} 

clients++; 

return instance; 
} 

/** 
* 建构函数私有以防止其它对象创建本类实例 
*/ 
public ConnectPool() { 
init(); 
} 

/** 
* 将连接对象返回给由名字指定的连接池 
* 
* @param name 在属性文件中定义的连接池名字 
* @param con 连接对象 
*/ 
public void freeConnection(String name, Connection con) 
{ 
DBConnectionPool pool = (DBConnectionPool) pools.get(name); 
if (pool != null) 
{ 
pool.freeConnection(con); 
} 
else 
{ 
System.out.println("pool ==null"); 
} 
clients--; 
} 

/** 
* 获得一个可用的(空闲的)连接.如果没有可用连接,且已有连接数小于最大连接数 
* 限制,则创建并返回新连接 
* 
* @param name 在属性文件中定义的连接池名字 
* @return Connection 可用连接或null 
*/ 
public Connection getConnection(String name) 
{ 
DBConnectionPool pool = (DBConnectionPool) pools.get(name); 
if (pool != null) 
{ 
//return pool.getConnection(); 
return pool.returnConnection(); 
} 
return null; 
} 

/** 
* 获得一个可用连接.若没有可用连接,且已有连接数小于最大连接数限制, 
* 则创建并返回新连接.否则,在指定的时间内等待其它线程释放连接. 
* 
* @param name 连接池名字 
* @param time 以毫秒计的等待时间 
* @return Connection 可用连接或null 
*/ 
public Connection getConnection(String name, long time) 
{ 
DBConnectionPool pool = (DBConnectionPool) pools.get(name); 
if (pool != null) 
{ 
return pool.getConnection(time); 
} 
return null; 
} 

/** 
* 关闭所有连接,撤销驱动程序的注册 
*/ 
public synchronized void release() 
{ 
// 等待直到最后一个客户程序调用 
if (--clients != 0) 
{ 
return; 
} 

Enumeration allPools = pools.elements(); 
while (allPools.hasMoreElements()) 
{ 
DBConnectionPool pool = (DBConnectionPool) allPools.nextElement(); 
pool.release(); 
} 
Enumeration allDrivers = drivers.elements(); 
while (allDrivers.hasMoreElements()) 
{ 
Driver driver = (Driver) allDrivers.nextElement(); 
try { 
DriverManager.deregisterDriver(driver); 

log("撤销JDBC驱动程序 " + driver.getClass().getName()+"的注册"); 
} 
catch (SQLException e) 
{ 
log(e, "无法撤销下列JDBC驱动程序的注册: " + driver.getClass().getName()); 
} 
} 
} 

/** 
* 根据指定属性创建连接池实例. 
* 
* @param props 连接池属性 
*/ 
private void createPools(Properties props) 
{ 
Enumeration propNames = props.propertyNames(); 
while (propNames.hasMoreElements()) 
{ 
String name = (String) propNames.nextElement(); 
if (name.endsWith(".url")) { 
String poolName = name.substring(0, name.lastIndexOf(".")); 
String url = props.getProperty(poolName + ".url"); 
if (url == null) { 
log("没有为连接池" + poolName + "指定URL"); 
continue; 
} 
String user = props.getProperty(poolName + ".user"); 
String password = props.getProperty(poolName + ".password"); 
String maxconn = props.getProperty(poolName + ".maxconn", "0"); 
int max; 
try{ 
max = Integer.valueOf(maxconn).intValue(); 
} 
catch (NumberFormatException e) 
{ 
log("错误的最大连接数限制: " + maxconn + " .连接池: " + poolName); 
max = 0; 
} 
DBConnectionPool pool = new DBConnectionPool(poolName, url, user, password, max); 
pools.put(poolName, pool); 
log("成功创建连接池" + poolName); 
} 
} 
} 

/** 
* 读取属性完成初始化 
*/ 
private void init() 
{ 
try 
{ 
Properties p = new Properties(); 
String configs = System.getProperty("user.dir")+"confdb.properties"; 

System.out.println("configs file local at "+configs); 
FileInputStream is = new FileInputStream(configs); 
Properties dbProps = new Properties(); 
try 
{ 
dbProps.load(is); 
} 
catch (Exception e) 
{ 
System.err.println("不能读取属性文件. " +"请确保db.properties在CLASSPATH指定的路径中"); 
return; 
} 
String logFile = dbProps.getProperty("logfile", "DBConnectionManager.log"); 
try{ 

log = new PrintWriter(new FileWriter(logFile, true), true); 
} 
catch (IOException e) 
{ 
System.err.println("无法打开日志文件: " + logFile); 
log = new PrintWriter(System.err); 
} 
loadDrivers(dbProps); 
createPools(dbProps); }catch(Exception e){} 
} 

/** 
171 * 装载和注册所有JDBC驱动程序 
172 * 
173 * @param props 属性 
174 */ 
private void loadDrivers(Properties props) 
{ 
String driverClasses = props.getProperty("drivers"); 
StringTokenizer st = new StringTokenizer(driverClasses); 
while (st.hasMoreElements()) 
{ 
String driverClassName = st.nextToken().trim(); 
try{ 
Driver driver = (Driver) 
Class.forName(driverClassName).newInstance(); 
DriverManager.registerDriver(driver); 
drivers.addElement(driver); 
System.out.println(driverClassName); 
log("成功注册JDBC驱动程序" + driverClassName); 
} 
catch (Exception e) 
{ 
log("无法注册JDBC驱动程序: " + 
driverClassName + ", 错误: " + e); 
} 
} 
} 

/** 
* 将文本信息写入日志文件 
*/ 
private void log(String msg) 
{ 
log.println(new Date() + ": " + msg); 
} 

/** 
* 将文本信息与异常写入日志文件 
*/ 
private void log(Throwable e, String msg) 
{ 
log.println(new Date() + ": " + msg); 
e.printStackTrace(log); 
} 

/** 
* 此内部类定义了一个连接池.它能够根据要求创建新连接,直到预定的最 
* 大连接数为止.在返回连接给客户程序之前,它能够验证连接的有效性. 
*/ 

class DBConnectionPool 
{ 
//private int checkedOut; 
private Vector freeConnections = new Vector(); 
private int maxConn; 
private String name; 
private String password; 
private String URL; 
private String user; 

/** 
* 创建新的连接池 
* 
* @param name 连接池名字 
* @param URL 数据库的JDBC URL 
* @param user 数据库帐号,或 null 
* @param password 密码,或 null 
* @param maxConn 此连接池允许建立的最大连接数 
*/ 
public DBConnectionPool(String name, String URL, String user, String password,int maxConn) 
{ 
this.name = name; 
this.URL = URL; 
this.user = user; 
this.password = password; 
this.maxConn = maxConn; 
} 
/** 
* 将不再使用的连接返回给连接池 
* 
* @param con 客户程序释放的连接 
*/ 
public synchronized void freeConnection(Connection con) { 
// 将指定连接加入到向量末尾 
try 
{ 
if(con.isClosed()){System.out.println("before freeConnection con is closed");} 
freeConnections.addElement(con); 
Connection contest = (Connection) freeConnections.lastElement(); 
if(contest.isClosed()){System.out.println("after freeConnection contest is closed");} 
notifyAll(); 
}catch(SQLException e){System.out.println(e);} 
} 

/** 
* 从连接池获得一个可用连接.如没有空闲的连接且当前连接数小于最大连接 
* 数限制,则创建新连接.如原来登记为可用的连接不再有效,则从向量删除之, 
* 然后递归调用自己以尝试新的可用连接. 
*/ 
public synchronized Connection getConnection() 
{ 
Connection con = null; 
if (freeConnections.size() > 0) 
{ 
// 获取向量中第一个可用连接 
con = (Connection) freeConnections.firstElement(); 
freeConnections.removeElementAt(0); 
try { 
if (con.isClosed()) 
{ 
log("从连接池" + name+"删除一个无效连接"); 
System.out.println("从连接池" + name+"删除一个无效连接"); 
// 递归调用自己,尝试再次获取可用连接 
con = getConnection(); 
} 
} 
catch (SQLException e) 
{ 
log("从连接池" + name+"删除一个无效连接时错误"); 
System.out.println("从连接池" + name+"删除一个无效连接出错"); 
// 递归调用自己,尝试再次获取可用连接 
con = getConnection(); 
} 
if(freeConnections.size()>maxConn) 
{ System.out.println(" 删除一个溢出连接 "); 
releaseOne(); 
} 
} 


else if((maxConn == 0)||(freeConnections.size()<maxConn)) 
{ 
con = newConnection(); 
} 

return con; 
} 

public synchronized Connection returnConnection() 
{ 
Connection con = null; 
//如果闲置小于最大连接,返回一个新连接 
if(freeConnections.size()<maxConn) 
{ 
con = newConnection(); 
} 
//如果闲置大于最大连接，返回一个可用的旧连接 
else if(freeConnections.size()>=maxConn) 
{ 

con = (Connection) freeConnections.firstElement(); 
System.out.println(" [a 连接池可用连接数 ] : "+"[ "+freeConnections.size()+" ]"); 
freeConnections.removeElementAt(0); 
System.out.println(" [b 连接池可用连接数 ] : "+"[ "+freeConnections.size()+" ]"); 
try 
{ 
if (con.isClosed()) 
{ 
log("从连接池" + name+"删除一个无效连接"); 
System.out.println("从连接池" + name+"删除一个无效连接"); 
returnConnection(); 
} 
}catch (SQLException e) 
{ 
log("从连接池" + name+"删除一个无效连接时错误"); 
System.out.println("从连接池" + name+"删除一个无效连接出错"); 
returnConnection(); 
} 
} 
return con; 
} 

/** 
* 从连接池获取可用连接.可以指定客户程序能够等待的最长时间 
* 参见前一个getConnection()方法. 
* 
* @param timeout 以毫秒计的等待时间限制 
*/ 
public synchronized Connection getConnection(long timeout) 
{ 
long startTime = new Date().getTime(); 
Connection con; 
while ((con = getConnection()) == null) 
{ 
try 
{ 
wait(timeout); 
} 
catch (InterruptedException e) {} 
if ((new Date().getTime() - startTime) >= timeout) { 
// wait()返回的原因是超时 
return null; 
} 
} 
return con; 
} 

/** 
* 关闭所有连接 
*/ 
public synchronized void release() 
{ 
Enumeration allConnections = freeConnections.elements(); 
while (allConnections.hasMoreElements()) 
{ 
Connection con = (Connection) allConnections.nextElement(); 
try { 
con.close(); 
log("关闭连接池" + name+"中的一个连接"); 
} 
catch (SQLException e) 
{ 
log(e, "无法关闭连接池" + name+"中的连接"); 
} 
} 
freeConnections.removeAllElements(); 
} 
/** 
* 关闭一个连接 
*/ 
public synchronized void releaseOne() 
{ 
if(freeConnections.firstElement()!=null) 
{ Connection con = (Connection) freeConnections.firstElement(); 
try { 
con.close(); 
System.out.println("关闭连接池" + name+"中的一个连接"); 
log("关闭连接池" + name+"中的一个连接"); 
} 
catch (SQLException e) 
{ 

System.out.println("无法关闭连接池" + name+"中的一个连接"); 
log(e, "无法关闭连接池" + name+"中的连接"); 
} 
} 
else 
{ 
System.out.println("releaseOne() bug......................................................."); 

} 
} 

/** 
* 创建新的连接 
*/ 
private Connection newConnection() 
{ 
Connection con = null; 
try 
{ 
if (user == null) { 
con = DriverManager.getConnection(URL); 
} 
else{ 
con = DriverManager.getConnection(URL, user, password); 
} 
log("连接池" + name+"创建一个新的连接"); 

} 
catch (SQLException e) { 
log(e, "无法创建下列URL的连接: " + URL); 
return null; 
} 
return con; 
} 
} 
}

================================
/** 
* Title: ConnectPool.java 
* Description: 数据库操作 
* Copyright: Copyright (c) 2002/12/25 
* Company: 
* Author : 
* remark : 加入指针回滚 
* Version 2.0 
*/ 

import java.io.*; 
import com.sjky.pool.*; 
import java.sql.*; 
import java.util.*; 
import java.util.Date; 
import java.net.*; 

public class PoolMan extends ConnectPool { 

private ConnectPool connMgr; 
private Statement stmt; 
private Connection con ; 
private ResultSet rst; 

/** 
*对象连接初始化 
* */ 

public Connection getPool(String name) throws Exception 
{ 
try{ 
connMgr = ConnectPool.getInstance(); 
con = connMgr.getConnection(name); 
}catch(Exception e) 
{ 
System.err.println("不能创建连接!请尝试重启应用服务器"); 

} 
return con; 
} 

/** 
*同以上方法,加入连接空闲等待时间 
*待用方法 
* */ 

public Connection getPool_t(String name, long time) throws Exception 
{ 
try{ 
connMgr = ConnectPool.getInstance(); 
con = connMgr.getConnection(name,time); 
}catch(Exception e) 
{ 
System.err.println("不能创建连接!"); 

} 
return con; 
} 
/** 
*执行查询方法1 
* */ 
public ResultSet executeQuery(String SqlStr) throws Exception 
{ 
ResultSet result = null; 
try 
{ 
stmt = con.createStatement(); 
result = stmt.executeQuery(SqlStr); 
// here add one line by jnma 12.11 
con.commit(); 
} 
catch(java.sql.SQLException e) 
{ 
throw new Exception("执行查询语句出错"); 
} 
return result; 
} 
/** 
*执行查询方法2 
* */ 
public ResultSet getRst(String SqlStr) throws Exception 
{ 
// ResultSet result = null; 
try 
{ 
stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); 
rst = stmt.executeQuery(SqlStr); 
// here add one line by jnma 12.11 
con.commit(); 
} 
catch(java.sql.SQLException e) 
{ 
throw new Exception("执行查询语句出错"); 
} 
return rst; 
} 
/** 
*执行更新 
* */ 
public int Update(String SqlStr) throws Exception 
{ 
int result = -1; 
try 
{ 
stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); 
result = stmt.executeUpdate(SqlStr); 
// here add one line by jnma 12.11 
con.commit(); 
if(result==0) 
System.out.println("执行delete,update,insert SQL出错"); 
} 
catch(java.sql.SQLException e) 
{ 
System.err.println("执行delete,update,insert SQL出错"); 
} 
return result; 
} 

/** 
*执行事务处理 
* */ 
public boolean handleTransaction(Vector SqlArray) throws Exception 
{ 
boolean result = false; 
int ArraySize = SqlArray.size(); 
try 
{ 
stmt = con.createStatement(); 
con.setAutoCommit(false); 
System.out.println("ArraySize is" +ArraySize); 
for(int i=0;i<ArraySize;i++) 
{ 
System.out.println(" 开始执行语句"+(String)SqlArray.elementAt(i)); 
stmt.executeUpdate((String)SqlArray.elementAt(i)); 
System.out.println(" 执行成功"); 
} 
con.commit(); 
con.setAutoCommit(true) ;//必须 
System.out.println("事务执行成功"); 
result = true; 
} 
catch(java.sql.SQLException e) 
{ 
try 
{ 
System.out.println(e.toString()); 
System.out.println("数据库操作失败"); 
con.rollback(); 
} 
catch(java.sql.SQLException Te) 
{ 
System.err.println("事务出错回滚异常"); 
} 
} 
try 
{ 
con.setAutoCommit(true); 
} 
catch(java.sql.SQLException e) 
{ 
System.err.println("设置自动提交失败"); 
} 
return result; 
} 

/** 
*释放连接 
* */ 
public void close(String name) throws Exception 
{ 
try 
{ 
if(stmt!=null) 
stmt.close(); 
if(con!=null) 
{ 
connMgr.freeConnection(name,con); 

System.out.println(" [c 正在释放一个连接 ] "); 

} 
} 
catch(java.sql.SQLException e) 
{ 
System.err.println("释放连接出错"); 
} 
} 

} 
===========================
属性文件db.properties放在conf下 

#drivers=com.inet.tds.TdsDriver 
#logfile=c: esin-2.1.4DBConnectPool-log.txt 
#test.maxconn=1000 
#test.url=jdbc:inetdae:SERVER:1433?sql7=true 
#test.user=sa 
#test.password=test 

drivers=com.microsoft.jdbc.sqlserver.SQLServerDriver 
logfile=F: esin-2.1.4DBConnectPool-log.txt 
test.maxconn=20 
test.url=jdbc:microsoft:sqlserver://192.168.0.5:1433;DatabaseName=test 
test.user=sa 
test.password=test 


#drivers=oracle.jdbc.driver.OracleDriver 
#logfile=c: esin-2.1.4DBConnectPool-log.txt 
#test.maxconn=100 
#test.url=jdbc:oracle:thin:@192.168.0.10:1521:myhome 
#test.user=system 
#test.password=manager 
#mysql端3306 

#drivers=org.gjt.mm.mysql.Driver 
#logfile=c: esin-2.1.4DBConnectPool-log.txt 
#test.maxconn=100 
#test.url=jdbc:mysql://192.168.0.4:3306/my_test 
#test.user=root 
#test.password=system 



原作者：薄冰
来 源：163.com