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功能完善的Java连接池调用实例（转）

文章来源：www.jspcn.net 原作者：薄冰

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/**
* 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;

[@more@]


/**
* 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;
}
}
}

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/**
* Title: PoolMan.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");
}
}

}
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属性文件db.properties放在conf下

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#drivers=com.inet.tds.TdsDriver
#logfile=c:resin-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:resin-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:resin-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:resin-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


本文标题：功能完善的Java连接池调用实例（转）
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