数据库连接池问题 数据库连接池怎样写给,请教以下高手,给个例子 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 用应用服务器提供的数据库连接池开源的框架可以用C3P0到google搜一下,现成的例子多的一大把对于个人来说,明白连接池的原理是最重要的 贴个简单的连接池程序,你参考一下吧package common;import java.sql.*;import java.lang.reflect.*;import java.util.*;import java.io.*;/** * <p>Title: 简单的数据库连接池程序</p> * * <p>Description: 实现简单的数据库连接池的管理功能</p> * * <p>Copyright: Copyright (c) 2005</p> * * <p>Company: EagleInfo</p> * * @author feng_mingjie * @version 1.0 */public class SimpleConnetionPool { private static LinkedList m_notUsedConnection = new LinkedList(); private static HashSet m_usedUsedConnection = new HashSet(); private static String m_url = ""; private static String m_user = ""; private static String m_password = ""; static final boolean DEBUG = true; static private long m_lastClearClosedConnection = System.currentTimeMillis(); public static long CHECK_CLOSED_CONNECTION_TIME = 4 * 60 * 60 * 1000; //4 hours static { initDriver(); } private SimpleConnetionPool() { } private static void initDriver() { Driver driver = null; //load oracle driver try { driver = (Driver) Class.forName("oracle.jdbc.driver.OracleDriver").newInstance(); installDriver(driver); } catch (Exception e) { e.printStackTrace(); } } public static void installDriver(Driver driver) { try { DriverManager.registerDriver(driver); } catch (Exception e) { e.printStackTrace(); } } public static synchronized Connection getConnection() { clearClosedConnection(); while (m_notUsedConnection.size() > 0) { try { ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst(); if (wrapper.connection.isClosed()) { continue; } m_usedUsedConnection.add(wrapper); if (DEBUG) { wrapper.debugInfo = new Throwable("Connection initial statement"); } return wrapper.connection; } catch (Exception e) { } } int newCount = getIncreasingConnectionCount(); LinkedList list = new LinkedList(); ConnectionWrapper wrapper = null; for (int i = 0; i < newCount; i++) { wrapper = getNewConnection(); if (wrapper != null) { list.add(wrapper); } } if (list.size() == 0) { return null; } wrapper = (ConnectionWrapper) list.removeFirst(); m_usedUsedConnection.add(wrapper); m_notUsedConnection.addAll(list); list.clear(); return wrapper.connection; } private static ConnectionWrapper getNewConnection() { try { Connection con = DriverManager.getConnection(m_url, m_user, m_password); ConnectionWrapper wrapper = new ConnectionWrapper(con); return wrapper; } catch (Exception e) { e.printStackTrace(); } return null; } static synchronized void pushConnectionBackToPool(ConnectionWrapper con) { boolean exist = m_usedUsedConnection.remove(con); if (exist) { m_notUsedConnection.addLast(con); } } public static int close() { int count = 0; Iterator iterator = m_notUsedConnection.iterator(); while (iterator.hasNext()) { try { ( (ConnectionWrapper) iterator.next()).close(); count++; } catch (Exception e) { } } m_notUsedConnection.clear(); iterator = m_usedUsedConnection.iterator(); while (iterator.hasNext()) { try { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); wrapper.close(); if (DEBUG) { // wrapper.debugInfo.printStackTrace(); } count++; } catch (Exception e) { } } m_usedUsedConnection.clear(); return count; } private static void clearClosedConnection() { long time = System.currentTimeMillis(); //sometimes user change system time,just return if (time < m_lastClearClosedConnection) { time = m_lastClearClosedConnection; return; } //no need check very often if (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) { return; } m_lastClearClosedConnection = time; //begin check Iterator iterator = m_notUsedConnection.iterator(); while (iterator.hasNext()) { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); try { if (wrapper.connection.isClosed()) { iterator.remove(); } } catch (Exception e) { iterator.remove(); if (DEBUG) { System.out.println("connection is closed, this connection initial StackTrace"); wrapper.debugInfo.printStackTrace(); } } } //make connection pool size smaller if too big int decrease = getDecreasingConnectionCount(); if (m_notUsedConnection.size() < decrease) { return; } while (decrease-- > 0) { ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst(); try { wrapper.connection.close(); } catch (Exception e) { } } } /** * get increasing connection count, not just add 1 connection * @return count */ public static int getIncreasingConnectionCount() { int count = 1; int current = getConnectionCount(); count = current / 4; if (count < 1) { count = 1; } return count; } /** * get decreasing connection count, not just remove 1 connection * @return count */ public static int getDecreasingConnectionCount() { int count = 0; int current = getConnectionCount(); if (current < 10) { return 0; } return current / 3; } public synchronized static void printDebugMsg() { printDebugMsg(System.out); } public synchronized static void printDebugMsg(PrintStream out) { if (DEBUG == false) { return; } StringBuffer msg = new StringBuffer(); msg.append("debug message in " + SimpleConnetionPool.class.getName()); msg.append("\r\n"); msg.append("total count is connection pool: " + getConnectionCount()); msg.append("\r\n"); msg.append("not used connection count: " + getNotUsedConnectionCount()); msg.append("\r\n"); msg.append("used connection, count: " + getUsedConnectionCount()); out.println(msg); Iterator iterator = m_usedUsedConnection.iterator(); while (iterator.hasNext()) { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); wrapper.debugInfo.printStackTrace(out); } out.println(); } public static synchronized int getNotUsedConnectionCount() { return m_notUsedConnection.size(); } public static synchronized int getUsedConnectionCount() { return m_usedUsedConnection.size(); } public static synchronized int getConnectionCount() { return m_notUsedConnection.size() + m_usedUsedConnection.size(); } public static String getUrl() { return m_url; } public static void setUrl(String url) { if (url == null) { return; } m_url = url.trim(); } public static String getUser() { return m_user; } public static void setUser(String user) { if (user == null) { return; } m_user = user.trim(); } public static String getPassword() { return m_password; } public static void setPassword(String password) { if (password == null) { return; } m_password = password.trim(); }}class ConnectionWrapper implements InvocationHandler { private final static String CLOSE_METHOD_NAME = "close"; public Connection connection = null; private Connection m_originConnection = null; public long lastAccessTime = System.currentTimeMillis(); Throwable debugInfo = new Throwable("Connection initial statement"); ConnectionWrapper(Connection con) { Class[] interfaces = {java.sql.Connection.class}; this.connection = (Connection) Proxy.newProxyInstance( con.getClass().getClassLoader(), interfaces, this); m_originConnection = con; } void close() throws SQLException { m_originConnection.close(); } public Object invoke(Object proxy, Method m, Object[] args) throws Throwable { Object obj = null; if (CLOSE_METHOD_NAME.equals(m.getName())) { SimpleConnetionPool.pushConnectionBackToPool(this); } else { obj = m.invoke(m_originConnection, args); } lastAccessTime = System.currentTimeMillis(); return obj; }} http://community.csdn.net/Expert/topic/5057/5057319.xml?temp=.9077265http://community.csdn.net/Expert/topic/5082/5082758.xml?temp=.3046686连接池有很多,帮你找了2个连接.希望对你有帮助.我也是在学习中.. 推荐 Apache 的 DBCP 连接池,是一个成熟的开原产品,效率很高。 SOCKET 长连接 java剪切文件 csdn怎么上传附件呢? 请教:求一个简单聊天工具的JAVA源代码 数据库联接??? 如何将 gif,jpeg图片读入内存,转换成bmp的格式,并将结果以 byte[] 输出。 一个有关关闭画图的问题 怎样根据查询返回的字段值(数值或字符型值)的宽度动态设置JTabel的Column的宽度 我是新手,各位大虾,请问学习JAVA有没有什么好用的书!!谢谢。有分挣哦! 高手们帮我看看这段程序吧!怎么我的输出流传递不进去? 谁有记事本的源代码? 连接池的疑惑
开源的框架可以用C3P0
到google搜一下,现成的例子多的一大把
对于个人来说,明白连接池的原理是最重要的
package common;import java.sql.*;
import java.lang.reflect.*;
import java.util.*;
import java.io.*;/**
* <p>Title: 简单的数据库连接池程序</p>
*
* <p>Description: 实现简单的数据库连接池的管理功能</p>
*
* <p>Copyright: Copyright (c) 2005</p>
*
* <p>Company: EagleInfo</p>
*
* @author feng_mingjie
* @version 1.0
*/public class SimpleConnetionPool {
private static LinkedList m_notUsedConnection = new LinkedList();
private static HashSet m_usedUsedConnection = new HashSet();
private static String m_url = "";
private static String m_user = "";
private static String m_password = "";
static final boolean DEBUG = true;
static private long m_lastClearClosedConnection = System.currentTimeMillis();
public static long CHECK_CLOSED_CONNECTION_TIME = 4 * 60 * 60 * 1000; //4 hours static {
initDriver();
} private SimpleConnetionPool() {
} private static void initDriver() {
Driver driver = null;
//load oracle driver
try {
driver = (Driver) Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
installDriver(driver);
} catch (Exception e) {
e.printStackTrace();
}
} public static void installDriver(Driver driver) {
try {
DriverManager.registerDriver(driver);
} catch (Exception e) {
e.printStackTrace();
}
}
public static synchronized Connection getConnection() {
clearClosedConnection();
while (m_notUsedConnection.size() > 0) {
try {
ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst();
if (wrapper.connection.isClosed()) {
continue;
}
m_usedUsedConnection.add(wrapper);
if (DEBUG) {
wrapper.debugInfo = new Throwable("Connection initial statement");
}
return wrapper.connection;
} catch (Exception e) {
}
}
int newCount = getIncreasingConnectionCount();
LinkedList list = new LinkedList();
ConnectionWrapper wrapper = null;
for (int i = 0; i < newCount; i++) {
wrapper = getNewConnection();
if (wrapper != null) {
list.add(wrapper);
}
}
if (list.size() == 0) {
return null;
}
wrapper = (ConnectionWrapper) list.removeFirst();
m_usedUsedConnection.add(wrapper); m_notUsedConnection.addAll(list);
list.clear(); return wrapper.connection;
} private static ConnectionWrapper getNewConnection() {
try {
Connection con = DriverManager.getConnection(m_url, m_user, m_password);
ConnectionWrapper wrapper = new ConnectionWrapper(con);
return wrapper;
} catch (Exception e) {
e.printStackTrace();
}
return null;
} static synchronized void pushConnectionBackToPool(ConnectionWrapper con) {
boolean exist = m_usedUsedConnection.remove(con);
if (exist) {
m_notUsedConnection.addLast(con);
}
} public static int close() {
int count = 0; Iterator iterator = m_notUsedConnection.iterator();
while (iterator.hasNext()) {
try {
( (ConnectionWrapper) iterator.next()).close();
count++;
} catch (Exception e) {
}
}
m_notUsedConnection.clear(); iterator = m_usedUsedConnection.iterator();
while (iterator.hasNext()) {
try {
ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
wrapper.close();
if (DEBUG) {
// wrapper.debugInfo.printStackTrace();
}
count++;
} catch (Exception e) {
}
}
m_usedUsedConnection.clear(); return count;
} private static void clearClosedConnection() {
long time = System.currentTimeMillis();
//sometimes user change system time,just return
if (time < m_lastClearClosedConnection) {
time = m_lastClearClosedConnection;
return;
}
//no need check very often
if (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) {
return;
}
m_lastClearClosedConnection = time; //begin check
Iterator iterator = m_notUsedConnection.iterator();
while (iterator.hasNext()) {
ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
try {
if (wrapper.connection.isClosed()) {
iterator.remove();
}
} catch (Exception e) {
iterator.remove();
if (DEBUG) {
System.out.println("connection is closed, this connection initial StackTrace");
wrapper.debugInfo.printStackTrace();
}
}
} //make connection pool size smaller if too big
int decrease = getDecreasingConnectionCount();
if (m_notUsedConnection.size() < decrease) {
return;
} while (decrease-- > 0) {
ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst();
try {
wrapper.connection.close();
} catch (Exception e) {
}
}
} /**
* get increasing connection count, not just add 1 connection
* @return count
*/
public static int getIncreasingConnectionCount() {
int count = 1;
int current = getConnectionCount();
count = current / 4;
if (count < 1) {
count = 1;
}
return count;
} /**
* get decreasing connection count, not just remove 1 connection
* @return count
*/
public static int getDecreasingConnectionCount() {
int count = 0;
int current = getConnectionCount();
if (current < 10) {
return 0;
}
return current / 3;
} public synchronized static void printDebugMsg() {
printDebugMsg(System.out);
} public synchronized static void printDebugMsg(PrintStream out) {
if (DEBUG == false) {
return;
}
StringBuffer msg = new StringBuffer();
msg.append("debug message in " + SimpleConnetionPool.class.getName());
msg.append("\r\n");
msg.append("total count is connection pool: " + getConnectionCount());
msg.append("\r\n");
msg.append("not used connection count: " + getNotUsedConnectionCount());
msg.append("\r\n");
msg.append("used connection, count: " + getUsedConnectionCount());
out.println(msg);
Iterator iterator = m_usedUsedConnection.iterator();
while (iterator.hasNext()) {
ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
wrapper.debugInfo.printStackTrace(out);
}
out.println();
} public static synchronized int getNotUsedConnectionCount() {
return m_notUsedConnection.size();
} public static synchronized int getUsedConnectionCount() {
return m_usedUsedConnection.size();
}
return m_notUsedConnection.size() + m_usedUsedConnection.size();
} public static String getUrl() {
return m_url;
} public static void setUrl(String url) {
if (url == null) {
return;
}
m_url = url.trim();
} public static String getUser() {
return m_user;
} public static void setUser(String user) {
if (user == null) {
return;
}
m_user = user.trim();
} public static String getPassword() {
return m_password;
} public static void setPassword(String password) {
if (password == null) {
return;
}
m_password = password.trim();
}}class ConnectionWrapper implements InvocationHandler {
private final static String CLOSE_METHOD_NAME = "close";
public Connection connection = null;
private Connection m_originConnection = null;
public long lastAccessTime = System.currentTimeMillis();
Throwable debugInfo = new Throwable("Connection initial statement"); ConnectionWrapper(Connection con) {
Class[] interfaces = {java.sql.Connection.class};
this.connection = (Connection) Proxy.newProxyInstance(
con.getClass().getClassLoader(),
interfaces, this);
m_originConnection = con;
} void close() throws SQLException {
m_originConnection.close();
} public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
Object obj = null;
if (CLOSE_METHOD_NAME.equals(m.getName())) {
SimpleConnetionPool.pushConnectionBackToPool(this);
}
else {
obj = m.invoke(m_originConnection, args);
}
lastAccessTime = System.currentTimeMillis();
return obj;
}
}
http://community.csdn.net/Expert/topic/5082/5082758.xml?temp=.3046686
连接池有很多,帮你找了2个连接.希望对你有帮助.
我也是在学习中..