Is there Session in java's webservice?

Question

I wanna store my database connection in a global variable,
for example, a Session or an Application,
what can I do?

Answer 1

Thank you very much!
I search a java file named DBConnectionManager.java which could do the job.
The source code is below:
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
//����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();
//��������������
static synchronized public DBConnectionManager getInstance() {
if (instance == null) {
instance = new DBConnectionManager();
clients++;
return instance;
//����������
private DBConnectionManager() {
init();
//������������
//������������
public void freeConnection(String name, Connection con) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
pool.freeConnection(con);
//����������������
//������������
public Connection getConnection(String name) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection();
return null;
public Connection getConnection(String name, long time) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection(time);
return null;
//����getconnection
//������������
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("����JDBC��������" + driver.getClass().getName());
catch (SQLException e) {
log(e, "��������JDBC��������������" + 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("����������" + poolName + "������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("������������������" + maxconn + ".������" + poolName);
max = 0;
DBConnectionPool pool = new DBConnectionPool(poolName, url, user,
password, max);
pools.put(poolName, pool);
log("��������������" + poolName);
private void init() {
InputStream is = getClass().getResourceAsStream("/db.properties");
Properties dbProps = new Properties();
try {
dbProps.load(is);
catch (Exception e) {
System.err.println("������������������������db.properties������CLASSPATH��");
return;
String logFile = dbProps.getProperty("logfile", "DBConnectionManager.log");
try {
log = new PrintWriter(new FileWriter(logFile, true), true);
catch (IOException e) {
System.err.println("������������������" + 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("����������������" + driverClassName);
catch (Exception e) {
log("����������������:" + driverClassName + ",����" + 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("��������" + name + "������������");
con = getConnection();
catch (SQLException e) {
log("��������" + name + "������������");
con = getConnection();
else if (maxconn == 0 || checkOut < maxconn) {
con = newConnection();
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("����������" + name + "��������");
catch (SQLException e) {
log(e, "��������������" + name + "��������");
freeConnections.removeAllElements();
private Connection newConnection() {
Connection con = null;
try {
con = DriverManager.getConnection(URL, user, password);
log("������" + name + "����������������");
catch (SQLException e) {
log(e, "������������URL������" + URL);
return null;
return con;
}