Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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.
 */

import android.text.TextUtils;
import android.webkit.MimeTypeMap;

public class Main {
    /**
     * Helper to convert unknown or unmapped attachments to something useful based on filename
     * extensions. The mime type is inferred based upon the table below. It's not perfect, but
     * it helps.
     *
     * <pre>
     *                   |---------------------------------------------------------|
     *                   |                  E X T E N S I O N                      |
     *                   |---------------------------------------------------------|
     *                   | .eml        | known(.png) | unknown(.abc) | none        |
     * | M |-----------------------------------------------------------------------|
     * | I | none        | msg/rfc822  | image/png   | app/abc       | app/oct-str |
     * | M |-------------| (always     |             |               |             |
     * | E | app/oct-str |  overrides  |             |               |             |
     * | T |-------------|             |             |-----------------------------|
     * | Y | text/plain  |             |             | text/plain                  |
     * | P |-------------|             |-------------------------------------------|
     * | E | any/type    |             | any/type                                  |
     * |---|-----------------------------------------------------------------------|
     * </pre>
     *
     * NOTE: Since mime types on Android are case-*sensitive*, return values are always in
     * lower case.
     *
     * @param fileName The given filename
     * @param mimeType The given mime type
     * @return A likely mime type for the attachment
     */
    public static String inferMimeType(final String fileName, final String mimeType) {
        String resultType = null;
        String fileExtension = getFilenameExtension(fileName);
        boolean isTextPlain = "text/plain".equalsIgnoreCase(mimeType);

        if ("eml".equals(fileExtension)) {
            resultType = "message/rfc822";
        } else {
            boolean isGenericType = isTextPlain || "application/octet-stream".equalsIgnoreCase(mimeType);
            // If the given mime type is non-empty and non-generic, return it
            if (isGenericType || TextUtils.isEmpty(mimeType)) {
                if (!TextUtils.isEmpty(fileExtension)) {
                    // Otherwise, try to find a mime type based upon the file extension
                    resultType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(fileExtension);
                    if (TextUtils.isEmpty(resultType)) {
                        // Finally, if original mimetype is text/plain, use it; otherwise synthesize
                        resultType = isTextPlain ? mimeType : "application/" + fileExtension;
                    }
                }
            } else {
                resultType = mimeType;
            }
        }

        // No good guess could be made; use an appropriate generic type
        if (TextUtils.isEmpty(resultType)) {
            resultType = isTextPlain ? "text/plain" : "application/octet-stream";
        }
        return resultType.toLowerCase();
    }

    /**
     * Extract and return filename's extension, converted to lower case, and not including the "."
     *
     * @return extension, or null if not found (or null/empty filename)
     */
    public static String getFilenameExtension(String fileName) {
        String extension = null;
        if (!TextUtils.isEmpty(fileName)) {
            int lastDot = fileName.lastIndexOf('.');
            if ((lastDot > 0) && (lastDot < fileName.length() - 1)) {
                extension = fileName.substring(lastDot + 1).toLowerCase();
            }
        }
        return extension;
    }
}