Provides a set of static methods that extend the Java metaobject
/*
Java Reflection in Action
Ira R. Forman and Nate Forman
ISBN 1932394184
Publisher: Manning Publications Co.
*/
/* Copyright 2002 -- Ira R. Forman and Nate Forman */
/**
* This class provides a set of static methods that extend the Java metaobject
* protocol.
*
* @author: Ira R. Forman
*/
import java.lang.reflect.*;
import java.util.*;
abstract public class Mopex {
/**
* Returns a syntactically correct name for a class object. If the class
* object represents an array, the proper number of square bracket pairs are
* appended to the component type.
*
* @return java.lang.String
* @param cls
* java.lang.Class
*/
//start extract classNameToString
public static String getTypeName(Class cls) {
if (!cls.isArray()) {
return cls.getName();
} else {
return getTypeName(cls.getComponentType()) + "[]";
}
}
//stop extract classNameToString
/**
* Returns an array of the superclasses of cls.
*
* @return java.lang.Class[]
* @param cls
* java.lang.Class
*/
//start extract getSuperclasses
public static Class[] getSuperclasses(Class cls) {
int i = 0;
for (Class x = cls.getSuperclass(); x != null; x = x.getSuperclass())
i++;
Class[] result = new Class[i];
i = 0;
for (Class x = cls.getSuperclass(); x != null; x = x.getSuperclass())
result[i++] = x;
return result;
}
//stop extract getSuperclasses
/**
* Returns an array of the instance variablies of the the specified class.
* An instance variable is defined to be a non-static field that is declared
* by the class or inherited.
*
* @return java.lang.Field[]
* @param cls
* java.lang.Class
*/
//start extract getInstanceVariables
public static Field[] getInstanceVariables(Class cls) {
List accum = new LinkedList();
while (cls != null) {
Field[] fields = cls.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
if (!Modifier.isStatic(fields[i].getModifiers())) {
accum.add(fields[i]);
}
}
cls = cls.getSuperclass();
}
Field[] retvalue = new Field[accum.size()];
return (Field[]) accum.toArray(retvalue);
}
//stop extract getInstanceVariables
/**
* Returns an array of fields that are the declared instance variables of
* cls. An instance variable is a field that is not static.
*
* @return java.lang.reflect.Field[]
* @param cls
* java.lang.Class
*/
//start extract getDeclaredIVS
public static Field[] getDeclaredIVs(Class cls) {
Field[] fields = cls.getDeclaredFields();
// Count the IVs
int numberOfIVs = 0;
for (int i = 0; i < fields.length; i++) {
if (!Modifier.isStatic(fields[i].getModifiers()))
numberOfIVs++;
}
Field[] declaredIVs = new Field[numberOfIVs];
// Populate declaredIVs
int j = 0;
for (int i = 0; i < fields.length; i++) {
if (!Modifier.isStatic(fields[i].getModifiers()))
declaredIVs[j++] = fields[i];
}
return declaredIVs;
}
//stop extract getDeclaredIVS
/**
* Return an array of the supported instance variables of this class. A
* supported instance variable is not static and is either declared or
* inherited from a superclass.
*
* @return java.lang.reflect.Field[]
* @param cls
* java.lang.Class
*/
//start extract getSupportedIVS
public static Field[] getSupportedIVs(Class cls) {
if (cls == null) {
return new Field[0];
} else {
Field[] inheritedIVs = getSupportedIVs(cls.getSuperclass());
Field[] declaredIVs = getDeclaredIVs(cls);
Field[] supportedIVs = new Field[declaredIVs.length
+ inheritedIVs.length];
for (int i = 0; i < declaredIVs.length; i++) {
supportedIVs[i] = declaredIVs[i];
}
for (int i = 0; i < inheritedIVs.length; i++) {
supportedIVs[i + declaredIVs.length] = inheritedIVs[i];
}
return supportedIVs;
}
}
//stop extract getSupportedIVS
/**
* Returns an array of the methods that are not static.
*
* @return java.lang.reflect.Method[]
* @param cls
* java.lang.Class
*/
//start extract getInstanceMethods
public static Method[] getInstanceMethods(Class cls) {
List instanceMethods = new ArrayList();
for (Class c = cls; c != null; c = c.getSuperclass()) {
Method[] methods = c.getDeclaredMethods();
for (int i = 0; i < methods.length; i++)
if (!Modifier.isStatic(methods[i].getModifiers()))
instanceMethods.add(methods[i]);
}
Method[] ims = new Method[instanceMethods.size()];
for (int j = 0; j < instanceMethods.size(); j++)
ims[j] = (Method) instanceMethods.get(j);
return ims;
}
//stop extract getInstanceMethods
/**
* Returns an array of methods to which instances of this class respond.
*
* @return java.lang.reflect.Method[]
* @param cls
* java.lang.Class
*/
//start extract getSupportedMethods
public static Method[] getSupportedMethods(Class cls) {
return getSupportedMethods(cls, null);
}
//stop extract getSupportedMethods
/**
* This method retrieves the modifiers of a Method without the unwanted
* modifiers specified in the second parameter. Because this method uses
* bitwise operations, multiple unwanted modifiers may be specified by
* bitwise or.
*
* @return int
* @param m
* java.lang.Method
* @param unwantedModifiers
* int
*/
//start extract getModifiersWithout
public static int getModifiersWithout(Method m, int unwantedModifiers) {
int mods = m.getModifiers();
return (mods ^ unwantedModifiers) & mods;
}
//stop extract getModifiersWithout
/**
* Returns a Method that has the signature specified by the calling
* parameters.
*
* @return Method
* @param cls
* java.lang.Class
* @param name
* String
* @param paramTypes
* java.lang.Class[]
*/
//start extract getSupportedMethod
public static Method getSupportedMethod(Class cls, String name,
Class[] paramTypes) throws NoSuchMethodException {
if (cls == null) {
throw new NoSuchMethodException();
}
try {
return cls.getDeclaredMethod(name, paramTypes);
} catch (NoSuchMethodException ex) {
return getSupportedMethod(cls.getSuperclass(), name, paramTypes);
}
}
//stop extract getSupportedMethod
/**
* Returns a Method array of the methods to which instances of the specified
* respond except for those methods defined in the class specifed by limit
* or any of its superclasses. Note that limit is usually used to eliminate
* them methods defined by java.lang.Object.
*
* @return Method[]
* @param cls
* java.lang.Class
* @param limit
* java.lang.Class
*/
//start extract getSupportedMethods
public static Method[] getSupportedMethods(Class cls, Class limit) {
Vector supportedMethods = new Vector();
for (Class c = cls; c != limit; c = c.getSuperclass()) {
Method[] methods = c.getDeclaredMethods();
for (int i = 0; i < methods.length; i++) {
boolean found = false;
for (int j = 0; j < supportedMethods.size(); j++)
if (equalSignatures(methods[i], (Method) supportedMethods
.elementAt(j))) {
found = true;
break;
}
if (!found)
supportedMethods.add(methods[i]);
}
}
Method[] mArray = new Method[supportedMethods.size()];
for (int k = 0; k < mArray.length; k++)
mArray[k] = (Method) supportedMethods.elementAt(k);
return mArray;
}
//stop extract getSupportedMethods
/**
* This field is initialized with a method object for the equalSignatures
* method. This is an optimization in that selectMethods can use this field
* instead of calling getMethod each time it is called.
*/
//start extract equalSignaturesMethod
static private Method equalSignaturesMethod;
static {
Class[] fpl = { Method.class, Method.class };
try {
equalSignaturesMethod = Mopex.class.getMethod("equalSignatures",
fpl);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
}
}
//stop extract equalSignaturesMethod
/**
* Determines if the signatures of two method objects are equal. In Java, a
* signature comprises the method name and the array of of formal parameter
* types. For two signatures to be equal, the method names must be the same
* and the formal parameters must be of the same type (in the same order).
*
* @return boolean
* @param m1
* java.lang.Method
* @param m2
* java.lang.Method
*/
//start extract equalSignatures
public static boolean equalSignatures(Method m1, Method m2) {
if (!m1.getName().equals(m2.getName()))
return false;
if (!Arrays.equals(m1.getParameterTypes(), m2.getParameterTypes()))
return false;
return true;
}
//stop extract equalSignatures
/**
* Return a string that represents the signature of the specified method.
*
* @return String
* @param m
* java.lang.Method
*/
//start extract signatureToString
public static String signatureToString(Method m) {
return m.getName() + "("
+ formalParametersToString(m.getParameterTypes()) + ")";
}
//stop extract signatureToString
/**
* Returns a string that can be used as a formal parameter list for a method
* that has the parameter types of the specified array.
*
* @return String
* @param pts
* java.lang.Class[]
*/
//start extract formalParametersToString
public static String formalParametersToString(Class[] pts) {
String result = "";
for (int i = 0; i < pts.length; i++) {
result += getTypeName(pts[i]) + " p" + i;
if (i < pts.length - 1)
result += ",";
}
return result;
}
//stop extract formalParametersToString
/**
* Returns a string that is an actual parameter list that matches the formal
* parameter list produced by formalParametersToString.
*
* @return String
* @param pts
* java.lang.Class[]
*/
//start extract actualParametersToString
public static String actualParametersToString(Class[] pts) {
String result = "";
for (int i = 0; i < pts.length; i++) {
result += "p" + i;
if (i < pts.length - 1)
result += ",";
}
return result;
}
//stop extract actualParametersToString
/**
* Returns a String that represents the header for a constructor.
*
* @return String
* @param c
* java.lang.Constructor
*/
//start extract constructorHeaderToString
public static String headerToString(Constructor c) {
String mods = Modifier.toString(c.getModifiers());
if (mods.length() == 0)
return headerSuffixToString(c);
else
return mods + " " + headerSuffixToString(c);
}
//stop extract constructorHeaderToString
/**
* Returns a String that represents the header suffix for a constructor. The
* term "header suffix" is not a standard Java term. We use it to mean the
* Java header without the modifiers.
*
* @return String
* @param c
* java.lang.Constructor
*/
//start extract constructorHeaderToString
public static String headerSuffixToString(Constructor c) {
String header = signatureToString(c);
Class[] eTypes = c.getExceptionTypes();
if (eTypes.length != 0)
header += " throws " + classArrayToString(eTypes);
return header;
}
//stop extract constructorHeaderToString
/**
* Returns a String that represents the signature for a constructor.
*
* @return String
* @param c
* java.lang.Constructor
*/
//start extract constructorHeaderToString
public static String signatureToString(Constructor c) {
return c.getName() + "("
+ formalParametersToString(c.getParameterTypes()) + ")";
}
//stop extract constructorHeaderToString
/**
* Returns a String that represents the header of a method.
*
* @return String
* @param m
* java.lang.Method
*/
//start extract headerToString
public static String headerToString(Method m) {
String mods = Modifier.toString(m.getModifiers());
if (mods.length() == 0)
return headerSuffixToString(m);
else
return mods + " " + headerSuffixToString(m);
}
//stop extract headerToString
/**
* Returns a String that represents the suffix of the header of a method.
* The suffix of a header is not a standard Java term. We use the term to
* mean the Java header without the method modifiers.
*
* @return String
* @param m
* java.lang.Method
*/
//start extract headerToString
public static String headerSuffixToString(Method m) {
String header = getTypeName(m.getReturnType()) + " "
+ signatureToString(m);
Class[] eTypes = m.getExceptionTypes();
if (eTypes.length != 0) {
header += " throws " + classArrayToString(eTypes);
}
return header;
}
//stop extract headerToString
/**
* Returns a String that is a comma separated list of the typenames of the
* classes in the array pts.
*
* @return String
* @param pts
* java.lang.Class[]
*/
//start extract classArrayToString
public static String classArrayToString(Class[] pts) {
String result = "";
for (int i = 0; i < pts.length; i++) {
result += getTypeName(pts[i]);
if (i < pts.length - 1)
result += ",";
}
return result;
}
//stop extract classArrayToString
/**
* Turns true if and only if the header suffixes of the two specified
* methods are equal. The header suffix is defined to be the signature, the
* return type, and the exception types.
*
* @return boolean
* @param m1
* java.lang.Method
* @param m2
* java.lang.Method
*/
public static boolean equalsHeaderSuffixes(Method m1, Method m2) {
if (m1.getReturnType() != m2.getReturnType())
return false;
if (!Arrays.equals(m1.getExceptionTypes(), m2.getExceptionTypes()))
return false;
return equalSignatures(m1, m2);
}
/**
* Creates constructor with the signature of c and a new name. It adds some
* code after generating a super statement to call c. This method is used
* when generating a subclass of class that declared c.
*
* @return String
* @param c
* java.lang.Constructor
* @param name
* String
* @param code
* String
*/
//start extract createRenamedConstructor
public static String createRenamedConstructor(Constructor c, String name,
String code) {
Class[] pta = c.getParameterTypes();
String fpl = formalParametersToString(pta);
String apl = actualParametersToString(pta);
Class[] eTypes = c.getExceptionTypes();
String result = name + "(" + fpl + ")\n";
if (eTypes.length != 0)
result += " throws " + classArrayToString(eTypes) + "\n";
result += "{\n super(" + apl + ");\n" + code + "}\n";
return result;
}
//stop extract createRenamedConstructor
/**
* Returns a String that is formatted as a Java method declaration having
* the same header as the specified method but with the code parameter
* substituted for the method body.
*
* @return String
* @param m
* java.lang.Method
* @param code
* String
*/
//start extract createReplacementMethod
public static String createReplacementMethod(Method m, String code) {
Class[] pta = m.getParameterTypes();
String fpl = formalParametersToString(pta);
Class[] eTypes = m.getExceptionTypes();
String result = m.getName() + "(" + fpl + ")\n";
if (eTypes.length != 0)
result += " throws " + classArrayToString(eTypes) + "\n";
result += "{\n" + code + "}\n";
return result;
}
//stop extract createReplacementMethod
/**
* Returns a string for a cooperative override of the method m. That is, The
* string has the same return type and signature as m but the body has a
* super call that is sandwiched between the strings code1 and code2.
*
* @return String
* @param m
* java.lang.Method
* @param code1
* String
* @param code2
* String
*/
//start extract createCooperativeWrapper
public static String createCooperativeWrapper(Method m, String code1,
String code2) {
Class[] pta = m.getParameterTypes();
Class retType = m.getReturnType();
String fpl = formalParametersToString(pta);
String apl = actualParametersToString(pta);
Class[] eTypes = m.getExceptionTypes();
String result = retType.getName() + " " + m.getName() + "(" + fpl
+ ")\n";
if (eTypes.length != 0)
result += " throws " + classArrayToString(eTypes) + "\n";
result += "{\n" + code1 + " ";
if (retType != void.class)
result += retType.getName() + " cooperativeReturnValue = ";
result += "super." + m.getName() + "(" + apl + ");\n";
result += code2;
if (retType != void.class)
result += " return cooperativeReturnValue;\n";
result += "}\n";
return result;
}
/**
* Returns the method object for the unique method named mName. If no such
* method exists, a null is returned. If there is more than one such method,
* a runtime exception is thrown.
*
* @return Method
* @param cls
* java.lang.Class
* @param mName
* String
*/
public static Method getUniquelyNamedMethod(Class cls, String mName) {
Method result = null;
Method[] mArray = cls.getDeclaredMethods();
for (int i = 0; i < mArray.length; i++)
if (mName.equals(mArray[i].getName())) {
if (result == null)
result = mArray[i];
else
throw new RuntimeException("name is not unique");
}
return result;
}
/**
* Finds the first (from the bottom of the inheritance hierarchy) field with
* the specified name. Note that Class.getField returns only public fields.
*
* @return Field
* @param cls
* java.lang.Class
* @param name
* String
*/
//start extract findField
public static Field findField(Class cls, String name)
throws NoSuchFieldException {
if (cls != null) {
try {
return cls.getDeclaredField(name);
} catch (NoSuchFieldException e) {
return findField(cls.getSuperclass(), name);
}
} else {
throw new NoSuchFieldException();
}
}
}
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