/*
* Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package java.beans;
import java.lang.reflect.
AccessibleObject;
import java.lang.reflect.
Array;
import java.lang.reflect.
Constructor;
import java.lang.reflect.
InvocationTargetException;
import java.lang.reflect.
Method;
import java.security.
AccessControlContext;
import java.security.
AccessController;
import java.security.
PrivilegedActionException;
import java.security.
PrivilegedExceptionAction;
import com.sun.beans.finder.
ClassFinder;
import com.sun.beans.finder.
ConstructorFinder;
import com.sun.beans.finder.
MethodFinder;
import sun.reflect.misc.
MethodUtil;
/**
* A <code>Statement</code> object represents a primitive statement
* in which a single method is applied to a target and
* a set of arguments - as in <code>"a.setFoo(b)"</code>.
* Note that where this example uses names
* to denote the target and its argument, a statement
* object does not require a name space and is constructed with
* the values themselves.
* The statement object associates the named method
* with its environment as a simple set of values:
* the target and an array of argument values.
*
* @since 1.4
*
* @author Philip Milne
*/
public class
Statement {
private static
Object[]
emptyArray = new
Object[]{};
static
ExceptionListener defaultExceptionListener = new
ExceptionListener() {
public void
exceptionThrown(
Exception e) {
System.
err.
println(
e);
// e.printStackTrace();
System.
err.
println("Continuing ...");
}
};
private final
AccessControlContext acc =
AccessController.
getContext();
private final
Object target;
private final
String methodName;
private final
Object[]
arguments;
ClassLoader loader;
/**
* Creates a new {@link Statement} object
* for the specified target object to invoke the method
* specified by the name and by the array of arguments.
* <p>
* The {@code target} and the {@code methodName} values should not be {@code null}.
* Otherwise an attempt to execute this {@code Expression}
* will result in a {@code NullPointerException}.
* If the {@code arguments} value is {@code null},
* an empty array is used as the value of the {@code arguments} property.
*
* @param target the target object of this statement
* @param methodName the name of the method to invoke on the specified target
* @param arguments the array of arguments to invoke the specified method
*/
@
ConstructorProperties({"target", "methodName", "arguments"})
public
Statement(
Object target,
String methodName,
Object[]
arguments) {
this.
target =
target;
this.
methodName =
methodName;
this.
arguments = (
arguments == null) ?
emptyArray :
arguments.
clone();
}
/**
* Returns the target object of this statement.
* If this method returns {@code null},
* the {@link #execute} method
* throws a {@code NullPointerException}.
*
* @return the target object of this statement
*/
public
Object getTarget() {
return
target;
}
/**
* Returns the name of the method to invoke.
* If this method returns {@code null},
* the {@link #execute} method
* throws a {@code NullPointerException}.
*
* @return the name of the method
*/
public
String getMethodName() {
return
methodName;
}
/**
* Returns the arguments for the method to invoke.
* The number of arguments and their types
* must match the method being called.
* {@code null} can be used as a synonym of an empty array.
*
* @return the array of arguments
*/
public
Object[]
getArguments() {
return this.
arguments.
clone();
}
/**
* The {@code execute} method finds a method whose name is the same
* as the {@code methodName} property, and invokes the method on
* the target.
*
* When the target's class defines many methods with the given name
* the implementation should choose the most specific method using
* the algorithm specified in the Java Language Specification
* (15.11). The dynamic class of the target and arguments are used
* in place of the compile-time type information and, like the
* {@link java.lang.reflect.Method} class itself, conversion between
* primitive values and their associated wrapper classes is handled
* internally.
* <p>
* The following method types are handled as special cases:
* <ul>
* <li>
* Static methods may be called by using a class object as the target.
* <li>
* The reserved method name "new" may be used to call a class's constructor
* as if all classes defined static "new" methods. Constructor invocations
* are typically considered {@code Expression}s rather than {@code Statement}s
* as they return a value.
* <li>
* The method names "get" and "set" defined in the {@link java.util.List}
* interface may also be applied to array instances, mapping to
* the static methods of the same name in the {@code Array} class.
* </ul>
*
* @throws NullPointerException if the value of the {@code target} or
* {@code methodName} property is {@code null}
* @throws NoSuchMethodException if a matching method is not found
* @throws SecurityException if a security manager exists and
* it denies the method invocation
* @throws Exception that is thrown by the invoked method
*
* @see java.lang.reflect.Method
*/
public void
execute() throws
Exception {
invoke();
}
Object invoke() throws
Exception {
AccessControlContext acc = this.
acc;
if ((
acc == null) && (
System.
getSecurityManager() != null)) {
throw new
SecurityException("AccessControlContext is not set");
}
try {
return
AccessController.
doPrivileged(
new
PrivilegedExceptionAction<
Object>() {
public
Object run() throws
Exception {
return
invokeInternal();
}
},
acc
);
}
catch (
PrivilegedActionException exception) {
throw
exception.
getException();
}
}
private
Object invokeInternal() throws
Exception {
Object target =
getTarget();
String methodName =
getMethodName();
if (
target == null ||
methodName == null) {
throw new
NullPointerException((
target == null ? "target" :
"methodName") + " should not be null");
}
Object[]
arguments =
getArguments();
if (
arguments == null) {
arguments =
emptyArray;
}
// Class.forName() won't load classes outside
// of core from a class inside core. Special
// case this method.
if (
target ==
Class.class &&
methodName.
equals("forName")) {
return
ClassFinder.
resolveClass((
String)
arguments[0], this.
loader);
}
Class<?>[]
argClasses = new
Class<?>[
arguments.length];
for(int
i = 0;
i <
arguments.length;
i++) {
argClasses[
i] = (
arguments[
i] == null) ? null :
arguments[
i].
getClass();
}
AccessibleObject m = null;
if (
target instanceof
Class) {
/*
For class methods, simluate the effect of a meta class
by taking the union of the static methods of the
actual class, with the instance methods of "Class.class"
and the overloaded "newInstance" methods defined by the
constructors.
This way "System.class", for example, will perform both
the static method getProperties() and the instance method
getSuperclass() defined in "Class.class".
*/
if (
methodName.
equals("new")) {
methodName = "newInstance";
}
// Provide a short form for array instantiation by faking an nary-constructor.
if (
methodName.
equals("newInstance") && ((
Class)
target).
isArray()) {
Object result =
Array.
newInstance(((
Class)
target).
getComponentType(),
arguments.length);
for(int
i = 0;
i <
arguments.length;
i++) {
Array.
set(
result,
i,
arguments[
i]);
}
return
result;
}
if (
methodName.
equals("newInstance") &&
arguments.length != 0) {
// The Character class, as of 1.4, does not have a constructor
// which takes a String. All of the other "wrapper" classes
// for Java's primitive types have a String constructor so we
// fake such a constructor here so that this special case can be
// ignored elsewhere.
if (
target ==
Character.class &&
arguments.length == 1 &&
argClasses[0] ==
String.class) {
return new
Character(((
String)
arguments[0]).
charAt(0));
}
try {
m =
ConstructorFinder.
findConstructor((
Class)
target,
argClasses);
}
catch (
NoSuchMethodException exception) {
m = null;
}
}
if (
m == null &&
target !=
Class.class) {
m =
getMethod((
Class)
target,
methodName,
argClasses);
}
if (
m == null) {
m =
getMethod(
Class.class,
methodName,
argClasses);
}
}
else {
/*
This special casing of arrays is not necessary, but makes files
involving arrays much shorter and simplifies the archiving infrastrcure.
The Array.set() method introduces an unusual idea - that of a static method
changing the state of an instance. Normally statements with side
effects on objects are instance methods of the objects themselves
and we reinstate this rule (perhaps temporarily) by special-casing arrays.
*/
if (
target.
getClass().
isArray() &&
(
methodName.
equals("set") ||
methodName.
equals("get"))) {
int
index = ((
Integer)
arguments[0]).
intValue();
if (
methodName.
equals("get")) {
return
Array.
get(
target,
index);
}
else {
Array.
set(
target,
index,
arguments[1]);
return null;
}
}
m =
getMethod(
target.
getClass(),
methodName,
argClasses);
}
if (
m != null) {
try {
if (
m instanceof
Method) {
return
MethodUtil.
invoke((
Method)
m,
target,
arguments);
}
else {
return ((
Constructor)
m).
newInstance(
arguments);
}
}
catch (
IllegalAccessException iae) {
throw new
Exception("Statement cannot invoke: " +
methodName + " on " +
target.
getClass(),
iae);
}
catch (
InvocationTargetException ite) {
Throwable te =
ite.
getTargetException();
if (
te instanceof
Exception) {
throw (
Exception)
te;
}
else {
throw
ite;
}
}
}
throw new
NoSuchMethodException(
toString());
}
String instanceName(
Object instance) {
if (
instance == null) {
return "null";
} else if (
instance.
getClass() ==
String.class) {
return "\""+(
String)
instance + "\"";
} else {
// Note: there is a minor problem with using the non-caching
// NameGenerator method. The return value will not have
// specific information about the inner class name. For example,
// In 1.4.2 an inner class would be represented as JList$1 now
// would be named Class.
return
NameGenerator.
unqualifiedClassName(
instance.
getClass());
}
}
/**
* Prints the value of this statement using a Java-style syntax.
*/
public
String toString() {
// Respect a subclass's implementation here.
Object target =
getTarget();
String methodName =
getMethodName();
Object[]
arguments =
getArguments();
if (
arguments == null) {
arguments =
emptyArray;
}
StringBuffer result = new
StringBuffer(
instanceName(
target) + "." +
methodName + "(");
int
n =
arguments.length;
for(int
i = 0;
i <
n;
i++) {
result.
append(
instanceName(
arguments[
i]));
if (
i !=
n -1) {
result.
append(", ");
}
}
result.
append(");");
return
result.
toString();
}
static
Method getMethod(
Class<?>
type,
String name,
Class<?>...
args) {
try {
return
MethodFinder.
findMethod(
type,
name,
args);
}
catch (
NoSuchMethodException exception) {
return null;
}
}
}