org.objenesis.tck.AbstractLoader Maven / Gradle / Ivy
/**
* Copyright 2006-2017 the original author or authors.
*
* Licensed 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.objenesis.tck;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.util.Properties;
/**
* Class loading a property file and delegating the treatment of each line to a concrete implementations.
*
* @author Henri Tremblay
*/
public abstract class AbstractLoader {
private final ClassLoader classloader;
private final ErrorHandler errorHandler;
/**
* Handler for reporting errors from the AbstractLoader.
*/
public interface ErrorHandler {
/**
* Called whenever, trying to retrieve a candidate class from its name, a
* ClassNotFoundException is thrown
*
* @param name Candidate class name
*/
void classNotFound(String name);
}
/**
* Error handler that logs errors to a text stream.
*/
public static class LoggingErrorHandler implements CandidateLoader.ErrorHandler {
private final PrintStream out;
/**
* @param out Stream in which to log
*/
public LoggingErrorHandler(PrintStream out) {
this.out = out;
}
public void classNotFound(String name) {
out.println("Class not found : " + name);
}
}
/**
* @param classloader ClassLoader from which candidates classes are loaded
* @param errorHandler Handler called in case of error
*/
public AbstractLoader(ClassLoader classloader, ErrorHandler errorHandler) {
this.classloader = classloader;
this.errorHandler = errorHandler;
}
/**
* @param inputStream Stream containing the properties
* @param type Type of the candidate loaded from the stream
* @throws IOException If something goes wrong while reading the stream
*/
public void loadFrom(InputStream inputStream, final Candidate.CandidateType type) throws IOException {
// Properties contains a convenient key=value parser, however it stores
// the entries in a Hashtable which loses the original order.
// So, we create a special Properties instance that writes its
// entries directly to the concrete implementations.
Properties properties = new Properties() {
private static final long serialVersionUID = 1L;
@Override
public Object put(Object key, Object value) {
handlePropertyEntry((String) key, (String) value, type);
return null;
}
};
properties.load(inputStream);
}
/**
* Load a candidate property file
*
* @param resource File name
* @param type Type of the candidate loaded from the stream
* @throws IOException If there's problem reading the file
*/
public void loadFromResource(String resource, Candidate.CandidateType type) throws IOException {
InputStream candidatesConfig = classloader.getResourceAsStream(resource);
if(candidatesConfig == null) {
throw new IOException("Resource '" + resource + "' not found");
}
try {
loadFrom(candidatesConfig, type);
}
finally {
candidatesConfig.close();
}
}
private void handlePropertyEntry(String key, String value, Candidate.CandidateType type) {
try {
Class candidate = Class.forName(key, true, classloader);
handlePropertyEntry(candidate, value, type);
}
catch(ClassNotFoundException e) {
errorHandler.classNotFound(key);
}
}
/**
* Will receive one class and its description pairs from the file
*
* @param clazz class on the line
* @param description description of the class
* @param type type of the candidate
*/
protected abstract void handlePropertyEntry(Class clazz, String description, Candidate.CandidateType type);
}