通过https下载文件到指定路径

 public static void downloadFile(String urlString, String pathName) {
    try{
        try {
            javax.net.ssl.TrustManager[] trustAllCerts = new javax.net.ssl.TrustManager[]{
                new javax.net.ssl.X509TrustManager() {
                    public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                        return null;
                    }
                    public void checkClientTrusted(java.security.cert.X509Certificate[] certs, String authType) {
                    }
                    public void checkServerTrusted(java.security.cert.X509Certificate[] certs, String authType) {
                    }
                }
            };
            javax.net.ssl.SSLContext sc = javax.net.ssl.SSLContext.getInstance("SSL");
            sc.init(null, trustAllCerts, new java.security.SecureRandom());
            javax.net.ssl.HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

            javax.net.ssl.HostnameVerifier allHostsValid = new javax.net.ssl.HostnameVerifier() {
                public boolean verify(String hostname, javax.net.ssl.SSLSession session) {
                    return true;
                }
            };
            javax.net.ssl.HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);
        } catch (java.security.NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (java.security.KeyManagementException e) {
            e.printStackTrace();
        } 

        java.net.URL url = new java.net.URL(urlString);
        java.net.HttpURLConnection conn = (java.net.HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.setConnectTimeout(60*1000);
        conn.setReadTimeout(5*60*1000);
        conn.connect();

        try {
            java.nio.channels.ReadableByteChannel rbChannel = java.nio.channels.Channels.newChannel(
                conn.getInputStream()
            );
            java.io.FileOutputStream fs = new java.io.FileOutputStream(pathName);
            java.nio.channels.FileChannel chan = fs.getChannel();
            while (chan.transferFrom(rbChannel, 0, Long.MAX_VALUE)>0){};
            chan.force(false);
            chan.close();

        } catch (java.io.IOException e) {
            e.printStackTrace();
        }

    } catch(java.net.MalformedURLException e){
        e.printStackTrace();
    } catch (java.io.IOException e) {
        e.printStackTrace();
    }
}