com.google.gwt.dev.util.FileBackedObject Maven / Gradle / Ivy
/*
* Copyright 2008 Google Inc.
*
* 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 com.google.gwt.dev.util;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.UnableToCompleteException;
import java.io.File;
import java.io.IOException;
import java.io.Serializable;
/**
* Represents a File that contains the serialized form of a Serializable object.
*
* @param the type of object serialized into the file
*/
public class FileBackedObject implements Serializable {
private final File backingFile;
private final Class clazz;
/**
* Constructs an empty FileBackedObject. A temporary File will be used and
* this file will be deleted when the JVM exits.
*
* @param clazz the type of object to be serialized
* @throws IOException if the temporary file could not be created
*/
public FileBackedObject(Class clazz) throws IOException {
this(clazz, File.createTempFile("fileBackedObject", ".ser"));
backingFile.deleteOnExit();
}
/**
* Constructs a FileBackedObject using an existing File object.
*
* @param clazz the type of object to be serialized
* @param backingFile the file to read from or write to
*/
public FileBackedObject(Class clazz, File backingFile) {
this.clazz = clazz;
this.backingFile = backingFile;
}
/**
* Returns the underlying File object.
*/
public File getFile() {
return backingFile;
}
/**
* Construct a new instance of the object stored in the backing file.
*
* @param logger a sink for error messages
* @return a new instance of the object stored in the backing file
* @throws UnableToCompleteException if the backing store does not contain an
* object of type T
*/
public T newInstance(TreeLogger logger) throws UnableToCompleteException {
try {
return Util.readFileAsObject(backingFile, clazz);
} catch (ClassNotFoundException e) {
logger.log(TreeLogger.ERROR, "Missing class definition", e);
throw new UnableToCompleteException();
} catch (IOException e) {
logger.log(TreeLogger.ERROR, "Unable to instantiate object", e);
throw new UnableToCompleteException();
}
}
/**
* Set the contents of the backing file.
*
* @param logger a sink for error messages
* @param object the object to store
* @throws UnableToCompleteException if the object could not be serialized
*/
public void set(TreeLogger logger, T object) throws IllegalStateException,
UnableToCompleteException {
assert clazz.isInstance(object);
Util.writeObjectAsFile(logger, backingFile, object);
}
@Override
public String toString() {
return backingFile.toString() + "<" + clazz.getName() + ">";
}
}