从URL获取上次修改时间

/*

 *  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 com.nowjava;

import java.io.InputStream;

import java.io.IOException;
/*
时代Java公众号 - nowjava.com 提供
*/

import java.io.File;

import java.net.UnknownServiceException;

import java.net.URL;

import java.net.URLConnection;


public class Main {

    static public long getLastModified(URL url) throws IOException {

        if ("file".equals(url.getProtocol())) {

            String externalForm = url.toExternalForm();

            // Remove the "file:"

            File file = new File(externalForm.substring(5));


            return file.lastModified();

        } else {

            URLConnection connection = url.openConnection();

            long modified = connection.getLastModified();

            try {
            /*来自 
             时 代 J a v a - nowjava.com*/

                InputStream is = connection.getInputStream();

                if (is != null)

                    is.close();

            }