从 Java 中的 HTTPS URL 下载图像

问题
我必须制作一个显示药包图像的应用程序。我发现这个网站有一些图片，但我尝试用Java语言的小程序下载可用的图片，但失败了。

我认为 HTTPS 是导致问题的原因。

有办法吗？

编辑：代码和错误

1. public class DescargarArchivo {
   
2. 
   
3. public static void main(String[] args) {
   
4.     String url = "https://medicamentos.sanidadmadrid.org/comun/visorCaratulas.aspx?cod=672629";
   
5.     String name = "test.jpg";
   
6. 
   
7.     String folder = "downloads/";
   
8. 
   
9.     File dir = new File(folder);
   
10. 
    
11.     if (!dir.exists())
    
12.             if (!dir.mkdir())
    
13.                     return;
    
14. 
    
15.     File file = new File(folder + name);
    
16. 
    
17.     try {
    
18. 
    
19.             URLConnection conn = new URL(url).openConnection();
    
20.             conn.connect();
    
21. 
    
22.             System.out.println("\ndownload: \n");
    
23.             System.out.println(">> URL: " + url);
    
24.             System.out.println(">> Name: " + name);
    
25.             System.out.println(">> size: " + conn.getContentLength()
    
26.                             + " bytes");
    
27. 
    
28.             InputStream in = conn.getInputStream();
    
29.             OutputStream out = new FileOutputStream(file);
    
30. 
    
31.             int b = 0;
    
32. 
    
33.             while (b != -1) {
    
34.                     b = in.read();
    
35. 
    
36.                     if (b != -1)
    
37.                             out.write(b);
    
38.             }
    
39. 
    
40.             out.close();
    
41.             in.close();
    
42. 
    
43.             System.out.println("\ncomplete download\n");
    
44.     } catch (MalformedURLException e) {
    
45.             System.out.println("url: " + url + " invalid");
    
46.     } catch (IOException e) {
    
47.             e.printStackTrace();
    
48.     }
    
49. }
    
50. }
    
51. 
    
52. javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    
53. at sun.security.ssl.Alerts.getSSLException(Unknown Source)
    
54. at sun.security.ssl.SSLSocketImpl.fatal(Unknown Source)
    
55. at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
    
56. at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
    
57. at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source)
    
58. at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source)
    
59. at sun.security.ssl.Handshaker.processLoop(Unknown Source)
    
60. at sun.security.ssl.Handshaker.process_record(Unknown Source)
    
61. at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
    
62. at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
    
63. at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
    
64. at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
    
65. at sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
    
66. at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
    
67. at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(Unknown Source)
    
68. at com.test.java.net.DescargarArchivo.main(DescargarArchivo.java:34)
    
69. Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    
70.     at sun.security.validator.PKIXValidator.doBuild(Unknown Source)
    
71.     at sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
    
72.     at sun.security.validator.Validator.validate(Unknown Source)
    
73.     at sun.security.ssl.X509TrustManagerImpl.validate(Unknown Source)
    
74.     at sun.security.ssl.X509TrustManagerImpl.checkTrusted(Unknown Source)
    
75.     at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
    
76.     ... 12 more
    
77. Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    
78.     at sun.security.provider.certpath.SunCertPathBuilder.build(Unknown Source)
    
79.     at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source)
    
80.     at java.security.cert.CertPathBuilder.build(Unknown Source)
    
81.     ... 18 more
    

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回答
您需要设置权限以允许服务器证书。在这里它解释了如何设置它，以便所有证书都是可信的。