Java 文件下载SSLHandshakeException

当我尝试使用Java代码以编程方式下载文件时，我遇到了一个异常：

Exception in thread "main" 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
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
    at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1513)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1441)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
    at java.net.URL.openStream(URL.java:1045)
    at DownloadFileExample.download(DownloadFileExample.java:15)
    at DownloadFileExample.main(DownloadFileExample.java:24)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
    at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
    at sun.security.validator.Validator.validate(Validator.java:260)
    at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491)
    ... 20 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
    ... 26 more

以下是我的代码，包括我要下载的文件：

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

public class DownloadFileExample
{
    public static void download(String downloadURL) throws IOException
    {
        URL website = new URL(downloadURL);
        String fileName = "downloaded.zip";

        try (InputStream inputStream = website.openStream())
        {
            Files.copy(inputStream, Paths.get(fileName), StandardCopyOption.REPLACE_EXISTING);
        }
    }

    public static void main(String[] arguments) throws IOException
    {
        String downloadURL = "https://mh-nexus.de/downloads/HxDSetupEN.zip";
        download(downloadURL);
    }
}

---

起初我尝试使用

HTTP

协议下载，但它给了我一个

301永久移动

状态代码，因此我意识到它重定向到

HTTPS

。然而，

HTTPS

给了我上面的

SSLHandshakeException

。使用浏览器，下载工作完美无瑕。如何使用Java代码正确下载文件？

好的，我找到了解决方案。我只需要安装一个完全信任的

SSL

证书。虽然这通常不是一个好主意，但对我来说很有用

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;

public class DownloadFileExample
{
    public static void download(String downloadURL) throws IOException
    {
        URL website = new URL(downloadURL);
        String fileName = "downloaded.zip";

        try (InputStream inputStream = website.openStream())
        {
            Files.copy(inputStream, Paths.get(fileName), StandardCopyOption.REPLACE_EXISTING);
        }
    }

    private static void trustAllCertificates() throws NoSuchAlgorithmException, KeyManagementException
    {
        TrustManager[] trustManagers = new TrustManager[]{new X509TrustManager()
        {
            public X509Certificate[] getAcceptedIssuers()
            {
                return new X509Certificate[0];
            }

            public void checkClientTrusted(
                    X509Certificate[] certs, String authType)
            {
            }

            public void checkServerTrusted(
                    X509Certificate[] certs, String authType)
            {
            }
        }};

        SSLContext sslContext = SSLContext.getInstance("SSL");
        sslContext.init(null, trustManagers, new SecureRandom());
        HttpsURLConnection.setDefaultSSLSocketFactory(sslContext.getSocketFactory());
    }

    public static void main(String[] arguments) throws IOException, NoSuchAlgorithmException, KeyManagementException
    {
        trustAllCertificates();

        String downloadURL = "https://mh-nexus.de/downloads/HxDSetupEN.zip";
        download(downloadURL);
    }
}

---

这是因为证书网站不在JRE的白名单上

选择权 1） 将服务器证书包括在JRE白名单中（JRE/lib/security/cacerts） 要下载服务器证书，请使用浏览器打开站点，右键单击绿锁，选择“查看证书”并下载

探索cacerts和导入可信证书的最简单方法是使用类似portecle（）的GUI工具。也可以使用keytool

keytool -import -trustcacerts -keystore /opt/java/jre/lib/security/cacerts -alias mycert -noprompt -storepass changeit -file /tmp/examplecert.crt

看

2） 使用您自己的信任库并包含服务器证书

System.setProperty ("javax.net.ssl.trustStore" path_to_your_cacerts_file);

---

3） 完全不要使用truststore（Plaza响应）

您需要有效的证书才能通过代码下载。