/**
* Adds a new provider, at a specified position. The position is the preference order in which
* providers are searched for requested algorithms. Note that it is not guaranteed that this
* preference will be respected. The position is 1-based, that is, 1 is most preferred, followed
* by 2, and so on.
*
* <p>If the given provider is installed at the requested position, the provider that used to be
* at that position, and all providers with a position greater than <code>position</code>, are
* shifted up one position (towards the end of the list of installed providers).
*
* <p>A provider cannot be added if it is already installed.
*
* <p>First, if there is a security manager, its <code>checkSecurityAccess</code> method is called
* with the string <code>"insertProvider."+provider.getName()</code> to see if it's ok to add a
* new provider. If the default implementation of <code>checkSecurityAccess</code> is used (i.e.,
* that method is not overriden), then this will result in a call to the security manager's <code>
* checkPermission</code> method with a <code>
* SecurityPermission("insertProvider."+provider.getName())</code> permission.
*
* @param provider the provider to be added.
* @param position the preference position that the caller would like for this provider.
* @return the actual preference position in which the provider was added, or -1 if the provider
* was not added because it is already installed.
* @throws NullPointerException if provider is null
* @throws SecurityException if a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkSecurityAccess}</code> method denies access to add a
* new provider
* @see #getProvider
* @see #removeProvider
* @see java.security.SecurityPermission
*/
public static synchronized int insertProviderAt(Provider provider, int position) {
String providerName = provider.getName();
check("insertProvider." + providerName);
ProviderList list = Providers.getFullProviderList();
ProviderList newList = ProviderList.insertAt(list, provider, position - 1);
if (list == newList) {
return -1;
}
Providers.setProviderList(newList);
return newList.getIndex(providerName) + 1;
}
/**
* Looks up providers, and returns the property (and its associated provider) mapping the key, if
* any. The order in which the providers are looked up is the provider-preference order, as
* specificed in the security properties file.
*/
private static ProviderProperty getProviderProperty(String key) {
ProviderProperty entry = null;
List providers = Providers.getProviderList().providers();
for (int i = 0; i < providers.size(); i++) {
String matchKey = null;
Provider prov = (Provider) providers.get(i);
String prop = prov.getProperty(key);
if (prop == null) {
// Is there a match if we do a case-insensitive property name
// comparison? Let's try ...
for (Enumeration e = prov.keys(); e.hasMoreElements() && prop == null; ) {
matchKey = (String) e.nextElement();
if (key.equalsIgnoreCase(matchKey)) {
prop = prov.getProperty(matchKey);
break;
}
}
}
if (prop != null) {
ProviderProperty newEntry = new ProviderProperty();
newEntry.className = prop;
newEntry.provider = prov;
return newEntry;
}
}
return entry;
}
/**
* Returns the provider installed with the specified name, if any. Returns null if no provider
* with the specified name is installed or if name is null.
*
* @param name the name of the provider to get.
* @return the provider of the specified name.
* @see #removeProvider
* @see #addProvider
*/
public static Provider getProvider(String name) {
return Providers.getProviderList().getProvider(name);
}
/**
* Returns an array containing all the installed providers. The order of the providers in the
* array is their preference order.
*
* @return an array of all the installed providers.
*/
public static Provider[] getProviders() {
return Providers.getFullProviderList().toArray();
}
/**
* Removes the provider with the specified name.
*
* <p>When the specified provider is removed, all providers located at a position greater than
* where the specified provider was are shifted down one position (towards the head of the list of
* installed providers).
*
* <p>This method returns silently if the provider is not installed or if name is null.
*
* <p>First, if there is a security manager, its <code>checkSecurityAccess</code> method is called
* with the string <code>"removeProvider."+name</code> to see if it's ok to remove the provider.
* If the default implementation of <code>checkSecurityAccess</code> is used (i.e., that method is
* not overriden), then this will result in a call to the security manager's <code>checkPermission
* </code> method with a <code>SecurityPermission("removeProvider."+name)</code> permission.
*
* @param name the name of the provider to remove.
* @throws SecurityException if a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkSecurityAccess}</code> method denies access to remove
* the provider
* @see #getProvider
* @see #addProvider
*/
public static synchronized void removeProvider(String name) {
check("removeProvider." + name);
ProviderList list = Providers.getFullProviderList();
ProviderList newList = ProviderList.remove(list, name);
Providers.setProviderList(newList);
}