由於專案需要，需要呼叫第三方的API介面，為了簡單方便與快速開發，便採用了httpClient來進行呼叫。

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.6</version>
</dependency>

但在第三方的一個HTTPS的介面時，IDE中報瞭如下錯誤。

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

解決辦法：

將httpClient中關於證書認證的實現機制註釋掉，即不對任何https的證書進行校驗。程式碼如下：

import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;

import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.X509Certificate;

/**
 * 信任https證書
 *
 * @author puhaiyang
 * @date 2018/11/14
 */
public class SslUtil {
    public static CloseableHttpClient SslHttpClientBuild() {
        Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.INSTANCE)
                .register("https", trustAllHttpsCertificates())
                .build();
        //建立ConnectionManager，新增Connection配置資訊
        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
        CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(connectionManager).build();
        return httpClient;
    }

    /**
     * 信任所有證書
     */
    private static SSLConnectionSocketFactory trustAllHttpsCertificates() {
        SSLConnectionSocketFactory socketFactory = null;
        TrustManager[] trustAllCerts = new TrustManager[1];
        TrustManager tm = new miTM();
        trustAllCerts[0] = tm;
        SSLContext sc = null;
        try {
            sc = SSLContext.getInstance("TLS");//sc = SSLContext.getInstance("TLS")
            sc.init(null, trustAllCerts, null);
            socketFactory = new SSLConnectionSocketFactory(sc, NoopHostnameVerifier.INSTANCE);
            //HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        }
        return socketFactory;
    }

    static class miTM implements TrustManager, X509TrustManager {

        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }

        public void checkServerTrusted(X509Certificate[] certs, String authType) {
            //don't check
        }

        public void checkClientTrusted(X509Certificate[] certs, String authType) {
            //don't check
        }
    }
}
 

然後將以前的httpClient生成的程式碼用上寫剛剛寫的這個來進行生成就可以了！

        // 建立httpClient物件
//        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpClient httpClient = SslUtil.SslHttpClientBuild();