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Download file from HTTPS server using Java

I want to download a file from a server that uses the HTTPS secure connection protocol. I could do it on a regular server, but how can I do it using HTTPS. If anyone used a sample API, please help me find useful resources.

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4 answers

Accessing the HTTPS URL with Java is the same as accessing the HTTP URL. You can always use

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

But you may have some problem if the server certificate chain cannot be verified. Therefore, you may need to disable certificate verification for testing purposes and trust all certificates.

To do this, write:

// 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
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. HTTPS. :

// But are u denied access?
// well here is the solution.
public static void TheKing_DownloadFileFromURL(String search, String path) throws IOException {

    // This will get input data from the server
    InputStream inputStream = null;

    // This will read the data from the server;
    OutputStream outputStream = null;

    try {
        // This will open a socket from client to server
        URL url = new URL(search);

        // This user agent is for if the server wants real humans to visit
        String USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36";

        // This socket type will allow to set user_agent
        URLConnection con = url.openConnection();

        // Setting the user agent
        con.setRequestProperty("User-Agent", USER_AGENT);

        //Getting content Length
        int contentLength = con.getContentLength();
        System.out.println("File contentLength = " + contentLength + " bytes");


        // Requesting input data from server
        inputStream = con.getInputStream();

        // Open local file writer
        outputStream = new FileOutputStream(path);

        // Limiting byte written to file per loop
        byte[] buffer = new byte[2048];

        // Increments file size
        int length;
        int downloaded = 0; 

        // Looping until server finishes
        while ((length = inputStream.read(buffer)) != -1) 
        {
            // Writing data
            outputStream.write(buffer, 0, length);
            downloaded+=length;
            //System.out.println("Downlad Status: " + (downloaded * 100) / (contentLength * 1.0) + "%");


        }
    } catch (Exception ex) {
        //Logger.getLogger(WebCrawler.class.getName()).log(Level.SEVERE, null, ex);
    }

    // closing used resources
    // The computer will not be able to use the image
    // This is a must
    outputStream.close();
    inputStream.close();
}

... , .

+1

, http vs https. HttpURLConnection URL- .

0

You should be able to do this with the same code if SSL certifcate does not complete the verification. This usually happens if its a self-signed ceritifcate, or if the certificate is from a CA that your system is not aware of.

In this case, you must process the certificate verification in code. Only this part of your code will change. Everything else will remain the same.

First try the same code and see if you have a certificate exception.

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