Android：HTTPS 网址在 Okhttp3 中不起作用

Question

我在我的 android 应用程序中使用 Okhttp3 来下载文件。我在使用 https 网址时遇到问题。

我有两个网址

    String url1 = "https://cbsenet.nic.in/cbsenet/PDFDEC2014/Paper%20III/D-01-3.pdf";
    String url2 = "https://www.ugcnetonline.in/question_papers/June2014_paper-II/J-02-14-II.pdf";

url2工作正常，而对于url1，我遇到异常

线程“main”中的异常 javax.net.ssl.SSLHandshakeException：sun.security.validator.ValidatorException：PKIX 路径构建失败：sun.security.provider.certpath.SunCertPathBuilderException：无法找到请求目标的有效认证路径

我创建了一个示例 java 程序来演示问题

public static void main(String[] args) throws IOException {

    String url1 = "https://cbsenet.nic.in/cbsenet/PDFDEC2014/Paper%20III/D-01-3.pdf";
    String url2 = "https://www.ugcnetonline.in/question_papers/June2014_paper-II/J-02-14-II.pdf";

    Request request = new Request.Builder()
            .url(url1)
            .build();

    OkHttpClient client = new OkHttpClient();
    Response response = client.newCall(request).execute();
    System.out.println(response.body().string());
}

Answer 1

这是我的解决方案，它有效

private static OkHttpClient generateDefaultOkHttp() {
    OkHttpClient.Builder builder = new OkHttpClient.Builder();
    try {
        // Create a trust manager that does not validate certificate chains
        final TrustManager[] trustAllCerts = new TrustManager[]{
                new X509TrustManager() {
                    @SuppressLint("TrustAllX509TrustManager")
                    @Override
                    public void checkClientTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
                    }

                    @SuppressLint("TrustAllX509TrustManager")
                    @Override
                    public void checkServerTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
                    }

                    @Override
                    public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                        return new java.security.cert.X509Certificate[]{};
                    }
                }
        };

        // Install the all-trusting trust manager
        final SSLContext sslContext = SSLContext.getInstance("SSL");
        sslContext.init(null, trustAllCerts, new java.security.SecureRandom());
        // Create an ssl socket factory with our all-trusting manager
        final SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();


        builder.sslSocketFactory(sslSocketFactory, (X509TrustManager) trustAllCerts[0]);
        builder.hostnameVerifier(new HostnameVerifier() {
            @SuppressLint("BadHostnameVerifier")
            @Override
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        });
    } catch (Exception e) {
        e.printStackTrace();
    }
    builder.connectTimeout(60, TimeUnit.SECONDS)
            .readTimeout(60, TimeUnit.SECONDS)
            .writeTimeout(60, TimeUnit.SECONDS)
            .retryOnConnectionFailure(true);
    return builder.build();
}