功能完善的Java連接池調用實例（轉）

文章來源：www.jspcn.net 原作者：薄冰

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

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

/**
* 管理類DBConnectionManager支持對一個或多個由屬性文件定義的數據庫連接
* 池的訪問.客戶程序可以調用getInstance()方法訪問本類的唯一實例.
*/

public class ConnectPool {
static public ConnectPool instance; // 唯一實例

static public int clients;

public Vector drivers = new Vector(); // 驅動

public PrintWriter log;

public Hashtable pools = new Hashtable(); // 連接

/**
* 返回唯一實例.如果是第一次調用此方法,則創建實例
*
* @return DBConnectionManager 唯一實例
*/
static synchronized public ConnectPool getInstance() {
if (instance == null) {
instance = new ConnectPool();
}

clients++;

return instance;
}

/**
* 建構函數私有以防止其它對象創建本類實例
*/
public ConnectPool() {
init();
}

/**
* 將連接對象返回給由名字指定的連接池
*
* @param name
* 在屬性文件中定義的連接池名字
* @param con
* 連接對象
*/
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--;
}

/**
* 獲得一個可用的(空閑的)連接.如果沒有可用連接,且已有連接數小于最大連接數 限制,則創建并返回新連接
*
* @param name
* 在屬性文件中定義的連接池名字
* @return Connection 可用連接或null
*/
public Connection getConnection(String name) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
// return pool.getConnection();
return pool.returnConnection();
}
return null;
}

/**
* 獲得一個可用連接.若沒有可用連接,且已有連接數小于最大連接數限制, 則創建并返回新連接.否則,在指定的時間內等待其它線程釋放連接.
*
* @param name
* 連接池名字
* @param time
* 以毫秒計的等待時間
* @return Connection 可用連接或null
*/
public Connection getConnection(String name, long time) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection(time);
}
return null;
}

/**
* 關閉所有連接,撤銷驅動程序的注冊
*/
public synchronized void release() {
// 等待直到最后一個客戶程序調用
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("撤銷JDBC驅動程序 " + driver.getClass().getName() + "的注冊");
} catch (SQLException e) {
log(e, "無法撤銷下列JDBC驅動程序的注冊: " + driver.getClass().getName());
}
}
}

/**
* 根據指定屬性創建連接池實例.
*
* @param props
* 連接池屬性
*/
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("沒有為連接池" + 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("錯誤的最大連接數限制: " + 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);
}
}
}

/**
* 讀取屬性完成初始化
*/
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("不能讀取屬性文件. "
+ "請確保db.properties在CLASSPATH指定的路徑中");
return;
}
String logFile = dbProps.getProperty("logfile",
"DBConnectionManager.log");
try {

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

/**
* 171 * 裝載和注冊所有JDBC驅動程序 172 * 173 *
*
* @param props
* 屬性 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("成功注冊JDBC驅動程序" + driverClassName);
} catch (Exception e) {
log("無法注冊JDBC驅動程序: " + driverClassName + ", 錯誤: " + e);
}
}
}

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

/**
* 將文本信息與異常寫入日志文件
*/
private void log(Throwable e, String msg) {
log.println(new Date() + ": " + msg);
e.printStackTrace(log);
}

/**
* 此內部類定義了一個連接池.它能夠根據要求創建新連接,直到預定的最 大連接數為止.在返回連接給客戶程序之前,它能夠驗證連接的有效性.
*/

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;

/**
* 創建新的連接池
*
* @param name
* 連接池名字
* @param URL
* 數據庫的JDBC URL
* @param user
* 數據庫帳號,或 null
* @param password
* 密碼,或 null
* @param maxConn
* 此連接池允許建立的最大連接數
*/
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;
}

/**
* 將不再使用的連接返回給連接池
*
* @param con
* 客戶程序釋放的連接
*/
public synchronized void freeConnection(Connection con) {
// 將指定連接加入到向量末尾
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);
}
}

/**
* 從連接池獲得一個可用連接.如沒有空閑的連接且當前連接數小于最大連接 數限制,則創建新連接.如原來登記為可用的連接不再有效,則從向量刪除之,
* 然后遞歸調用自己以嘗試新的可用連接.
*/
public synchronized Connection getConnection() {
Connection con = null;
if (freeConnections.size() > 0) {
// 獲取向量中第一個可用連接
con = (Connection) freeConnections.firstElement();
freeConnections.removeElementAt(0);
try {
if (con.isClosed()) {
log("從連接池" + name + "刪除一個無效連接");
System.out.println("從連接池" + name + "刪除一個無效連接");
// 遞歸調用自己,嘗試再次獲取可用連接
con = getConnection();
}
} catch (SQLException e) {
log("從連接池" + name + "刪除一個無效連接時錯誤");
System.out.println("從連接池" + name + "刪除一個無效連接出錯");
// 遞歸調用自己,嘗試再次獲取可用連接
con = getConnection();
}
if (freeConnections.size() > maxConn) {
System.out.println(" 刪除一個溢出連接 ");
releaseOne();
}
}

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

return con;
}

public synchronized Connection returnConnection() {
Connection con = null;
// 如果閑置小于最大連接,返回一個新連接
if (freeConnections.size() < maxConn) {
con = newConnection();
}
// 如果閑置大于最大連接，返回一個可用的舊連接
else if (freeConnections.size() >= maxConn) {

con = (Connection) freeConnections.firstElement();
System.out.println(" [a 連接池可用連接數 ] : " + "[ "
+ freeConnections.size() + " ]");
freeConnections.removeElementAt(0);
System.out.println(" [b 連接池可用連接數 ] : " + "[ "
+ freeConnections.size() + " ]");
try {
if (con.isClosed()) {
log("從連接池" + name + "刪除一個無效連接");
System.out.println("從連接池" + name + "刪除一個無效連接");
returnConnection();
}
} catch (SQLException e) {
log("從連接池" + name + "刪除一個無效連接時錯誤");
System.out.println("從連接池" + name + "刪除一個無效連接出錯");
returnConnection();
}
}
return con;
}

/**
* 從連接池獲取可用連接.可以指定客戶程序能夠等待的最長時間 參見前一個getConnection()方法.
*
* @param timeout
* 以毫秒計的等待時間限制
*/
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()返回的原因是超時
return null;
}
}
return con;
}

/**
* 關閉所有連接
*/
public synchronized void release() {
Enumeration allConnections = freeConnections.elements();
while (allConnections.hasMoreElements()) {
Connection con = (Connection) allConnections.nextElement();
try {
con.close();
log("關閉連接池" + name + "中的一個連接");
} catch (SQLException e) {
log(e, "無法關閉連接池" + name + "中的連接");
}
}
freeConnections.removeAllElements();
}

/**
* 關閉一個連接
*/
public synchronized void releaseOne() {
if (freeConnections.firstElement() != null) {
Connection con = (Connection) freeConnections.firstElement();
try {
con.close();
System.out.println("關閉連接池" + name + "中的一個連接");
log("關閉連接池" + name + "中的一個連接");
} catch (SQLException e) {

System.out.println("無法關閉連接池" + name + "中的一個連接");
log(e, "無法關閉連接池" + name + "中的連接");
}
} else {
System.out
.println("releaseOne() bug.......................................................");

}
}

/**
* 創建新的連接
*/
private Connection newConnection() {
Connection con = null;
try {
if (user == null) {
con = DriverManager.getConnection(URL);
} else {
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;
}
}
}

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/**
* Title: PoolMan.java
* Description: 數據庫操作
* Copyright: Copyright (c) 2002/12/25
* Company:
* Author :
* remark : 加入指針回滾
* 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;

/**
* 對象連接初始化
*/

public Connection getPool(String name) throws Exception {
try {
connMgr = ConnectPool.getInstance();
con = connMgr.getConnection(name);
} catch (Exception e) {
System.err.println("不能創建連接!請嘗試重啟應用服務器");

}
return con;
}

/**
* 同以上方法,加入連接空閑等待時間 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("不能創建連接!");

}
return con;
}

/**
* 執行查詢方法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("執行查詢語句出錯");
}
return result;
}

/**
* 執行查詢方法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("執行查詢語句出錯");
}
return rst;
}

/**
* 執行更新
*/
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("執行delete,update,insert SQL出錯");
} catch (java.sql.SQLException e) {
System.err.println("執行delete,update,insert SQL出錯");
}
return result;
}

/**
* 執行事務處理
*/
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(" 開始執行語句" + (String) SqlArray.elementAt(i));
stmt.executeUpdate((String) SqlArray.elementAt(i));
System.out.println(" 執行成功");
}
con.commit();
con.setAutoCommit(true);// 必須
System.out.println("事務執行成功");
result = true;
} catch (java.sql.SQLException e) {
try {
System.out.println(e.toString());
System.out.println("數據庫操作失敗");
con.rollback();
} catch (java.sql.SQLException Te) {
System.err.println("事務出錯回滾異常");
}
}
try {
con.setAutoCommit(true);
} catch (java.sql.SQLException e) {
System.err.println("設置自動提交失敗");
}
return result;
}

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

System.out.println(" [c 正在釋放一個連接 ] ");

}
} catch (java.sql.SQLException e) {
System.err.println("釋放連接出錯");
}
}

}
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屬性文件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