可供参考的【数据库连接池(DBCP)】二
可供参考的【数据库连接池(DBCP)】2
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.Vector;
public class PersonDefine_ConnectionPool implements Runnable {
public String ProductionDB = "axdb_tmp";//給的默認值
private String database_driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";//給的默認值
// private String
// dakabase_url="jdbc:sybase:Tds:IP:port/dakabase_test?useUnicode=true&characterEncoding=UTF-8";
private String database_url = "jdbc:sqlserver://localhost:1433;DatabaseName=mgr_live"; //給的默認值
private String username = "sa";
private String password = "12345678";
private int maxConnections = 50;
private boolean waitIfBusy = true;
private Vector availableConnections, busyConnections;
private boolean connectionPending = false;
public PersonDefine_ConnectionPool(Properties props) throws SQLException {
System.out.println("jdbc:PersonDefine_ConnectionPool...");
int initialConnections = 0;
this.ProductionDB = props.getProperty("ELITEDATA.ProductionDB");
this.database_driver = props.getProperty("ELITEDATA.database_driver").trim();
this.database_url = props.getProperty("ELITEDATA.database_url");
this.username=props.getProperty("ELITEDATA.database_username");
this.password=props.getProperty("ELITEDATA.database_password");
this.maxConnections = maxConnections;
this.waitIfBusy = waitIfBusy;
if (initialConnections > maxConnections) {
initialConnections = maxConnections;
}
availableConnections = new Vector(initialConnections);
busyConnections = new Vector();
for (int i = 0; i < initialConnections; i++) {
availableConnections.addElement(makeNewConnection());
}
}
public synchronized Connection getConnection() throws SQLException {
System.out.println("jdbc:Get PersonDefine_ConnectionPool...");
if (!availableConnections.isEmpty()) {
Connection existingConnection = (Connection) availableConnections.lastElement();
int lastIndex = availableConnections.size() - 1;
availableConnections.removeElementAt(lastIndex);
// If connection on available list is closed (e.g.,
// it timed out), then remove it from available list
// and repeat the process of obtaining a connection.
// Also wake up threads that were waiting for a
// connection because maxConnection limit was reached.
if (existingConnection.isClosed()) {
notifyAll(); // Freed up a spot for anybody waiting
return (getConnection());
} else {
busyConnections.addElement(existingConnection);
return (existingConnection);
}
} else {
// Three possible cases:
// 1) You haven't reached maxConnections limit. So
// establish one in the background if there isn't
// already one pending, then wait for
// the next available connection (whether or not
// it was the newly established one).
// 2) You reached maxConnections limit and waitIfBusy
// flag is false. Throw SQLException in such a case.
// 3) You reached maxConnections limit and waitIfBusy
// flag is true. Then do the same thing as in second
// part of step 1: wait for next available connection.
if ((totalConnections() < maxConnections) && !connectionPending) {
makeBackgroundConnection();
} else if (!waitIfBusy) {
throw new SQLException("PersonDefine_ConnectionPool limit reached");
}
// Wait for either a new connection to be established
// (if you called makeBackgroundConnection) or for
// an existing connection to be freed up.
try {
wait();
} catch (InterruptedException ie) {
}
// Someone freed up a connection, so try again.
return (getConnection());
}
}
// You can't just make a new connection in the foreground
// when none are available, since this can take several
// seconds with a slow network connection. Instead,
// start a thread that establishes a new connection,
// then wait. You get woken up either when the new connection
// is established or if someone finishes with an existing
// connection.
private void makeBackgroundConnection() {
connectionPending = true;
System.out.println("jdbc:Make Background PersonDefine_ConnectionPool...");
try {
Thread connectThread = new Thread(this);
connectThread.start();
} catch (OutOfMemoryError oome) {
System.out.println("jdbc:PersonDefine_ConnectionPool out of Memory..." + oome);
}
}
public void run() {
try {
System.out.println("jdbc:run PersonDefine_ConnectionPool...");
Connection connection = makeNewConnection();
synchronized (this) {
availableConnections.addElement(connection);
connectionPending = false;
notifyAll();
}
} catch (Exception e) { // SQLException or OutOfMemory
System.out.println("jdbc:PersonDefine_ConnectionPool out of Memory...");
}
}
// This explicitly makes a new connection. Called in
// the foreground when initializing the ConnectionPool,
// and called in the background when running.
private Connection makeNewConnection() throws SQLException {
try {
System.out.println("jdbc:make new PersonDefine_ConnectionPool...");
// Load database dakabase_driver if not already loaded
Class.forName(database_driver);
// Establish network connection to database
Connection connection = DriverManager.getConnection(database_url, username, password);
return (connection);
} catch (ClassNotFoundException cnfe) {
// Simplify try/catch blocks of people using this by
// throwing only one exception type.
System.out.println("jdbc:PersonDefine_ConnectionPool Can't find class for database_driver:");
throw new SQLException("Can't find class for PersonDefine_ConnectionPool: " + database_driver);
}
}
public synchronized void free(Connection connection) {
System.out.println("jdbc:free PersonDefine_ConnectionPool...");
busyConnections.removeElement(connection);
availableConnections.addElement(connection);
// Wake up threads that are waiting for a connection
notifyAll();
}
public synchronized int totalConnections() {
return (availableConnections.size() + busyConnections.size());
}
/**
* Close all the connections. Use with caution: be sure no connections are
* in use before calling. Note that you are not <I>required</I> to call
* this when done with a ConnectionPool, since connections are guaranteed to
* be closed when garbage collected. But this method gives more control
* regarding when the connections are closed.
*/
public synchronized void closeAllConnections() {
System.out.println("jdbc:close all PersonDefine_ConnectionPool...");
closeConnections(availableConnections);
availableConnections = new Vector();
closeConnections(busyConnections);
busyConnections = new Vector();
}
private void closeConnections(Vector connections) {
try {
System.out.println("jdbc:close PersonDefine_ConnectionPool...");
for (int i = 0; i < connections.size(); i++) {
Connection connection = (Connection) connections.elementAt(i);
if (!connection.isClosed()) {
connection.close();
}
}
} catch (SQLException sqle) {
System.out.println("jdbc: PersonDefine_ConnectionPool..." + sqle);
}
}
public synchronized String toString() {
String info = "ConnectionPool(PersonDefine_ConnectionPool)(" + database_url + "," + username + ")" + ", available=" + availableConnections.size() + ", busy="
+ busyConnections.size() + ", max=" + maxConnections;
return (info);
}
}