Package org.apache.commons.jexl3.internal.introspection

Class Introspector

  • public final class Introspector
extends java.lang.Object
    This basic function of this class is to return a Method object for a particular class given the name of a method and the parameters to the method in the form of an Object[].

    The first time the Introspector sees a class it creates a class method map for the class in question. Basically the class method map is a Hashtable where Method objects are keyed by the aggregation of the method name and the array of parameters classes. This mapping is performed for all the public methods of a class and stored.

    Since:
    1.0

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      private static class  Introspector.CacheMiss
      A Constructor get cache-miss.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private java.util.Map<java.lang.Class<?>,​ClassMap> classMethodMaps
      Holds the method maps for the classes we know about, keyed by Class.
      private java.util.Map<java.lang.String,​java.lang.Class<?>> constructibleClasses
      Holds the set of classes we have introspected.
      private java.util.Map<MethodKey,​java.lang.reflect.Constructor<?>> constructorsMap
      Holds the map of classes ctors we know about as well as unknown ones.
      private static java.lang.reflect.Constructor<?> CTOR_MISS
      The cache-miss marker for the constructors map.
      private java.lang.ClassLoader loader
      The class loader used to solve constructors if needed.
      private java.util.concurrent.locks.ReadWriteLock lock
      The read/write lock.
      private org.apache.commons.logging.Log logger
      the logger.
      private JexlPermissions permissions
      The permissions.

    • Constructor Summary

      Constructors 
      Constructor Description
      Introspector​(org.apache.commons.logging.Log log, java.lang.ClassLoader cloader)
      Create the introspector.
      Introspector​(org.apache.commons.logging.Log log, java.lang.ClassLoader loader, JexlPermissions perms)
      Create the introspector.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.Class<?> getClassByName​(java.lang.String className)
      Gets a class by name through this introspector class loader.
      java.lang.reflect.Constructor<?> getConstructor​(java.lang.Class<?> c, MethodKey key)
      Gets the constructor defined by the MethodKey.
      java.lang.reflect.Constructor<?> getConstructor​(MethodKey key)
      Gets the constructor defined by the MethodKey.
      java.lang.reflect.Field getField​(java.lang.Class<?> c, java.lang.String key)
      Gets the field named by key for the class c.
      java.lang.String[] getFieldNames​(java.lang.Class<?> c)
      Gets the array of accessible field names known for a given class.
      java.lang.ClassLoader getLoader()
      Gets the class loader used by this introspector.
      private ClassMap getMap​(java.lang.Class<?> c)
      Gets the ClassMap for a given class.
      java.lang.reflect.Method getMethod​(java.lang.Class<?> c, java.lang.String name, java.lang.Object... params)
      Gets a method defined by a class, a name and a set of parameters.
      java.lang.reflect.Method getMethod​(java.lang.Class<?> c, MethodKey key)
      Gets the method defined by the MethodKey for the class c.
      java.lang.String[] getMethodNames​(java.lang.Class<?> c)
      Gets the array of accessible methods names known for a given class.
      java.lang.reflect.Method[] getMethods​(java.lang.Class<?> c, java.lang.String methodName)
      Gets the array of accessible method known for a given class.
      private static boolean isLoadedBy​(java.lang.ClassLoader loader, java.lang.Class<?> clazz)
      Checks whether a class is loaded through a given class loader or one of its ascendants.
      void setLoader​(java.lang.ClassLoader classLoader)
      Sets the class loader used to solve constructors.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • CTOR_MISS

        private static final java.lang.reflect.Constructor<?> CTOR_MISS
        The cache-miss marker for the constructors map.

      • logger

        private final org.apache.commons.logging.Log logger
        the logger.

      • lock

        private final java.util.concurrent.locks.ReadWriteLock lock
        The read/write lock.

      • classMethodMaps

        private final java.util.Map<java.lang.Class<?>,​ClassMap> classMethodMaps
        Holds the method maps for the classes we know about, keyed by Class.

      • constructorsMap

        private final java.util.Map<MethodKey,​java.lang.reflect.Constructor<?>> constructorsMap
        Holds the map of classes ctors we know about as well as unknown ones.

      • constructibleClasses

        private final java.util.Map<java.lang.String,​java.lang.Class<?>> constructibleClasses
        Holds the set of classes we have introspected.

      • loader

        private volatile java.lang.ClassLoader loader
        The class loader used to solve constructors if needed.

        Cheap read-write lock pattern: exclusive lock for write, read visibility through volatile.

    • Constructor Detail

      • Introspector

        public Introspector​(org.apache.commons.logging.Log log,
                    java.lang.ClassLoader cloader)
        Create the introspector.
        Parameters:
        log - the logger to use
        cloader - the class loader

      • Introspector

        public Introspector​(org.apache.commons.logging.Log log,
                    java.lang.ClassLoader loader,
                    JexlPermissions perms)
        Create the introspector.
        Parameters:
        log - the logger to use
        loader - the class loader
        perms - the permissions

    • Method Detail

      • isLoadedBy

        private static boolean isLoadedBy​(java.lang.ClassLoader loader,
                                  java.lang.Class<?> clazz)
        Checks whether a class is loaded through a given class loader or one of its ascendants.
        Parameters:
        loader - the class loader
        clazz - the class to check
        Returns:
        true if clazz was loaded through the loader, false otherwise

      • getClassByName

        public java.lang.Class<?> getClassByName​(java.lang.String className)
        Gets a class by name through this introspector class loader.
        Parameters:
        className - the class name
        Returns:
        the class instance or null if it could not be found

      • getConstructor

        public java.lang.reflect.Constructor<?> getConstructor​(java.lang.Class<?> c,
                                                       MethodKey key)
        Gets the constructor defined by the MethodKey.
        Parameters:
        c - the class we want to instantiate
        key - Key of the constructor being searched for
        Returns:
        The desired constructor object or null if no unambiguous constructor could be found through introspection.

      • getConstructor

        public java.lang.reflect.Constructor<?> getConstructor​(MethodKey key)
        Gets the constructor defined by the MethodKey.
        Parameters:
        key - Key of the constructor being searched for
        Returns:
        The desired constructor object or null if no unambiguous constructor could be found through introspection.

      • getField

        public java.lang.reflect.Field getField​(java.lang.Class<?> c,
                                        java.lang.String key)
        Gets the field named by key for the class c.
        Parameters:
        c - Class in which the field search is taking place
        key - Name of the field being searched for
        Returns:
        the desired field or null if it does not exist or is not accessible

      • getFieldNames

        public java.lang.String[] getFieldNames​(java.lang.Class<?> c)
        Gets the array of accessible field names known for a given class.
        Parameters:
        c - the class
        Returns:
        the class field names

      • getLoader

        public java.lang.ClassLoader getLoader()
        Gets the class loader used by this introspector.
        Returns:
        the class loader

      • getMap

        private ClassMap getMap​(java.lang.Class<?> c)
        Gets the ClassMap for a given class.
        Parameters:
        c - the class
        Returns:
        the class map

      • getMethod

        public java.lang.reflect.Method getMethod​(java.lang.Class<?> c,
                                          MethodKey key)
        Gets the method defined by the MethodKey for the class c.
        Parameters:
        c - Class in which the method search is taking place
        key - Key of the method being searched for
        Returns:
        The desired method object
        Throws:
        MethodKey.AmbiguousException - if no unambiguous method could be found through introspection

      • getMethod

        public java.lang.reflect.Method getMethod​(java.lang.Class<?> c,
                                          java.lang.String name,
                                          java.lang.Object... params)
        Gets a method defined by a class, a name and a set of parameters.
        Parameters:
        c - the class
        name - the method name
        params - the method parameters
        Returns:
        the desired method object
        Throws:
        MethodKey.AmbiguousException - if no unambiguous method could be found through introspection

      • getMethodNames

        public java.lang.String[] getMethodNames​(java.lang.Class<?> c)
        Gets the array of accessible methods names known for a given class.
        Parameters:
        c - the class
        Returns:
        the class method names

      • getMethods

        public java.lang.reflect.Method[] getMethods​(java.lang.Class<?> c,
                                             java.lang.String methodName)
        Gets the array of accessible method known for a given class.
        Parameters:
        c - the class
        methodName - the method name
        Returns:
        the array of methods (null or not empty)

      • setLoader

        public void setLoader​(java.lang.ClassLoader classLoader)
        Sets the class loader used to solve constructors.

        Also cleans the constructors and methods caches.

        Parameters:
        classLoader - the class loader; if null, use this instance class loader