org.springframework.jdbc.datasource.SingleConnectionDataSource Maven / Gradle / Ivy
/*
* Copyright 2002-2005 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.jdbc.datasource;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.SQLException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.jdbc.CannotGetJdbcConnectionException;
import org.springframework.util.ObjectUtils;
/**
* Implementation of SmartDataSource that wraps a single Connection which is not
* closed after use. Obviously, this is not multi-threading capable.
*
* Note that at shutdown, someone should close the underlying connection via the
* close() method. Client code will never call close on the Connection
* handle if it is SmartDataSource-aware (e.g. uses
* DataSourceUtils.releaseConnection).
*
*
If client code will call close() in the assumption of a pooled
* Connection, like when using persistence tools, set "suppressClose" to "true".
* This will return a close-suppressing proxy instead of the physical Connection.
* Be aware that you will not be able to cast this to a native OracleConnection
* or the like anymore (you need to use a NativeJdbcExtractor for this then).
*
*
This is primarily intended for testing. For example, it enables easy testing
* outside an application server, for code that expects to work on a DataSource.
* In contrast to DriverManagerDataSource, it reuses the same Connection all the
* time, avoiding excessive creation of physical Connections.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see java.sql.Connection#close()
* @see DataSourceUtils#releaseConnection
* @see org.springframework.jdbc.support.nativejdbc.NativeJdbcExtractor
*/
public class SingleConnectionDataSource extends DriverManagerDataSource
implements SmartDataSource, DisposableBean {
private boolean suppressClose;
/** Wrapped connection */
private Connection target;
/** Proxy connection */
private Connection connection;
/**
* Constructor for bean-style configuration.
*/
public SingleConnectionDataSource() {
}
/**
* Create a new SingleConnectionDataSource with the given standard
* DriverManager parameters.
* @param driverClassName the JDBC driver class name
* @param url the JDBC URL to use for accessing the DriverManager
* @param username the JDBC username to use for accessing the DriverManager
* @param password the JDBC password to use for accessing the DriverManager
* @param suppressClose if the returned connection should be a
* close-suppressing proxy or the physical connection.
* @see java.sql.DriverManager#getConnection(String, String, String)
*/
public SingleConnectionDataSource(
String driverClassName, String url, String username, String password, boolean suppressClose)
throws CannotGetJdbcConnectionException {
super(driverClassName, url, username, password);
this.suppressClose = suppressClose;
}
/**
* Create a new SingleConnectionDataSource with the given standard
* DriverManager parameters.
* @param url the JDBC URL to use for accessing the DriverManager
* @param username the JDBC username to use for accessing the DriverManager
* @param password the JDBC password to use for accessing the DriverManager
* @param suppressClose if the returned connection should be a
* close-suppressing proxy or the physical connection.
* @see java.sql.DriverManager#getConnection(String, String, String)
*/
public SingleConnectionDataSource(String url, String username, String password, boolean suppressClose)
throws CannotGetJdbcConnectionException {
super(url, username, password);
this.suppressClose = suppressClose;
}
/**
* Create a new SingleConnectionDataSource with the given standard
* DriverManager parameters.
* @param url the JDBC URL to use for accessing the DriverManager
* @param suppressClose if the returned connection should be a
* close-suppressing proxy or the physical connection.
* @see java.sql.DriverManager#getConnection(String, String, String)
*/
public SingleConnectionDataSource(String url, boolean suppressClose)
throws CannotGetJdbcConnectionException {
super(url);
this.suppressClose = suppressClose;
}
/**
* Create a new SingleConnectionDataSource with a given connection.
* @param target underlying target connection
* @param suppressClose if the connection should be wrapped with a* connection that
* suppresses close() calls (to allow for normal close() usage in applications that
* expect a pooled connection but do not know our SmartDataSource interface).
*/
public SingleConnectionDataSource(Connection target, boolean suppressClose) {
if (target == null) {
throw new IllegalArgumentException("Connection is null in SingleConnectionDataSource");
}
this.suppressClose = suppressClose;
init(target);
}
/**
* Set if the returned connection should be a close-suppressing proxy
* or the physical connection.
*/
public void setSuppressClose(boolean suppressClose) {
this.suppressClose = suppressClose;
}
/**
* Return if the returned connection will be a close-suppressing proxy
* or the physical connection.
*/
public boolean isSuppressClose() {
return suppressClose;
}
/**
* This is a single connection: Do not close it when returning to the "pool".
*/
public boolean shouldClose(Connection con) {
return (con != this.connection && con != this.target);
}
/**
* Initialize the underlying connection via DriverManager.
*/
protected void init() throws SQLException {
init(getConnectionFromDriverManager());
}
/**
* Initialize the underlying connection.
* Wraps the connection with a close-suppressing proxy if necessary.
* @param target the JDBC Connection to use
*/
protected void init(Connection target) {
this.target = target;
this.connection = this.suppressClose ? getCloseSuppressingConnectionProxy(target) : target;
}
/**
* Close the underlying connection.
* The provider of this DataSource needs to care for proper shutdown.
*
As this bean implements DisposableBean, a bean factory will
* automatically invoke this on destruction of its cached singletons.
*/
public void destroy() throws SQLException {
if (this.target != null) {
this.target.close();
}
}
public Connection getConnection() throws SQLException {
synchronized (this) {
if (this.connection == null) {
// no underlying connection -> lazy init via DriverManager
init();
}
}
if (this.connection.isClosed()) {
throw new SQLException(
"Connection was closed in SingleConnectionDataSource. Check that user code checks " +
"shouldClose() before closing connections, or set suppressClose to true");
}
if (logger.isDebugEnabled()) {
logger.debug("Returning single connection: " + this.connection);
}
return this.connection;
}
/**
* Specifying a custom username and password doesn't make sense
* with a single connection. Returns the single connection if given
* the same username and password, though.
*/
public Connection getConnection(String username, String password) throws SQLException {
if (ObjectUtils.nullSafeEquals(username, getUsername()) &&
ObjectUtils.nullSafeEquals(password, getPassword())) {
return getConnection();
}
else {
throw new SQLException("SingleConnectionDataSource does not support custom username and password");
}
}
/**
* Wrap the given Connection with a proxy that delegates every method call to it
* but suppresses close calls.
* @param target the original Connection to wrap
* @return the wrapped Connection
*/
protected Connection getCloseSuppressingConnectionProxy(Connection target) {
return (Connection) Proxy.newProxyInstance(
ConnectionProxy.class.getClassLoader(),
new Class[] {ConnectionProxy.class},
new CloseSuppressingInvocationHandler(target));
}
/**
* Invocation handler that suppresses close calls on JDBC Connections.
*/
private static class CloseSuppressingInvocationHandler implements InvocationHandler {
private static final String GET_TARGET_CONNECTION_METHOD_NAME = "getTargetConnection";
private static final String CONNECTION_CLOSE_METHOD_NAME = "close";
private final Connection target;
public CloseSuppressingInvocationHandler(Connection target) {
this.target = target;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on ConnectionProxy interface coming in...
// Handle getTargetConnection method: return underlying connection.
if (method.getName().equals(GET_TARGET_CONNECTION_METHOD_NAME)) {
return this.target;
}
// Handle close method: don't pass the call on.
if (method.getName().equals(CONNECTION_CLOSE_METHOD_NAME)) {
return null;
}
// Invoke method on target connection.
try {
return method.invoke(this.target, args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
}