Class java.beans.Beans
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Class java.beans.Beans
java.lang.Object
|
+----java.beans.Beans
public class Beans
extends Object
This class provides some general purpose beans control methods.
Beans()
getInstanceOf(Object, Class)
From a given bean, obtain an object representing a specified
type view of that source object.
instantiate(ClassLoader, String)
Instantiate a bean.
isDesignTime()
Test if we are in design-mode.
isGuiAvailable()
isInstanceOf(Object, Class)
Check if a bean can be viewed as a given target type.
setDesignTime(boolean)
Used to indicate whether of not we are running in an application
builder environment.
setGuiAvailable(boolean)
Used to indicate whether of not we are running in an environment
where GUI interaction is available.
Beans
public Beans()
instantiate
public static Object instantiate(ClassLoader cls,
String beanName) throws IOException, ClassNotFoundException
Instantiate a bean.
The bean is created based on a name relative to a class-loader.
This name should be a dot-separated name such as "a.b.c".
In Beans 1.0 the given name can indicate either a serialized object
or a class. Other mechanisms may be added in the future. In
beans 1.0 we first try to treat the beanName as a serialized object
name then as a class name.
When using the beanName as a serialized object name we convert the
given beanName to a resource pathname and add a trailing ".ser" suffix.
We then try to load a serialized object from that resource.
For example, given a beanName of "x.y", Beans.instantiate would first
try to read a serialized object from the resource "x/y.ser" and if
that failed it would try to load the class "x.y" and create an
instance of that class.
If the bean is a subtype of java.applet.Applet, then it is given
some special initialization. First, it is supplied with a default
AppletStub and AppletContext. Second, if it was instantiated from
a classname the applet's "init" method is called. (If the bean was
deserialized this step is skipped.)
Note that for beans which are applets, it is the caller's responsiblity
to call "start" on the applet. For correct behaviour, this should be done
after the applet has been added into a visible AWT container.
Note that applets created via beans.instantiate run in a slightly
different environment than applets running inside browsers. In
particular, bean applets have no access to "parameters", so they may
wish to provide property get/set methods to set parameter values. We
advise bean-applet developers to test their bean-applets against both
the JDK appletviewer (for a reference browser environment) and the
BDK BeanBox (for a reference bean container).
Parameters:
classLoader - the class-loader from which we should create
the bean. If this is null, then the system
class-loader is used.
beanName - the name of the bean within the class-loader.
For example "sun.beanbox.foobah"
Throws: ClassNotFoundException
if the class of a serialized
object could not be found.
Throws: IOException
if an I/O error occurs.
getInstanceOf
public static Object getInstanceOf(Object bean,
Class targetType)
From a given bean, obtain an object representing a specified
type view of that source object.
The result may be the same object or a different object. If
the requested target view isn't available then the given
bean is returned.
This method is provided in Beans 1.0 as a hook to allow the
addition of more flexible bean behaviour in the future.
Parameters:
obj - Object from which we want to obtain a view.
targetType - The type of view we'd like to get.
isInstanceOf
public static boolean isInstanceOf(Object bean,
Class targetType)
Check if a bean can be viewed as a given target type.
The result will be true if the Beans.getInstanceof method
can be used on the given bean to obtain an object that
represents the specified targetType type view.
Parameters:
bean - Bean from which we want to obtain a view.
targetType - The type of view we'd like to get.
Returns:
"true" if the given bean supports the given targetType.
isDesignTime
public static boolean isDesignTime()
Test if we are in design-mode.
Returns:
True if we are running in an application construction
environment.
isGuiAvailable
public static boolean isGuiAvailable()
Returns:
True if we are running in an environment where beans
can assume that an interactive GUI is available, so they
can pop up dialog boxes, etc. This will normally return
true in a windowing environment, and will normally return
false in a server environment or if an application is
running as part of a batch job.
setDesignTime
public static void setDesignTime(boolean isDesignTime) throws SecurityException
Used to indicate whether of not we are running in an application
builder environment. Note that this method is security checked
and is not available to (for example) untrusted applets.
Parameters:
isDesignTime - True if we're in an application builder tool.
setGuiAvailable
public static void setGuiAvailable(boolean isGuiAvailable) throws SecurityException
Used to indicate whether of not we are running in an environment
where GUI interaction is available. Note that this method is
security checked and is not available to (for example) untrusted
applets.
Parameters:
isGuiAvailable - True if GUI interaction is available.
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