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/*
@VaadinApache2LicenseForJavaFiles@
*/
package com.vaadin.data.util.sqlcontainer.connection;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashSet;
import java.util.Set;
/**
* Simple implementation of the JDBCConnectionPool interface. Handles loading
* the JDBC driver, setting up the connections and ensuring they are still
* usable upon release.
*/
@SuppressWarnings("serial")
public class SimpleJDBCConnectionPool implements JDBCConnectionPool {
private int initialConnections = 5;
private int maxConnections = 20;
private String driverName;
private String connectionUri;
private String userName;
private String password;
private transient Set<Connection> availableConnections;
private transient Set<Connection> reservedConnections;
private boolean initialized;
public SimpleJDBCConnectionPool(String driverName, String connectionUri,
String userName, String password) throws SQLException {
if (driverName == null) {
throw new IllegalArgumentException(
"JDBC driver class name must be given.");
}
if (connectionUri == null) {
throw new IllegalArgumentException(
"Database connection URI must be given.");
}
if (userName == null) {
throw new IllegalArgumentException(
"Database username must be given.");
}
if (password == null) {
throw new IllegalArgumentException(
"Database password must be given.");
}
this.driverName = driverName;
this.connectionUri = connectionUri;
this.userName = userName;
this.password = password;
/* Initialize JDBC driver */
try {
Class.forName(driverName).newInstance();
} catch (Exception ex) {
throw new RuntimeException("Specified JDBC Driver: " + driverName
+ " - initialization failed.", ex);
}
}
public SimpleJDBCConnectionPool(String driverName, String connectionUri,
String userName, String password, int initialConnections,
int maxConnections) throws SQLException {
this(driverName, connectionUri, userName, password);
this.initialConnections = initialConnections;
this.maxConnections = maxConnections;
}
private void initializeConnections() throws SQLException {
availableConnections = new HashSet<Connection>(initialConnections);
reservedConnections = new HashSet<Connection>(initialConnections);
for (int i = 0; i < initialConnections; i++) {
availableConnections.add(createConnection());
}
initialized = true;
}
public synchronized Connection reserveConnection() throws SQLException {
if (!initialized) {
initializeConnections();
}
if (availableConnections.isEmpty()) {
if (reservedConnections.size() < maxConnections) {
availableConnections.add(createConnection());
} else {
throw new SQLException("Connection limit has been reached.");
}
}
Connection c = availableConnections.iterator().next();
availableConnections.remove(c);
reservedConnections.add(c);
return c;
}
public synchronized void releaseConnection(Connection conn) {
if (conn == null || !initialized) {
return;
}
/* Try to roll back if necessary */
try {
if (!conn.getAutoCommit()) {
conn.rollback();
}
} catch (SQLException e) {
/* Roll back failed, close and discard connection */
try {
conn.close();
} catch (SQLException e1) {
/* Nothing needs to be done */
}
reservedConnections.remove(conn);
return;
}
reservedConnections.remove(conn);
availableConnections.add(conn);
}
private Connection createConnection() throws SQLException {
Connection c = DriverManager.getConnection(connectionUri, userName,
password);
c.setAutoCommit(false);
if (driverName.toLowerCase().contains("mysql")) {
try {
Statement s = c.createStatement();
s.execute("SET SESSION sql_mode = 'ANSI'");
s.close();
} catch (Exception e) {
// Failed to set ansi mode; continue
}
}
return c;
}
public void destroy() {
for (Connection c : availableConnections) {
try {
c.close();
} catch (SQLException e) {
// No need to do anything
}
}
for (Connection c : reservedConnections) {
try {
c.close();
} catch (SQLException e) {
// No need to do anything
}
}
}
private void writeObject(java.io.ObjectOutputStream out) throws IOException {
initialized = false;
out.defaultWriteObject();
}
}
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