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Java™ Platform Standard Ed. 6 |
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java.lang.Object java.beans.Introspector
public class Introspector
The Introspector class provides a standard way for tools to learn about the properties, events, and methods supported by a target Java Bean.
For each of those three kinds of information, the Introspector will separately analyze the bean's class and superclasses looking for either explicit or implicit information and use that information to build a BeanInfo object that comprehensively describes the target bean.
For each class "Foo", explicit information may be available if there exists a corresponding "FooBeanInfo" class that provides a non-null value when queried for the information. We first look for the BeanInfo class by taking the full package-qualified name of the target bean class and appending "BeanInfo" to form a new class name. If this fails, then we take the final classname component of this name, and look for that class in each of the packages specified in the BeanInfo package search path.
Thus for a class such as "sun.xyz.OurButton" we would first look for a BeanInfo class called "sun.xyz.OurButtonBeanInfo" and if that failed we'd look in each package in the BeanInfo search path for an OurButtonBeanInfo class. With the default search path, this would mean looking for "sun.beans.infos.OurButtonBeanInfo".
If a class provides explicit BeanInfo about itself then we add that to the BeanInfo information we obtained from analyzing any derived classes, but we regard the explicit information as being definitive for the current class and its base classes, and do not proceed any further up the superclass chain.
If we don't find explicit BeanInfo on a class, we use low-level reflection to study the methods of the class and apply standard design patterns to identify property accessors, event sources, or public methods. We then proceed to analyze the class's superclass and add in the information from it (and possibly on up the superclass chain).
Because the Introspector caches BeanInfo classes for better performance,
take care if you use it in an application that uses
multiple class loaders.
In general, when you destroy a ClassLoader
that has been used to introspect classes,
you should use the
or
Introspector.flushCaches
method
to flush all of the introspected classes out of the cache.
Introspector.flushFromCaches
For more information about introspection and design patterns, please consult the JavaBeans specification.
Field Summary | |
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static int |
IGNORE_ALL_BEANINFO
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static int |
IGNORE_IMMEDIATE_BEANINFO
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static int |
USE_ALL_BEANINFO
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Method Summary | |
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static String |
decapitalize(String name)
Utility method to take a string and convert it to normal Java variable name capitalization. |
static void |
flushCaches()
Flush all of the Introspector's internal caches. |
static void |
flushFromCaches(Class<?> clz)
Flush the Introspector's internal cached information for a given class. |
static BeanInfo |
getBeanInfo(Class<?> beanClass)
Introspect on a Java Bean and learn about all its properties, exposed methods, and events. |
static BeanInfo |
getBeanInfo(Class<?> beanClass,
Class<?> stopClass)
Introspect on a Java bean and learn all about its properties, exposed methods, below a given "stop" point. |
static BeanInfo |
getBeanInfo(Class<?> beanClass,
int flags)
Introspect on a Java bean and learn about all its properties, exposed methods, and events, subject to some control flags. |
static String[] |
getBeanInfoSearchPath()
Gets the list of package names that will be used for finding BeanInfo classes. |
static void |
setBeanInfoSearchPath(String[] path)
Change the list of package names that will be used for finding BeanInfo classes. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final int USE_ALL_BEANINFO
public static final int IGNORE_IMMEDIATE_BEANINFO
public static final int IGNORE_ALL_BEANINFO
Method Detail |
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public static BeanInfo getBeanInfo(Class<?> beanClass) throws IntrospectionException
If the BeanInfo class for a Java Bean has been previously Introspected then the BeanInfo class is retrieved from the BeanInfo cache.
beanClass
- The bean class to be analyzed.
IntrospectionException
- if an exception occurs during
introspection.flushCaches()
,
flushFromCaches(java.lang.Class>)
public static BeanInfo getBeanInfo(Class<?> beanClass, int flags) throws IntrospectionException
If the BeanInfo class for a Java Bean has been previously Introspected based on the same arguments then the BeanInfo class is retrieved from the BeanInfo cache.
beanClass
- The bean class to be analyzed.flags
- Flags to control the introspection.
If flags == USE_ALL_BEANINFO then we use all of the BeanInfo
classes we can discover.
If flags == IGNORE_IMMEDIATE_BEANINFO then we ignore any
BeanInfo associated with the specified beanClass.
If flags == IGNORE_ALL_BEANINFO then we ignore all BeanInfo
associated with the specified beanClass or any of its
parent classes.
IntrospectionException
- if an exception occurs during
introspection.public static BeanInfo getBeanInfo(Class<?> beanClass, Class<?> stopClass) throws IntrospectionException
If the BeanInfo class for a Java Bean has been previously Introspected based on the same arguments, then the BeanInfo class is retrieved from the BeanInfo cache.
beanClass
- The bean class to be analyzed.stopClass
- The baseclass at which to stop the analysis. Any
methods/properties/events in the stopClass or in its baseclasses
will be ignored in the analysis.
IntrospectionException
- if an exception occurs during
introspection.public static String decapitalize(String name)
Thus "FooBah" becomes "fooBah" and "X" becomes "x", but "URL" stays as "URL".
name
- The string to be decapitalized.
public static String[] getBeanInfoSearchPath()
public static void setBeanInfoSearchPath(String[] path)
First, if there is a security manager, its checkPropertiesAccess
method is called. This could result in a SecurityException.
path
- Array of package names.
SecurityException
- if a security manager exists and its
checkPropertiesAccess
method doesn't allow setting
of system properties.SecurityManager.checkPropertiesAccess()
public static void flushCaches()
public static void flushFromCaches(Class<?> clz)
clz
- Class object to be flushed.
NullPointerException
- If the Class object is null.
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Java™ Platform Standard Ed. 6 |
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