使用Java从HTTPS服务器下载文件

Question

我想从使用安全连接协议HTTPS的服务器下载文件。我可以在普通服务器上进行操作，但是，如何使用HTTPS进行操作。如果有人使用了示例API，请帮助我找到有用的资源。

Answer 1

与Java访问HTTPS URL相同，然后访问HTTP URL。您可以随时使用

URL url = new URL("https://hostname:port/file.txt");
URLConnection connection = url.openConnection();
InputStream is = connection.getInputStream();
// .. then download the file

但是，当无法验证服务器的证书链时，您可能会遇到一些问题。因此，出于测试目的，您可能需要禁用证书验证并信任所有证书。

为此，请写：

// Create a new trust manager that trust all certificates
TrustManager[] trustAllCerts = new TrustManager[]{
    new 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) {
        }
    }
};

// Activate the new trust manager
try {
    SSLContext sc = SSLContext.getInstance("SSL");
    sc.init(null, trustAllCerts, new java.security.SecureRandom());
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
} catch (Exception e) {
}

// And as before now you can use URL and URLConnection
URL url = new URL("https://hostname:port/file.txt");
URLConnection connection = url.openConnection();
InputStream is = connection.getInputStream();
// .. then download the file