org.apache.tools.ant.util.ReflectUtil Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.tools.ant.util;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import org.apache.tools.ant.BuildException;
import java.lang.reflect.Field;
/**
* Utility class to handle reflection on java objects.
* The class contains static methods to call reflection
* methods, catch any exceptions, converting them
* to BuildExceptions.
*/
// CheckStyle:FinalClassCheck OFF - backward compatible
public class ReflectUtil {
/** private constructor */
private ReflectUtil() {
}
/**
* Create an instance of a class using the constructor matching
* the given arguments.
* @since Ant 1.8.0
*/
public static Object newInstance(Class ofClass,
Class[] argTypes,
Object[] args) {
try {
Constructor con = ofClass.getConstructor(argTypes);
return con.newInstance(args);
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* Call a method on the object with no parameters.
* @param obj the object to invoke the method on.
* @param methodName the name of the method to call
* @return the object returned by the method
*/
public static Object invoke(Object obj, String methodName) {
try {
Method method;
method = obj.getClass().getMethod(
methodName, (Class[]) null);
return method.invoke(obj, (Object[]) null);
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* Call a method on the object with no parameters.
* Note: Unlike the invoke method above, this
* calls class or static methods, not instance methods.
* @param obj the object to invoke the method on.
* @param methodName the name of the method to call
* @return the object returned by the method
*/
public static Object invokeStatic(Object obj, String methodName) {
try {
Method method;
method = ((Class) obj).getMethod(
methodName, (Class[]) null);
return method.invoke(obj, (Object[]) null);
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* Call a method on the object with one argument.
* @param obj the object to invoke the method on.
* @param methodName the name of the method to call
* @param argType the type of argument.
* @param arg the value of the argument.
* @return the object returned by the method
*/
public static Object invoke(
Object obj, String methodName, Class argType, Object arg) {
try {
Method method;
method = obj.getClass().getMethod(
methodName, new Class[] {argType});
return method.invoke(obj, new Object[] {arg});
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* Call a method on the object with two argument.
* @param obj the object to invoke the method on.
* @param methodName the name of the method to call
* @param argType1 the type of the first argument.
* @param arg1 the value of the first argument.
* @param argType2 the type of the second argument.
* @param arg2 the value of the second argument.
* @return the object returned by the method
*/
public static Object invoke(
Object obj, String methodName, Class argType1, Object arg1,
Class argType2, Object arg2) {
try {
Method method;
method = obj.getClass().getMethod(
methodName, new Class[] {argType1, argType2});
return method.invoke(obj, new Object[] {arg1, arg2});
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* Get the value of a field in an object.
* @param obj the object to look at.
* @param fieldName the name of the field in the object.
* @return the value of the field.
* @throws BuildException if there is an error.
*/
public static Object getField(Object obj, String fieldName)
throws BuildException {
try {
Field field = obj.getClass().getDeclaredField(fieldName);
field.setAccessible(true);
return field.get(obj);
} catch (Exception t) {
throwBuildException(t);
return null; // NotReached
}
}
/**
* A method to convert an invocationTargetException to
* a buildexception and throw it.
* @param t the invocation target exception.
* @throws BuildException the converted exception.
*/
public static void throwBuildException(Exception t)
throws BuildException {
throw toBuildException(t);
}
/**
* A method to convert an invocationTargetException to
* a buildexception.
* @param t the invocation target exception.
* @return the converted exception.
* @since ant 1.7.1
*/
public static BuildException toBuildException(Exception t) {
if (t instanceof InvocationTargetException) {
Throwable t2 = ((InvocationTargetException) t)
.getTargetException();
if (t2 instanceof BuildException) {
return (BuildException) t2;
}
return new BuildException(t2);
} else {
return new BuildException(t);
}
}
/**
* A method to test if an object responds to a given
* message (method call)
* @param o the object
* @param methodName the method to check for
* @return true if the object has the method.
* @throws BuildException if there is a problem.
*/
public static boolean respondsTo(Object o, String methodName)
throws BuildException {
try {
Method[] methods = o.getClass().getMethods();
for (int i = 0; i < methods.length; i++) {
if (methods[i].getName().equals(methodName)) {
return true;
}
}
return false;
} catch (Exception t) {
throw toBuildException(t);
}
}
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