package zpxx;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
//建立DBConnectionManager
public class DBConnectionManager
{
static private DBConnectionManager instance;
static private int clients;
private Vector drivers=new Vector();
private PrintWriter log;
private Hashtable pools=new Hashtable();
//返回唯一的實列
static synchronized public DBConnectionManager getInstance()
{
if(instance==null)
{
instance=new DBConnectionManager();
}
clients++;
return instance;
}
//構造函數！
private DBConnectionManager()
{
init();
}
//結束構造函數
//釋放一個連接
public void freeConnection(String name,Connection con)
{
DBConnectionPool pool=(DBConnectionPool)pools.get(name);
if(pool!=null)
{
pool.freeConnection(con);
}
}
//結束釋放一個連接
//取得一個連接
public Connection getConnection(String name)
{
DBConnectionPool pool=(DBConnectionPool)pools.get(name);
if(pool!=null)
{
return pool.getConnection();
}
return null;
}
public Connection getConnection(String name,String customer)
{
DBConnectionPool pool=(DBConnectionPool)pools.get(name);
if(pool!=null)
{
return pool.getConnection(customer);
}
return null;
}
public Connection getConnection(String name,long time)
{
DBConnectionPool pool=(DBConnectionPool)pools.get(name);
if(pool!=null)
{
return pool.getConnection(time);
}
return null;
}
//結束getconnection
//關閉所有連接
public synchronized void release()
{
// 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("撤消JDBC驅動程序"+driver.getClass().getName());
}
catch(SQLException e)
{
log(e,"無法撤消JDBC驅動程序的註冊"+driver.getClass().getName());
}
}
}
public synchronized void release(String customer)
{
// if(--clients!=0)
// return;
Enumeration allPools=pools.elements();
while(allPools.hasMoreElements())
{
DBConnectionPool pool=(DBConnectionPool)allPools.nextElement();
pool.release(customer);
}
Enumeration allDrivers=drivers.elements();
while(allDrivers.hasMoreElements())
{
Driver driver=(Driver)allDrivers.nextElement();
try
{
DriverManager.deregisterDriver(driver);
log(customer+"撤消JDBC驅動程序"+driver.getClass().getName());
}
catch(SQLException e)
{
log(e,"無法撤消JDBC驅動程序的註冊"+driver.getClass().getName());
}
}
}
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("沒有連接池"+poolName+"指定的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("錯誤的最大連接數："+maxconn+".連接池"+poolName);
max=0;
}
DBConnectionPool pool=new DBConnectionPool(poolName,url,user,password,max);
pools.put(poolName,pool);
log("成功創建連接池"+poolName);
}
}
}
private void init()
{
InputStream is=getClass().getResourceAsStream("db.properties");
Properties dbProps=new Properties();
try
{
dbProps.load(is);
}
catch(Exception e)
{
System.err.println("不能讀取屬性文件。請確保db.properties在你的CLASSPATH中");
return;
}
String logFile=dbProps.getProperty("logfile","DBConnectionManager.log");
try
{
log=new PrintWriter(new FileWriter(logFile,true),true);
}
catch(IOException e)
{
System.err.println("無法打開日誌文件："+logFile);
log=new PrintWriter(System.err);
}
loadDriver(dbProps);
createPools(dbProps);
}
private void loadDriver(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);
log("成功註冊驅動程序"+driverClassName);
}
catch(Exception e)
{
log("無法註冊驅動程序:"+driverClassName+",錯誤"+e);
}
}
}
private void log(String msg)
{
log.println(new Date()+":"+msg);
}
private void log(Throwable e,String msg)
{
log.println(new Date()+":"+msg);
e.printStackTrace(log);
}
class DBConnectionPool
{
private int checkOut;
private Vector freeConnections=new Vector();
private int maxconn;
private String name;
private String password;
private String URL;
private String user;
public DBConnectionPool(String name,String URL,String user,String password,int maxconn)
{
this.name=name;
this.URL=URL;
this.password=password;
this.user=user;
this.maxconn=maxconn;
}
public synchronized void freeConnection(Connection con)
{
freeConnections.addElement(con);
checkOut--;
notifyAll();
}
public synchronized Connection getConnection()
{
Connection con=null;
if(freeConnections.size()>0)
{
con=(Connection)freeConnections.firstElement();
freeConnections.removeElementAt(0);
try
{
if(con.isClosed())
{
log("從連接池"+name+"刪除一個連接");
con=getConnection();
}
}
catch(SQLException e)
{
log("從連接池"+name+"刪除一個連接");
con=getConnection();
}
}
else if(maxconn==0||checkOut<maxconn)
{
con=newConnection();
}
if(con!=null)
{
checkOut++;
}
return con;
}
public synchronized Connection getConnection(String customer)
{
Connection con=null;
if(freeConnections.size()>0)
{
con=(Connection)freeConnections.firstElement();
freeConnections.removeElementAt(0);
try
{
if(con.isClosed())
{
log("從連接池"+name+"刪除一個連接");
con=getConnection();
}
}
catch(SQLException e)
{
log("從連接池"+name+"刪除一個連接");
con=getConnection();
}
}
else if(maxconn==0||checkOut<maxconn)
{
con=newConnection(customer);
}
if(con!=null)
{
checkOut++;
}
return con;
}
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)
{
return null;
}
}
return con;
}
public void release()
{
Enumeration allConnections=freeConnections.elements();
while(allConnections.hasMoreElements())
{
Connection con=(Connection)allConnections.nextElement();
try
{
con.close();
log("關閉連接池"+name+"中的連接");
}
catch(SQLException e)
{
log(e,"無法關閉連接池"+name+"中的連接");
}
}
freeConnections.removeAllElements();
}
public void release(String customer)
{
Enumeration allConnections=freeConnections.elements();
while(allConnections.hasMoreElements())
{
Connection con=(Connection)allConnections.nextElement();
try
{
con.close();
log(customer+"關閉連接池"+name+"中的連接");
}
catch(SQLException e)
{
log(e,"無法關閉連接池"+name+"中的連接");
}
}
freeConnections.removeAllElements();
}
private Connection newConnection()
{
Connection con=null;
try
{
con=DriverManager.getConnection(URL,user,password);
log("連接池"+name+"創建一個新的連接");
}
catch(SQLException e)
{
log(e,"無法創建下列URL的連接"+URL);
return null;
}
return con;
}
private Connection newConnection(String customer)
{
Connection con=null;
try
{
con=DriverManager.getConnection(URL,user,password);
log(customer+"從連接池"+name+"創建一個新的連接");
}
catch(SQLException e)
{
log(e,"無法創建下列URL的連接"+URL);
return null;
}
return con;
}
}
}
