功能完善的Java连接池调用实例

╰+攻爆jí腚メ 2022-06-03 04:06 160阅读 0赞

/\*\*  
\* 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")+"/conf/db.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:/resin-2.1.4/DBConnectPool-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:/resin-2.1.4/DBConnectPool-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:/resin-2.1.4/DBConnectPool-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:/resin-2.1.4/DBConnectPool-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