/*
* 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.openjpa.example.gallery.constraint;
import java.util.Arrays;
import java.util.List;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import org.apache.openjpa.example.gallery.ImageType;
/**
* Simple check that file format is of a supported type
*/
public class ImageContentValidator implements ConstraintValidator<ImageContent, byte[]> {
private List<ImageType> allowedTypes = null;
/**
* Configure the constraint validator based on the image
* types it should support.
* @param constraint the constraint definition
*/
public void initialize(ImageContent constraint) {
allowedTypes = Arrays.asList(constraint.value());
}
/**
* Validate a specified value.
*/
public boolean isValid(byte[] value, ConstraintValidatorContext context) {
if (value == null) {
return false;
}
// Verify the GIF header is either GIF87 or GIF89
if (allowedTypes.contains(ImageType.GIF)) {
String gifHeader = new String(value, 0, 6);
if (value.length >= 6 &&
(gifHeader.equalsIgnoreCase("GIF87a") ||
gifHeader.equalsIgnoreCase("GIF89a"))) {
return true;
}
}
// Verify the JPEG begins with SOI & ends with EOI
if (allowedTypes.contains(ImageType.JPEG)) {
if (value.length >= 4 &&
value[0] == 0xff && value[1] == 0xd8 &&
value[value.length - 2] == 0xff &&
value[value.length -1] == 0xd9) {
return true;
}
}
// Unknown file format
return false;
}
}