SyncProvider
* instances to be used by disconnected RowSet objects.
* The SyncProvider instances in turn provide the
* javax.sql.RowSetReader object the RowSet object
* needs to populate itself with data and the
* javax.sql.RowSetWriter object it needs to
* propagate changes to its
* data back to the underlying data source.
*
* Because the methods in the SyncFactory class are all static,
* there is only one SyncFactory object
* per Java VM at any one time. This ensures that there is a single source from which a
* RowSet implementation can obtain its SyncProvider
* implementation.
*
*
SyncFactory class provides an internal registry of available
* synchronization provider implementations (SyncProvider objects).
* This registry may be queried to determine which
* synchronization providers are available.
* The following line of code gets an enumeration of the providers currently registered.
* * java.util.Enumeration e = SyncFactory.getRegisteredProviders(); ** All standard
RowSet implementations must provide at least two providers:
* CachedRowSet implementation
* or an implementation derived from it
* WebRowSet objects
* SyncProvider
* implementations RIOptimisticProvider and RIXmlProvider,
* which satisfy this requirement.
*
* The SyncFactory class provides accessor methods to assist
* applications in determining which synchronization providers are currently
* registered with the SyncFactory.
*
* Other methods let RowSet persistence providers be
* registered or de-registered with the factory mechanism. This
* allows additional synchronization provider implementations to be made
* available to RowSet objects at run time.
*
* Applications can apply a degree of filtering to determine the level of
* synchronization that a SyncProvider implementation offers.
* The following criteria determine whether a provider is
* made available to a RowSet object:
*
RowSet object, and
* the SyncFactory does not contain a reference to this provider,
* a SyncFactoryException is thrown stating that the synchronization
* provider could not be found.
*
* RowSet implementation is instantiated with a specified
* provider and the specified provider has been properly registered, the
* requested provider is supplied. Otherwise a SyncFactoryException
* is thrown.
*
* RowSet object does not specify a
* SyncProvider implementation and no additional
* SyncProvider implementations are available, the reference
* implementation providers are supplied.
* SyncProvider Implementations
* Both vendors and developers can register SyncProvider
* implementations using one of the following mechanisms.
*
* -Drowset.provider.classname=com.fred.providers.HighAvailabilityProvider **
* #Default JDBC RowSet sync providers listing * # * * # Optimistic synchronization provider * rowset.provider.classname.0=com.sun.rowset.providers.RIOptimisticProvider * rowset.provider.vendor.0=Oracle Corporation * rowset.provider.version.0=1.0 * * # XML Provider using standard XML schema * rowset.provider.classname.1=com.sun.rowset.providers.RIXMLProvider * rowset.provider.vendor.1=Oracle Corporation * rowset.provider.version.1=1.0 ** The
SyncFactory checks this file and registers the
* SyncProvider implementations that it contains. A
* developer or vendor can add other implementations to this file.
* For example, here is a possible addition:
* * rowset.provider.classname.2=com.fred.providers.HighAvailabilityProvider * rowset.provider.vendor.2=Fred, Inc. * rowset.provider.version.2=1.0 ** *
SyncFactory will attempt to load
* SyncProvider implementations from that JNDI context.
* For example, the following code fragment registers a provider implementation
* on a JNDI context. This is something a deployer would normally do. In this
* example, MyProvider is being registered on a CosNaming
* namespace, which is the namespace used by J2EE resources.
*
* import javax.naming.*;
*
* Hashtable svrEnv = new Hashtable();
* srvEnv.put(Context.INITIAL_CONTEXT_FACTORY, "CosNaming");
*
* Context ctx = new InitialContext(svrEnv);
* com.fred.providers.MyProvider = new MyProvider();
* ctx.rebind("providers/MyProvider", syncProvider);
*
* SyncFactory instance. This allows the SyncFactory
* to browse within the JNDI context looking for SyncProvider
* implementations.
* * Hashtable appEnv = new Hashtable(); * appEnv.put(Context.INITIAL_CONTEXT_FACTORY, "CosNaming"); * appEnv.put(Context.PROVIDER_URL, "iiop://hostname/providers"); * Context ctx = new InitialContext(appEnv); * * SyncFactory.registerJNDIContext(ctx); ** If a
RowSet object attempts to obtain a MyProvider
* object, the SyncFactory will try to locate it. First it searches
* for it in the system properties, then it looks in the resource files, and
* finally it checks the JNDI context that has been set. The SyncFactory
* instance verifies that the requested provider is a valid extension of the
* SyncProvider abstract class and then gives it to the
* RowSet object. In the following code fragment, a new
* CachedRowSet object is created and initialized with
* env, which contains the binding to MyProvider.
* * Hashtable env = new Hashtable(); * env.put(SyncFactory.ROWSET_SYNC_PROVIDER, "com.fred.providers.MyProvider"); * CachedRowSet crs = new com.sun.rowset.CachedRowSetImpl(env); ** Further details on these mechanisms are available in the *
javax.sql.rowset.spi package specification.
*
* @author Jonathan Bruce
* @see javax.sql.rowset.spi.SyncProvider
* @see javax.sql.rowset.spi.SyncFactoryException
*/
public class SyncFactory {
/**
* Creates a new SyncFactory object, which is the singleton
* instance.
* Having a private constructor guarantees that no more than
* one SyncProvider object can exist at a time.
*/
private SyncFactory() {
}
/**
* The standard property-id for a synchronization provider implementation
* name.
*/
public static final String ROWSET_SYNC_PROVIDER =
"rowset.provider.classname";
/**
* The standard property-id for a synchronization provider implementation
* vendor name.
*/
public static final String ROWSET_SYNC_VENDOR =
"rowset.provider.vendor";
/**
* The standard property-id for a synchronization provider implementation
* version tag.
*/
public static final String ROWSET_SYNC_PROVIDER_VERSION =
"rowset.provider.version";
/**
* The standard resource file name.
*/
private static String ROWSET_PROPERTIES = "rowset.properties";
/**
* Permission required to invoke setJNDIContext and setLogger
*/
private static final SQLPermission SET_SYNCFACTORY_PERMISSION =
new SQLPermission("setSyncFactory");
/**
* The initial JNDI context where SyncProvider implementations can
* be stored and from which they can be invoked.
*/
private static Context ic;
/**
* The Logger object to be used by the SyncFactory.
*/
private static volatile Logger rsLogger;
/**
* The registry of available SyncProvider implementations.
* See section 2.0 of the class comment for SyncFactory for an
* explanation of how a provider can be added to this registry.
*/
private static HashtableSyncProvider specification for the
* required naming conventions for SyncProvider
* implementations.
* * Synchronization providers bound to a JNDI context can be * registered by binding a SyncProvider instance to a JNDI namespace. * *
* {@code
* SyncProvider p = new MySyncProvider();
* InitialContext ic = new InitialContext();
* ic.bind ("jdbc/rowset/MySyncProvider", p);
* }
*
* Furthermore, an initial JNDI context should be set with the
* SyncFactory using the setJNDIContext method.
* The SyncFactory leverages this context to search for
* available SyncProvider objects bound to the JNDI
* context and its child nodes.
*
* @param providerID A String object with the unique ID of the
* synchronization provider being registered
* @throws SyncFactoryException if an attempt is made to supply an empty
* or null provider name
* @see #setJNDIContext
*/
public static synchronized void registerProvider(String providerID)
throws SyncFactoryException {
ProviderImpl impl = new ProviderImpl();
impl.setClassname(providerID);
initMapIfNecessary();
implementations.put(providerID, impl);
}
/**
* Returns the SyncFactory singleton.
*
* @return the SyncFactory instance
*/
public static SyncFactory getSyncFactory() {
/*
* Using Initialization on Demand Holder idiom as
* Effective Java 2nd Edition,ITEM 71, indicates it is more performant
* than the Double-Check Locking idiom.
*/
return SyncFactoryHolder.factory;
}
/**
* Removes the designated currently registered synchronization provider from the
* Factory SPI register.
*
* @param providerID The unique-id of the synchronization provider
* @throws SyncFactoryException If an attempt is made to
* unregister a SyncProvider implementation that was not registered.
*/
public static synchronized void unregisterProvider(String providerID)
throws SyncFactoryException {
initMapIfNecessary();
if (implementations.containsKey(providerID)) {
implementations.remove(providerID);
}
}
private static String colon = ":";
private static String strFileSep = "/";
private static synchronized void initMapIfNecessary() throws SyncFactoryException {
// Local implementation class names and keys from Properties
// file, translate names into Class objects using Class.forName
// and store mappings
final Properties properties = new Properties();
if (implementations == null) {
implementations = new Hashtable<>();
try {
// check if user is supplying his Synchronisation Provider
// Implementation if not using Oracle's implementation.
// properties.load(new FileInputStream(ROWSET_PROPERTIES));
// The rowset.properties needs to be in jdk/jre/lib when
// integrated with jdk.
// else it should be picked from -D option from command line.
// -Drowset.properties will add to standard properties. Similar
// keys will over-write
/*
* Dependent on application
*/
String strRowsetProperties;
try {
strRowsetProperties = AccessController.doPrivileged(new PrivilegedActionSyncProvider instance identified by providerID.
*
* @param providerID the unique identifier of the provider
* @return a SyncProvider implementation
* @throws SyncFactoryException If the SyncProvider cannot be found,
* the providerID is {@code null}, or
* some error was encountered when trying to invoke this provider.
*/
public static SyncProvider getInstance(String providerID)
throws SyncFactoryException {
if(providerID == null) {
throw new SyncFactoryException("The providerID cannot be null");
}
initMapIfNecessary(); // populate HashTable
initJNDIContext(); // check JNDI context for any additional bindings
ProviderImpl impl = (ProviderImpl) implementations.get(providerID);
if (impl == null) {
// Requested SyncProvider is unavailable. Return default provider.
return new com.sun.rowset.providers.RIOptimisticProvider();
}
try {
ReflectUtil.checkPackageAccess(providerID);
} catch (java.security.AccessControlException e) {
SyncFactoryException sfe = new SyncFactoryException();
sfe.initCause(e);
throw sfe;
}
// Attempt to invoke classname from registered SyncProvider list
Class c = null;
try {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
/**
* The SyncProvider implementation of the user will be in
* the classpath. We need to find the ClassLoader which loads
* this SyncFactory and try to load the SyncProvider class from
* there.
**/
c = Class.forName(providerID, true, cl);
if (c != null) {
return (SyncProvider) c.newInstance();
} else {
return new com.sun.rowset.providers.RIOptimisticProvider();
}
} catch (IllegalAccessException e) {
throw new SyncFactoryException("IllegalAccessException: " + e.getMessage());
} catch (InstantiationException e) {
throw new SyncFactoryException("InstantiationException: " + e.getMessage());
} catch (ClassNotFoundException e) {
throw new SyncFactoryException("ClassNotFoundException: " + e.getMessage());
}
}
/**
* Returns an Enumeration of currently registered synchronization
* providers. A RowSet implementation may use any provider in
* the enumeration as its SyncProvider object.
*
* At a minimum, the reference synchronization provider allowing
* RowSet content data to be stored using a JDBC driver should be
* possible.
*
* @return Enumeration A enumeration of available synchronization
* providers that are registered with this Factory
* @throws SyncFactoryException If an error occurs obtaining the registered
* providers
*/
public static Enumeration
* This method checks to see that there is an {@code SQLPermission}
* object which grants the permission {@code setSyncFactory}
* before allowing the method to succeed. If a
* {@code SecurityManager} exists and its
* {@code checkPermission} method denies calling {@code setLogger},
* this method throws a
* {@code java.lang.SecurityException}.
*
* @param logger A Logger object instance
* @throws java.lang.SecurityException if a security manager exists and its
* {@code checkPermission} method denies calling {@code setLogger}
* @throws NullPointerException if the logger is null
* @see SecurityManager#checkPermission
*/
public static void setLogger(Logger logger) {
SecurityManager sec = System.getSecurityManager();
if (sec != null) {
sec.checkPermission(SET_SYNCFACTORY_PERMISSION);
}
if(logger == null){
throw new NullPointerException("You must provide a Logger");
}
rsLogger = logger;
}
/**
* Sets the logging object that is used by
* This method checks to see that there is an {@code SQLPermission}
* object which grants the permission {@code setSyncFactory}
* before allowing the method to succeed. If a
* {@code SecurityManager} exists and its
* {@code checkPermission} method denies calling {@code setLogger},
* this method throws a
* {@code java.lang.SecurityException}.
*
* @param logger a Logger object instance
* @param level a Level object instance indicating the degree of logging
* required
* @throws java.lang.SecurityException if a security manager exists and its
* {@code checkPermission} method denies calling {@code setLogger}
* @throws NullPointerException if the logger is null
* @see SecurityManager#checkPermission
* @see LoggingPermission
*/
public static void setLogger(Logger logger, Level level) {
// singleton
SecurityManager sec = System.getSecurityManager();
if (sec != null) {
sec.checkPermission(SET_SYNCFACTORY_PERMISSION);
}
if(logger == null){
throw new NullPointerException("You must provide a Logger");
}
logger.setLevel(level);
rsLogger = logger;
}
/**
* Returns the logging object for applications to retrieve
* synchronization events posted by SyncProvider implementations.
* @return The {@code Logger} that has been specified for use by
* {@code SyncProvider} implementations
* @throws SyncFactoryException if no logging object has been set.
*/
public static Logger getLogger() throws SyncFactoryException {
Logger result = rsLogger;
// only one logger per session
if (result == null) {
throw new SyncFactoryException("(SyncFactory) : No logger has been set");
}
return result;
}
/**
* Sets the initial JNDI context from which SyncProvider implementations
* can be retrieved from a JNDI namespace
*
* This method checks to see that there is an {@code SQLPermission}
* object which grants the permission {@code setSyncFactory}
* before allowing the method to succeed. If a
* {@code SecurityManager} exists and its
* {@code checkPermission} method denies calling {@code setJNDIContext},
* this method throws a
* {@code java.lang.SecurityException}.
*
* @param ctx a valid JNDI context
* @throws SyncFactoryException if the supplied JNDI context is null
* @throws java.lang.SecurityException if a security manager exists and its
* {@code checkPermission} method denies calling {@code setJNDIContext}
* @see SecurityManager#checkPermission
*/
public static synchronized void setJNDIContext(javax.naming.Context ctx)
throws SyncFactoryException {
SecurityManager sec = System.getSecurityManager();
if (sec != null) {
sec.checkPermission(SET_SYNCFACTORY_PERMISSION);
}
if (ctx == null) {
throw new SyncFactoryException("Invalid JNDI context supplied");
}
ic = ctx;
}
/**
* Controls JNDI context initialization.
*
* @throws SyncFactoryException if an error occurs parsing the JNDI context
*/
private static synchronized void initJNDIContext() throws SyncFactoryException {
if ((ic != null) && (lazyJNDICtxRefresh == false)) {
try {
parseProperties(parseJNDIContext());
lazyJNDICtxRefresh = true; // touch JNDI namespace once.
} catch (NamingException e) {
e.printStackTrace();
throw new SyncFactoryException("SPI: NamingException: " + e.getExplanation());
} catch (Exception e) {
e.printStackTrace();
throw new SyncFactoryException("SPI: Exception: " + e.getMessage());
}
}
}
/**
* Internal switch indicating whether the JNDI namespace should be re-read.
*/
private static boolean lazyJNDICtxRefresh = false;
/**
* Parses the set JNDI Context and passes bindings to the enumerateBindings
* method when complete.
*/
private static Properties parseJNDIContext() throws NamingException {
NamingEnumeration bindings = ic.listBindings("");
Properties properties = new Properties();
// Hunt one level below context for available SyncProvider objects
enumerateBindings(bindings, properties);
return properties;
}
/**
* Scans each binding on JNDI context and determines if any binding is an
* instance of SyncProvider, if so, add this to the registry and continue to
* scan the current context using a re-entrant call to this method until all
* bindings have been enumerated.
*/
private static void enumerateBindings(NamingEnumeration bindings,
Properties properties) throws NamingException {
boolean syncProviderObj = false; // move to parameters ?
try {
Binding bd = null;
Object elementObj = null;
String element = null;
while (bindings.hasMore()) {
bd = (Binding) bindings.next();
element = bd.getName();
elementObj = bd.getObject();
if (!(ic.lookup(element) instanceof Context)) {
// skip directories/sub-contexts
if (ic.lookup(element) instanceof SyncProvider) {
syncProviderObj = true;
}
}
if (syncProviderObj) {
SyncProvider sync = (SyncProvider) elementObj;
properties.put(SyncFactory.ROWSET_SYNC_PROVIDER,
sync.getProviderID());
syncProviderObj = false; // reset
}
}
} catch (javax.naming.NotContextException e) {
bindings.next();
// Re-entrant call into method
enumerateBindings(bindings, properties);
}
}
/**
* Lazy initialization Holder class used by {@code getSyncFactory}
*/
private static class SyncFactoryHolder {
static final SyncFactory factory = new SyncFactory();
}
}
/**
* Internal class that defines the lazy reference construct for each registered
* SyncProvider implementation.
*/
class ProviderImpl extends SyncProvider {
private String className = null;
private String vendorName = null;
private String ver = null;
private int index;
public void setClassname(String classname) {
className = classname;
}
public String getClassname() {
return className;
}
public void setVendor(String vendor) {
vendorName = vendor;
}
public String getVendor() {
return vendorName;
}
public void setVersion(String providerVer) {
ver = providerVer;
}
public String getVersion() {
return ver;
}
public void setIndex(int i) {
index = i;
}
public int getIndex() {
return index;
}
public int getDataSourceLock() throws SyncProviderException {
int dsLock = 0;
try {
dsLock = SyncFactory.getInstance(className).getDataSourceLock();
} catch (SyncFactoryException sfEx) {
throw new SyncProviderException(sfEx.getMessage());
}
return dsLock;
}
public int getProviderGrade() {
int grade = 0;
try {
grade = SyncFactory.getInstance(className).getProviderGrade();
} catch (SyncFactoryException sfEx) {
//
}
return grade;
}
public String getProviderID() {
return className;
}
/*
public javax.sql.RowSetInternal getRowSetInternal() {
try
{
return SyncFactory.getInstance(className).getRowSetInternal();
} catch(SyncFactoryException sfEx) {
//
}
}
*/
public javax.sql.RowSetReader getRowSetReader() {
RowSetReader rsReader = null;
try {
rsReader = SyncFactory.getInstance(className).getRowSetReader();
} catch (SyncFactoryException sfEx) {
//
}
return rsReader;
}
public javax.sql.RowSetWriter getRowSetWriter() {
RowSetWriter rsWriter = null;
try {
rsWriter = SyncFactory.getInstance(className).getRowSetWriter();
} catch (SyncFactoryException sfEx) {
//
}
return rsWriter;
}
public void setDataSourceLock(int param)
throws SyncProviderException {
try {
SyncFactory.getInstance(className).setDataSourceLock(param);
} catch (SyncFactoryException sfEx) {
throw new SyncProviderException(sfEx.getMessage());
}
}
public int supportsUpdatableView() {
int view = 0;
try {
view = SyncFactory.getInstance(className).supportsUpdatableView();
} catch (SyncFactoryException sfEx) {
//
}
return view;
}
}
SyncProvider
* implementation provided by the SyncFactory. All
* SyncProvider implementations can log their events to
* this object and the application can retrieve a handle to this
* object using the getLogger method.
* SyncProvider
* implementations provided by the SyncFactory SPI. All
* SyncProvider implementations can log their events
* to this object and the application can retrieve a handle to this
* object using the getLogger method.
*