错误 [Ljava.lang.Object；将 X509Certificate 的数组列表转换为数组时，无法转换为 [Ljava.security.cert.X509Certificate

Question

我对这个 ssl 和证书很陌生。我有一个 jks 文件，其中包含一些服务器信任的证书。我正在尝试从 jks 文件中读取所有证书并将其 return 到 getAcceptedIssuers() 方法。证书的类型为 X509Certificate。我实现的方法正确读取 jks 文件并创建 X509Certificate 证书的数组列表。接下来，当我尝试将数组列表转换为数组时，我得到了这个异常

[Ljava.lang.Object; cannot be cast to [Ljava.security.cert.X509Certificate;
    at com.sample.ssl.GetCertificates.loadCertificatesFromCompanJks(GetCertificates.java:125)
    at com.sample.ssl.GetCertificates.getAcceptedIssuers(GetCertificates.java:44)
    at sun.security.ssl.AbstractTrustManagerWrapper.checkAlgorithmConstraints(Unknown Source)
    at sun.security.ssl.AbstractTrustManagerWrapper.checkAdditionalTrust(Unknown Source)
    at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(Unknown Source)
    at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source)
    at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source)
    at sun.security.ssl.Handshaker.processLoop(Unknown Source)
    at sun.security.ssl.Handshaker.process_record(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.getSession(Unknown Source)
    at org.apache.http.conn.ssl.AbstractVerifier.verify(AbstractVerifier.java:91)
    at org.apache.http.conn.ssl.SSLSocketFactory.connectSocket(SSLSocketFactory.java:397)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:148)
    at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:149)
    at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:121)
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:573)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:425)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:820)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:754)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:732)
    at com.sample.ssl.GetCertificates.postMessage(GetCertificates.java:82)
    at com.sample.ssl.GetCertificates.main(GetCertificates.java:138)

我的代码如下

public class GetCertificates {
    static private TrustManager[] trustmgr = new TrustManager[]{new X509TrustManager() {

        private X509Certificate[] certs = null;

        public void checkClientTrusted(X509Certificate[] certs, String authType) {
            System.out.println("checkClientTrusted");
        }

        public void checkServerTrusted(X509Certificate[] certs, String authType) {
            System.out.println("checkServerTrusted");
        }

        public X509Certificate[] getAcceptedIssuers() {
            System.out.println("getAcceptedIssuers");
            certs = loadCertificatesFromCompanJks("C:/Users/vinod/Desktop/keystore.jks", "mypassword");
            // return new
            // X509Certificate[]{};
            return certs;
        }
    }};

    public void postMessage() {
        try {
            // here I prepare Url to execute and make a call
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static X509Certificate[] loadCertificatesFromCompanJks(String jksPath, String keyStorePassword) {
        try {
            X509Certificate X509Certificate[] = null;
            Certificate[] certs = null;

            ArrayList<X509Certificate> serverCerts = new ArrayList<X509Certificate>();
            FileInputStream is = new FileInputStream(jksPath);
            KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
            String password = keyStorePassword;
            keystore.load(is, password.toCharArray());

            Enumeration e = keystore.aliases();
            for (; e.hasMoreElements(); ) {

                String alias = (String) e.nextElement();
                Certificate cert = keystore.getCertificate(alias);
                X509Certificate cert1 = (X509Certificate) cert;
                serverCerts.add(cert1);
            }
            is.close();
            System.out.println("Number of server certificates : " + serverCerts.size());
            X509Certificate = (java.security.cert.X509Certificate[]) serverCerts.toArray();
            return X509Certificate;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        new GetCertificates().postMessage();
    }
}

Answer 1

改变

        X509Certificate = (java.security.cert.X509Certificate[]) serverCerts.toArray();

至

        X509Certificate = serverCerts.toArray(new java.security.cert.X509Certificate[0]);

因为 toArray return Object[] 无法转换为 X509Certificate[] 即使数组的每个元素都可以转换为 X509Certificate

Answer 2

你的错误在这里：

X509Certificate = (java.security.cert.X509Certificate[]) serverCerts.toArray();

toArray() 的重载将 return 一个 Object[] 和一个 Object[] 不能转换为不同的数组类型。

将该行更改为：

X509Certificate = serverCerts.toArray(new X509Certificate[serverCerts.size()]);

在这里，您正在分配正确类型和大小的数组，并将其传递给 toArray 以从列表中填充。

(你也可以这样写...

X509Certificate = serverCerts.toArray(new X509Certificate[0]);

...但这会导致不必要的分配。请阅读 toArray(...) 的 javadocs 以获得更好的理解。（不可否认，额外分配的成本很小，您可以通过传递预分配/共享的零大小数组来避免它。））

当你这样做的时候，改变你的变量名以符合 Java 风格约定。在同一行代码中为类型和变量使用相同的标识符是非常令人困惑的！

Answer 3

你要转换的是数组的元素而不是数组本身，这就是转换失败的原因。当您从列表中执行 toArray 而不指定类型时，您会得到一个 Object 数组，尽管这些对象的类型为 X509Certificate，因此您可以单独向上转换它们中的每一个，但您不能转换数组本身。如果您尝试转换它，那么您将运行放入此异常中。您的列表需要转换为 X509Certificate 类型的元素数组。

作为 Java8 中的替代方法，您可以这样做：

X509Certificate[] x509Certificates = serverCerts.parallelStream().toArray(X509Certificate[]::new);

我还建议尽可能继续使用 CamelCase 表示法。您使用大写字母作为变量名的首字母。它也应该更具描述性，因为您返回的是一组证书，而不仅仅是一个。

这个：

X509Certificate应该是这样的x509Certificates

错误 [Ljava.lang.Object；将 X509Certificate 的数组列表转换为数组时，无法转换为 [Ljava.security.cert.X509Certificate

Error [Ljava.lang.Object; cannot be cast to [Ljava.security.cert.X509Certificate when converting an arraylist of X509Certificate to array

java

ssl-certificate

x509certificate

jks

trustmanager