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/*
 * Copyright (c) 2015-present Alipay.com, https://www.alipay.com
 *
 * 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 cn.com.antcloud.api.acapi;

public class AntCloudUtils {

    /**
     * 获取文件的真实媒体类型。目前只支持JPG, GIF, PNG, BMP四种图片文件。
     *
     * @param bytes 文件字节流
     * @return 媒体类型(MEME - TYPE)
     */
    public static String getMimeType(byte[] bytes) {
        String suffix = getFileSuffix(bytes);
        String mimeType;

        if ("JPG".equals(suffix)) {
            mimeType = "image/jpeg";
        } else if ("GIF".equals(suffix)) {
            mimeType = "image/gif";
        } else if ("PNG".equals(suffix)) {
            mimeType = "image/png";
        } else if ("BMP".equals(suffix)) {
            mimeType = "image/bmp";
        } else {
            mimeType = "application/octet-stream";
        }

        return mimeType;
    }

    /**
     * 获取文件的真实后缀名。目前只支持JPG, GIF, PNG, BMP四种图片文件。
     *
     * @param bytes 文件字节流
     * @return JPG, GIF, PNG or null
     */
    public static String getFileSuffix(byte[] bytes) {
        if (bytes == null || bytes.length < 10) {
            return null;
        }

        if (bytes[0] == 'G' && bytes[1] == 'I' && bytes[2] == 'F') {
            return "GIF";
        } else if (bytes[1] == 'P' && bytes[2] == 'N' && bytes[3] == 'G') {
            return "PNG";
        } else if (bytes[6] == 'J' && bytes[7] == 'F' && bytes[8] == 'I' && bytes[9] == 'F') {
            return "JPG";
        } else if (bytes[0] == 'B' && bytes[1] == 'M') {
            return "BMP";
        } else {
            return null;
        }
    }

}