org.postgresql.util

Enum ClassLoaderStrategy

java.lang.Object

java.lang.Enum<ClassLoaderStrategy>

org.postgresql.util.ClassLoaderStrategy

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable<ClassLoaderStrategy>

public enum ClassLoaderStrategy
extends java.lang.Enum<ClassLoaderStrategy>

Order in which the driver searches classloaders when loading a class named by a connection property. The driver's own classloader can see only what is on its classpath, so in a non-flat class path (for example an application server or an OSGi container) a user-supplied class may be visible only through the thread context classloader.

The class is NOT public API, so it is subject to change.

Enum Constant Summary

Enum Constants

Enum Constant and Description
CONTEXT_FIRST Try the thread context classloader first, then fall back to the driver's classloader.
DRIVER Use the driver's classloader only.
DRIVER_FIRST Try the driver's classloader first, then fall back to the thread context classloader.

Field Summary

Fields

Modifier and Type	Field and Description
java.lang.String	value

Method Summary

Modifier and Type	Method and Description
java.util.List<java.lang.ClassLoader>	classLoaders(java.lang.ClassLoader driverClassLoader, java.lang.ClassLoader contextClassLoader) Returns the non-null classloaders to try, in priority order.
static ClassLoaderStrategy	of(java.util.Properties info) Resolves the strategy from the PGProperty.CLASS_LOADER_STRATEGY connection property.
static ClassLoaderStrategy	valueOf(java.lang.String name) Returns the enum constant of this type with the specified name.
static ClassLoaderStrategy[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

DRIVER

public static final ClassLoaderStrategy DRIVER

Use the driver's classloader only. This was the behaviour before the strategy became configurable and is the safest choice when the thread context classloader is undefined.

DRIVER_FIRST

public static final ClassLoaderStrategy DRIVER_FIRST

Try the driver's classloader first, then fall back to the thread context classloader. The fallback heals environments where the class is reachable only through the context classloader, while keeping the driver's classloader authoritative.

CONTEXT_FIRST

public static final ClassLoaderStrategy CONTEXT_FIRST

Try the thread context classloader first, then fall back to the driver's classloader. Use this in containers that manage class loading and expect their context classloader to win, even when the driver's classloader could resolve a class of the same name.

Field Detail

value

public final java.lang.String value

Method Detail

values

public static ClassLoaderStrategy[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (ClassLoaderStrategy c : ClassLoaderStrategy.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static ClassLoaderStrategy valueOf(java.lang.String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

java.lang.IllegalArgumentException - if this enum type has no constant with the specified name

java.lang.NullPointerException - if the argument is null

of

public static ClassLoaderStrategy of(java.util.Properties info)
                              throws PSQLException

Resolves the strategy from the PGProperty.CLASS_LOADER_STRATEGY connection property.

Parameters:

info - connection properties

Returns:

the configured strategy, or DRIVER_FIRST when the property is absent

Throws:

PSQLException - if the property holds an unknown value

classLoaders

public java.util.List<java.lang.ClassLoader> classLoaders(java.lang.ClassLoader driverClassLoader,
                                                          java.lang.ClassLoader contextClassLoader)

Returns the non-null classloaders to try, in priority order. A null input (for instance a null context classloader) is dropped, so the list contains only classloaders the caller can use.

Parameters:

driverClassLoader - the driver's own classloader

contextClassLoader - the thread context classloader

Returns:

an ordered list of non-null classloaders to try