org.openbp.common
Class ReflectUtil

java.lang.Object
  org.openbp.common.ReflectUtil

public final class ReflectUtil
extends java.lang.Object

This class contains various static utility methods concerning reflections and class processing.

Author:

Heiko Erhardt

Field Summary

static int	CM_PRINT Print error message to standard error
static int	CM_THROW Re-throw any exceptions

Method Summary

static java.lang.Object	callMethod(java.lang.Object o, java.lang.reflect.Method method, java.lang.Object[] argValues, int errorHandlingMode) Calls a method using Java reflection.
static java.lang.Object	callMethod(java.lang.Object o, java.lang.String methodName, java.lang.Class[] argClasses, java.lang.Object[] argValues, int errorHandlingMode) Calls a method using Java reflection.
static java.lang.Class	determineClass(java.lang.String stringRepresentation) Determines the class object by type string.
static java.lang.reflect.Method	findByQualifiedMethodSignature(java.lang.String signature) Finds a method according to its signature.
static java.lang.reflect.Method	findByUnqualifiedMethodSignature(java.lang.Class objectClass, java.lang.String signature) Finds a method according to its signature.
static java.lang.Class	findClassInPackageList(java.lang.String className, java.util.List packageList) Searches for a particular class in a list of packages.
static java.lang.Class	findClassInPackageList(java.lang.String className, java.util.List packageList, java.lang.ClassLoader cl) Searches for a particular class in a list of packages.
static java.lang.reflect.Field	getFieldOrNull(java.lang.Class cls, java.lang.String name) Get a field using reflections.
static java.lang.reflect.Method	getMethodOrNull(java.lang.Class cls, java.lang.String name, java.lang.Class[] args) Get a method using reflections.
static java.lang.String	getPrintableClassName(java.lang.Class cls) Gets a printable form of a class name.
static java.lang.String	getQualifiedMethodSignature(java.lang.reflect.Method method) Creates a string that specifies the method signature containing a fullly qualified method name.
static java.lang.String	getUnqualifiedMethodSignature(java.lang.reflect.Method method) Creates a string that specifies the method signature containing an unqualified method name.
static java.lang.Object	instantiate(java.lang.Class cls, java.lang.ClassLoader cl, java.lang.Class type, java.lang.String displayName) Creates an object instance given its class using the default constructor.
static java.lang.Object	instantiate(java.lang.Class cls, java.lang.Class type, java.lang.String displayName) Creates an object instance given its class using the default constructor.
static java.lang.Object	instantiate(java.lang.String className, java.lang.ClassLoader cl, java.lang.Class type, java.lang.String displayName) Creates an object instance by its fully qualified class name using the default constructor.
static java.lang.Object	instantiate(java.lang.String className, java.lang.Class type, java.lang.String displayName) Creates a class by its fully qualified class name using the default constructor (convenience method).
static java.lang.Object	instantiateByConstructor(java.lang.Class cls, java.lang.Class[] argTypes, java.lang.Object[] args, java.lang.Class type, java.lang.String displayName, boolean allowDefaultConstructor) Creates an object instance given its class using the constructor with the given argument types.
static java.lang.Class	loadClass(java.lang.String className) Loads a class by its fully qualified class name.
static java.lang.Class	loadClass(java.lang.String className, java.lang.ClassLoader cl) Loads a class by its fully qualified class name.

Methods inherited from class java.lang.Object

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

Field Detail

CM_PRINT

public static final int CM_PRINT

Print error message to standard error

See Also:

Constant Field Values

CM_THROW

public static final int CM_THROW

Re-throw any exceptions

See Also:

Constant Field Values

Method Detail

findClassInPackageList

public static java.lang.Class findClassInPackageList(java.lang.String className,
                                                     java.util.List packageList)

Searches for a particular class in a list of packages.

Parameters:

className - Unqualified name of the class

packageList - List of package to search the class in (contains strings)

Returns:

The class or null if no such class could be found

findClassInPackageList

public static java.lang.Class findClassInPackageList(java.lang.String className,
                                                     java.util.List packageList,
                                                     java.lang.ClassLoader cl)

Searches for a particular class in a list of packages.

Parameters:

className - Unqualified name of the class

packageList - List of package to search the class in (contains strings)

cl - The class loader which shall load the class or null for the default loader

Returns:

The class or null if no such class could be found

loadClass

public static java.lang.Class loadClass(java.lang.String className)

Loads a class by its fully qualified class name.

Parameters:

className - Qualified class name

Returns:

The class or null if no such class exists

loadClass

public static java.lang.Class loadClass(java.lang.String className,
                                        java.lang.ClassLoader cl)

Loads a class by its fully qualified class name.

Parameters:

className - Qualified class name

cl - The class loader which shall load the class or null for the default loader

Returns:

The class or null if no such class exists

instantiate

public static java.lang.Object instantiate(java.lang.String className,
                                           java.lang.ClassLoader cl,
                                           java.lang.Class type,
                                           java.lang.String displayName)

Creates an object instance by its fully qualified class name using the default constructor.

Parameters:

className - Qualified class name

cl - The class loader which shall load the class or null for the default loader

type - If not null, the method will check if the instantiated class matches the given type

displayName - Display name of the type of object to instantiate for error messages

Returns:

The new object

Throws:

ReflectException - On any error. The exception message will describe the cause of the error. The exception will encapsulate the exception that led to the error.

instantiate

public static java.lang.Object instantiate(java.lang.Class cls,
                                           java.lang.Class type,
                                           java.lang.String displayName)

Creates an object instance given its class using the default constructor.

Parameters:

cls - Object class to use for the instantiation

type - If not null, the method will check if the instantiated class matches the given type

displayName - Display name of the type of object to instantiate for error messages

Returns:

The new object

Throws:

ReflectException - On any error. The exception message will describe the cause of the error. The exception will encapsulate the exception that led to the error.

instantiate

public static java.lang.Object instantiate(java.lang.Class cls,
                                           java.lang.ClassLoader cl,
                                           java.lang.Class type,
                                           java.lang.String displayName)

Creates an object instance given its class using the default constructor.

Parameters:

cls - Object class to use for the instantiation

cl - The class loader which shall load the class or null for the default loader

type - If not null, the method will check if the instantiated class matches the given type

displayName - Display name of the type of object to instantiate for error messages

Returns:

The new object

Throws:

ReflectException - On any error. The exception message will describe the cause of the error. The exception will encapsulate the exception that led to the error.

instantiate

public static java.lang.Object instantiate(java.lang.String className,
                                           java.lang.Class type,
                                           java.lang.String displayName)

Creates a class by its fully qualified class name using the default constructor (convenience method).

Parameters:

className - Qualified class name

type - If not null, the method will check if the instantiated class matches the given type

displayName - Display name of the type of object to instantiate for error messages

Returns:

The new object

Throws:

ReflectException - On any error. The exception message will describe the cause of the error. The exception will encapsulate the exception that led to the error.

instantiateByConstructor

public static java.lang.Object instantiateByConstructor(java.lang.Class cls,
                                                        java.lang.Class[] argTypes,
                                                        java.lang.Object[] args,
                                                        java.lang.Class type,
                                                        java.lang.String displayName,
                                                        boolean allowDefaultConstructor)

Creates an object instance given its class using the constructor with the given argument types.

Parameters:

cls - Object class to use for the instantiation

argTypes - Object classes of the constructor arguments

args - constructor arguments

type - If not null, the method will check if the instantiated class matches the given type

displayName - Display name of the type of object to instantiate for error messages

allowDefaultConstructor - If true, the default constructor will be used, if no constructor with the given argument types could be found. This might result in an error, if the Class has no accessible default constructor.

Returns:

The new object

Throws:

ReflectException - On any error. The exception message will describe the cause of the error. The exception will encapsulate the exception that led to the error.

callMethod

public static java.lang.Object callMethod(java.lang.Object o,
                                          java.lang.String methodName,
                                          java.lang.Class[] argClasses,
                                          java.lang.Object[] argValues,
                                          int errorHandlingMode)
                                   throws java.lang.Exception

Calls a method using Java reflection.

Parameters:

o - Object to invoke the method upon

methodName - Name of the method

argClasses - Argument classes or null

argValues - Argument values or null

errorHandlingMode - Mode that describes how errors are to be handled.
(any combination of CM_PRINT | CM_THROW)

Returns:

The return value of the method call

Throws:

java.lang.Exception - If an error occurred and errorHandlingMode was set to CM_THROW

callMethod

public static java.lang.Object callMethod(java.lang.Object o,
                                          java.lang.reflect.Method method,
                                          java.lang.Object[] argValues,
                                          int errorHandlingMode)
                                   throws java.lang.Exception

Calls a method using Java reflection.

Parameters:

o - Object to invoke the method upon

method - Method to invoke

argValues - Argument values or null

errorHandlingMode - Mode that describes how errors are to be handled.
(any combination of CM_PRINT | CM_THROW)

Returns:

The return value of the method call

Throws:

java.lang.Exception - If an error occurred and errorHandlingMode was set to CM_THROW

getQualifiedMethodSignature

public static java.lang.String getQualifiedMethodSignature(java.lang.reflect.Method method)

Creates a string that specifies the method signature containing a fullly qualified method name.

Parameters:

method - Method

Returns:

String in the form class.method(argclass1,argclass2,...), e. g.
"org.openbp.common.ReflectUtil.callMethod(java.lang.Object,java.lang.reflect.Method,java.lang.Object[],int)"

getUnqualifiedMethodSignature

public static java.lang.String getUnqualifiedMethodSignature(java.lang.reflect.Method method)

Creates a string that specifies the method signature containing an unqualified method name.

Parameters:

method - Method

Returns:

String in the form class.method(argclass1,argclass2,...), e. g.
"org.openbp.common.ReflectUtil.callMethod(java.lang.Object,java.lang.reflect.Method,java.lang.Object[],int)"

findByQualifiedMethodSignature

public static java.lang.reflect.Method findByQualifiedMethodSignature(java.lang.String signature)
                                                               throws java.lang.NoSuchMethodException,
                                                                      java.lang.ClassNotFoundException

Finds a method according to its signature.

Parameters:

signature - Signature as generated by getQualifiedMethodSignature(java.lang.reflect.Method)

Returns:

The method

Throws:

java.lang.NoSuchMethodException - If no matching method was found

java.lang.ClassNotFoundException - If an argument class could not be loaded by the thread or standard class loader

findByUnqualifiedMethodSignature

public static java.lang.reflect.Method findByUnqualifiedMethodSignature(java.lang.Class objectClass,
                                                                        java.lang.String signature)
                                                                 throws java.lang.NoSuchMethodException,
                                                                        java.lang.ClassNotFoundException

Finds a method according to its signature.

Parameters:

objectClass - Class to search for the method

signature - Signature as generated by getQualifiedMethodSignature(java.lang.reflect.Method)

Returns:

The method

Throws:

java.lang.NoSuchMethodException - If no matching method was found

java.lang.ClassNotFoundException - If an argument class could not be loaded by the thread or standard class loader

getPrintableClassName

public static java.lang.String getPrintableClassName(java.lang.Class cls)

Gets a printable form of a class name. By default, array class names are printed like "Lclass;". This looks awful. Therefore, we format them a little prettier, like "class[]".

Parameters:

cls - The class to get the name for

Returns:

Formatted class name

determineClass

public static java.lang.Class determineClass(java.lang.String stringRepresentation)

Determines the class object by type string.

Parameters:

stringRepresentation - Example: java.lang.String or java.lang.String[] or int

Returns:

The class

getMethodOrNull

public static java.lang.reflect.Method getMethodOrNull(java.lang.Class cls,
                                                       java.lang.String name,
                                                       java.lang.Class[] args)

Get a method using reflections. Does not throw an exception if it's not there.

Parameters:

cls - Class

name - Name of the method to locate

args - Arguments of the method signature looking for

Returns:

The method or null if the specified method does not exist

getFieldOrNull

public static java.lang.reflect.Field getFieldOrNull(java.lang.Class cls,
                                                     java.lang.String name)

Get a field using reflections. Does not throw an exception if it's not there.

Parameters:

cls - Class

name - Name of the field to locate

Returns:

The field or null if the specified field does not exist