使用 Java 从 https 获取图像

Question

有没有办法通过 Java 从 https url 获取图像？

目前我在尝试什么：

URL url = new URL("https://ns6.host.md:8443/sitepreview/http/zugo.md/media/images/thumb/23812__yu400x250.jpg");

System.out.println("Image: " + ImageIO.read(url));

但是，我得到：

Exception in thread "main" javax.imageio.IIOException: Can't get input stream from URL!
Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No 
Caused by: java.security.cert.CertificateException: No name matching ns6.host.md found

我该怎么办？我必须获取 url 上的 6k 多张图片。

Answer 1

在获取图像之前，您必须先解决 SSL 问题。它说在 JAVA_HOME/jre/lib/security 的受信任商店中没有找到名称为 ns6.host.md 的任何受信任主机。您可以将该主机的 public 密钥添加到您的 TrustStore，或者在这种情况下忽略 SSL 错误：

HttpsURLConnection.setDefaultHostnameVerifier(getUnsecureHostNameVerifier());

try {
        SSLContext e = SSLContext.getInstance("TLS");
        e.init(new KeyManager[0], new TrustManager[]{new DefaultTrustManager()}, new SecureRandom());
        SSLContext.setDefault(e);
        HttpsURLConnection.setDefaultSSLSocketFactory(e.getSocketFactory());
    } catch (Exception var1) {
        throw new Exception("SSL Error", var1);
    }

 public static class DefaultTrustManager implements X509TrustManager {
    public DefaultTrustManager() {
    }

    public void checkClientTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {
    }

    public void checkServerTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {
    }

    public X509Certificate[] getAcceptedIssuers() {
        return new X509Certificate[0];
    }
}

Answer 2

有两个问题。您可以使用浏览器访问该站点，并查看错误。

服务器证书是自签名的，不受 Java 信任。您可以将其添加到信任库。
服务器证书与主机名"ns6.host.md"不匹配，你需要一个忽略它的HostnameVerifier。

另一个答案说了同样的话，它提供了代码，不幸的是它使用了一些私有API。

示例如何在bayou HttpClient中解决它，如果有人感兴趣： https://gist.github.com/zhong-j-yu/22af353e2c5a5aed5857

public static void main(String[] args) throws Exception
{
    HttpClient client = new HttpClientConf()
        .sslContext(new SslConf().trustAll().createContext()) // trust self-signed certs
        .sslEngineConf(engine -> disableHostNameVerification(engine))
        .trafficDump(System.out::print)
        .newClient();
    // typically, app creates one client and use it for all requests

    String url = "https://ns6.host.md:8443/sitepreview/http/zugo.md/media/images/thumb/23812__yu400x250.jpg";
    HttpResponse response = client.doGet(url).sync();
    ByteBuffer bb = response.bodyBytes(Integer.MAX_VALUE).sync();

    InputStream is = new ByteArrayInputStream(bb.array(), bb.arrayOffset()+bb.position(), bb.remaining());
    BufferedImage image = ImageIO.read(is);

}

static void disableHostNameVerification(SSLEngine engine)
{
    SSLParameters sslParameters = engine.getSSLParameters();
    {
        // by default, it's set to "HTTPS", and the server certificate must match the request host.
        // disable it for this example, since the server certificate is ill constructed.
        sslParameters.setEndpointIdentificationAlgorithm(null);
    }
    engine.setSSLParameters(sslParameters);
}

使用 Java 从 https 获取图像

Getting images from https with Java

java

https