The InitialContext.java Java example source code
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package javax.naming;
import java.util.Hashtable;
import javax.naming.spi.NamingManager;
import com.sun.naming.internal.ResourceManager;
/**
* This class is the starting context for performing naming operations.
*<p>
* All naming operations are relative to a context.
* The initial context implements the Context interface and
* provides the starting point for resolution of names.
*<p>
* <a name=ENVIRONMENT>
* When the initial context is constructed, its environment
* is initialized with properties defined in the environment parameter
* passed to the constructor, and in any
* <a href=Context.html#RESOURCEFILES>application resource files.
* In addition, a small number of standard JNDI properties may
* be specified as system properties or as applet parameters
* (through the use of {@link Context#APPLET}).
* These special properties are listed in the field detail sections of the
* <a href=Context.html#field_detail>Context and
* <a href=ldap/LdapContext.html#field_detail>LdapContext
* interface documentation.
*<p>
* JNDI determines each property's value by merging
* the values from the following two sources, in order:
* <ol>
* <li>
* The first occurrence of the property from the constructor's
* environment parameter and (for appropriate properties) the applet
* parameters and system properties.
* <li>
* The application resource files (<tt>jndi.properties).
* </ol>
* For each property found in both of these two sources, or in
* more than one application resource file, the property's value
* is determined as follows. If the property is
* one of the standard JNDI properties that specify a list of JNDI
* factories (see <a href=Context.html#LISTPROPS>Context),
* all of the values are
* concatenated into a single colon-separated list. For other
* properties, only the first value found is used.
*
*<p>
* The initial context implementation is determined at runtime.
* The default policy uses the environment property
* "{@link Context#INITIAL_CONTEXT_FACTORY java.naming.factory.initial}",
* which contains the class name of the initial context factory.
* An exception to this policy is made when resolving URL strings, as described
* below.
*<p>
* When a URL string (a <tt>String of the form
* <em>scheme_id:rest_of_name) is passed as a name parameter to
* any method, a URL context factory for handling that scheme is
* located and used to resolve the URL. If no such factory is found,
* the initial context specified by
* <tt>"java.naming.factory.initial" is used. Similarly, when a
* <tt>CompositeName object whose first component is a URL string is
* passed as a name parameter to any method, a URL context factory is
* located and used to resolve the first name component.
* See {@link NamingManager#getURLContext
* <tt>NamingManager.getURLContext()} for a description of how URL
* context factories are located.
*<p>
* This default policy of locating the initial context and URL context
* factories may be overridden
* by calling
* <tt>NamingManager.setInitialContextFactoryBuilder().
*<p>
* NoInitialContextException is thrown when an initial context cannot
* be instantiated. This exception can be thrown during any interaction
* with the InitialContext, not only when the InitialContext is constructed.
* For example, the implementation of the initial context might lazily
* retrieve the context only when actual methods are invoked on it.
* The application should not have any dependency on when the existence
* of an initial context is determined.
*<p>
* When the environment property "java.naming.factory.initial" is
* non-null, the InitialContext constructor will attempt to create the
* initial context specified therein. At that time, the initial context factory
* involved might throw an exception if a problem is encountered. However,
* it is provider implementation-dependent when it verifies and indicates
* to the users of the initial context any environment property- or
* connection- related problems. It can do so lazily--delaying until
* an operation is performed on the context, or eagerly, at the time
* the context is constructed.
*<p>
* An InitialContext instance is not synchronized against concurrent
* access by multiple threads. Multiple threads each manipulating a
* different InitialContext instance need not synchronize.
* Threads that need to access a single InitialContext instance
* concurrently should synchronize amongst themselves and provide the
* necessary locking.
*
* @author Rosanna Lee
* @author Scott Seligman
*
* @see Context
* @see NamingManager#setInitialContextFactoryBuilder
* NamingManager.setInitialContextFactoryBuilder
* @since JNDI 1.1 / Java 2 Platform, Standard Edition, v 1.3
*/
public class InitialContext implements Context {
/**
* The environment associated with this InitialContext.
* It is initialized to null and is updated by the constructor
* that accepts an environment or by the <tt>init() method.
* @see #addToEnvironment
* @see #removeFromEnvironment
* @see #getEnvironment
*/
protected Hashtable<Object,Object> myProps = null;
/**
* Field holding the result of calling NamingManager.getInitialContext().
* It is set by getDefaultInitCtx() the first time getDefaultInitCtx()
* is called. Subsequent invocations of getDefaultInitCtx() return
* the value of defaultInitCtx.
* @see #getDefaultInitCtx
*/
protected Context defaultInitCtx = null;
/**
* Field indicating whether the initial context has been obtained
* by calling NamingManager.getInitialContext().
* If true, its result is in <code>defaultInitCtx.
*/
protected boolean gotDefault = false;
/**
* Constructs an initial context with the option of not
* initializing it. This may be used by a constructor in
* a subclass when the value of the environment parameter
* is not yet known at the time the <tt>InitialContext
* constructor is called. The subclass's constructor will
* call this constructor, compute the value of the environment,
* and then call <tt>init() before returning.
*
* @param lazy
* true means do not initialize the initial context; false
* is equivalent to calling <tt>new InitialContext()
* @throws NamingException if a naming exception is encountered
*
* @see #init(Hashtable)
* @since 1.3
*/
protected InitialContext(boolean lazy) throws NamingException {
if (!lazy) {
init(null);
}
}
/**
* Constructs an initial context.
* No environment properties are supplied.
* Equivalent to <tt>new InitialContext(null).
*
* @throws NamingException if a naming exception is encountered
*
* @see #InitialContext(Hashtable)
*/
public InitialContext() throws NamingException {
init(null);
}
/**
* Constructs an initial context using the supplied environment.
* Environment properties are discussed in the class description.
*
* <p> This constructor will not modify environment
* or save a reference to it, but may save a clone.
* Caller should not modify mutable keys and values in
* <tt>environment after it has been passed to the constructor.
*
* @param environment
* environment used to create the initial context.
* Null indicates an empty environment.
*
* @throws NamingException if a naming exception is encountered
*/
public InitialContext(Hashtable<?,?> environment)
throws NamingException
{
if (environment != null) {
environment = (Hashtable)environment.clone();
}
init(environment);
}
/**
* Initializes the initial context using the supplied environment.
* Environment properties are discussed in the class description.
*
* <p> This method will modify environment and save
* a reference to it. The caller may no longer modify it.
*
* @param environment
* environment used to create the initial context.
* Null indicates an empty environment.
*
* @throws NamingException if a naming exception is encountered
*
* @see #InitialContext(boolean)
* @since 1.3
*/
@SuppressWarnings("unchecked")
protected void init(Hashtable<?,?> environment)
throws NamingException
{
myProps = (Hashtable<Object,Object>)
ResourceManager.getInitialEnvironment(environment);
if (myProps.get(Context.INITIAL_CONTEXT_FACTORY) != null) {
// user has specified initial context factory; try to get it
getDefaultInitCtx();
}
}
/**
* A static method to retrieve the named object.
* This is a shortcut method equivalent to invoking:
* <p>
* <code>
* InitialContext ic = new InitialContext();
* Object obj = ic.lookup();
* </code>
* <p> If name is empty, returns a new instance of this context
* (which represents the same naming context as this context, but its
* environment may be modified independently and it may be accessed
* concurrently).
*
* @param <T> the type of the returned object
* @param name
* the name of the object to look up
* @return the object bound to <tt>name
* @throws NamingException if a naming exception is encountered
*
* @see #doLookup(String)
* @see #lookup(Name)
* @since 1.6
*/
@SuppressWarnings("unchecked")
public static <T> T doLookup(Name name)
throws NamingException {
return (T) (new InitialContext()).lookup(name);
}
/**
* A static method to retrieve the named object.
* See {@link #doLookup(Name)} for details.
* @param <T> the type of the returned object
* @param name
* the name of the object to look up
* @return the object bound to <tt>name
* @throws NamingException if a naming exception is encountered
* @since 1.6
*/
@SuppressWarnings("unchecked")
public static <T> T doLookup(String name)
throws NamingException {
return (T) (new InitialContext()).lookup(name);
}
private static String getURLScheme(String str) {
int colon_posn = str.indexOf(':');
int slash_posn = str.indexOf('/');
if (colon_posn > 0 && (slash_posn == -1 || colon_posn < slash_posn))
return str.substring(0, colon_posn);
return null;
}
/**
* Retrieves the initial context by calling
* <code>NamingManager.getInitialContext()
* and cache it in defaultInitCtx.
* Set <code>gotDefault so that we know we've tried this before.
* @return The non-null cached initial context.
* @exception NoInitialContextException If cannot find an initial context.
* @exception NamingException If a naming exception was encountered.
*/
protected Context getDefaultInitCtx() throws NamingException{
if (!gotDefault) {
defaultInitCtx = NamingManager.getInitialContext(myProps);
gotDefault = true;
}
if (defaultInitCtx == null)
throw new NoInitialContextException();
return defaultInitCtx;
}
/**
* Retrieves a context for resolving the string name <code>name.
* If <code>name name is a URL string, then attempt
* to find a URL context for it. If none is found, or if
* <code>name is not a URL string, then return
* <code>getDefaultInitCtx().
*<p>
* See getURLOrDefaultInitCtx(Name) for description
* of how a subclass should use this method.
* @param name The non-null name for which to get the context.
* @return A URL context for <code>name or the cached
* initial context. The result cannot be null.
* @exception NoInitialContextException If cannot find an initial context.
* @exception NamingException In a naming exception is encountered.
* @see javax.naming.spi.NamingManager#getURLContext
*/
protected Context getURLOrDefaultInitCtx(String name)
throws NamingException {
if (NamingManager.hasInitialContextFactoryBuilder()) {
return getDefaultInitCtx();
}
String scheme = getURLScheme(name);
if (scheme != null) {
Context ctx = NamingManager.getURLContext(scheme, myProps);
if (ctx != null) {
return ctx;
}
}
return getDefaultInitCtx();
}
/**
* Retrieves a context for resolving <code>name.
* If the first component of <code>name name is a URL string,
* then attempt to find a URL context for it. If none is found, or if
* the first component of <code>name is not a URL string,
* then return <code>getDefaultInitCtx().
*<p>
* When creating a subclass of InitialContext, use this method as
* follows.
* Define a new method that uses this method to get an initial
* context of the desired subclass.
* <blockquote>
* protected XXXContext getURLOrDefaultInitXXXCtx(Name name)
* throws NamingException {
* Context answer = getURLOrDefaultInitCtx(name);
* if (!(answer instanceof XXXContext)) {
* if (answer == null) {
* throw new NoInitialContextException();
* } else {
* throw new NotContextException("Not an XXXContext");
* }
* }
* return (XXXContext)answer;
* }
* </pre>
* When providing implementations for the new methods in the subclass,
* use this newly defined method to get the initial context.
* <blockquote>
* public Object XXXMethod1(Name name, ...) {
* throws NamingException {
* return getURLOrDefaultInitXXXCtx(name).XXXMethod1(name, ...);
* }
* </pre>
*
* @param name The non-null name for which to get the context.
* @return A URL context for <code>name or the cached
* initial context. The result cannot be null.
* @exception NoInitialContextException If cannot find an initial context.
* @exception NamingException In a naming exception is encountered.
*
* @see javax.naming.spi.NamingManager#getURLContext
*/
protected Context getURLOrDefaultInitCtx(Name name)
throws NamingException {
if (NamingManager.hasInitialContextFactoryBuilder()) {
return getDefaultInitCtx();
}
if (name.size() > 0) {
String first = name.get(0);
String scheme = getURLScheme(first);
if (scheme != null) {
Context ctx = NamingManager.getURLContext(scheme, myProps);
if (ctx != null) {
return ctx;
}
}
}
return getDefaultInitCtx();
}
// Context methods
// Most Javadoc is deferred to the Context interface.
public Object lookup(String name) throws NamingException {
return getURLOrDefaultInitCtx(name).lookup(name);
}
public Object lookup(Name name) throws NamingException {
return getURLOrDefaultInitCtx(name).lookup(name);
}
public void bind(String name, Object obj) throws NamingException {
getURLOrDefaultInitCtx(name).bind(name, obj);
}
public void bind(Name name, Object obj) throws NamingException {
getURLOrDefaultInitCtx(name).bind(name, obj);
}
public void rebind(String name, Object obj) throws NamingException {
getURLOrDefaultInitCtx(name).rebind(name, obj);
}
public void rebind(Name name, Object obj) throws NamingException {
getURLOrDefaultInitCtx(name).rebind(name, obj);
}
public void unbind(String name) throws NamingException {
getURLOrDefaultInitCtx(name).unbind(name);
}
public void unbind(Name name) throws NamingException {
getURLOrDefaultInitCtx(name).unbind(name);
}
public void rename(String oldName, String newName) throws NamingException {
getURLOrDefaultInitCtx(oldName).rename(oldName, newName);
}
public void rename(Name oldName, Name newName)
throws NamingException
{
getURLOrDefaultInitCtx(oldName).rename(oldName, newName);
}
public NamingEnumeration<NameClassPair> list(String name)
throws NamingException
{
return (getURLOrDefaultInitCtx(name).list(name));
}
public NamingEnumeration<NameClassPair> list(Name name)
throws NamingException
{
return (getURLOrDefaultInitCtx(name).list(name));
}
public NamingEnumeration<Binding> listBindings(String name)
throws NamingException {
return getURLOrDefaultInitCtx(name).listBindings(name);
}
public NamingEnumeration<Binding> listBindings(Name name)
throws NamingException {
return getURLOrDefaultInitCtx(name).listBindings(name);
}
public void destroySubcontext(String name) throws NamingException {
getURLOrDefaultInitCtx(name).destroySubcontext(name);
}
public void destroySubcontext(Name name) throws NamingException {
getURLOrDefaultInitCtx(name).destroySubcontext(name);
}
public Context createSubcontext(String name) throws NamingException {
return getURLOrDefaultInitCtx(name).createSubcontext(name);
}
public Context createSubcontext(Name name) throws NamingException {
return getURLOrDefaultInitCtx(name).createSubcontext(name);
}
public Object lookupLink(String name) throws NamingException {
return getURLOrDefaultInitCtx(name).lookupLink(name);
}
public Object lookupLink(Name name) throws NamingException {
return getURLOrDefaultInitCtx(name).lookupLink(name);
}
public NameParser getNameParser(String name) throws NamingException {
return getURLOrDefaultInitCtx(name).getNameParser(name);
}
public NameParser getNameParser(Name name) throws NamingException {
return getURLOrDefaultInitCtx(name).getNameParser(name);
}
/**
* Composes the name of this context with a name relative to
* this context.
* Since an initial context may never be named relative
* to any context other than itself, the value of the
* <tt>prefix parameter must be an empty name ("").
*/
public String composeName(String name, String prefix)
throws NamingException {
return name;
}
/**
* Composes the name of this context with a name relative to
* this context.
* Since an initial context may never be named relative
* to any context other than itself, the value of the
* <tt>prefix parameter must be an empty name.
*/
public Name composeName(Name name, Name prefix)
throws NamingException
{
return (Name)name.clone();
}
public Object addToEnvironment(String propName, Object propVal)
throws NamingException {
myProps.put(propName, propVal);
return getDefaultInitCtx().addToEnvironment(propName, propVal);
}
public Object removeFromEnvironment(String propName)
throws NamingException {
myProps.remove(propName);
return getDefaultInitCtx().removeFromEnvironment(propName);
}
public Hashtable<?,?> getEnvironment() throws NamingException {
return getDefaultInitCtx().getEnvironment();
}
public void close() throws NamingException {
myProps = null;
if (defaultInitCtx != null) {
defaultInitCtx.close();
defaultInitCtx = null;
}
gotDefault = false;
}
public String getNameInNamespace() throws NamingException {
return getDefaultInitCtx().getNameInNamespace();
}
};
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