Java不接受同名的2个方法

Question

我需要运行下面显示的代码(获取自:Which Cipher Suites to enable for SSL Socket?)。

问题是代码包含几个名为:createSocket 的方法，参数类型不同。 eclipse 告诉我错误说:

我读到 Java 可以有多个同名方法，只要参数不同(方法重载)。我不知道为什么这会给我带来问题？

代码是:

class SSLSocketFactoryEx extends SSLSocketFactory
{
    public SSLSocketFactoryEx() throws NoSuchAlgorithmException, KeyManagementException
    {
        initSSLSocketFactoryEx(null,null,null);
    }

    public SSLSocketFactoryEx(KeyManager[] km, TrustManager[] tm, SecureRandom random) throws NoSuchAlgorithmException, KeyManagementException
    {
        initSSLSocketFactoryEx(km, tm, random);
    }

    public SSLSocketFactoryEx(SSLContext ctx) throws NoSuchAlgorithmException, KeyManagementException
    {
        initSSLSocketFactoryEx(ctx);
    }

    public String[] getDefaultCipherSuites()
    {
        return m_ciphers;
    }

    public String[] getSupportedCipherSuites()
    {
        return m_ciphers;
    }

    public String[] getDefaultProtocols()
    {
        return m_protocols;
    }

    public String[] getSupportedProtocols()
    {
        return m_protocols;
    }

    public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(s, host, port, autoClose);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

    public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(address, port, localAddress, localPort);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

    public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(host, port, localHost, localPort);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

    public Socket createSocket(InetAddress host, int port) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(host, port);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

    public Socket createSocket(String host, int port) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(host, port);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

    private void initSSLSocketFactoryEx(KeyManager[] km, TrustManager[] tm, SecureRandom random)
    throws NoSuchAlgorithmException, KeyManagementException
    {
        m_ctx = SSLContext.getInstance("TLS");
        m_ctx.init(km, tm, random);

        m_protocols = GetProtocolList();
        m_ciphers = GetCipherList();
    }

    private void initSSLSocketFactoryEx(SSLContext ctx)
    throws NoSuchAlgorithmException, KeyManagementException
    {
        m_ctx = ctx;

        m_protocols = GetProtocolList();
        m_ciphers = GetCipherList();
    }

    protected String[] GetProtocolList()
    {
        String[] preferredProtocols = { "TLSv1", "TLSv1.1", "TLSv1.2", "TLSv1.3" };
        String[] availableProtocols = null;

        SSLSocket socket = null;

        try
        {
            SSLSocketFactory factory = m_ctx.getSocketFactory();
            socket = (SSLSocket)factory.createSocket();

            availableProtocols = socket.getSupportedProtocols();
            Arrays.sort(availableProtocols);
        }
        catch(Exception e)
        {
            return new String[]{ "TLSv1" };
        }
        finally
        {
            if(socket != null)
                socket.close();
        }

        List<String> aa = new ArrayList<String>();
        for(int i = 0; i < preferredProtocols.length; i++)
        {
            int idx = Arrays.binarySearch(availableProtocols, preferredProtocols[i]);
            if(idx >= 0)
                aa.add(preferredProtocols[i]);
        }

        return aa.toArray(new String[0]);
    }

    protected String[] GetCipherList()
    {
        String[] preferredCiphers = {

            // *_CHACHA20_POLY1305 are 3x to 4x faster than existing cipher suites.
            //   http://googleonlinesecurity.blogspot.com/2014/04/speeding-up-and-strengthening-https.html
            // Use them if available. Normative names can be found at (TLS spec depends on IPSec spec):
            //   http://tools.ietf.org/html/draft-nir-ipsecme-chacha20-poly1305-01
            //   http://tools.ietf.org/html/draft-mavrogiannopoulos-chacha-tls-02
            "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305",
            "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305",
            "TLS_ECDHE_ECDSA_WITH_CHACHA20_SHA",
            "TLS_ECDHE_RSA_WITH_CHACHA20_SHA",

            "TLS_DHE_RSA_WITH_CHACHA20_POLY1305",
            "TLS_RSA_WITH_CHACHA20_POLY1305",
            "TLS_DHE_RSA_WITH_CHACHA20_SHA",
            "TLS_RSA_WITH_CHACHA20_SHA",

            // Done with bleeding edge, back to TLS v1.2 and below
            "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
            "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",

            "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
            "TLS_DHE_DSS_WITH_AES_256_GCM_SHA384",
            "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
            "TLS_DHE_DSS_WITH_AES_128_GCM_SHA256",

            // TLS v1.0 (with some SSLv3 interop)
            "TLS_DHE_RSA_WITH_AES_256_CBC_SHA384",
            "TLS_DHE_DSS_WITH_AES_256_CBC_SHA256",
            "TLS_DHE_RSA_WITH_AES_128_CBC_SHA",
            "TLS_DHE_DSS_WITH_AES_128_CBC_SHA",

            "TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA",
            "SSL_DH_RSA_WITH_3DES_EDE_CBC_SHA",
            "SSL_DH_DSS_WITH_3DES_EDE_CBC_SHA",

            // RSA key transport sucks, but they are needed as a fallback.
            // For example, microsoft.com fails under all versions of TLS
            // if they are not included. If only TLS 1.0 is available at
            // the client, then google.com will fail too. TLS v1.3 is
            // trying to deprecate them, so it will be interesteng to see
            // what happens.
            "TLS_RSA_WITH_AES_256_CBC_SHA256",
            "TLS_RSA_WITH_AES_256_CBC_SHA",
            "TLS_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_RSA_WITH_AES_128_CBC_SHA"
        };

        String[] availableCiphers = null;

        try
        {
            SSLSocketFactory factory = m_ctx.getSocketFactory();
            availableCiphers = factory.getSupportedCipherSuites();
            Arrays.sort(availableCiphers);
        }
        catch(Exception e)
        {
            return new String[] {
                "TLS_DHE_DSS_WITH_AES_128_CBC_SHA",
                "TLS_DHE_DSS_WITH_AES_256_CBC_SHA",
                "TLS_DHE_RSA_WITH_AES_128_CBC_SHA",
                "TLS_DHE_RSA_WITH_AES_256_CBC_SHA",
                "TLS_RSA_WITH_AES_256_CBC_SHA256",
                "TLS_RSA_WITH_AES_256_CBC_SHA",
                "TLS_RSA_WITH_AES_128_CBC_SHA256",
                "TLS_RSA_WITH_AES_128_CBC_SHA",
                "TLS_EMPTY_RENEGOTIATION_INFO_SCSV"
            };
        }

        List<String> aa = new ArrayList<String>();
        for(int i = 0; i < preferredCiphers.length; i++)
        {
            int idx = Arrays.binarySearch(availableCiphers, preferredCiphers[i]);
            if(idx >= 0)
                aa.add(preferredCiphers[i]);
        }

        aa.add("TLS_EMPTY_RENEGOTIATION_INFO_SCSV");

        return aa.toArray(new String[0]);
    }

    private SSLContext m_ctx;

    private String[] m_ciphers;
    private String[] m_protocols;
}

编辑:我尝试在相关方法之前使用@override:

@Override
    public Socket  createSocket(Socket s, String host, int port, boolean autoClose) throws IOException
    {
        SSLSocketFactory factory = m_ctx.getSocketFactory();
        SSLSocket ss = (SSLSocket)factory.createSocket(s, host, port, autoClose);

        ss.setEnabledProtocols(m_protocols);
        ss.setEnabledCipherSuites(m_ciphers);

        return ss;
    }

什么都没有改变，问题依然存在。

另外，请注意，在代码的末尾，有这一部分:

@Override
    public Socket createSocket(Socket arg0, String arg1, int arg2, boolean arg3)
            throws IOException {
        // TODO Auto-generated method stub
        return null;
    }

当我评论该方法时错误消失了。SSLFactory 是在类中构建的。我怎样才能重新访问它以检查它的代码？

Answer 1

您的问题似乎是 createSocket(Socket, String, int, boolean)已经存在于您正在扩展的父类(super class)中 ( SSLSocketFactory)。

在 Java 中扩展一个类时，该父类(super class)中的方法成为子类中的方法(除非方法的 scope does not allow it )。因此，当您添加 createSocket(Socket, String, int, boolean)子类的方法 eclipse 认为您正在尝试定义一个与父类(super class)方法具有相同签名的新方法。尝试添加 @Override您的方法版本上方的注释。

或者因为父类(super class)已经实现了那个方法，你可以删除你的实现并且仍然能够调用 createSocket(Socket, String, int, boolean)通过你的SSLSocketFactoryEx类。

编辑:鉴于您提供的信息，我需要修改此答案。对您来说，不仅仅是您试图重写一个 super 方法，而是 super 方法已经在您的类中被重写了。如果您需要保留方法的功能(即 SSLSocketFactory 的 createSocket(Socket, String, int, boolean) 实现不足以满足您的需求)，则必须删除其他重写方法。每个子类重写只能工作一次，所以你不能重写同一个方法两次。因此，只需删除一个 Overridden 方法并将您的代码插入另一个方法，这样您的类中就只有一个实现。

请记住，Java 确实 允许具有不同参数的同名方法。 但是只是重命名参数并不算作不同的参数。您类(class)中的这两种方法都具有相同的签名 createSocket(Socket, String, int, boolean)无论参数名称如何。