如何访问https的网站?-【httpclient】

备注：本处代码使用groovy和httpclient4.3作为例子进行讲述

在普通方式下，当使用httpclient进行访问某个网站时，大致使用如下的代码进行访问：

CloseableHttpClient httpclient = HttpClients.createDefault();

HttpGet httpMethod = new HttpGet(url);

response = httpclient.execute(httpMethod);

当使用上述代码来访问https的网站时，就会抛出如下的异常：

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

要解决此问题，可以通过如下的方式：

首先创建一个类DefaultTrustManager

class DefaultTrustManager implements X509TrustManager{
    @Override
    void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {

    }

    @Override
    void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {

    }

    @Override
    X509Certificate[] getAcceptedIssuers() {
        return null
    }
}

然后在创建httpclient时，使用如下的代码：

def trustManagers =  new TrustManager[1]
trustManagers[0] = new DefaultTrustManager()

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(new KeyManager[0], trustManagers, new SecureRandom());
SSLContext.setDefault(sslContext);

sslContext.init(null, trustManagers, null);
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext,
        SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);

CloseableHttpClient httpclient = HttpClients.custom()
        .setSSLSocketFactory(sslsf)
        .build();

这样在访问某些https的网站时就能正常访问了。